NZ703609B2

NZ703609B2 - Adam6 mice

Info

Publication number: NZ703609B2
Application number: NZ703609A
Authority: NZ
Inventors: Lynn Macdonald; Andrew J Murphy; Sean Stevens
Original assignee: Regeneron Pharmaceuticals Inc
Priority date: 2011-02-25
Filing date: 2012-02-24
Publication date: 2016-08-02

Abstract

Discloses a genetically modified mouse whose genome: (i) lacks a functional endogenous ADAM6 locus; and (ii) includes an inserted nucleotide sequence encoding a mouse ADAM6 protein or functional fragment thereof. Further discloses a related method of making such an engineered mouse, a method of increasing mouse fertility, a mouse immunoglobulin heavy chain locus, and a mouse B-cell. increasing mouse fertility, a mouse immunoglobulin heavy chain locus, and a mouse B-cell.

Description

s Form No 5 This is a divisional application of NZ 612643.

NEW ZEALAND Patents Act 1953 REGENERON PHARMACEUTICALS, INC COMPLETE SPECIFICATION Invention Title: ADAM6 MICE I/We Regeneron Pharmaceuticals, Inc. organised and existing under the laws of New York, of 777 Old Saw Mill River Road, Tarrytown, New York, 10591, United States of America; hereby declare the invention, for which we pray that a patent may be d to us, and the method by which it is performed, to be particularly described in and by the following statement:- ADAM6 MICE This application is a divisional application of New Zealand Patent Application No 612643, the entire ts of which are incorporated herein by reference.

FIELD OF ION [0001A] Genetically modified mice, cells, embryos, and tissues that comprise a nucleic acid ce encoding a functional ADAM6 locus are described. Modifications include human and/or humanized immunoglobulin loci. Mice that lack a onal endogenous ADAM6 gene but that comprise ADAM6 function are described, including mice that comprise an ectopic nucleic acid sequence that encodes an ADAM6 protein. Genetically modified male mice that comprise a modification of an endogenous immunoglobulin VH locus that renders the mouse incapable of making a functional ADAM6 n and results in a loss in fertility, and that further comprise ADAM6 function in the male mice are described, including mice that comprise an ectopic nucleic acid sequence that restores fertility to the male mouse.

BACKGROUND OF INVENTION Mice that contain human antibody genes are known in the art. Pharmaceutical applications for antibodies in the last two decades have fueled a great deal of research into making dies that are le for use as human therapeutics. Early antibody therapeutics, which were based on mouse dies, were not ideal as human therapeutics e repeated administration of mouse antibodies to humans results in immunogenicity that can confound long-term treatment regimens. ons based on humanizing mouse antibodies to make them appear more human and less mouse-like were developed. Methods for expressing human immunoglobulin sequences for use in antibodies followed, mostly based on in vitro expression of human immunoglobulin libraries in phage, bacteria, or yeast. Finally, attempts were made to make useful human antibodies from human lymphocytes in vitro, in mice engrafted with human hematopoietic cells, and in transchromosomal or transgenic mice with ed endogenous globulin loci. In the transgenic mice, it was necessary to disable the endogenous mouse immunoglobulin genes so that the randomly integrated fully human transgenes would function as the source of immunoglobulin sequences expressed in the mouse. Such mice can make human antibodies suitable for use as human therapeutics, but these mice display substantial problems with their immune systems. These problems (1) make the mice tical for generating a sufficiently diverse antibody repertoire, (2) require the use of extensive ineering fixes, (3) provide a imal clonal selection process likely due to incompatibility between human and mouse elements, and (4) render these mice an unreliable source of large and diverse populations of human variable sequences needed to be truly useful for making human therapeutics.

There remains a need in the art for making improved cally modified mice that are useful in generating immunoglobulin sequences, including human antibody sequences. There also remains a need for mice that are capable of nging immunoglobulin gene ts to form useful rearranged immunoglobulin genes, or capable of making ns from altered immunoglobulin loci, while at the same time reducing or eliminating deleterious changes that might result from the genetic modifications.

SUMMARY OF INVENTION in one aspect, nucleic acid constructs, cells, embryos, mice, and methods are ed for making mice that comprise a modification that results in a nonfunctional endogenous mouse ADAM6 protein or ADAM6 gene (9.9., a ut of or a deletion in an endogenous ADAM6 gene), wherein the mice se a nucleic acid sequence that encodes an ADAM6 protein or ortholog or homolog or nt thereof that is functional in a male mouse. in one aspect, nucleic acid constructs, cells, embryos, mice, and methods are provided for making mice that comprise a modification of an endogenous mouse immunoglobulin locus, wherein the mice comprise an ADAM6 protein or ortholog or homolog or fragment thereof that is functional in a male mouse. in one embodiment, the endogenous mouse immunoglobulin locus is an immunoglobulin heavy chain locus, and the modification reduces or eliminates ADAM6 activity of a cell or tissue of a male mouse. in one aspect, mice are ed that comprise an ectopic nucleotide sequence encoding a mouse ADAM6 or ortholog or homolog or functional fragment thereof; mice are also provided that comprise an endogenous nucleotide sequence encoding a mouse ADAM6 or ortholog or homolog or fragment thereof, and at least one genetic modification of a heavy chain immunoglobulin locus.

In one , methods are provided for making mice that comprise a cation of an endogenous mouse immunoglobulin locus, wherein the mice comprise an ADAM6 protein or ortholog or homolog or fragment thereof that is functional in a male mouse. Mice ing to the invention are obtainable, for example, by the methods described herein.

In one aspect, methods are provided for making mice that comprise a genetic modification of an globulin heavy chain locus, wherein application of the methods result in male mice that comprise a modified immunoglobulin heavy chain locus (or a deletion thereof), and the male mice are capable of generating offspring by mating. In one embodiment, the male mice are capable of producing sperm that can transit from a mouse uterus through a mouse oviduct to fertilize a mouse egg.

In one aspect, methods are ed for making mice that se a genetic modification of an immunoglobulin heavy chain locus, wherein application of the s result in male mice that comprise a modified immunoglobulin heavy chain locus (or a deletion thereof), and the male mice exhibit a reduction in fertility, and the mice se a genetic modiﬁcation that restores in whole or in part the reduction in fertility. In various embodiments, the reduction in fertility is terized by an inability of the sperm of the male mice to migrate from a mouse uterus through a mouse t to fertilize a mouse egg. in various embodiments, the reduction in fertility is characterized by sperm that exhibit an in vivo migration defect. In various embodiments, the genetic cation that restores in whole or in part the ion in fertility is a nucleic acid sequence encoding a mouse ADAM6 gene or ortholog or homolog or nt thereof that is functional in a male mouse.

In one embodiment, the genetic modification comprises replacing endogenous immunoglobulin heavy chain variable loci with immunoglobulin heavy chain variable loci of another species (6.9., a non—mouse species). ln one embodiment, the genetic cation comprises insertion of orthologous immunoglobulin heavy chain variable loci into endogenous immunoglobulin heavy chain variable loci. in a specific embodiment, the species is human. In one embodiment, the genetic modification comprises on of an endogenous immunoglobulin heavy chain variable locus in whole or in part, wherein the deletion results in a loss of endogenous ADAM6 function. in a ic embodiment, the loss of endogenous ADAM6 function is associated with a reduction in fertility in male mice.

In one aspect, mice are provided that comprise a modification that reduces or eliminates mouse ADAM6 sion from an endogenous ADAM6 allele such that a male mouse having the modification exhibits a reduced fertility (e.g., a highly reduced ability to generate offspring by mating), or is essentially infertile, due to the reduction or elimination of endogenous ADAM6 function, wherein the mice further comprise an ectopic ADAM6 sequence or homolog or ortholog or functional fragment thereof. In one aspect, the modification that reduces or eliminates mouse ADAM6 expression is a cation (9.9., an insertion, a deletion, a replacement, etc.) in a mouse globulin locus. in one embodiment, the reduction or loss of ADAM6 function comprises an inability or substantial inability of the mouse to produce sperm that can travel from a mouse uterus through a mouse oviduct to fertilize a mouse egg. in a specific embodiment, at least about 95%, 96%, 97%, 98%, or 99% of the sperm cells produced in an ate volume of the mouse are incapable of traversing through an oviduct in vivo ing copulation and fertilizing a mouse ovum. in one embodiment, the reduction or loss of ADAM6 function comprises an inability to form or substantial inability to form a complex of ADAM2 and/or ADAM3 and/or ADAM6 on a surface of a sperm cell of the mouse. In one embodiment, the loss of ADAM6 function comprises a substantial inability to fertilize a mouse egg by copulation with a female mouse.

In one aspect, a mouse is provided that lacks a functional endogenous ADAMS gene, and comprises a protein (or an ectopic nucleotide sequence that encodes a protein) that confers ADAMS functionality on the mouse. In one embodiment, the mouse is a male mouse and the functionality comprises enhanced fertility as compared with a mouse that lacks a functional endogenous ADAM6 gene.

In one embodiment, the protein is encoded by a genomic sequence located within an immunoglobulin locus in the germline of the mouse. In a specific embodiment, the immunoglobulin locus is a heavy chain locus. In another ic embodiment, the heavy chain locus comprises at least one human VH, at least one human DH and at least one human JH gene segment. In one ment, the ectopic protein is enCoded by a c sequence located within a non—immunoglobulin locus in the germline of the mouse. In one embodiment, the non-immunoglobulin locus is a transcriptionally active locus. In a specific embodiment, the transcriptionally active locus is the ROSA26 locus. In a specific embodiment, the transcriptionally active locus is ated with tissue-specific expression. In one embodiment, the tissue-specific sion is present in reproductive tissues. In one embodiment, the protein is encoded by a genomic sequence randomly inserted into the ne of the mouse.

In one embodiment, the mouse ses a human or chimeric human/mouse or chimeric human/rat light chain (e.g., human variable, mouse or rat constant) and a chimeric human variable/mouse or rat constant heavy chain. In a specific embodiment, the mouse comprises a transgene that comprises a chimeric human variable/rat or mouse constant light chain gene operably linked to a riptionally active er, 9.9., a ROSA26 promoter. In a further specific embodiment, the chimeric mouse or rat light chain transgene comprises a rearranged human light chain variable region sequence in the germline of the mouse.

In one embodiment, the ectopic nucleotide sequence is located within an globulin locus in the germline of the mouse. In a specific embodiment, the globulin locus is a heavy chain locus. In one embodiment, the heavy chain locus comprises at least one human VH, at least one human DH and at least one human JH gene segment. In one embodiment, the ectopic nucleotide sequence is located within a non- immunoglobulin locus in the germline of the mouse. In one embodiment, the non- immunoglobulin locus is a transcriptionally active locus. In a specific embodiment, the transcriptionally active locus is the ROSA26 locus. In one embodiment, the c nucleotide sequence is positioned randomly inserted into the germline of the mouse.

In one aspect, a mouse is provided that lacks a functional endogenous ADAMS gene, wherein the mouse comprises an c nucleotide sequence that complements the loss of mouse ADAMS function. In one embodiment, the ectopic nucleotide sequence confers upon the mouse an ability to produce offspring that is comparable to a corresponding wild-type mouse that contains a functional endogenous ADAMS gene. In one embodiment, the sequence confers upon the mouse an ability to form a complex of ADAMZ and/or ADAM3 and/or ADAMS on the surface of sperm cell of the mouse. In one embodiment, the sequence confers upon the mouse an ability to travel from a mouse uterus through a mouse oviduct to a mouse ovum to fertilize the ovum.

In one embodiment, the mouse lacking the functional endogenous ADAMS gene and comprising the ectopic nucleotide sequence produces at least about 50%, 60%, 70%, 80%, or 90% of the number of litters a wild—type mouse of the same age and strain produces in a six-month time period.

In one embodiment, the mouse lacking the functional endogenous ADAMS gene and comprising the ectopic nucleotide ce produces at least about 1.5—fold, about 2-fold, about 25-fold, about 3—fold, about 4-fold, about 6—fold, about 7-fold, about 8- fold, or about 10~foId or more progeny when bred over a nth time period than a mouse of the same age and the same or similar strain that lacks the functional nous ADAMS gene and that lacks the ectopic nucleotide sequence that is bred over substantially the same time period and under substantially the same conditions.

In one embodiment, the mouse lacking the onal nous ADAMS gene and comprising the ectopic nucleotide sequence produces an average of at least about , 3-fold, or 4—fold higher number of pups per litter in a 4— or 6-month breeding period than a mouse that lacks the functional endogenous ADAMS gene and that lacks the ectopic nucleotide sequence, and that is bred for the same period of time.

In one embodiment, the mouse lacking the onal endogenous ADAMS gene and sing the ectopic nucleotide sequence is a male mouse, and the male mouse produces sperm that when red from oviducts at about 5-6 hours post- copulation ts an oviduct migration that is at least 10-fold, at least 20-fold, at least 30— fold, at least 40—fold, at least 50-fold, at least 60-fold, at least 70-fold, at least 80-fold, at least 90-fold, ld, 110-fold, or 120-fold or higher than a mouse that lacks the functional endogenous ADAMS gene and that lacks the ectopic nucleotide sequence.

In one embodiment, the mouse lacking the functional endogenous ADAMS gene and comprising the ectopic nucleotide sequence when copulated with a female mouse generates sperm that is capable of traversing the uterus and ng and traversing the t within about 6 hours at an efficiency that is about equal to sperm from a wild-type mouse. in one embodiment, the mouse lacking the functional endogenous ADAM6 gene and comprising the ectopic nucleotide sequence produces about 1.5-fold, about 2- fold, about 3—fold, or about 4-fold or more s in a comparable period of time than a mouse that lacks the functional ADAM6 gene and that lacks the ectopic nucleotide sequence. in one aspect, a mouse comprising in its germline a non-mouse nucleic acid sequence that encodes an immunoglobulin n is ed, wherein the non-mouse immunoglobulin sequence comprises an insertion of a mouse ADAM6 gene or homolog or ortholog or functional fragment thereof. In one ment, the non-mouse immunoglobulin sequence comprises a human immunoglobulin sequence. In one embodiment, the sequence comprises a human immunoglobulin heavy chain ce. In one embodiment, the sequence comprises a human globulin light chain ce.

In one embodiment, the sequence comprises one or more V gene segments, one or more D gene segments, and one or more J gene segments; in one embodiment, the sequence ses one or more V gene segments and one or more J gene segments. in one embodiment, the one or more V, D, and J gene segments, or one or more V and J gene segments, are not rearranged. In one embodiment, the one or more V, D, and J gene segments, or one or more V and J gene segments, are rearranged. ln one embodiment, following rearrangement of the one or more V, D, and J gene segments, or one or more V and J gene segments, the mouse comprises in its genome at least one nucleic acid sequence encoding a mouse ADAM6 gene or homolog or ortholog or functional fragment thereof. In one embodiment, following rearrangement the mouse ses in its genome at least two nucleic acid sequences encoding a mouse ADAM6 gene or homolog or og or functional fragment thereof. in one embodiment, foliowing rearrangement the mouse comprises in its genome at least one nucleic acid sequence encoding a mouse ADAM6 gene or homolog or ortholog or functional fragment thereof. In one embodiment, the mouse comprises the ADAM6 gene or homolog or ortholog or functional fragment thereof in a B cell. In one embodiment, the mouse comprises the ADAM6 gene or homolog or ortholog or functional fragment thereof in a non-B cell.

In one aspect, mice are provided that express a human globulin heavy chain variable region or functional nt thereof from an endogenous mouse immunoglobulin heavy chain locus, wherein the mice comprise an ADAM6 activity that is functional in a male mouse.

In one embodiment, the male mice comprise a single unmodified endogenous ADAM6 ailele or ortholog of homolog or functional fragment f at an endogenous ADAM6 locus.

] In one embodiment, the male mice se an ectopic mouse ADAM6 sequence or homolog or orthoiog or functional fragment thereof that encodes a protein that confers ADAM6 function.

In one embodiment, the maIe mice comprise an ADAM6 ce or homoiog or orthoiog or functional fragment thereof at a location in the mouse genome that approximates the location of the endogenous mouse ADAM6 allele, 6.9., 3’ of a final V gene segment sequence and 5’ of an initial D gene segment.

In one embodiment, the maIe mice comprise an ADAM6 sequence or homolog or orthoiog or functional fragment thereof flanked upstream, downstream, or upstream and downstream (with respect to the direction of transcription of the ADAM6 ce) of a c acid sequence encoding an immunoglobuiin variable gene segment. In a ic embodiment, the immunoglobuiin variable gene segment is a human gene segment. In one embodiment, the immunoglobuiin variabIe gene segment is a human gene segment, and the sequence encoding the mouse ADAM6 or ortholog or homolog or nt thereof functionaI in a mouse is between human V gene segments; in one embodiment, the mouse comprises two or more human V gene ts, and the sequence is at a on between the final V gene segment and the penultimate V gene segment; in one embodiment, the sequence is at a position following the final V gene t and the first D gene segment.

In one aspect, a male mouse is provided that comprises a nonfunctional nous ADAM6 gene, or a deletion of an endogenous ADAM6 gene, in its germline; wherein sperm ceIIs of the mouse are capable of ting an oviduct of a female mouse and fertilizing an egg. In one embodiment, the mice comprise an extrachromosomal copy of a mouse ADAM6 gene or ortholog or homolog or functional fragment thereof that is functional in a male mouse. In one embodiment, the mice se an ectopic mouse ADAM6 gene or og or homolog or functional fragment f that is functional in a male mouse.

] In one aspect, mice are provided that se a genetic modification that reduces endogenous mouse ADAM6 function, wherein the mouse comprises at least some ADAM6 functionality provided either by an endogenous unmodified aIIele that is functional in whole or in part (e.g., a heterozygote), or by expression from an c sequence that encodes an ADAM6 or an orthoiog or homolog or functional fragment thereof that is functionaI in a male mouse.

In one embodiment, the mice comprise ADAM6 function sufficient to confer upon male mice the ability to generate offspring by mating, as compared with male mice that lack a functional ADAM6. In one embodiment, the ADAM6 function is conferred by the presence of an ectopic nucleotide sequence that encodes a mouse ADAM6 or a homolog or ortholog or functional fragment thereof. ADAM6 homoiogs or ogs or fragments thereof that are functional in a male mouse include those that restore, in whole or in part, the loss of ability to generate offspring observed in a male mouse that lacks sufficient endogenous mouse ADAM6 activity, e.g., the loss in ability observed in an ADAM6 knockout mouse. In this sense ADAM6 knockout mice include mice that comprise an endogenous locus or nt thereof, but that is not functional, i.e., that does not s ADAM6 (ADAM6a and/or ADAM6b) at all, or that expresses ADAM6 a and/or ADAM6b) at a level that is insufficient to support an essentially normal ability to generate offspring of a wild-type male mouse. The loss of function can be due, e.g., to a cation in a structural gene of the locus (i.e., in an ADAM6a or ADAM6b coding region) or in a regulatory region of the locus (e.g., in a sequence 5’ to the ADAM6a gene, or 3’ of the ADAM6a or ADAM6b coding , wherein the sequence controls, in whole or in part, transcription of an ADAM6 gene, expression of an ADAM6 RNA, or expression of an ADAM6 protein). in various embodiments, orthologs or homologs or fragments thereof that are functional in a male mouse are those that enable a sperm of a male mouse (or a majority of sperm cells in the ejaculate of a male mouse) to transit a mouse oviduct and fertilize a mouse ovum. in one embodiment, male mice that express the human immunoglobulin variable region or functional fragment thereof comprise ient ADAM6 activity to confer upon the male mice the ability to generate offspring by mating with female mice and, in one embodiment, the male mice exhibit an ability to generate offspring when mating with female mice that is in one embodiment at least 25%, in one embodiment, at least 30%, in one embodiment at least 40%, in one ment at least 50%, in one embodiment at least 60%, in one embodiment at least 70%, in one embodiment at least 80%, in one ment at least 90%, and in one embodiment about the same as, that of mice with one or two endogenous fied ADAM6 s. in one embodiment male mice express sufficient ADAM6 (or an ortholog or homolog or functional fragment thereof) to enable a sperm cell from the male mice to traverse a female mouse oviduct and fertilize a mouse egg. in one embodiment, the ADAM6 functionality is conferred by a nucleic acid sequence that is contiguous with a mouse chromosomal sequence (e.g., the nucleic acid is randomly integrated into a mouse some; or placed at a specific location, e.g., by targeting the nucleic acid to a specific location, e.g., by site-specific recombinase-mediated (e.g., Ore-mediated) insertion or homologous recombination). In one embodiment, the ADAM6 sequence is t on a nucleic acid that is distinct from a chromosome of the mouse (e.g., the ADAM6 sequence is t on an episome, i.e., extrachromosomally, e.g., in an expression construct, a vector, a YAC, a transchromosome, etc.) In one aspect, genetically modified mice and cells are provided that comprise a modification of an endogenous immunoglobulin heavy chain locus, wherein the mice s at least a portion of an immunoglobulin heavy chain sequence, e.g., at least a portion of a human sequence, wherein the mice comprise an ADAM6 ty that is functional in a male mouse. In one embodiment, the modification reduces or ates ADAM6 activity of the mouse. In one embodiment, the mouse is ed such that both alleles that encode ADAM6 activity are either absent or express an ADAM6 that does not substantially on to support normal mating in a male mouse. In one embodiment, the mouse further comprises an c nucleic acid sequence encoding a mouse ADAM6 or ortholog or homolog or functional fragment thereof.

In one aspect, genetically modified mice and cells are provided that se a modification of an endogenous immunoglobulin heavy chain locus, wherein the modification reduces or eliminates ADAM6 activity expressed from an ADAM6 sequence of the locus, and wherein the mice comprise an ADAM6 protein or og or homolog or functional fragment thereof. In various embodiments, the ADAM6 protein or fragment thereof is encoded by an ectopic ADAM6 sequence. In various embodiments, the ADAM6 protein or fragment thereof is expressed from an endogenous ADAM6 . in various embodiments, the mouse comprises a first immunoglobulin heavy chain allele comprises a first modification that reduces or eliminates expression of a functional ADAM6 from the first immunoglobulin heavy chain , and the mouse comprises a second immunoglobulin heavy chain allele that comprises a second modification that does not substantially reduce or does not eliminate expression of a functional ADAM6 from the second immunoglobulin heavy chain allele. in one embodiment, the second modification is located 3’ (with respect to the transcriptional directionality of the mouse V gene segment) of a final mouse V gene segment and located 5’ (with respect to the transcriptional directionality of the constant sequence) of a mouse (or chimeric human/mouse) immunoglobulin heavy chain constant gene or fragment thereof (9.9., a nucleic acid sequence encoding a human and/or mouse: CH1 and/or hinge and/or CH2 and/or CH3).

In one embodiment, the modification is at a first immunoglobulin heavy chain allele at a first locus that encodes a first ADAM6 allele, and the ADAM6 on s from expression of an endogenous ADAM6 at a second immunoglobulin heavy chain allele at a second locus that encodes a functional ADAM6, wherein the second immunoglobulin heavy chain allele comprises at least one modification of a V, D, and/or J gene segment. in a specific embodiment, the at least one modification of the V, D, and or J gene segment is a deletion, a ement with a human V, D, and/or J gene t, a replacement with a camelid V, D, and/or J gene segment, a replacement with a humanized or zed V, D, and/or J gene segment, a replacement of a heavy chain sequence with a tight chain sequence, and a combination thereof. In one embodiment, the at least one cation is the deletion of one or more heavy chain V, D, and/or J gene segments and a replacement with one or more light chain V and/or J gene ts (6.9., a human light chain V and/or J gene segment) at the heavy chain locus.

In one embodiment, the modification is at a first immunoglobulin heavy chain allele at a first locus and a second immunoglobulin heavy chain allele at a second locus, and the ADAM6 function results from expression of an ectopic ADAM6 at a non- immunoglobulin locus in the germline of the mouse. in a specific embodiment, the non- immunoglobulin locus is the ROSAZS locus. in a specific embodiment, the non- immunoglobulin locus is transcriptionally active in reproductive tissue. in one aspect, a mouse comprising a heterozygous or a homozygous knockout of ADAM6 is provided. In one ment, the mouse further comprises a modified immunoglobulin sequence that is a human or a humanized globulin sequence, or a camelid or camelized human or mouse immunoglobulin sequence. ln one embodiment, the modified immunoglobulin ce is present at the nous mouse heavy chain immunoglobulin locus. in one embodiment, the modified immunoglobulin sequence comprises a human heavy chain variable gene sequence at an endogenous mouse globulin heavy chain locus. in one embodiment, the human heavy chain variable gene sequence es an endogenous mouse heavy chain variable gene sequence at the endogenous mouse immunoglobulin heavy chain locus.

In one , a mouse incapable of expressing a functional endogenous mouse ADAM6 from an endogenous mouse ADAM6 locus is provided. In one embodiment, the mouse comprises an c nucleic acid sequence that encodes an ADAM6, or functional fragment thereof, that is functional in the mouse. In a specific embodiment, the ectopic c acid sequence encodes a protein that rescues a loss in the ability to te offspring exhibited by a male mouse that is homozygous for an ADAM6 ut. in a Specific embodiment, the ectopic nucleic acid sequence encodes a mouse ADAM6 protein. ln one aspect, a mouse is provided that lacks a functional endogenous ADAM6 locus, and that comprises an ectopic nucleic acid sequence that confers upon the mouse ADAM6 function. in one embodiment, the nucleic acid sequence comprises an endogenous mouse ADAM6 sequence or functional fragment thereof. In one embodiment, the endogenous mouse ADAM6 sequence comprises ADAM6a— and ADAMBb-encoding sequence located in a wild-type mouse between the 3’—most mouse immunoglobulin heavy chain V gene segment (VH) and the t mouse immunoglobulin heavy chain D gene segment (DH). in one embodiment, the nucleic acid sequence ses a sequence encoding mouse ADAM6a or functional fragment thereof and/or a sequence encoding mouse ADAMSb or functional fragment thereof, wherein the ADAM6a and/or ADAM6b or functional fragment(s) thereof is ly linked to a promoter. In one embodiment, the promoter is a human er. In one embodiment, the promoter is the mouse ADAMS promoter. In a specific embodiment, the ADAMS promoter comprises sequence located between the first codon of the first ADAMS gene closest to the mouse 5’—most DH gene segment and the recombination signal sequence of the 5’-most DH gene segment, n ’ is indicated with respect to direction of transcription of the mouse immunoglobulin genes.

In one embodiment, the promoter is a viral promoter. In a specific ment, the viral promoter is a cytomegalovirus (CMV) er. In one embodiment, the promoter is a tin promoter.

In one embodiment, the promoter is an inducible promoter. In one embodiment, the inducible promoter regulates expression in non-reproductive tissues. In one embodiment, the inducible promoter regulates expression in reproductive tissues. In a specific embodiment, the expression of the mouse ADAM6a and/or ADAM6b sequences or functional fragments(s) f is developmentally regulated by the inducible promoter in reproductive tissues. ] in one embodiment, the mouse ADAM6a and/or ADAM6b are selected from the ADAMSa of SEQ lD NO:1 and/or ADAM6b of sequence SEQ lD N012. in one embodiment, the mouse ADAMS promoter is a promoter of SEQ ID NO:3. in a specific embodiment, the mouse ADAMS promoter comprises the nucleic acid sequence of SEQ ID NO:3 directly am (with respect to the direction of transcription of ADAM6a) of the first codon of ADAM6a and extending to the end of SEQ lD NO:3 upstream of the ADAMS coding region. in another specific embodiment, the ADAMS er is a fragment extending from within about 5 to about 20 nucleotides upstream of the start codon of ADAM6a to about 0.5kb, 1kb, 2kb, or 3kb or more upstream of the start codon of ADAMSa.

In one embodiment, the c acid sequence comprises SEQ ID NO:3 or a fragment thereof that when placed into a mouse that is infertile or that has low fertility clue to a lack of ADAMS, es fertility or restores fertility to about a ype fertility. in one embodiment, SEQ lD NO:3 or a fragment thereof confers upon a male mouse the ability to produce a sperm cell that is capable of traversing a female mouse oviduct in order to fertilize a mouse egg. in one aspect, a mouse is provided that comprises a deletion of an endogenous nucleotide ce that s an ADAMS protein, a replacement of an endogenous mouse VH gene segment with a human VH gene segment, and an ectopic nucleotide sequence that encodes a mouse ADAMS n or ortholog or homolog or fragment thereof that is functional in a male mouse.

In one embodiment, the mouse comprises an immunoglobulin heavy chain Iocus that comprises a deletion of an endogenous giobulin locus nucleotide sequence that comprises an endogenous ADAM6 gene, ses a nucleotide sequence ng one or more human immunoglobulin gene segments, and wherein the ectopic nucleotide sequence encoding the mouse ADAMS protein is within or directly adjacent to the nucleotide sequence encoding the one or more human immunoglobuiin gene segments.

In one embodiment, the mouse comprises a replacement of all or substantially all endogenous VH gene ts with a nucleotide sequence encoding one or more human VH gene segments, and the ectopic nucleotide sequence encoding the mouse ADAM6 protein is within, or directly adjacent to, the nucleotide sequence encoding the one or more human VH gene segments. In one embodiment, the mouse r comprises a ement of one or more endogenous DH gene segments with one or more human DH gene segments at the endogenous DH gene locus. In one embodiment, the mouse further comprises a ement of one or more endogenous JH gene segments with one or more human JH gene segments at the endogenous JH gene locus. In one ment, the mouse comprises a replacement of all or substantially aII endogenous VH, DH, and JH gene segments and a replacement at the endogenous VH, DH, and JH gene loci with human VH, DH, and JH gene segments, wherein the mouse comprises an ectopic sequence encoding a mouse ADAM6 protein. In a specific embodiment, the ectopic sequence encoding the mouse ADAMS protein is placed between the imate 3’—most VH gene segment of the human VH gene segments present, and the ultimate 3’ VH gene segment of the human VH gene segments t. In a specific embodiment, the mouse comprises a deletion of all or substantially all mouse VH gene segments, and a ement with all or substantially all human VH gene segments, and the ectopic nucleotide ce encoding the mouse ADAM6 protein is placed ream of human gene t VH1-2 and upstream of human gene segment VH6-i.

] In a specific embodiment, the mouse comprises a replacement of aII or substantiaIIy aII endogenous VH gene segments with a nucleotide sequence encoding one or more human VH gene ts, and the ectopic nucleotide sequence encoding the mouse ADAM6 protein is within, or directly adjacent to, the nucleotide sequence encoding the one or more human VH gene segments.

In one embodiment, the ectopic nucleotide sequence that encodes the mouse ADAMS protein is present on a transgene in the genome of the mouse. In one embodiment, the ectopic nucleotide sequence that encodes the mouse ADAMG protein is present extrachromosomally in the mouse.

In one aspect, a mouse is provided that comprises a modification of an endogenous globulin heavy chain locus, wherein the mouse expresses a B cell that ses a rearranged immunoglobulin sequence operably linked to a heavy chain constant region gene sequence, and the B cell comprises in its genome (e.g., on a B cell chromosome) a gene encoding an ADAM6 or ortholog or homolog or fragment thereof that is functional in a male mouse. in one embodiment, the rearranged globulin sequence operably linked to the heavy chain constant region gene sequence ses a human heavy chain V, D, and/or J sequence; a mouse heavy chain V, D, and/or J sequence; a human or mouse light chain V and/or J sequence. In one embodiment, the heavy chain constant region gene sequence comprises a human or a mouse heavy chain sequence selected from the group consisting of a CH1, a hinge, a CH2, a CH3, and a combination thereof.

In one aspect, a genetically modified mouse is provided, wherein the mouse comprises a functionally silenced immunoglobulin light chain gene, and further comprises a replacement of one or more endogenous immunoglobulin heavy chain variable region gene segments with one or more human immunoglobulin heavy chain le region gene segments, wherein the mouse lacks a functional endogenous ADAM6 locus, and wherein the mouse ses an ectopic nucleotide sequence that expresses a mouse ADAM6 protein or an og or homolog or fragment thereof that is functional in a male mouse. in one aspect, a mouse is ed that lacks a functional endogenous mouse ADAM6 locus or ce and that comprises an ectopic nucleotide sequence encoding a mouse ADAM6 locus or functional fragment of a mouse ADAM6 locus or sequence, wherein the mouse is capable of mating with a mouse of the opposite sex to produce a progeny that ses the ectopic ADAM6 locus or sequence. in one embodiment, the mouse is male. in one embodiment, the mouse is female. in one aspect, a genetically modified mouse is provided, n the mouse comprises a human immunoglobulin heavy chain variable region gene segment at an endogenous mouse immunoglobulin heavy chain variable region gene locus, the mouse lacks an endogenous functional ADAM6 sequence at the endogenous mouse immunoglobulin heavy chain variable region gene locus, and wherein the mouse comprises an ectopic tide sequence that expresses a mouse ADAM6 protein or an ortholog or homolog or fragment f that is functional in a male mouse. in one embodiment, the ectopic nucleotide sequence that expresses the mouse ADAM6 protein is extrachromosomal. in one embodiment, the ectopic nucleotide sequence that expresses the mouse ADAM6 protein is ated at one or more loci in a genome of the mouse. in a specific ment, the one or more loci include an immunoglobulin locus. in one aspect, a mouse is provided that expresses an immunoglobulin heavy chain sequence from a ed endogenous mouse immunoglobulin heavy chain locus, wherein the heavy chain is derived from a human V gene segment, a D gene segment, and a J gene segment, wherein the mouse comprises an ADAM6 activity that is functional in the mouse.

In one embodiment, the mouse ses a plurality of human V gene segments, a plurality of D gene segments, and a plurality of J gene segments. In one embodiment, the D gene segments are human D gene segments. In one ment, the J gene segments are human J gene segments. In one embodiment, the mouse r ses a humanized heavy chain constant region sequence, wherein the humanization comprises replacement of a sequence ed from a CH1, hinge, CH2, CH3, and a combination thereof. in a specific embodiment, the heavy chain is derived from a human V gene segment, a human D gene segment, a human J gene segment, a human CH1 sequence, a human or mouse hinge sequence, a mouse CH2 sequence, and a mouse CH3 sequence. In another specific embodiment, the mouse further comprises a human light chain constant ce.

In one ment, the D gene segment is flanked 5’ (with respect to riptional direction of the D gene segment) by a sequence encoding an ADAM6 activity that is functional in the mouse. in one embodiment, the ADAM6 activity that is functional in the mouse results from expression of a tide sequence located 5’ of the 5’-most D gene segment and 3’ of the 3’-most V gene segment (with respect to the direction of transcription of the V gene segment) of the modified endogenous mouse heavy chain immunoglobulin locus. in one embodiment, the ADAM6 activity that is functional in the mouse results from expression of a nucleotide sequence located between two human V gene segments in the modified endogenous mouse heavy chain immunoglobulin locus. in one embodiment, the two human V gene segments are a human VH1-2 gene segment and a VHS-1 gene segment. in one embodiment, the nucleotide sequence comprises a sequence ed from a mouse ADAM6b sequence or functional fragment thereof, a mouse ADAM6a sequence or functional fragment thereof, and a combination thereof.

In one embodiment, the tide ce between the two human V gene ts is placed in te transcription orientation with respect to the human V gene segments. in a specific embodiment, nucleotide sequence encodes, from 5’ to 3’ with respect to the direction of transcription of ADAM6 genes, and ADAM6a sequence followed by an ADAM6b sequence.

In one embodiment, the mouse comprises a replacement of a human ADAM6 pseudogene sequence between human V gene segments VH1—2 and VH6-1 with a mouse ADAM6 sequence or a functional fragment thereof. in one embodiment, the sequence encoding the ADAM6 activity that is onal in the mouse is a mouse ADAM6 sequence or functional fragment thereof. in one embodiment, the mouse comprises an endogenous mouse DFL16.1 gene segment (9.9., in a mouse heterozygous for the modified nous mouse immunoglobulin heavy chain locus), or a human DH1-1 gene segment. in one embodiment, the D gene segment of the immunoglobulin heavy chain expressed by the mouse is derived from an nous mouse DFL16.1 gene t or a human DH1-1 gene segment.

In one aspect, a mouse is provided that comprises a nucleic acid sequence encoding a mouse ADAM6 (or homolog or ortholog or functional fragment thereof) in a DNA-bearing cell of non-rearranged B cell lineage, but does not comprise the nucleic acid sequence encoding the mouse ADAM6 (or homolog or ortholog or functional fragment thereof) in a B cell that comprise rearranged immunoglobulin loci, n the nucleic acid sequence encoding the mouse ADAM6 (or homolog or ortholog or functional fragment f) occurs in the genome at a position that is ent from a position in which a mouse ADAM6 gene s in a wild~type mouse. in one embodiment, the nucleic acid sequence encoding the mouse ADAM6 (or homolog or ortholog or functional fragment thereof) is present in all or substantially all DNA-bearing cells that are not of rearranged B cell lineage; in one embodiment, the nucleic acid sequence is t in germline cells of the mouse, but not in a chromosome of a rearranged B cell. in one aspect, a mouse is provided that comprises a nucleic acid sequence encoding a mouse ADAM6 (or homolog or ortholog or functional fragment thereof) in all or substantially all DNA—bearing cells, including B cells that comprise rearranged immunoglobulin loci, wherein the nucleic acid sequence encoding the mouse ADAM6 (or homolog or ortholog or onal fragment thereof) occurs in the genome at a on that is different from a position in which a mouse ADAM6 gene appears in a wild-type mouse. in one embodiment, the nucleic acid sequence encoding the mouse ADAM6 (or homolog or ortholog or onal fragment thereof) is on a nucleic acid that is contiguous with the rearranged globulin locus. in one embodiment, the nucleic acid that is contiguous with the rearranged immunoglobulin locus is a chromosome. in one embodiment, the chromosome is a chromosome that is found in a wild-type mouse and the chromosome comprises a modification of a mouse immunoglobulin locus. in one aspect, a genetically modified mouse is provided, wherein the mouse comprises a B cell that comprises in its genome an ADAM6 sequence or og or homolog thereof. in one ment, the ADAM6 sequence or ortholog or homolog thereof is at an immunoglobulin heavy chain locus. in one embodiment, the ADAM6 sequence or ortholog or homolog thereof is at a locus that is not an immunoglobulin locus.

In one embodiment, the ADAM6 sequence is on a transgene driven by a heterologous promoter. In a specific embodiment, the logous promoter is a non-immunoglobulin promoter. In a specific embodiment, B cell ses an ADAM6 protein or ortholog or homolog thereof.

In one embodiment, 90% or more of the B cells of the mouse comprise a gene encoding an ADAM6 protein or an ortholog f or a homolog thereof or a fragment thereof that is functional in the mouse. In a specific embodiment, the mouse is a male mouse.

In one embodiment, the B cell genome comprises a first allele and a second allele comprising the ADAM6 sequence or ortholog or homoIog thereof. In one ment, the B cell genome comprises a first allele but not a second allele comprising the ADAM6 sequence or ortholog or g thereof.

In one aspect, a mouse is provided that comprises a modification at one or more endogenous ADAM6 alleles.

In one embodiment, the modification renders the mouse incapable of expressing a onal ADAM6 protein from at least one of the one or more endogenous ADAM6 alleles. In a specific embodiment, the mouse is incapable of expressing a functional ADAM6 protein from each of the endogenous ADAM6 alleles.

In one embodiment, the mice are incapable of sing a functional ADAM6 n from each endogenous ADAM6 allele, and the mice comprise an ectopic ADAM6 sequence.

] In one embodiment, the mice are incapable of sing a functional ADAM6 protein from each endogenous ADAM6 allele, and the mice comprise an ectopic ADAM6 ce located within 1, 2, 3, 4, 5, 10, 20, 30,40, 50, 60, 70, 80, 90, 100, 110, or 120 or more kb upstream (with respect to the direction of ription of the mouse heavy chain locus) of a mouse immunoglobulin heavy chain constant region sequence. In a specific embodiment, the ectopic ADAM6 sequence is at the endogenous immunoglobulin heavy chain locus (e.g., in an intergenic V-D region, between two V gene segments, between a V and a D gene segment, between a D and a J gene segment, etc). In a specific embodiment, the ectopic ADAM6 sequence is located within a 90 to 100 kb intergenic sequence between the final mouse V gene segment and the first mouse D gene segment.

In another specific embodiment, the endogenous 90 to 100 kb intergenic V—D ce is removed, and the ectopic ADAM6 sequence is placed between the final V and the first D gene segment.

In one aspect, an infertile male mouse is ed, wherein the mouse ses a deletion of two or more endogenous ADAM6 alleles. In one aspect, a female mouse is provided that is a carrier of a male infertility trait, wherein the female mouse comprises in its germline a nonfunctional ADAM6 allele or a knockout of an endogenous ADAM6 allele. in one aspect, a mouse that lacks an endogenous immunoglobulin heavy chain V, D, and J gene segment is provided, wherein a majority of the B cells of the mouse comprise an ADAM6 sequence or ortholog or homolog thereof. in one embodiment, the mouse lacks endogenous immunoglobulin heavy chain gene segments selected from two or more V gene segments, two or more D gene segments, two or more J gene segments, and a combination thereof. In one embodiment, the mouse lacks immunoglobulin heavy chain gene segments ed from at least one and up to 89 V gene segments, at least one and up to 13 D gene segments, at least one and up to four J gene segments, and a combination thereof. in one embodiment, the mouse lacks a genomic DNA fragment from chromosome 12 comprising about three megabases of the endogenous immunoglobulin heavy chain locus. In a specific ment, the mouse lacks all functional endogenous heavy chain V, D, and J gene segments. In a specific embodiment, the mouse lacks 89 VH gene segments, 13 DH gene segments and four JH gene segments. in one aspect, a mouse is provided, wherein the mouse has a genome in the ne comprising a modification of an immunoglobulin heavy chain locus, wherein the modification to the immunoglobulin heavy chain locus comprises the replacement of one or more mouse immunoglobulin variable region sequences with one or more non-mouse immunoglobulin variable region sequences, and wherein the mouse comprises a nucleic acid sequence encoding a mouse ADAMS protein. in a preferred embodiment, the DH and JH sequences and at least 3, at least 10, at least 20, at least 40, at least 60, or at least 80 VH sequences of the immunoglobulin heavy chain locus are replaced by non-mouse immunoglobulin variable region sequences. In a r red embodiment, the DH, JH, and all VH sequences of the immunoglobulin heavy chain locus are ed by use immunoglobulin variable region ces. The non-mouse globulin variable region sequences can be arranged. in a preferred embodiment, the non-mouse globulin variable region sequences comprise complete non-rearranged DH and JH regions and at least 3, at least 10, at least 20, at least 40, at least 60, or at least 80 non— rearranged VH sequences of the non—mouse species. in a further preferred embodiment, the non-mouse immunoglobulin variable region sequences se the complete variable region, including all VH, DH, and JH regions, of the use species. The non-mouse s can be Homo sapiens and the non-mouse immunoglobulin variable region sequences can be human sequences.

In one aspect, a mouse that expresses an antibody that comprises at least one human variable domain/non—human constant domain immunoglobulin ptide is provided, wherein the mouse expresses a mouse ADAMG protein or ortholog or g thereof from a locus other than an immunoglobulin locus.

In one embodiment, the ADAMS protein or ortholog or homolog thereof is sed in a B cell of the mouse, wherein the B cell comprises a rearranged immunoglobulin sequence that comprises a human variable sequence and a non-human constant ce.

In one embodiment, the non-human constant sequence is a rodent sequence.

In one embodiment, the rodent is selected from a mouse, a rat, and a hamster. in one aspect, a method is provided for making an infertile male mouse, sing ing an nous ADAM6 allele of a donor ES cell nonfunctional (or knocking out said allele), introducing the donor ES cell into a host , gestating the host embryo in a surrogate mother, and allowing the surrogate mother to give birth to progeny derived in whole or in part from the donor ES cell. In one embodiment, the method further comprises breeding progeny to obtain an infertile male mouse. in one aspect, a method is provided for making a mouse with a genetic cation of interest, wherein the mouse is infertile, the method comprising the steps of (a) making a genetic modification of interest in a genome; (b) modifying the genome to knockout an endogenous ADAM6 allele, or render an endogenous ADAMS allele ctional; and, (c) employing the genome in making a mouse. in various embodiments, the genome is from an ES cell or used in a nuclear transfer experiment.

In one aspect, a mouse made using a targeting vector, nucleotide construct, or cell as described herein is ed.

In one aspect, a progeny of a mating of a mouse as described herein with a second mouse that is a wild—type mouse or genetically modified is provided. in one aspect, a method for maintaining a mouse strain is provided, wherein the mouse strain comprises a replacement of a mouse immunoglobulin heavy chain sequence with one or more heterologous immunoglobulin heavy chain sequences. In one embodiment, the one or more heterologous immunoglobulin heavy chain sequences are human immunoglobulin heavy chain sequences.

In one embodiment, the mouse strain comprises a on of one or more mouse VH, DH, and/or JH gene segments. in one embodiment, the mouse further comprises one or more human VH gene segments, one or more human DH gene ts, and/or one or more human JH gene segments. In one embodiment, the mouse comprises at least 3, at least 10, at least 20, at least 40, at least 60, or at least 80 human VH segments, at least 27 human DH gene segments, and at least six JH gene segments. in a ic embodiment, the mouse comprises at least 3, at least 10, at least 20, at least 40, at least 60, or at least 80 human VH segments, the at least 27 human DH gene segments, and the at least six JH gene segments are operably linked to a constant region gene. In one embodiment, the constant region gene is a mouse nt region gene. In one ment, the nt region gene comprises a mouse constant region gene sequence selected from a CH1, a hinge, a CH2, a CH3, and/or a CH4 or a combination thereof.

In one embodiment, the method comprises generating a male mouse heterozygous for the replacement of the mouse immunoglobulin heavy chain ce, and ng the heterozygous male mouse with a wild-type female mouse or a female mouse that is homozygous or heterozygous for the human heavy chain sequence. In one embodiment, the method comprises ining the strain by repeatedly breeding heterozygous males with females that are wild type or homozygous or heterozygous for the human heavy chain sequence.

In one ment, the method comprises obtaining cells from male or female mice homozygous or heterozygous for the human heavy chain sequence, and employing those cells as donor cells or nuclei therefrom as donor nuclei, and using the cells or nuclei to make genetically modified animals using host cells and/or gestating the cells and/or nuclei in surrogate mothers.

In one embodiment, only male mice that are heterozygous for the replacement at the heavy chain locus are bred to female mice. In a specific embodiment, the female mice are homozygous, heterozygous, or wild type with respect to a replaced heavy chain locus. in one embodiment, the mouse r comprises a replacement of k and/or K light chain variable sequences at an endogenous immunoglobulin light chain locus with heterologous immunoglobulin light chain sequences. In one embodiment, the heterologous immunoglobulin light chain sequences are human immunoglobulin 7» and/or K light chain variable ces. in one embodiment, the mouse further comprises a transgene at a locus other than an endogenous immunoglobulin locus, wherein the transgene comprises a sequence ng a rearranged or unrearranged heterologous 7» or K light chain sequence (e.g., ranged VL and unrearranged JL, or rearranged VJ) operably linked (for unrearranged) or fused (for rearranged) to an globulin light chain constant region sequence. In one embodiment, the heterologous k or K light chain sequence is human. In one embodiment, the constant region sequence is selected from rodent, human, and non- human primate. In one embodiment, the constant region sequence is selected from mouse, rat, and r. In one embodiment, the transgene comprises a non- immunoglobulin promoter that drives expression of the light chain sequences. In a specific embodiment, the promoter is a transcriptionally active promoter. In a ic embodiment, the promoter is a ROSAZB promoter. in one aspect, a nucleic acid construct is ed, comprising an upstream homology arm and a downstream homology arm, wherein the upstream homology arm comprises a sequence that is identical or substantially identical to a human immunoglobulin heavy chain variable region sequence, the downstream homology arm comprises a ce that is identical or substantially identical to a human or mouse immunoglobulin variable region sequence, and ed between the am and downstream homology arms is a sequence that comprises a nucleotide sequence encoding a mouse ADAM6 protein. in a specific embodiment, the sequence encoding the mouse ADAM6 gene is operably linked with a mouse er with which the mouse ADAM6 is linked in a wild type mouse. ] in one aspect, a targeting vector is provided, comprising (a) a nucleotide sequence that is identical or ntially identical to a human variable region gene segment nucleotide sequence; and, (b) a nucleotide ce encoding a mouse ADAM6 or ortholog or homolog or fragment thereof that is functional in a mouse.

In one embodiment, the targeting vector further comprises a promoter operably linked to the sequence encoding the mouse ADAM6. in a specific ment, the promoter is a mouse ADAM6 promoter.

In one aspect, a nucleotide construct for modifying a mouse immunoglobulin heavy chain variable locus is provided, wherein the construct comprises at least one site- specific recombinase recognition site and a sequence encoding an ADAM6 protein or ortholog or homolog or fragment thereof that is onal in a mouse.

In one aspect, mouse cells and mouse embryos are provided, including but not limited to ES cells, pluripotent cells, and induced pluripotent cells, that comprise genetic modifications as described herein, Cells that are XX and cells that are XY are provided.

Cells that comprise a nucleus ning a modification as bed herein are also ed, e.g., a modification introduced into a cell by pronuclear injection. Cells, embryos, and mice that comprise a virally introduced ADAM6 gene are also provided, e.g., cells, s, and mice comprising a transduction construct comprising an ADAM6 gene that is functional in the mouse. in one aspect, a genetically modified mouse cell is provided, wherein the cell lacks a functional endogenous mouse ADAM6 locus, and the cell comprises an ectopic tide sequence that encodes a mouse ADAM6 protein or functional fragment thereof. in one embodiment, the cell r comprises a modification of an endogenous immunoglobulin heavy chain variable gene sequence. in a specific embodiment, the modification of the endogenous immunoglobulin heavy chain variable gene sequence comprises a deletion selected from a deletion of a mouse VH gene segment, a on of a mouse DH gene segment, a deletion of a mouse JH gene segment, and a combination thereof. in a specific embodiment, the mouse ses a replacement of one or more mouse immunoglobulin VH, DH, and/or JH ces with a human immunoglobulin sequence. In a specific embodiment, the human immunoglobulin sequence is selected from a human VH, a human VL, a human DH, a human JH, a human JL, and a combination thereof. 2] In one embodiment, the cell is a totipotent cell, a pluripotent cell, or an induced pluripotent cell. In a specific embodiment, the cell is a mouse ES cell.

In one aspect, a mouse B cell is provided, wherein the mouse B cell comprises a rearranged immunoglobulin heavy chain gene, n the B cell comprises on a some of the B cell a c acid sequence encoding an ADAM6 protein or ortholog or homolog or fragment thereof that is functional in a male mouse. In one embodiment, the mouse B cell comprises two alleles of the nucleic acid sequence.

In one embodiment, the nucleic acid sequence is on a nucleic acid molecule (e.g., a B cell chromosome) that is uous with the rearranged mouse immunoglobulin heavy chain locus.

In one embodiment, the nucleic acid sequence is on a nucleic acid molecule (e.g., a B celt chromosome) that is distinct from the nucleic acid molecule that comprises the rearranged mouse immunoglobulin heavy chain locus.

In one embodiment, the mouse B cell comprises a nged non-mouse immunoglobulin variable gene sequence operably linked to a mouse or human immunoglobulin constant region gene, wherein the B cell comprises a nucleic acid sequence that s an ADAM6 protein or ortholog or homolog or fragment thereof that is functional in a male mouse.

In one aspect, a somatic mouse cell is provided, comprising a chromosome that comprises a modified immunoglobulin heavy chain locus, and a nucleic acid sequence ng a mouse ADAM6 or ortholog or homolog or fragment thereof that is onal in a male mouse. in one embodiment, the nucleic acid sequence is on the same chromosome as the modified immunoglobulin heavy chain locus. In one embodiment, the nucleic acid is on a different chromosome than the modified immunoglobulin heavy chain locus. in one embodiment, the somatic cell comprises a single copy of the nucleic acid sequence. In one ment, the somatic cell comprises at least two copies of the c acid sequence. ln a specific embodiment, the somatic cell is a B cell. In a ic embodiment, the cell is a germ cell. ln a specific embodiment, the cell is a stem cell.

In one aspect, a mouse germ cell is provided, comprising a nucleic acid ce encoding a mouse ADAM6 (or homolog or ortholog or functional fragment thereof) on a chromosome of the germ cell, wherein the nucleic acid sequence encoding the mouse ADAM6 (or g or ortholog or functional fragment thereof) is at a on in the chromosome that is different from a position in a chromosome of a wild-type mouse germ cell. in one embodiment, the c acid sequence is at a mouse immunoglobulin locus. In one embodiment, the nucleic acid sequence is on the same chromosome of the germ cell as a mouse immunoglobulin locus. In one embodiment, the nucleic acid sequence is on a different chromosome of the germ cell than the mouse immunoglobulin locus. In one embodiment, the mouse immunoglobulin locus comprises a replacement of at least one mouse immunoglobulin sequence with at least one non—mouse globulin ce. In a specific embodiment, the at least one non—mouse immunoglobulin sequence is a human immunoglobulin sequence.

In one aspect, a pluripotent, induced otent, or totipotent cell derived from a mouse as described herein is ed. ln a specific embodiment, the cell is a mouse embryonic stem (ES) cell.

In one aspect, a tissue derived from a mouse as described herein is provided. in one embodiment, the tissue is derived from , lymph node or bone marrow of a mouse as described herein. ln one aspect, a nucleus derived from a mouse as described herein is provided.

In one embodiment, the nucleus is from a diploid cell that is not a B cell. in one aspect, a nucleotide ce encoding an immunoglobulin variable region made in a mouse as described herein is provided. in one aspect, an immunoglobulin heavy chain or immunoglobulin light chain variable region amino acid sequence of an antibody made in a mouse as described herein is provided.

In one , an immunoglobulin heavy chain or immunoglobulin light chain le region nucleotide sequence encoding a variable region of an antibody made in a mouse as described herein is provided.

In one aspect, an antibody or antigen-binding fragment thereof (e.g., Fab, F(ab)2, scFv) made in a mouse as described herein is provided. in one aspect, a method for making a genetically modified mouse is provided, comprising replacing one or more immunoglobulin heavy chain gene segments upstream (with respect to ription of the immunoglobulin heavy chain gene segments) of an nous ADAM6 locus of the mouse with one or more human immunoglobulin heavy chain gene segments, and replacing one or more immunoglobulin gene segments downstream (with respect to transcription of the immunoglobulin heavy chain gene segments) of the ADAM6 locus of the mouse with one or more human globulin heavy chain or light chain gene segments. In one embodiment, the one or more human immunoglobulin gene segments replacing one or more endogenous immunoglobulin gene segments upstream of an endogenous ADAMS locus of the mouse e V gene segments. In one embodiment, the human immunoglobulin gene segments replacing one or more endogenous immunoglobulin gene segments upstream of an endogenous ADAMS locus of the mouse include V and D gene segments. In one embodiment, the one or more human immunoglobulin gene segments ing one or more endogenous immunoglobulin gene segments downstream of an endogenous ADAMS locus of the mouse include J gene segments. In one embodiment, the one or more human immunoglobulin gene segments replacing one or more endogenous immunoglobulin gene segments ream of an endogenous ADAMS locus of the mouse include D and J gene segments. In one embodiment, the one or more human immunoglobulin gene segments replacing one or more endogenous immunoglobulin gene segments downstream of an endogenous ADAMS locus of the mouse include V, D and J gene ts.

In one embodiment, the one or more immunoglobulin heavy chain gene segments upstream and/or downstream of the ADAMS gene are replaced in a pluripotent, induced pluripotent, or totipotent cell to form a genetically modified progenitor cell; the cally modified itor cell is introduced into a host; and, the host comprising the genetically modified progenitor cell is ed to form a mouse comprising a genome derived from the genetically modified progenitor cell. In one embodiment, the host is an embryo. In a specific embodiment, the host is selected from a mouse pre—morula (e. g., 8- or 4-cell stage), a tetraploid embryo, an aggregate of embryonic cells, or a blastocyst.

In one aspect, a method for making a cally modified mouse is provided, comprising replacing a mouse nucleotide sequence that comprises a mouse immunoglobulin gene segment and a mouse ADAMS (or ortholog or g or fragment thereof functional in a male mouse) nucleotide sequence with a sequence comprising a human immunoglobulin gene segment to form a first chimeric locus, then inserting a sequence comprising a mouse encoding sequence (or a ce encoding an ortholog or homolog or functional fragment thereof) into the sequence comprising the human globulin gene segment to form a second ic locus.

In one embodiment, the second chimeric locus comprises a human immunoglobulin heavy chain variable (VH) gene segment. In one embodiment, the second chimeric locus comprises a human immunoglobulin light chain variable (VL) gene segment.

In a specific embodiment, the second chimeric locus comprises a human VH gene segment or a human VL gene segment operably linked to a human DH gene t and a human JH gene segment. In a further specific embodiment, the second chimeric locus is operably linked to a third chimeric locus that comprises a human CH1 sequence, or a human CH1 and human hinge sequence, fused with a mouse CH2 + CH3 sequence. in one aspect, use of a mouse that comprises an ectopic nucleotide sequence comprising a mouse ADAMS locus or sequence to make a fertile male mouse is ed, wherein the use comprises mating the mouse comprising the ectopic nucleotide sequence that comprises the mouse ADAM6 locus or sequence to a mouse that lacks a functional endogenous mouse ADAM6 locus or ce, and obtaining a progeny that is a female capable of producing progeny having the ectopic ADAM6 locus or sequence or that is a male that comprises the ectopic ADAMS locus or sequence, and the male exhibits a fertility that is imately the same as a fertility exhibited by a wild-type male mouse. in one aspect, use of a mouse as described herein to make an immunoglobulin variable region nucleotide sequence is provided.

In one , use of a mouse as described herein to make a fully human Fab or a fully human F(ab)2 is provided.

In one aspect, use of a mouse as described herein to make an immortalized cell line is provided. in one aspect, use of a mouse as bed herein to make a hybridoma or quadroma is provided. in one aspect, use of a mouse as described herein to make a phage library containing human heavy chain variable regions and human light chain variable regions is provided. in one aspect, use of a mouse as described herein to generate a variable region sequence for making a human antibody is provided, comprising (a) immunizing a mouse as described herein with an n of interest, (b) isolating a lymphocyte from the immunized mouse of (a), (c) exposing the lymphocyte to one or more labeled antibodies, (d) identifying a lymphocyte that is capable of g to the antigen of interest, and (e) amplifying one or more variable region nucleic acid sequence from the iymphocyte y generating a variable region sequence. in one embodiment, the lymphocyte is d from the spleen of the mouse. in one embodiment, the lymphocyte is d from a lymph node of the mouse. In one embodiment, the lymphocyte is derived from the bone marrow of the mouse. in one embodiment, the labeled antibody is a ﬂuorophore-conjugated antibody. in one embodiment, the one or more fluorophore—conjugated antibodies are ed from an lgM, an lgG, and/or a combination f. in one embodiment, the lymphocyte is a B cell. ln one ment, the one or more variable region nucleic acid sequence comprises a heavy chain variable region sequence. In one embodiment, the one or more le region nucleic acid ce comprises a light chain variable region sequence. in a specific embodiment, the light chain variable region sequence is an immunoglobulin K light chain variable region sequence. in one embodiment, the one or more variable region nucleic acid sequence comprises a heavy chain and a K light chain variable region sequence.

In one ment, use of a mouse as described herein to generate a heavy and a K light chain variable region sequence for making a human antibody is provided, comprising (a) immunizing a mouse as described herein with an antigen of interest, (b) isolating the spleen from the immunized mouse of (a), (c) exposing B lymphocytes from the spleen to one or more labeled antibodies, (d) identifying a B lymphocyte of (c) that is capable of binding to the antigen of interest, and (e) amplifying a heavy chain variable region nucleic acid sequence and a K light chain variable region nucleic acid sequence from the B lymphocyte thereby generating the heavy chain and K light chain variable region sequences.

In one embodiment, use of a mouse as bed herein to te a heavy and a K light chain variable region sequence for making a human antibody is provided, comprising (a) immunizing a mouse as described herein with an antigen of interest, (b) isolating one or more lymph nodes from the immunized mouse of (a), (c) exposing B lymphocytes from the one or more lymph nodes to one or more labeled antibodies, (d) identifying a B lymphocyte of (c) that is capable of g to the antigen of interest, and (e) amplifying a heavy chain variable region nucleic acid sequence and a K light chain variable region nucleic acid ce from the B cyte thereby generating the heavy chain and K light chain variable region sequences. 2] In one embodiment, use of a mouse as bed herein to generate a heavy and a K light chain variable region sequence for making a human antibody is provided, sing (a) immunizing a mouse as described herein with an antigen of interest, (b) isolating bone marrow from the immunized mouse of (a), (c) ng B cytes from the bone marrow to one or more labeled antibodies, (d) identifying a B lymphocyte of (c) that is capable of g to the antigen of interest, and (e) amplifying a heavy chain variable region nucleic acid sequence and a K light chain variable region nucleic acid sequence from the B lymphocyte thereby generating the heavy chain and K light chain variable region sequences. in various embodiments, the one or more labeled antibodies are selected from an lgM, an lgG, and/or a combination thereof. in various embodiments, use of a mouse as described herein to generate a heavy and K light chain le region sequence for making a human dy is provided, further comprising fusing the amplified heavy and light chain variable region sequences to human heavy and light chain constant region sequences, expressing the fused heavy and light chain sequences in a cell, and recovering the expressed heavy and light chain sequences thereby generating a human antibody.

In various embodiments, the human heavy chain nt regions are selected from lgM, lgD, lgA, IgE and IgG. In various specific embodiments, the IgG is ed from an IgG1, an IgGZ, an lgG3 and an IgG4. In various embodiments, the human heavy chain constant region comprises a CH1, a hinge, a CH2, a CH3, a CH4, or a combination thereof.

In various embodiments, the light chain constant region is an immunoglobulin K constant region. In various embodiments, the cell is selected from a HeLa cell, a DU145 cell, a anap cell, a MCF-7 cell, a MDA—MB-438 cell, a PC3 cell, a T47D cell, a THP-1 cell, a U87 cell, a SHSY5Y (human neuroblastoma) cell, a Saos-2 cell, a Vero cell, a CHO cell, a GH3 cell, a P012 cell, a human l cell (e.g., a PERCGT'V‘ cell), and a MC3T3 cell. In a specific embodiment, the cell is a CHO cell.

In one aspect, a method for generating a reverse-chimeric rodent-human dy specific against an antigen of interest Is provided, comprising the steps of immunizing a mouse as described herein with the antigen, isolating at least one cell from the mouse producing a reverse—chimeric mouse-human antibody specific against the n, culturing at least one cell producing the reverse—chimeric mouse-human antibody specific against the antigen, and obtaining said dy.

In one embodiment, the reverse-chimeric mouse—human antibody comprises a human heavy chain variable domain fused with a mouse or rat heavy chain constant gene, and a human light chain variable domain fused with a mouse or rat or human light chain constant gene.

In one embodiment, culturing at least one cell ing the reverse-chimeric rodent-human antibody specific against the antigen is med on at least one hybridoma cell generated from the at least one cell isolated from the mouse.

In one aspect, a method for generating a fully human antibody specific against an n of interest is provided, comprising the steps of immunizing a mouse as described herein with the antigen, isolating at least one cell from the mouse producing a reverse-chimeric —human antibody specific against the antigen, generating at least one cell producing a fully human antibody d from the reverse—chimeric rodent-human antibody specific t the antigen, and culturing at least one cell producing the fully human antibody, and obtaining said fully human antibody.

In s embodiments, the at least one cell isolated from the mouse producing a reverse-chimeric rodent—human antibody specific against the antigen is a splenocyte or a B cell. 0] In various embodiments, the antibody is a monoclonal antibody.

In various embodiments, immunization with the antigen of interest is carried out with protein, DNA, a combination of DNA and protein, or cells expressing the antigen. 2] In one aspect, use of a mouse as described herein to make a nucleic acid ce encoding an immunoglobulin variable region or nt thereof is provided. in one embodiment, the nucleic acid sequence is used to make a human dy or antigen— g nt thereof. In one embodiment, the mouse is used to make an antigen- binding protein selected from an antibody, at multi-specific antibody (e.g., a bi-specific antibody), an scFv, a bi-specific scFv, a y, a triabody, a tetrabody, a V-NAR, a VHH, a VL, a F(ab), a F(ab)2, a DVD (i.e., dual variable domain antigen-binding protein), a an SVD (i.e., single le domain n—binding protein), or a bispecific T-cell engager (BiTE). in one aspect, use of a mouse as described herein to introduce an ectopic ADAMS sequence into a mouse that lacks a onal endogenous mouse ADAMS sequence is provided, wherein the use comprises mating a mouse as described herein with the mouse that lacks the functional endogenous mouse ADAMS sequence.

In one aspect, use of genetic material from a mouse as described herein to make a mouse having an ectopic ADAMS sequence is ed. in one embodiment, the use comprises nuclear transfer using a nucleus of a cell of a mouse as bed herein.

In one embodiment, the use ses cloning a cell of a mouse as described herein to produce an animal derived from the cell. in one embodiment, the use comprises employing a sperm or an egg of a mouse as described herein in a process for making a mouse comprising the ectopic ADAMS sequence. in one aspect, a method for making a fertile male mouse comprising a modified immunoglobulin heavy chain locus is provided, sing fertilizing a first mouse germ cell that comprises a modification of an endogenous immunoglobulin heavy chain locus with a second mouse germ cell that comprises an ADAMS gene or ortholog or homolog or fragment thereof that is functional in a male mouse; forming a fertilized cell; allowing the fertilized cell to develop into an embryo; and, gestating the embryo in a surrogate to obtain a mouse.

In one embodiment, the fertilization is achieved by mating a male mouse and a female mouse. in one embodiment, the female mouse ses the ADAMS gene or ortholog or homolog or fragment thereof. in one embodiment, the male mouse comprises the ADAMS gene or ortholog or homolog or fragment thereof. ln one aspect, use of a nucleic acid sequence encoding a mouse ADAMS protein or an ortholog or homolog thereof or a functional fragment of the corresponding ADAMS protein for restoring or enhancing the fertility of a mouse having a genome comprising a modification of an immunoglobulin heavy chain locus is provided, wherein the modification reduces or eliminates endogenous ADAMS function. in one embodiment, the nucleic acid sequence is integrated into the genome of the mouse at an ectopic position. In one embodiment, the nucleic acid sequence is integrated into the genome of the mouse at an endogenous immunoglobulin locus. In a specific embodiment, the endogenous immunoglobulin locus is a heavy chain locus. In one embodiment, the nucleic acid sequence is integrated into the genome of the mouse at a position other than an endogenous globulin locus.

In one aspect, use of the mouse as described herein for the manufacture of a medicament (e.g., an antigen—binding protein), or for the manufacture of a sequence encoding a variable sequence of a medicament (e.g., an antigen—binding protein), for the treatment of a human disease or disorder is provided.

BRIEF DESCRIPTION OF FIGURES 0] shows a general illustration, not to scale, of direct genomic replacement of about three megabases (Mb) of a mouse immunoglobulin heavy chain variable gene locus (closed symbols) with about one megabase (Mb) of the human immunoglobulin heavy chain variable gene locus (open symbols).

FiG. 1B shows a general illustration, not to scale, of direct c replacement of about three megabases (Mb) of a mouse immunoglobulin K light chain variable gene locus (closed symbols) with about 0.5 megabases (Mb) of the first, or proximal, of two nearly identical repeats of a human immunoglobulin K light chain variable gene locus (open symbols). shows a detailed illustration, not to scale, of three initial steps (A—C) for direct genomic replacement of a mouse globulin heavy chain variable gene locus that resuits in deletion of all mouse VH, DH and JH gene segments and replacement with three human VH, all human DH and JH gene segments. A targeting vector for a first insertion of human immunoglobulin heavy chain gene segments is shown (23th ) with a 67 kb 5’ mouse homology arm, a selection cassette (open rectangle), a site—specific recombination site (open triangle), a 145 kb human genomic fragment and an 8 kb 3’ mouse homology arm. Human (open symbols) and mouse (closed symbols) immunoglobulin gene ts, additional selection cassettes (open rectangles) and site— specific recombination sites (open triangles) inserted from subsequent targeting vectors are shown. shows a detailed ration, not to scale, of six additional steps (D—l) for direct genomic replacement of a mouse immunoglobulin heavy chain le gene locus that results in the insertion of 77 additional human VH gene segments and removal of a final ion cassette. A ing vector for ion of additional human VH gene segments (18hVH BACvec) to the initial ion of human heavy chain gene segments (3hVH-CRE Hybrid Allele) is shown with a 20 kb 5’ mouse homology arm, a selection cassette (open rectangle), a 196 kb human genomic fragment and a 62 kb human homology arm that overlaps with the 5’ end of the l insertion of human heavy chain gene segments which is shown with a site-specific recombination site (open triangle) located 5’ to the human gene segments. Human (open symbols) and mouse (closed symbols) immunoglobulin gene segments and onal selection cassettes (open rectangles) inserted by subsequent ing vectors are shown. shows a ed illustration, not to scale, of three initial steps (A—C) for direct genomic replacement of a mouse immunoglobulin K light chain variable gene locus that results in deletion of all mouse VK, and JK gene segments (ng-CRE Hybrid Allele).

Selection cassettes (open rectangles) and site-specific recombination sites (open triangles) inserted from the targeting vectors are shown. shows a detailed illustration, not to scale, of five additional steps (D—H) for direct genomic replacement of a mouse immunoglobulin K light chain variable gene locus that results in the insertion of all human VK and JK gene segments of the proximal repeat and deletion of a final selection cassette (40hVKdHyg Hybrid Allele). Human (open symbols) and mouse (closed symbols) immunoglobulin gene ts and additional ion tes (open rectangles) inserted by subsequent targeting vectors are shown. 6] shows a general illustration, not to scale, of a screening strategy including the ons of quantitative PCR (qPCR) primer/probe sets to detect ion of human heavy chain gene sequences and loss of mouse heavy chain gene sequences in targeted embryonic stem (ES) cells. The ing strategy in ES cells and mice for a first human heavy gene insertion is shown with qPCR primer/probe sets for the deleted region (“loss” probes C and D), the region inserted (“hlgH” probes G and H) and flanking regions (“retention” probes A, B, E and F) on an unmodified mouse some (top) and a correctly targeted chromosome (bottom). 7] shows a representative calculation of observed probe copy number in parental and modified ES cells for a first insertion of human immunoglobulin heavy chain gene segments. Observed probe copy number for probes A h F were calculated as 2/2AACt. AACt is calculated as ave[ACt(sample) - medACt(control)] where ACt is the difference in Ct between test and reference probes (between 4 and 6 reference probes depending on the assay). The term medACt(control) is the median ACt of multiple (>60) non-targeted DNA samples from parental ES cells. Each modified ES cell clone was assayed in sextuplicate. To calculate copy numbers of lgH probes G and H in parental ES cells, these probes were assumed to have copy number of 1 in modified ES cells and a maximum Ct of 35 was used even though no amplification was observed. shows a entative calculation of copy numbers for four mice of each genotype calculated using only probes D and H. Wild-type mice: WT Mice; Mice heterozygous for a first insertion of human immunoglobulin gene segments: HET Mice; Mice homozygous for a first insertion of human immunoglobulin gene segments: Homo Mice. shows a ed illustration, not to scale, of the three steps employed for construction of a 3hVH BACvec by bacterial homologous ination (BHR). Human (open symbols) and mouse (closed symbols) immunoglobulin gene ts, selection cassettes (open rectangles) and site-specific recombination sites (open triangles) inserted from targeting vectors are shown. shows pulse-field gel eiectrophoresis (PFGE) of three BAC clones (B1, 82 and B3) after Noti ion. Markers M1, M2 and M3 are low range, mid range and lambda ladder PFG markers, respectively (New England BioLabs, Ipswich, MA). shows a schematic ration, not to scale, of sequentiaI modifications of a mouse globulin heavy chain locus with increasing amounts of human immunoglobulin heavy chain gene segments. Homozygous mice were made from each of the three different stages of heavy chain humanization. Open symbols indicate human sequence; closed symbols indicate mouse sequence. 2] FIG. SB shows a schematic illustration, not to scale, of sequential modifications of a mouse immunoglobulin K light chain locus with increasing amounts of human immunoglobulin K light chain gene segments. Homozygous mice were made from each of the three different stages OfK Iight chain humanization. Open symbols te human sequence; closed symbols indicate mouse sequence. shows FACS dot plots of B cell populations in wild type and VELOCIMMUNE® humanized mice. Cells from spleen (top row, third row from top and bottom row) or inguinal lymph node (second row from top) of wild type (wt), MMUNE® 1 (V1), VELOCIMMUNE® 2 (V2) or VELOCIMMUNE® 3 (V3) mice were stained for surface lgM expressing B cells (top row, and second row from top), surface immunoglobulin containing either K or A light chains (third row from top) or surface lgM of specific haplotypes (bottom row), and pOpulations separated by FACS. shows entative heavy chain CDR3 sequences of randomly selected VELOCIMMUNE® antibodies around the VH-DH-JH (CDR3) junction, demonstrating junctional diversity and nucleotide additions. Heavy chain CDR3 sequences are grouped according to DH gene segment usage, the germline of which is ed above each group in bold. VH gene segments for each heavy chain CDR3 sequence are noted within parenthesis at the 5’ end of each sequence (9.9., 3—72 is human VH3-72). JH gene segments for each heavy chain CDR3 are noted within parenthesis at the 3’ end of each sequence (e.g., 3 is human JH3). SEQ ID N05 for each sequence shown are as follows proceeding from top to bottom: SEQ ID NO:21; SEQ ID NO:22; SEQ ID NO:23; SEQ ID N024; SEQ ID NO:25; SEQ ID N026; SEQ ID NO:27; SEQ ID N028; SEQ ID N0229; SEQ ID NO:30; SEQ ID NO:31; SEQ ID NO:32; SEQ ID NO:33; SEQ ID NO:34; SEQ ID NO:35; SEQ ID NO:36; SEQ ID NO:37; SEQ ID NO:38; SEQ ID NO:39. shows entative light chain CDR3 sequences of randomly selected VELOCIMMUNE® antibodies around the VK-JK (CDR3) junction, demonstrating junctional diversity and nucleotide additions. VK gene segments for each light chain CDR3 sequence are noted within parenthesis at the 5’ end of each sequence (9.9., 1-6 is human VK1-6). JK gene segments for each light chain CDR3 are noted within parenthesis at the 3’ end of each sequence (e.g., 1 is human JK1). SEQ ID N05 for each sequence shown are as follows proceeding from top to bottom: SEQ ID NO:40; SEQ ID NO:41; SEQ ID NO:42; SEQ ID NO:43; SEQ ID NO:44; SEQ ID NO:45; SEQ ID NO:46; SEQ ID NO:47; SEQ ID NO:48; SEQ ID NO:49; SEQ ID NO:50; SEQ ID NO:51; SEQ ID NO:52; SEQ ID NO:53; SEQ ID NO:54; SEQ ID NO:55; SEQ ID NO:56; SEQ ID NO:57; SEQ ID NO:58. shows somatic hypermutation frequencies of heavy and light chains of VELOCIMMUNE® antibodies scored (after alignment to matching germline sequences) as percent of sequences changed at each nucleotide (NT; left column) or amino acid (AA; right column) position among sets of 38 (unimmunized lgM), 28 (unimmunized lgG), 32 (unimmunized ng from lgG), 36 (immunized IgG) or 36 (immunized IgK from IgG) sequences. Shaded bars indicate the locations of CDRs. shows levels of serum globulin for lgM and lgG isotypes in wild type (open bars) or VELOCIMMUNE® mice (closed bars). shows levels of serum immunoglobulin for lgA isotype in wild type (open bars) or VELOCIMMUNE® mice (closed bars). 9] shows levels of serum immunoglobulin for lgE e in wild type (open bars) or VELOCIMMUNE® mice (closed bars).

A shows antigen—specific lgG titers against eukin-6 receptor (IL—6R) of serum from seven VELOCIMMUNE® (VI) and five wild type (WT) mice after two (bleed 1) or three (bleed 2) rounds of immunization with the main of IL-6R. 8 shows anti-lL-BR-specific lgG isotype—specific titers from seven VELOCIMMUNE® (VI) and five wild type (WT) mice.

A shows the affinity distribution of nterleukin-6 receptor monoclonal antibodies generated in VELOCIMMUNE® mice. 8 shows the antigen-specific blocking of anti-interleukin-6 receptor onal antibodies generated in VELOCIMMUNE® (VI) and wild type (WT) mice. shows a schematic illustration, not to scale, of mouse ADAMSa and ADAM6b genes in a mouse immunoglobulin heavy chain locus. A targeting vector (mADAMS Targeting Vector) used for insertion of mouse ADAMSa and ADAM6b into a humanized endogenous heavy chain locus is shown with a selection cassette (HYG: hygromycin) flanked by site-specific recombination sites (Frt) including engineered restriction sites on the 5’ and 3’ ends. shows a schematic illustration, not to scale, of a human ADAMS pseudogene (hADAMSIII) located between human heavy chain variable gene segments 1- 2 (VH1—2) and 6—1 (VHS-1). A targeting vector for bacterial homologous ination (hADAMSIIJ ing Vector) to delete a human ADAMS pseudogene and insert unique restriction sites into a human heavy chain locus is shown with a selection cassette (NEO: neomycin) d by site-specific recombination sites (loxP) including engineered restriction sites on the 5’ and 3’ ends. An illustration, not to scale, of the resulting targeted humanized heavy chain locus containing a c fragment that encodes for the mouse ADAMSa and ADAM6b genes including a selection cassette d by site-specific recombination sites is shown.

A shows FACS contour plots of lymphocytes gated on singlets for surface expression of lgM and 3220 in the bone marrow for mice homozygous for human heavy and human K light chain variable gene loci (H+/+ +/+ K ) and mice homozygous for human heavy and human K light chain variable gene loci having an ectopic mouse genomic fragment encoding mouse ADAMS genes (H+’+AS’esK+/+). Percentage of immature (BZZOm‘lgM+) and mature (BZZOhighlgM+) B cells is noted in each contour plot. 7] 8 shows the total number of immature (82205“tlgM") and mature (BZZOhighlgM+) B cells in the bone marrow ed from femurs of mice homozygous for human heavy and human K light chain variable gene loci (H+/+ +l+ K ) and mice homozygous for human heavy and human K light chain variable gene loci having an ectopic mouse genomic fragment encoding mouse ADAMS genes (H+/+A6resK+/+). 8] A shows FACS contour plots of CD19+—gated B cells for surface expression of c—kit and CD43 in the bone marrow for mice homozygous for human heavy and human K light chain variable gene loci (H +l+ +/+ K ) and mice homozygous for human heavy and human K light chain le gene loci having an ectopic mouse genomic nt encoding mouse ADAMS genes (H+’+AS’eSK+’+). Percentage of pro-B (CD19+CD43*ckit+) and pre-B (CD19+CD43'ckit') cells is noted in the upper right and lower left quadrants, respectively, of each contour plot. 9] 8 shows the total number of pro-B cells (CD19+CD43+ckit+) and pre—B cells (CD19*CD43'ckit’) in the bone marrow isolated from femurs of mice homozygous for +/+ +/+ human heavy and human K light chain variable gene loci (H K ) and mice homozygous for human heavy and human K light chain le gene loci having an ectopic mouse genomic fragment encoding mouse ADAM6 genes (H+/+A6resK+/+). 0] A shows FACS contour plots of lymphocytes gated on singlets for surface expression of CD19 and CD43 in the bone marrow for mice homozygous for +/+ +/+ human heavy and human K light chain variable gene loci (H K ) and mice homozygous for human heavy and human K light chain variable gene loci having an c mouse genomic fragment encoding mouse ADAM6 genes (H+’+A6’esK+’+). Percentage of immature B (CD19+CD43'), pre—B (CD19+CD43"“) and pro-B (CD19+CD43+) cells is noted in each contour plot. 3 shows histograms of immature B (CD19+CD43') and pre-B CD43"“) cells in the bone marrow of mice homozygous for human heavy and 4-H» + human K light chain variable gene loci (H K H) and mice homozygous for human heavy and human K light chain variable gene loci having an ectopic mouse genomic fragment encoding mouse ADAM6 genes (H+’+A6”53K+’+).

A shows FACS contour plots of lymphocytes gated on singlets for surface expression of CD19 and CD3 in splenocytes for mice homozygous for human +/+ +/+ heavy and human K light chain variable gene loci (H K ) and mice homozygous for human heavy and human K light chain variable gene loci having an ectopic mouse genomic fragment encoding mouse ADAM6 genes (H"’+A6“*SK+’+). Percentage of B (CD19+CD3') and T (CD19'CD3+) cells is noted in each contour plot.

B shows FACs r plots for CD19”-gated B cells for surface expression of lg)» and IgK light chain in the spleen of mice homozygous for human heavy +/+ +/+ and human K light chain variable gene loci (H K ) and mice homozygous for human heavy and human K light chain variable gene loci having an ectopic mouse c nt encoding mouse ADAM6 genes (H+/+A6resl( ). Percentage of ng+ (upper left quadrant) and IgK+ (lower right quadrant) B cells is noted in each contour plot.

C shows the total number of CD19" B cells in the spleen of mice homozygous for human heavy and human K light chain variable gene loci (H+/+K+l+) and mice homozygous for human heavy and human K light chain le gene loci having an c mouse genomic fragment encoding mouse ADAM6 genes 6'ESK*’*), A shows FACs contour plots of CD19-gated B cells for surface expression of lgD and lgM in the spleen of mice homozygous for human heavy and human +/+ +/+ K light chain variable gene loci (H K ) and mice homozygous for human heavy and human K Iight chain variable gene loci having an ectopic mouse genomic fragment encoding mouse ADAM6 genes (H+’+A6'eSK*’+). Percentage of mature B cells lgDhi9“|gM‘"t) is noted for each contour pIot. The arrow on the right contour pIot illustrates the process of maturation for B cells in relation to IgM and IgD surface sion. 8 shows the totaI number of B cells in the spleen of mice homozygous for human heavy and human K light chain variable gene loci (H+/+K+l+) and mice homozygous for human heavy and human K light chain variable gene loci having an ectopic mouse genomic fragment encoding mouse ADAM6 genes (H+’+A6’°SK+’+) during maturation from CD19+lngghlgDint to CD19+IgMi”tlgDmgh. shows the antibody titer for first and second bleeds from mice homozygous for human heavy and human K light chain variable gene loci (H+"‘K+’+; n=5) and mice homozygous for human heavy and human K light chain variable gene loci having an ectopic mouse c nt ng mouse ADAM6 genes (H+’+A6’eSK+’+; n=5) that were immunized with a human cell surface receptor (Antigen A). 8] shows the antibody titer for first and second bleeds from mice homozygous for human heavy and human K light chain variabIe gene loci (H*’*K+’+; n=5) and mice homozygous for human heavy and human K light chain variable gene loci having an ectopic mouse genomic fragment encoding mouse ADAM6 genes (H“’*A6'e5K*/+; n=10) that were immunized with a human antibody ic for a human receptor tyrosine-protein kinase (Antigen B). shows the dy titer for first and second bleeds from mice homozygous for human heavy and human K light chain variable gene loci (H+l+K+/+; n=12) and mice homozygous for human heavy and human K light chain variable gene loci having an ectopic mouse genomic fragment encoding mouse ADAM6 genes (H+’+A6'93K”*; n=12) that were immunized with a secreted human protein that functions in regulation of the TGF- (3 signaling pathway (Antigen C). shows the antibody titer for first and second bleeds from mice gous for human heavy and human K light chain variable gene loci having an ectopic mouse genomic fragment encoding mouse ADAM6 genes (H+’+A6'eSK*’+; n=12) that were immunized with a human reCeptor ne kinase (Antigen D).

DETAILED DESCRIPTION OF INVENTION This invention is not limited to particular methods, and experimental conditions described, as such methods and conditions may vary. It is aIso to be understood that the terminoiogy used herein is for the e of describing particular embodiments only, and is not intended to be limiting, since the scope of the present invention is defined by the claims.

Unless d otherwise, all terms and phrases used herein include the meanings that the terms and phrases have ed in the art, unless the contrary is clearly indicated or clearly apparent from the t in which the term or phrase is used.

Although any methods and materials similar or equivalent to those described herein can be used in the practice or testing of the present invention, particular methods and materials are now described. All publications mentioned are hereby incorporated by reference.

The phrase “substantial” or “substantially” when used to refer to an amount of gene segments (e.g., “substantially all” V gene segments) includes both functional and non functional gene segments and include, in various ments, 9.9., 80% or more, 85% or more, 90% or more, 95% or more 96% or more, 97% or more, 98% or more, or 99% or more of all gene segments; in various embodiments, “substantially all” gene segments includes, 6.9., at least 95%, 96%, 97%, 98%, or 99% of functional (i.e., non-pseudogene) gene segments.

The term “replacement” includes n a DNA sequence is placed into a genome of a cell in such a way as to replace a sequence within the genome with a heterologous ce (e.g., a human sequence in a mouse), at the locus of the genomic sequence. The DNA sequence so placed may include one or more tory sequences that are part of source DNA used to obtain the sequence so placed (e.g., promoters, enhancers, 5’— or 3’-untranslated regions, appropriate recombination signal ces, etc). For example, in various embodiments, the replacement is a tution of an endogenous sequence for a heterologous sequence that results in the production of a gene product from the DNA sequence so placed (comprising the heterologous sequence), but not expression of the endogenous sequence; the replacement is of an endogenous genomic sequence with a DNA sequence that encodes a protein that has a similar function as a n encoded by the endogenous genomic sequence (e.g., the endogenous genomic sequence encodes an immunoglobulin gene or , and the DNA nt encodes one or more human immunogiobulin genes or domains). In various embodiments, an endogenous gene or fragment thereof is ed with a corresponding human gene or fragment thereof. A corresponding human gene or fragment thereof is a human gene or fragment that is an ortholog of, a homolog of, or is substantially cal or the same in structure and/or function, as the endogenous gene or fragment thereof that is replaced.

The mouse as a genetic model has been greatly enhanced by transgenic and knockout technologies, which have allowed for the study of the effects of the directed over- expression or deletion of specific genes. Despite all of its advantages, the mouse still presents c obstacles that render it an imperfect model for human diseases and an imperfect platform to test human therapeutics or make them. First, although about 99% of human genes have a mouse homolog ston et al. 2002, lnitial sequencing and comparative analysis of the mouse genome, Nature 420:520—562), potential therapeutics often fail to cross-react, or cross-react inadequately, with mouse orthologs of the intended human targets. To obviate this problem, selected target genes can be “humanized,” that is, the mouse gene can be eliminated and replaced by the corresponding human orthologous gene sequence (e.g., US 251, US 6,596,541 and US 7,105,348, incorporated herein by reference). Initially, s to humanize mouse genes by a “knockout-plus—transgenic humanization” strategy entailed crossing a mouse carrying a deletion (i.e., knockout) of the nous gene with a mouse carrying a randomly integrated human transgene (see, 6.9., Bril et al., 2006, Tolerance to factor Vlll in a enic mouse expressing human factor Vlll cDNA carrying an Arg(593) to Cys substitution, Thromb Haemost 95:341-347; Homanics et al., 2006, Production and characterization of murine models of classic and intermediate maple syrup urine disease, BMC Med Genet 7:33; Jamsai et al., 2006, A humanized BAC transgenic/knockout mouse model for HbE/beta—thalassemia, Genomics 88(3):309-15; Pan et al., 2006, Different role for mouse and human CD3delta/epsilon heterodimer in preT cell receptor (preTCR) function:human CD3deIta/epsilon dimer restores the defective preTCR function in CDSQamma- and CD39ammadelta-deficient mice, Mol Immunol 43:1741-1750). But those efforts were hampered by size limitations; conventional knockout logies were not sufficient to directly replace large mouse genes with their large human genomic rparts. A straightforward approach of direct homologous ement, in which an endogenous mouse gene is directly replaced by the human rpart gene at the same precise genetic location of the mouse gene (i.e., at the endogenous mouse locus), is rarely attempted because of technical difficulties. Until now, efforts at direct ement involved elaborate and burdensome procedures, thus limiting the length of genetic material that could be handled and the precision with which it could be manipulated. ously uced human immunoglobulin transgenes rearrange in precursor B cells in mice (Alt et al., 1985, lmmunoglobulin genes in transgenic mice, Trends Genet 1:231—236). This finding was exploited by engineering mice using the knockout—plus—transgenic approach to express human antibodies (Green et al., 1994, Antigen-specific human monoclonal antibodies from mice engineered with human lg heavy and light chain YACs, Nat Genet 7:13-21; Lonberg et al., 1994, Antigen-specific human antibodies from mice comprising four distinct c modifications, Nature 368:856-859; Jakobovits et al., 2007, From XenoMouse technology to panitumumab, the first fully human antibody product from transgenic mice, Nat Biotechnol25:1134-1143). The mouse immunoglobulin heavy chain and K light chain loci were inactivated in these mice by targeted deletion of small but critical portions of each endogenous locus, followed by introducing human immunoglobulin gene loci as randomly integrated large transgenes, as described above, or minichromosomes (Tomizuka et al., 2000, Double trans-chromosomic mice: maintenance of two individual human chromosome fragments containing lg heavy and kappa loci and expression of fully human dies, PNAS USA 972722-727). Such mice represented an important e in genetic engineering; fully human monoclonal antibodies isolated from them yielded promising eutic potential for treating a variety of human diseases (Gibson et al., 2006, ized phase Ill trial results of panitumumab, a fully human anti-epidermal growth factor receptor monoclonal antibody, in metastatic colorectal cancer, Clin Colorectal Cancer 6:29—31; Jakobovits et al., 2007; Kim et al., 2007, Clinical efficacy of zanolimumab (HuMax-CD4): two Phase II studies in refractory cutaneous T-cell lymphoma, Blood 109(11):4655—62; Lonberg, 2005, Human antibodies from transgenic animals, Nat hnol23z11 17-1125; Maker et al., 2005, Tumor regression and autoimmunity in patients treated with cytotoxic T lymphocyte- associated antigen 4 blockade and eukin 2: a phase II” study, Ann Surg Oncol 12:1005-1016; McClung et al., 2006, Denosumab in postmenopausal women with low bone mineral density, New Engl J Med 354:821-831). But, as discussed above, these mice exhibit compromised B cell development and immune deficiencies when compared to wild type mice. Such problems potentially limit the ability of the mice to support a vigorous l response and, consequently, generate fully human antibodies against some antigens. The deficiencies may be due to: (1) inefficient functionality clue to the random introduction of the human immunoglobulin enes and ing incorrect expression due to a lack of upstream and downstream control elements (Garrett et al., 2005, Chromatin architecture near a potential 3' end of the lgH locus involves modular regulation of e modifications during B-Cell pment and in vivo occupancy at CTCF sites, MOI Cell Biol 252151 1-1525; Manis et al., 2003, Elucidation of a downstream boundary of the 3' lgH regulatory region, Mol Immunol 392753-760; Pawlitzky et al., 2006, identification of a candidate tory element within the 5' flanking region of the mouse lgH locus defined by pro-B cell-specific hypersensitivity associated with binding of PU.1, Pax5, and E2A, J Immunol 39—6851); (2) inefficient pecies interactions between human nt domains and mouse components of the B—cell receptor ing complex on the cell surface, which may impair signaling processes required for normal maturation, proliferation, and survival of B cells ch et al., 1990, Molecular components of the B- cell antigen receptor x of the lgM class, Nature 343:760-762); and (3) inefficient interspecies interactions between soluble human immunoglobulins and mouse PC receptors that might reduce affinity selection (Rao et al., 2002, Differential expression of the inhibitory lgG Fc receptor chammaRllB on germinal center cells: implications for selection of high-affinity B cells, J Immunol 169:1859-1868) and immunoglobulin serum concentrations (Brambell et a/., 1964, A Theoretical Model of Gamma-Globulin Catabolism, Nature 203:1352-1354; Junghans and Anderson, 1996, The protection receptor for IgG catabolism is the beta2-microglobulin-containing neonatal inal transport receptor, PNAS USA 2-5516; Rao et 3]., 2002; Hjelm et a/., 2006, Antibody-mediated regulation of the immune response, Scand J l 64:177-184; Nimmerjahn and Ravetch, 2007, Fc—receptors as regulators of immunity, Adv Immunol 96:179-204). These deficiencies can be corrected by in situ humanization of only the variable s of the mouse immunoglobulin loci within their natural locations at the endogenous heavy and light chain loci. This would effectively result in mice that make “reverse ic” (i.e., human Vzmouse C) antibodies which would be capable of normal ctions and selection with the mouse environment based on retaining mouse constant regions. Further such reverse chimeric antibodies may be y reformatted into fully human antibodies for therapeutic cally modified animals that comprise a replacement at the endogenous immunogtobulin heavy chain locus with heterologous (e.g., from another species) immunoglobulin sequences can be made in ction with replacements at endogenous immunoglobulin light chain loci or in conjunction with immunoglobulin tight chain transgenes (e.g., chimeric immunoglobulin light chain transgenes or fully human fully mouse, etc.) The species from which the heterologous immunoglobulin heavy chain sequences are derived can vary widely; as with immunoglobulin light chain sequences ed in immunoglobulin light chain sequence replacements or immunoglobulin light chain transgenes. lmmunoglobulin le region nucleic acid sequences, 9.9., V, D, and/or J segments, are in various embodiments obtained from a human or a non—human animal.

Non—human s suitable for providing V, D, and/or J segments include, for example bony fish, cartilaginous fish such as sharks and rays, ians, reptiles, mammals, birds (e.g., chickens). Non-human animals include, for example, mammals. Mammals include, for exampie, non-human primates, goats, sheep, pigs, dogs, bovine (e.g., cow, bull, buffalo), deer, camels, ferrets and rodents and non-human primates (e.g., chimpanzees, tans, gorillas, marmosets, rhesus monkeys baboons). Suitable non-human animals are selected from the rodent family including rats, mice, and hamsters. in one embodiment, the non-human animals are mice. As clear from the context, various non- human animais can be used as sources of variable domains or variable region gene segments (e.g., , rays, mammals (e.g., camels, rodents such as mice and rats).

According to the context, non-human animals are also used as sources of nt region sequences to be used in connection with variable ces or segments, for example, rodent constant ces can be used in transgenes operably linked to human or non-human variable sequences (e.g., human or man primate variable ces operably linked to, e.g., rodent, e.g., mouse or rat or hamster, constant sequences). Thus, in various embodiments, human V, D, and/or J segments are operably linked to rodent (e.g., mouse or rat or hamster) constant region gene sequences. In some embodiments, the human V, D, and/or J segments (or one or more rearranged VDJ or VJ genes) are operably linked or fused to a mouse, rat, or hamster constant region gene sequence in, 9.9., a transgene integrated at a locus that is not an endogenous immunoglobulin locus. in a specific embodiment, a mouse is provided that comprises a replacement of VH, DH, and JH segments at an nous immunoglobulin heavy chain locus with one or more human VH, DH, and JH ts, wherein the one or more human VH, DH, and JH segments are operably linked to an endogenous globulin heavy chain gene; wherein the mouse comprises a transgene at a locus other than an endogenous globulin locus, wherein the transgene comprises an unrearranged or rearranged human VL and human JL segment operably linked to a mouse or rat or human constant region.

A method for a large in situ genetic replacement of the mouse germline immunoglobulin variable gene loci with human germline immunoglobulin variable gene loci while maintaining the ability of the mice to generate ing is described. Specifically, the precise replacement of six megabases of both the mouse heavy chain and K light chain immunoglobulin variable gene loci with their human counterparts while leaving the mouse constant regions intact is described. As a result, mice have been created that have a e ement of their entire germline immunoglobulin variable repertoire with equivalent human germline immunoglobulin variable sequences, while maintaining mouse constant regions. The human variable regions are linked to mouse constant regions to form chimeric human—mouse immunoglobulin loci that nge and express at physiologically appropriate levels. The antibodies expressed are “reverse chimeras,” i.e., they comprise human variable region sequences and mouse constant region ces.

These mice having humanized immunoglobulin variable regions that express antibodies having human variable regions and mouse constant regions are called VELOCIMMUNE® mice.

VELOCIMMUNE® humanized mice exhibit a fully functional humoral immune system that is essentially indistinguishable from that of wild-type mice. They display normal cell populations at all stages of B cell development. They t normal lymphoid organ logy. Antibody sequences of VELOCIMMUNE® mice exhibit normal V(D)J rearrangement and normal somatic hypermutation frequencies. Antibody tions in these mice reflect isotype distributions that result from normal class switching (6.9., normal isotype cis-switching). immunizing VELOCIMMUNE® mice results in robust humoral immune responses that generate a large, diverse antibody repertoires having human immunoglobulin variable domains suitable for use as therapeutic candidates. This platform provides a plentiful source of naturally affinity-matured human immunoglobulin variable region sequences for making pharmaceutically acceptable antibodies and other n- binding proteins. it is the precise ement of mouse immunoglobulin variable sequences with human immunoglobulin variable sequences that allows for making VELOCIMMUNE® mice.

Yet even a precise replacement of endogenous mouse immunoglobulin sequences at heavy and light chain loci with equivalent human immunoglobulin sequences, by sequential ineering of very large spans of human immunoglobulin sequences, may present certain challenges due to divergent evolution of the globulin loci between mouse and man. For example, intergenic sequences interspersed within the immunoglobulin loci are not identical n mice and humans and, in some circumstances, may not be functionally equivalent. Differences between mice and humans in their immunoglobulin loci can still result in abnormalities in humanized mice, particularly when humanizing or manipulating certain portions of endogenous mouse immunoglobulin heavy chain loci.

Some modifications at mouse globulin heavy chain loci are deleterious.

Deleterious modifications can include, for example, loss of the ability of the modified mice to mate and produce offspring.

A precise, scale, in situ replacement of six megabases of the variable s of the mouse heavy and light chain immunoglobulin loci (VH—DH-JH and VK-JK) with the corresponding 1.4 megabases human genomic sequences was performed, while g the ng mouse sequences intact and functional within the hybrid loci, including all mouse constant chain genes and locus transcriptional control regions ( and ). Specifically, the human VH, DH, JH, VK and JK gene sequences were introduced through stepwise insertion of 13 chimeric BAC targeting vectors bearing overlapping fragments of the human germline variable loci into mouse ES cells using VELOClGENE® genetic engineering technology (see, 9.9., US Pat. No. 6,586,251 and Valenzuela et al., 2003, High-throughput engineering of the mouse genome d with high-resolution expression analysis, Nat Biotechnol 21:652-659).

Humanization of the mouse globulin genes represents the largest genetic modification to the mouse genome to date. While previous efforts with randomly integrated human immunoglobulin transgenes have met with some success (discussed above), direct replacement of the mouse immunoglobulin genes with their human counterparts dramatically increases the efficiency with which fully-human dies can be efficiently generated in otherwise normal mice. Further, such mice exhibit a dramatically increased diversity of fully human antibodies that can be obtained after immunization with lly any antigen, as compared with mice bearing disabled endogenous loci and fully human antibody transgenes. Multiple versions of replaced, zed loci exhibit completely normal levels of mature and re B cells, in contrast to mice with randomly integrated human transgenes, which exhibit significantly reduced B cell populations at various stages of differentiation. While efforts to increase the number of human gene segments in human transgenic mice have reduced such defects, the expanded immunoglobulin oires have not altogether ted reductions in B cell populations as ed to wild-type mice.

Notwithstanding the near wild-type humoral immune function observed in mice with replaced immunoglobulin loci (i.e., VELOCIMMUNE® mice), there are other challenges encountered when employing a direct replacement of the immunoglobulin that is not encountered in some approaches that employ randomly integrated transgenes.

Differences in the genetic composition of the immunoglobulin loci between mice and humans has lead to the discovery of sequences beneficial for the propagation of mice with replaced immunoglobulin gene ts. ically, mouse ADAM genes located within the nous globulin locus are optimally present in mice with replaced immunoglobulin loci, due to their role in fertility.

Genomic Location and Function of Mouse ADAM6 Male mice that lack the ability to express any functional ADAM6 protein surprisingly exhibit a defect in the ability of the mice to mate and to generate offspring.

The mice lack the ability to express a functional ADAM6 protein by virtue of a replacement of all or substantially all mouse globulin variable region gene segments with human variable region gene segments. The loss of ADAM6 function results because the ADAM6 locus is located within a region of the endogenous mouse immunoglobulin heavy chain variable region gene locus, proximal to the 3’ end of the VH gene segment locus that is upstream of the DH gene segments. In order to breed mice that are homozygous for a replacement of all or substantially all endogenous mouse heavy chain variable gene segments with human heavy chain variable gene segments, it is generally a some ch to set up males and females that are each homozygous for the replacement and await a productive mating. Successful litters are low in frequency and size. d, males heterozygous for the replacement have been employed to mate with s homozygous for the replacement to generate progeny that are heterozygous for the replacement, then breed a homozygous mouse rom. The inventors have determined that the likely cause of the toss in fertility in the male mice is the absence in homozygous male mice of a functional ADAMS protein.

In various aspects, male mice that comprise a damaged (is, nonfunctional or marginally functional) ADAMS gene exhibit a reduction or elimination of ity. Because in mice (and other rodents) the ADAMS gene is d in the immunoglobulin heavy chain locus, the inventors have determined that in order to propagate mice, or create and maintain a strain of mice, that comprise a ed immunoglobulin heavy chain locus, various modified breeding or propagation schemes are employed. The low ity, or infertility, of male mice homozygous for a replacement of the endogenous immunoglobulin heavy chain variable gene locus s maintaining such a modification in a mouse strain difficult. In various embodiments, ining the strain comprises avoiding infertility problems exhibited by male mice gous for the replacement.

In one aspect, a method for maintaining a strain of mouse as described herein is provided. The strain of mouse need not comprise an ectopic ADAMS ce, and in various embodiments the strain of mouse is homozygous or heterozygous for a knockout (6.9., a functional knockout) of ADAMS.

The mouse strain comprises a modification of an endogenous immunoglobulin heavy chain locus that results in a reduction or loss in ity in a male mouse. In one embodiment, the modification comprises a deletion of a regulatory region and/or a coding region of an ADAMS gene. In a specific embodiment, the modification comprises a modification of an endogenous ADAMS gene (regulatory and/or coding region) that reduces or eliminates fertility of a male mouse that comprises the modification; in a specific embodiment, the modification reduces or eliminates fertility of a male mouse that is homozygous for the modification.

In one embodiment, the mouse strain is homozygous or heterozygous for a knockout (e.g., a functional knockout) or a on of an ADAMS gene.

In one embodiment, the mouse strain is maintained by isolating from a mouse that is homozygous or zygous for the modification a cell, and employing the donor cell in host embryo, and gestating the host embryo and donor cell in a surrogate mother, and obtaining from the surrogate mother a progeny that comprises the genetic cation. In one embodiment, the donor cell is an ES cell. In one embodiment, the donor cell is a pluripotent cell, 6.9., an induced pluripotent cell.

In one embodiment, the mouse strain is maintained by ing from a mouse that is homozygous or heterozygous for the modification a nucIeic acid sequence comprising the modification, and introducing the nucleic acid sequence into a host nucleus, and gestating a cell comprising the nucleic acid ce and the host nucleus in a suitable animal. in one embodiment, the nucleic acid sequence is introduced into a host oocyte embryo.

In one embodiment, the mouse strain is maintained by isolating from a mouse that is homozygous or heterozygous for the modification a nucleus, and introducing the nucleus into a host cell, and ing the nucleus and host cell in a suitable animal to obtain a progeny that is homozygous or heterozygous for the modification. in one embodiment, the mouse strain is maintained by employing in vitro fertilization (IVF) of a female mouse (wild-type, homozygous for the modification, or heterozygous for the cation) employing a sperm from a male mouse comprising the genetic modification. In one embodiment, the male mouse is heterozygous for the genetic modification. In one embodiment, the male mouse is homozygous for the genetic modification.

In one embodiment, the mouse strain is maintained by breeding a male mouse that is heterozygous for the genetic modiﬁcation with a female mouse to obtain progeny that comprises the genetic modification, identifying a male and a female progeny sing the genetic modification, and employing a male that is heterozygous for the genetic cation in a breeding with a female that is wild-type, homozygous, or heterozygous for the genetic modification to obtain progeny comprising the genetic modification. ln one embodiment, the step of breeding a male heterozygous for the genetic modification with a wild-type female, a female heterozygous for the genetic modification, or a female homozygous for the genetic modification is repeated in order to maintain the genetic modification in the mouse strain.

In one aspect, a method is provided for maintaining a mouse strain that comprises a replacement of an endogenous immunoglobulin heavy chain variable gene locus with one or more human immunoglobulin heavy chain sequences, comprising ng the mouse strain so as to generate heterozygous male mice, n the heterozygous male mice are bred to maintain the c modification in the strain. In a specific ment, the strain is not maintained by any breeding of a homozygous male with a wild-type female, or a female homozygous or heterozygous for the genetic modification.

The ADAMB protein is a member of the ADAM family of proteins, where ADAM is an acronym for A Disintegrin And Metalloprotease. The ADAM family of proteins is large and e, with diverse functions ing cell adhesion. Some members of the ADAM family are implicated in spermatogenesis and fertilization. For example, ADAMZ encodes a subunit of the protein fertilin, which is ated in sperm-egg interactions. ADAM3, or cyritestin, appears ary for sperm binding to the zona pellucida. The absence of either ADAM2 or ADAM3 results in infertility. it has been postulated that ADAMZ, ADAM3, and ADAM6 form a complex on the e of mouse sperm cells. The human ADAM6 gene, normally found between human VH gene segments VH1-2 and VH6-1, appears to be a pseudogene (Figure 12). In mice, there are two ADAM6 genes—ADAM6a and ADAM6b—that are found in an intergenic region between mouse VH and DH gene segments, and in the mouse the ADAMGa and ADAM6b genes are oriented in opposite transcriptional orientation to that of the surrounding immunoglobulin gene ts (). In mice, a functional ADAM6 locus is ntly required for normal ization. A functional ADAM6 locus or ce, then, refers to an ADAM6 locus or sequence that can complement, or rescue, the drastically reduced fertilization exhibited in male mice with missing or nonfunctional endogenous ADAM6 loci.

The position of the enic sequence in mice that encodes ADAM6a and ADAM6b renders the intergenic sequence susceptible to modification when modifying an endogenous mouse heavy chain. When VH gene segments are deleted or replaced, or when DH gene segments are deleted or replaced, there is a high probability that a resulting mouse will exhibit a severe deficit in ity. In order to compensate for the t, the mouse is modified to include a tide sequence that encodes a protein that will ment the loss in ADAM6 activity due to a modification of the endogenous mouse ADAM6 locus. In various embodiments, the complementing nucleotide sequence is one that encodes a mouse ADAMBa, a mouse ADAM6b, or a g or ortholog or functional fragment thereof that rescues the fertility deficit.

The nucleotide sequence that s fertility can be placed at any suitable position. it can be placed in the intergenic region, or in any suitable position in the genome (i.e., ectopically). In one embodiment, the nucleotide sequence can be introduced into a transgene that randomly integrates into the mouse genome. in one embodiment, the sequence can be maintained episomally, that is, on a separate c acid rather than on a mouse chromosome. Suitable positions include positions that are transcriptionally permissive or active, e.g., a ROSA26 locus (Zambrowicz et al., 1997, PNAS USA 94:3789- 3794), a BT-5 locus (Michael et al., 1999, Mech. Dev. 85:35-47), or an Oct4 locus (Wallace et al., 2000, Nucleic Acids Res. 28:1455-1464). Targeting nucleotide sequences to riptionally active loci are described, 6.9., in US 7,473,557, herein incorporated by reference.

Alternatively, the nucleotide sequence that rescues fertility can be coupled with an inducible promoter so as to facilitate optimal sion in the appropriate cells and/or s, e.g., reproductive tissues. Exemplary inducible promoters include promoters activated by physical (9.9., heat shock promoter) and/or chemical means (e.g,, lPTG or Tetracycline).

Further, expression of the nucleotide sequence can be linked to other genes so as to achieve expression at specific stages of development or within speciﬁc s. Such expression can be achieved by placing the nucleotide sequence in operable linkage with the promoter of a gene expressed at a ic stage of development. For example, immunoglobulin sequences from one species engineered into the genome of a host species are place in operable linkage with a er sequence of a CD19 gene (a B cell ic gene) from the host species. B cell-specific expression at precise developmental stages when immunoglobulins are expressed is achieved.

Yet another method to achieve robust expression of an inserted nucleotide sequence is to employ a constitutive promoter. ary constitutive promoters include SV40, CMV, UBC, EFlA, PGK and CAGG. In a similar fashion, the desired tide sequence is placed in operable linkage with a selected constitutive promoter, which provides high level of expression of the protein(s) encoded by the nucleotide sequence.

The term “ectOpic” is ed to e a displacement, or a placement at a position that is not normally encountered in nature (e.g., placement of a nucleic acid sequence at a position that is not the same on as the nucleic acid sequence is found in a wild-type mouse). The term, in various embodiments, is used in the sense of its object being out of its normal, or proper, position. For e, the phrase “an ectopic nucleotide sequence encoding...” refers to a nucleotide sequence that appears at a position at which it is not ly encountered in the mouse. For example, in the case of an ectopic nucleotide sequence encoding a mouse ADAM6 protein (or an ortholog or homolog or fragment thereof that provides the same or similar fertility benefit on male mice), the sequence can be placed at a different position in the mouse’s genome than is normally found in a wild-type mouse. ln such cases, novel sequence junctions of mouse sequence will be created by placing the sequence at a different position in the mouse’s genome than in a wild-type mouse. A onal homolog or ortholog of mouse ADAM6 is a sequence that confers a rescue of fertility loss (e.g., loss of the ability of a male mouse to te offspring by mating) that is observed in an ADAM6“ mouse. Functional homologs or orthologs include proteins that have at least about 89% identity or more, 6.9., up to 99% identity, to the amino acid sequence of ADAM6a and/or to the amino acid sequence of ADAM6b, and that can complement, or rescue ability to successfully mate, of a mouse that has a genotype that includes a deletion or knockout of ADAM6a and/or ADAMBb.

] The ectopic on can be anywhere (9.9., as with random insertion of a transgene containing a mouse ADAM6 sequence), or can be, 6.9., at a position that approximates (but is not precisely the same as) its location in a ype mouse (9.9., in a modified endogenous mouse immunoglobulin locus, but either upstream or downstream of its natural position, 9.9., within a modified immunoglobulin locus but between different gene segments, or at a different position in a mouse V-D intergenic sequence). One example of an ectopic placement is placement within a humanized immunoglobulin heavy chain locus.

For example, a mouse comprising a replacement of one or more endogenous VH gene ts with human VH gene ts, wherein the replacement removes an endogenous ADAM6 sequence, can be engineered to have a mouse ADAM6 ce located within a ce that contains the human VH gene segments. The resulting modification would generate a (ectopic) mouse ADAM6 sequence within a human gene sequence, and the ic) placement of the mouse ADAM6 sequence within the human gene sequence can approximate the position of the human ADAM6 pseudogene (ie., between two V segments) or can approximate the position of the mouse ADAM6 sequence (i.e., within the V-D intergenic region). The resulting sequence junctions d by the joining of a (ectopic) mouse ADAM6 sequence within or adjacent to a human gene sequence (9.9., an immunoglobulin gene sequence) within the ne of the mouse would be novel as ed to the same or similar position in the genome of a wild-type mouse.

In various embodiments, non-human animals are ed that lack an ADAM6 or ortholog or homolog thereof, wherein the lack renders the man animal infertile, or substantially reduces fertility of the non-human . in various embodiments, the lack of ADAM6 or ortholog or homolog thereof is due to a modification of an endogenous immunoglobulin heavy chain locus. A substantial reduction in fertility is, e.g., a reduction in fertility (e.g., breeding frequency, pups per litter, litters per year, etc.) of about 50%, 60%, 70%, 80%, 90%, or 95% or more. in various embodiments, the non-human animals are supplemented with a mouse ADAM6 gene or ortholog or g or onal fragment thereof that is functional in a male of the non—human animal, wherein the supplemented ADAM6 gene or ortholog or homolog or functional fragment thereof rescues the reduction in fertility in whole or in substantial part. A rescue of fertility in substantial part is, 9.9., a restoration of fertility such that the non-human animal ts a fertility that is at least 70%, 80%, or 90% or more as compared with an unmodified (i.e., an animal without a modification to the ADAM6 gene or ortholog or homolog thereof) heavy chain locus.

The sequence that confers upon the genetically modified animal (i.e., the animal that lacks a functional ADAM6 or ortholog or homolog thereof, due to, 9.9., a modification of a immunoglobulin heavy chain locus) is, in various embodiments, ed from an ADAM6 gene or ortholog or g thereof. For example, in a mouse, the loss of ADAM6 function is rescued by adding, in one embodiment, a mouse ADAM6 gene. In one embodiment, the loss of ADAM6 function in the mouse is rescued by adding an ortholog or homolog of a closely related specie with respect to the mouse, 69., a rodent, 9.9., a mouse of a different strain or species, a rat of any species, a rodent; wherein the addition of the ortholog or homolog to the mouse rescues the loss of ity due to loss of ADAMS function or loss of an ADAMS gene. Orthologs and homologs from other species, in s embodiments, are selected from a phylogenetically related species and, in various embodiments, exhibit a t identity with the endogenous ADAMS (or ortholog) that is about 80% or more, 85% or more, 90% or more, 95% or more, 96% or more, or 97% or more; and that rescue ADAMS-related or (in a non-mouse) ADAMS og-related loss of fertility. For example, in a cally modified male rat that lacks ADAMS function (9.9., a rat with an endogenous immunoglobulin heavy chain variable region replaced with a human immunoglobulin heavy chain variable region, or a knockout in the rat immunoglobulin heavy chain region), loss of fertility in the rat is rescued by addition of a rat ADAMS or, in some embodiments, an ortholog of a rat ADAMS (e.g., an ADAMS ortholog from another rat strain or species, or, in one embodiment, from a mouse).

Thus, in various embodiments, cally modified animals that exhibit no fertility or a reduction in fertility due to modification of a nucleic acid sequence encoding an ADAMS protein (or ortholog or homolog thereof) or a tory region operably linked with the nucleic acid sequence, comprise a nucleic acid sequence that complements, or restores, the loss in fertility where the nucleic acid sequence that complements or restores the loss in ity is from a ent strain of the same species or from a phylogenetically d species. In various embodiments, the complementing nucleic acid sequence is an ADAMS ortholog or homolog or functional fragment thereof. In various embodiments, the complementing ADAMS ortholog or homolog or functional fragment thereof is from a non- human animal that is closely related to the genetically modified animal having the fertility defect. For example, where the genetically modified animal is a mouse of a particular strain, an ADAMS ortholog or homolog or functional fragment thereof can be ed from a mouse of another strain, or a mouse of a related species. In one embodiment, where the cally modified animal comprising the ity defect is of the order Rodentia, the ADAMS ortholog or homolog or functional fragment thereof is from another animal of the order Rodentia. In one embodiment, the genetically modiﬁed animal comprising the fertility defect is of a suborder Myomoropha (e.g., jerboas, jumping mice, like hamsters, hamsters, New World rats and mice, voles, true mice and rats, gerbils, spiny mice, crested rats, climbing mice, rock mice, white-tailed rats, malagasy rats and mice, spiny e, mole rats, bamboo rats, zokors), and the ADAMS ortholog or homolog or functional nt thereof is selected from an animal of order Rodentia, or of the er Myomorpha. in one embodiment, the genetically modified animal is from the superfamily Dipodoidea, and the ADAMS ortholog or homolog or functional fragment thereof is from the superfamily Muroidea. in one embodiment, the genetically modified animal is from the amily Muroidea, and the ADAMS og or homolog or functional fragment thereof is from the superfamily idea. in one embodiment, the genetically modified animal is a rodent. In one embodiment, the rodent is selected from the superfamily Muroidea, and the ADAMS ortholog or homolog is from a different species within the superfamily Muroidea. in one embodiment, the genetically modified animal is from a family ed from Calomyscidae (e.9., mouse-like hamsters), Cricetidae (e.9., hamster, New World rats and mice, voles), Muridae (true mice and rats, gerbils, spiny mice, crested rats), idae (climbing mice, rock mice, with-tailed rats, sy rats and mice), Platacanthomyidae (e.9., spiny dormice), and Spalacidae (e.9., mole rates, bamboo rats, and zokors); and the ADAMS ortholog or homolog is selected from a different species of the same family. In a specific embodiment, the genetically modified rodent is selected from a true mouse or rat (family Muridae), and the ADAMS ortholog or homolog is from a species selected from a , spiny mouse, or crested rat. in one embodiment, the genetically modified mouse is from a member of the family Muridae, and the ADAMS ortholog or homolog is from a different species of the family Muridae. in a specific embodiment, the cally modified rodent is a mouse of the family e, and the ADAMS ortholog or homolog is from a rat, , spiny mouse, or crested rat of the family Muridae.

In various embodiments, one or more rodent ADAMS orthologs or homologs or functional fragments thereof of a rodent in a family es ity to a genetically modified rodent of the same family that lacks an ADAMS ortholog or homolog (e.9., Cricetidae (e.9., hamsters, New World rats and mice, voles); Muridae (e.9., true mice and rats, gerbils, spiny mice, crested rats)).

In various ments, ADAMS orthologs, homologs, and nts thereof are assessed for functionality by ascertaining r the ortholog, homolog, or fragment restores fertility to a genetically modiﬁed male non—human animal that lacks ADAMS activity (9.9., a rodent, e.9., a mouse or rat, that comprises a knockout of ADAMS or its ortholog). in various embodiments, functionality is defined as the ability of a sperm of a genetically modified animal lacking an endogenous ADAMS or ortholog or g thereof to migrate an t and fertilize an ovum of the same specie of genetically modified animal. in various aspects, mice that comprise deletions or replacements of the endogenous heavy chain variable region locus or portions thereof can be made that contain an ectopic nucleotide sequence that encodes a protein that confers similar fertility benefits to mouse ADAMS (9.9., an ortholog or a homolog or a fragment thereof that is onal in a male mouse). The ectopic nucleotide sequence can include a nucleotide sequence that encodes a protein that is an ADAMS homolog or ortholog (or fragment thereof) of a different mouse strain or a different species, 9.9., a different rodent s, and that s a t in fertility, e.g., increased number of litters over a ied time period, and/or increased number of pups per litter, and/or the ability of a sperm cell of a male mouse to traverse through a mouse oviduct to fertilize a mouse egg. in one embodiment, the ADAM6 is a homolog or ortholog that is at least 89% to 99% identical to a mouse ADAM6 protein (e.g., at least 89% to 99% identical to mouse ADAM6a or mouse ADAMBb). In one embodiment, the c nucleotide sequence encodes one or more ns independently ed from a protein at least 89% identical to mouse ADAM6a, a protein at least 89% identical to mouse ADAMGb, and a combination thereof. In one embodiment, the homolog or ortholog is a rat, hamster, mouse, or guinea pig protein that is or is modified to be about 89% or more identical to mouse ADAM6a and/or mouse ADAM6b. in one embodiment, the homolog or ortholog is or is at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% identical to a mouse ADAM6a and/or mouse .

Ectopic ADAM6 in Humanized Heavy Chain Mice Developments in gene targeting, e.g., the development of bacterial artificial chromosomes (BACs), now enable the recombination of relatively large genomic fragments. BAC engineering has allowed for the ability to make large deletions, and large insertions, into mouse ES cells.

Mice that make human antibodies have been available for some time now.

Although they represent an important advance in the development of human therapeutic antibodies, these mice display a number of icant abnormalities that limit their usefulness. For example, they display compromised B cell pment. The compromised development may be due to a variety of differences between the transgenic mice and wild—type mice.

Human antibodies might not optimally ct with mouse pre B cell or B cell receptors on the surface of mouse cells that signal for maturation, proliferation, or al during clonal selection. Fully human antibodies might not optimally ct with a mouse Fc receptor system; mice express Fc receptors that do not display a one~to-one correspondence with human Fc receptors. Finally, various mice that make fully human antibodies do not include all genuine mouse sequences, e.g., downstream enhancer elements and other locus control elements, which may be required for wild-type B cell development.

Mice that make fully human antibodies generally se endogenous immunoglobulin loci that are disabled in some way, and human transgenes that comprise variable and constant immunoglobulin gene segments are introduced into a random location in the mouse genome. As long as the endogenous locus is sufficiently disabled so as not to nge gene segments to form a functional immunoglobulin gene, the goal of making fully human antibodies in such a mouse can be achieved—albeit with compromised B cell development.

Although compelled to make fully human antibodies from the human transgene locus, generating human antibodies in a mouse is apparently an unfavored process. in some mice, the process is so unfavored as to result in formation of chimeric human variable/mouse constant heavy chains (but not light ) through the mechanism of trans-switching. By this mechanism, transcripts that encode fully human antibodies undergo isotype switching in trans from the human e to a mouse isotype. The process is in trans, because the fully human transgene is located apart from the endogenous locus that retains an undamaged copy of a mouse heavy chain constant region gene. Although in such mice switching is readily apparent the enon is still insufficient to rescue B cell development, which remains frankly impaired. In any event, trans-switched antibodies made in such mice retain fully human light chains, since the phenomenon of trans—switching apparently does not occur with respect to light chains; trans-switching presumably relies on switch sequences in endogenous loci used (albeit differently) in normal isotype switching in cis. Thus, even when mice engineered to make fully human antibodies select a trans-switching mechanism to make antibodies with mouse constant regions, the gy is still insufficient to rescue normal B cell development.

A primary concern in making antibody-based human therapeutics is making a iently large diversity of human immunoglobulin variable region sequences to identify useful variable domains that specifically recognize particular epitopes and bind them with a desirable ty, usually—but not always—with high affinity. Prior to the pment of VELOClMMUNE® mice (described herein), there was no indication that mice expressing human variable regions with mouse constant regions would exhibit any icant differences from mice that made human antibodies from a transgene. That supposition, however, was incorrect.

MMUNE® mice, which contain a precise replacement of mouse immunoglobulin le regions with human immunoglobulin variable regions at the nous mouse loci, display a surprising and able rity to wild—type mice with respect to B cell development. In a surprising and stunning development, VELOClMMUNE® mice displayed an essentially normal, wild-type response to immunization that differed only in one significant respect from wild-type mice—the variable regions generated in response to immunization are fully human.

VELOClMMUNE® mice contain a precise, scale replacement of germline variable regions of mouse globulin heavy chain (lgH) and immunoglobulin light chain (e.g., K light chain, ng) with corresponding human immunoglobulin variable regions, at the endogenous loci. in total, about six megabases of mouse loci are replaced with about 1.5 ses of human genomic sequence. This precise replacement results in a mouse with hybrid immunoglobulin loci that make heavy and light chains that have a human variable regions and a mouse nt region. The precise replacement of mouse VH-DH-JH and VK-JK ts leave flanking mouse sequences intact and functional at the hybrid immunoglobulin loci. The humoral immune system of the mouse functions like that of a wild-type mouse. B cell development is unhindered in any significant respect and a rich diversity of human variable regions is generated in the mouse upon antigen challenge.

VELOClMMUNE® mice are possible e globulin gene segments for heavy and K light chains rearrange rly in humans and mice, which is not to say that their loci are the same or even nearly so—~—clearly they are not. However, the loci are similar enough that humanization of the heavy chain variable gene locus can be accomplished by replacing about three million base pairs of contiguous mouse ce that contains all the VH, DH, and JH gene segments with about one million bases of uous human genomic sequence covering basically the equivalent sequence from a human immunoglobulin locus. in some embodiments, further replacement of certain mouse constant region gene sequences with human gene ces (e.g., ement of mouse CH1 sequence with human CH1 ce, and replacement of mouse CL sequence with human CL sequence) results in mice with hybrid immunoglobulin loci that make antibodies that have human variabie regions and partly human constant regions, suitable for, 9.9., making fully human antibody fragments, e.g., fully human Fab’s. Mice with hybrid immunoglobulin loci exhibit normal variable gene segment rearrangement, normal somatic hypermutation frequencies, and normal class switching. These mice t a humoral immune system that is indistinguishable from wild type mice, and display normal cell populations at all stages of B cell development and normal lymphoid organ structures—even where the mice lack a full repertoire of human variable region gene segments. lmmunizing these mice results in robust humoral responses that display a wide diversity of variable gene segment usage.

The precise replacement of mouse germline variable region gene segments allows for making mice that have partly human immunoglobulin loci. Because the partly human immunoglobulin loci rearrange, hypermutate, and class switch normally, the partly human globulin loci generate antibodies in a mouse that comprise human variable regions. Nucleotide sequences that encode the variable regions can be identified and cloned, then fused (9.9., in an in vitro system) with any sequences of choice, e.g., any immunoglobulin isotype suitable for a particular use, resulting in an antibody or antigenbinding protein derived wholly from human sequences.

Large-scale humanization by recombineering methods were used to modify mouse embryonic stem (ES) cells to precisely e up to three ses of the mouse heavy chain immunoglobulin locus that ed essentially all of the mouse VH, DH, and JH gene segments with equivalent human gene segments with up to a one megabase human genomic sequence containing some or essentially all human VH, DH, and JH gene segments, Up to a one-half megabase segment of the human genome comprising one of two repeats encoding essentially all human VK and JK gene segments was used to replace a three megabase segment of the mouse immunoglobulin K light chain locus containing essentially all of the mouse VK and JK gene segments.

Mice with such replaced immunoglobulin loci can comprise a tion or deletion of the endogenous mouse ADAM6 locus, which is normally found between the 3’- most VH gene segment and the 5’-most DH gene segment at the mouse immunoglobulin heavy chain locus. tion in this region can lead to reduction or ation of functionality of the endogenous mouse ADAM6 locus. if the 3’-most VH gene segments of the human heavy chain repertoire are used in a replacement, an intergenic region containing a pseudogene that appears to be a human ADAM6 pseudogene is present between these VH gene segments, i.e., between human VH’l-Z and VHt-G. However, male mice that comprise this human intergenic sequence exhibit a reduction in fertility.

Mice are described that comprise the replaced loci as bed above, and that also comprise an ectopic nucleic acid sequence encoding a mouse ADAM6, where the mice exhibit essentially normal fertility. in one embodiment, the ectopic nucleic acid ce comprises a mouse ADAM6a and/or a mouse ADAM6b sequence or functional fragments thereof placed between a human VH1-2 and a human VH6-1 at a modiﬁed endogenous heavy chain locus. In one embodiment, the ectopic nucleic acid sequence is SEQ lD NO:3, placed between a human VH1-2 and a human VHS-1 at a modified endogenous heavy chain locus. The direction of transcription of the ADAM6 genes of SEQ ID N013 are opposite with respect to the direction of ription of the surrounding human VH gene segments. Although examples herein show rescue of fertility by g the c sequence n the indicated human VH gene segments, skilled persons will recognize that ent of the ectopic ce at any suitable transcriptionallypermissive locus in the mouse genome (or even extrachromosomally) will be expected to similarly rescue fertility in a male mouse.

The phenomenon of complementing a mouse that lacks a functional ADAM6 locus with an c sequence that comprises a mouse ADAM6 gene or ortholog or homolog or functional fragment thereof is a general method that is applicable to rescuing any mice with nonfunctional or minimally functional endogenous ADAMS loci. Thus, a great many mice that comprise an ADAMS-disrupting modification of the immunoglobulin heavy chain locus can be rescued with the compositions and methods of the invention.

Accordingly, the invention comprises mice with a wide variety of modifications of immunoglobulin heavy chain loci that compromise endogenous ADAMS function, Some imiting) examples are provided in this description. In addition to the VELOClMMUNE® mice described, the compositions and methods d to ADAMS can be used in a great many applications, 6.9., when modifying a heavy chain locus in a wide variety of ways.

In one aspect, a mouse is provided that comprises an ectopic ADAMS sequence that encodes a onal ADAMS protein (or ortholog or g or functional fragment thereof), a replacement of all or substantially all mouse VH gene segments with one or more human VH gene ts, a replacement of all or substantially all mouse DH gene segments and JH gene segments with human DH and human JH gene segments; wherein the mouse lacks a CH1 and/or hinge region. in one embodiment, the mouse makes a single variable domain binding protein that is a dimer of immunoglobulin chains selected from: (a) human VH —- mouse CH1 — mouse CH2 - mouse CH3; (b) human VH - mouse hinge — mouse CH2 — mouse CH3; and, (0) human VH — mouse CH2 — mouse CH3. 1] in one aspect, the nucleotide sequence that rescues fertility is placed within a human immunoglobulin heavy chain variable region sequence (6.9., between human VH1-2 and VHt-S gene ts) in a mouse that has a replacement of one or more mouse immunoglobulin heavy chain variable gene segments , mDH’s, and/or mJH’s) with one or more human immunoglobulin heavy chain variable gene segments (hVH’s, hDH’s, and/or hJH’s), and the mouse further comprises a replacement of one or more mouse immunoglobulin K light chain variable gene segments (mVK’s and/or mJK’s) with one or more human immunoglobulin 1c light chain variable gene segments (hVK’s and/or hJK’s). ln one embodiment, the one or more mouse immunoglobulin heavy chain variable gene segments comprises about three megabases of the mouse immunoglobulin heavy chain locus. In one embodiment, the one or more mouse globulin heavy chain le gene segments comprises at least 89 VH gene ts, at least 13 DH gene segments, at least four JH gene segments or a combination thereof of the mouse globulin heavy chain locus. in one embodiment, the one or more human immunoglobulin heavy chain variable gene segments comprises about one megabase of a human immunoglobulin heavy chain locus. in one embodiment, the one or more human immunoglobulin heavy chain variable gene segments comprises at least 80 VH gene segments, at least 27 DH gene segments, at least six JH gene segments or a ation thereof of a human immunoglobulin heavy chain locus.

In one ment, the one or more mouse immunoglobulin K light chain variable gene segments comprises about three megabases of the mouse immunoglobulin K light chain locus. In one embodiment, the one or more mouse immunoglobulin K light chain variable gene segments comprises at least 137 VK gene segments, at least five JK gene segments or a combination thereof of the mouse immunoglobulin K light chain locus.

In one embodiment, the one or more human lmmunoglobulin K light chain variable gene segments comprises about one-half megabase of a human immunoglobulin K light chain locus. In a specific embodiment, the one or more human immunoglobulin K light chain le gene segments comprises the proximal repeat (with respect to the globulin K constant region) of a human immunoglobulin K light chain locus. In one ment, the one or more human immunoglobulin K light chain variable gene segments comprises at least 4OVK gene segments, at least five JK gene segments or a combination thereof of a human immunoglobulin K light chain locus. 4] In one ment, the nucleotide sequence is place between two human immunoglobulin gene segments. In a specific embodiment, the two human immunoglobulin gene segments are heavy chain gene segments. In one embodiment, the nucleotide sequence is placed between a human VH1-2 gene segment and a human VH1-6 gene t in a VELOCIMMUNE® mouse (US 6,596,541 and US 7,105,348, orated herein by reference). In one embodiment, the VELOCIMMUNE® mouse so modified comprises a replacement of mouse immunoglobulin heavy chain variable gene segments with at least 80 human VH gene segments, 27 human DH gene segments and six human JH gene segments, and a replacement of mouse immunoglobulin K light chain variable gene segments with at least 40 human VK gene segments and five human JK gene segments.

In one aspect, a functional mouse ADAM6 locus (or ortholog or homolog or functional fragment thereof) is present in the midst of human VH gene ts that replace endogenous mouse VH gene segments. In one ment, at least 89 mouse VH gene segments are d and replaced with one or more human VH gene segments, and the mouse ADAM6 locus is present immediately adjacent to the 3’ end of the human VH gene segments, or between two human VH gene segments. In a specific embodiment, the mouse ADAM6 locus is present between two VH gene segments within about 20 kilo bases (kb) to about 40 kilo bases (kb) of the 3’ terminus of the inserted human VH gene segments. In a specific embodiment, the mouse ADAM6 locus is present between two VH gene segments within about 29 kb to about 31 kb of the 3’ terminus of the inserted human VH gene segments. In a specific embodiment, the mouse ADAM6 locus is t within about 30 kb of the 3’ terminus of the inserted human VH gene segments. In a specific embodiment, the mouse ADAM6 locus is present within about 30,184 bp of the 3’ terminus of the inserted human VH gene segments. In a specific embodiment, the replacement includes human VH gene segments VHi-Z and VHS-1, and the mouse ADAM6 locus is t downstream of the VH1—2 gene segment and upstream of the VHS-1 gene segment.

In a specific embodiment, the mouse ADAM6 locus is present n a human VH1-2 gene segment and a human VH6—1 gene segment, wherein the 5’ end of the mouse ADAM6 locus is about 13,848 bp from the 3’ terminus of the human VH1-2 gene segment and the 3’ end of the ADAM6 locus is about 29,737 bp 5’ of the human VH6-1 gene segment. In a specific embodiment, the mouse ADAM6 locus comprises SEQ ID NO:3 or a fragment thereof that s ADAM6 function within cells of the mouse. In a ic embodiment, the arrangement of human VH gene segments is then the following (from upstream to downstream with respect to direction of transcription of the human VH gene segments): human VH1-2 -— mouse ADAM6 locus —- human VHS-1. In a ic embodiment, the ADAM6 pseudogene between human VH1-2 and human VH6-1 is replaced with the mouse ADAM6 locus. In one embodiment, the orientation of one or more of mouse ADAM6a and mouse ADAM6b of the mouse ADAM6 locus is opposite with respect to direction of transcription as ed with the orientation of the human VH gene segments. Alternatively, the mouse ADAM6 locus is present in the intergenic region n the 3’-most human VH gene segment and the 5’-most DH gene segment. This can be the case whether the 5’-most DH segment is mouse or human.

Similarly, a mouse modified with one or more human VL gene segments (e.g., VK or V?» segments) replacing all or substantially all endogenous mouse VH gene segments can be modified so as to either maintain the endogenous mouse ADAM6 locus, as bed above, e.g., by employing a targeting vector having a downstream homology arm that includes a mouse ADAM6 locus or functional fragment f, or to replace a damaged mouse ADAM6 locus with an ectopic sequence positioned between two human VL gene segments or between the human VL gene segments and a DH gene segment (whether human or mouse, e.g., VA + m/hDH), or a J gene segment (whether human or mouse, e.g., VK + JH). In one embodiment, the replacement includes two or more human VL gene segments, and the mouse ADAM6 locus or functional fragment thereof is present between the two 3’-most VL gene segments. In a ic ment, the arrangement of human VL gene ts is then the following (from upstream to downstream with respect to direction of transcription of the human gene segments): human VL3’-1 — mouse ADAM6 locus -— human VL3’. In one embodiment, the orientation of one or more of mouse ADAM6a and mouse ADAM6b of the mouse ADAM6 locus is opposite with respect to ion of transcription as compared with the orientation of the human VL gene segments.

Alternatively, the mouse ADAM6 locus is present in the intergenic region between the 3’- most human VL gene t and the t DH gene segment. This can be the case whether the 5’-most DH segment is mouse or human. in one aspect, a mouse is provided with a replacement of one or more endogenous mouse VH gene segments, and that comprises at least one endogenous mouse DH gene segment. in such a mouse, the modification of the endogenous mouse VH gene segments can comprise a modification of one or more of the 3’—most VH gene segments, but not the 5’-most DH gene segment, where care is taken so that the modification of the one or more 3’-most VH gene segments does not disrupt or render the endogenous mouse ADAM6 locus nonfunctional. For example, in one embodiment the mouse comprises a replacement of all or substantially all endogenous mouse VH gene segments with one or more human VH gene segments, and the mouse ses one or more nous DH gene segments and a functional endogenous mouse ADAM6 locus. in another embodiment, the mouse comprises the modification of endogenous mouse 3’—most VH gene segments, and a modification of one or more endogenous mouse DH gene ts, and the modification is carried out so as to maintain the integrity of the endogenous mouse ADAM6 locus to the extent that the endogenous ADAM6 locus s functional. In one example, such a modification is done in two steps: (1) replacing the 3’-most nous mouse VH gene segments with one or more human VH gene segments employing a targeting vector with an am homology arm and a downstream homology arm wherein the downstream homology arm includes all or a portion of a onal mouse ADAM6 locus; (2) then replacing and endogenous mouse DH gene segment with a targeting vector having an upstream homology arm that includes a all or a functional portion of a mouse ADAM6 locus. in various aspects, employing mice that contain an ectopic sequence that s a mouse ADAM6 protein or an ortholog or homolog or functional homolog f are useful where modifications disrupt the function of nous mouse ADAM6. The probability of disrupting endogenous mouse ADAM6 on is high when making modifications to mouse immunoglobulin loci, in particular when modifying mouse immunoglobulin heavy chain variable regions and surrounding sequences. Therefore, such mice provide particular benefit when making mice with immunoglobulin heavy chain loci that are deleted in whole or in part, are humanized in whole or in part, or are replaced (e.g., with VK or V)» sequences) in whole or in part. Methods for making the genetic modifications described for the mice described below are known to those d in the art.

Mice containing an ectopic sequence encoding a mouse ADAM6 protein, or a substantially identical or r protein that confers the fertility benefits of a mouse ADAM6 protein, are particularly useful in conjunction with modifications to a mouse immunoglobulin heavy chain variable gene locus that disrupt or delete the nous mouse ADAM6 sequence. Although primarily described in connection with mice that express antibodies with human variable regions and mouse constant regions, such mice are useful in connection with any genetic modifications that disrupt endogenous mouse ADAM6 genes.

Persons of skill will recognize that this encompasses a wide y of genetically modified mice that contain modifications of mouse immunoglobulin heavy chain variable gene loci.

These include, for example, mice with a deletion or a replacement of all or a portion of mouse immunoglobulin heavy chain gene segments, regardless of other modifications.

Non-limiting examples are described below.

In some s, genetically modified mice are provided that comprise an ectopic mouse, rodent, or other ADAM6 gene (or ortholog or homolog or fragment) functional in a mouse, and one or more human immunoglobulin variable and/or constant region gene segments. In various ments, other ADAM6 gene orthologs or homologs or fragments functional in a mouse may e ces from bovine, , primate, rabbit or other non—human sequences.

In one aspect, a mouse is provided that comprises an ectopic ADAM6 sequence that encodes a functional ADAM6 protein, a replacement of all or substantially all mouse VH gene segments with one or more human VH gene segments; a replacement of all or substantially all mouse DH gene segments with one or more human DH gene segments; and a replacement of all or substantially all mouse JH gene segments with one or more human JH gene segments.

In one embodiment, the mouse further ses a ement of a mouse CH1 nucleotide sequence with a human CH1 tide sequence. In one embodiment, the mouse further comprises a replacement of a mouse hinge nucleotide sequence with a human hinge nucleotide sequence. In one embodiment, the mouse further comprises a replacement of an immunoglobulin light chain variable locus (VL and JL) with a human immunoglobulin light chain le locus. In one embodiment, the mouse further comprises a replacement of a mouse immunoglobulin light chain constant region nucleotide sequence with a human immunoglobulin light chain constant region tide sequence. In a specific embodiment, the VL, JL, and CL are immunoglobulin K light chain sequences. In a ic embodiment, the mouse comprises a mouse CH2 and a mouse CH3 immunoglobulin constant region sequence fused with a human hinge and a human CH1 sequence, such that the mouse immunoglobulin loci rearrange to form a gene that encodes a binding protein sing (a) a heavy chain that has a human variable region, a human CH1 region, a human hinge region, and a mouse CH2 and a mouse CH3 region; and (b) a gene that encodes an immunoglobulin light chain that comprises a human variable domain and a human nt region. in one aspect, a mouse is provided that comprises an c ADAMS sequence that encodes a functional ADAM6 protein, a replacement of all or substantially all mouse VH gene segments with one or more human VL gene segments, and optionally a replacement of all or substantially all DH gene segments and/or JH gene segments with one or more human DH gene segments and/or human JH gene segments, or optionally a replacement of all or substantially all DH gene segments and JH gene segments with one or more human JL gene segments. ] in one embodiment, the mouse comprises a replacement of all or ntially all mouse VH, DH, and JH gene segments with one or more VL, one or more DH, and one or more J gene segments (e.g., JK or J7»), wherein the gene segments are operabiy linked to an nous mouse hinge region, wherein the mouse forms a rearranged immunoglobulin chain gene that contains, from 5’ to 3’ in the direction of transcription, human VL — human or mouse DH -— human or mouse J -— mouse hinge — mouse CH2 — mouse CH3. In one embodiment, the J region is a human JK region. in one embodiment, the J region is a human JH . ln one embodiment, the J region is a human J)» region.

In one embodiment, the human VL region is selected from a human V7t region and a human VK region. in specific embodiments, the mouse expresses a single variable domain antibody having a mouse or human constant region and a variable region derived from a human VIC, a human DH and a human JK; a human VK, a human DH, and a human JH; a human V)», a human DH, and a human J7»; a human V)», a human DH, and a human JH; a human VK, a human DH, and a human J)»; a human V)», a human DH, and a human JK. In speciﬁc embodiment, recombination recognition sequences are modified so as to allow for productive rearrangements to occur between recited V, D, and J gene ts or between recited V and J gene segments.

In one aspect, a mouse is provided that comprises an ectopic ADAMS ce that encodes a functionai ADAMS protein (or ortholog or homolog or functional fragment thereof), a ement of all or substantially all mouse VH gene segments with one or more human VL gene segments, a replacement of all or substantially all mouse DH gene segment and JH gene segments with human JL gene segments; wherein the mouse lacks a CH1 and/or hinge . in one embodiment, the mouse lacks a sequence ng a CH1 domain. in one embodiment, the mouse lacks a ce encoding a hinge region. In one embodiment, the mouse lacks a sequence encoding a CH1 domain and a hinge region.

In a specific embodiment, the mouse expresses a binding protein that comprises a human immunogiobulin light chain variable domain 0» or K) fused to a mouse CH2 domain that is attached to a mouse CH3 domain.

In one aspect, a mouse is provided that comprises an ectopic ADAM6 sequence that encodes a functional ADAMS n (or ortholog or homolog or functional fragment thereof), a ement of all or substantially all mouse VH gene segments with one or more human VL gene segments, a replacement of all or substantially all mouse DH and JH gene segments with human JL gene segments. in one embodiment, the mouse ses a deletion of an immunogiobulin heavy chain nt region gene sequence encoding a CH1 region, a hinge region, 3 CH1 and a hinge region, or a CH1 region and a hinge region and a CH2 region. 2] In one embodiment, the mouse makes a single le domain binding protein comprising a homodimer ed from the following: (a) human VL — mouse CH1 —- mouse CH2 —- mouse CH3; (b) human VL -— mouse hinge -— mouse CH2 — mouse CH3; (c) human VL — mouse CH2 — mouse CH3.

In one aspect, a mouse is provided with a ed endogenous heavy chain immunogiobulin locus, comprising a disabled or deleted endogenous mouse ADAM6 locus, wherein the mouse comprises a nucleic acid sequence that ses a human or mouse or human/mouse or other chimeric antibody. in one embodiment, the nucleic acid ce is present on a transgene integrated that is randomly ated into the mouse genome. in one embodiment, the nucleic acid sequence is on an episome (e.g., a chromosome) not found in a wild-type mouse. in one embodiment, the mouse further comprises a disabled endogenous immunogiobulin light chain locus. in a specific embodiment, the endogenous immunogiobulin light chain locus is selected from a kappa (K) and a lambda (A) light chain locus. in a specific embodiment, the mouse comprises a disabled endogenous K light chain locus and a disabled A light chain locus, wherein the mouse expresses an antibody that comprises a human immunogiobulin heavy chain variable domain and a human immunogiobulin light chain domain. In one embodiment, the human immunogiobulin light chain domain is selected from a human K light chain domain and a human h light chain domain.

In one aspect, a genetically modified animal is provided that expresses a chimeric antibody and expresses an ADAM6 protein or ortholog or homolog thereof that is functional in the cally modified animal. in one embodiment, the genetically modified animal is ed from a mouse and a rat. In one embodiment, the genetically modified animal is a mouse, and the ADAMS protein or ortholog or homolog thereof is from a mouse strain that is a different strain than the genetically modified animal. In one embodiment, the genetically modified animal is a rodent of family Cricetidae (e.g., a hamster, a New World rat or mouse, a vole), and the ADAMS protein ortholog or homolog is from a rodent of family Muridae (e.g., true mouse or rat, gerbil, spiny mouse, d rat). In one ment, the genetically modified animal is a rodent of the family Muridae, and the ADAMS n ortholog or homolog is from a rodent of family Cricetidae. 7] in one embodiment, the chimeric antibody comprises a human variable domain and a constant region sequence of a rodent. ln one embodiment, the rodent is selected from a rodent of the family Cricetidae and a rodent of family Muridae, in a ic embodiment, the rodent of the family Cricetidae and of the family Muridae is a mouse. In a specific embodiment, the rodent of the family Cricetidae and of the family Muridae is a rat. in one ment, the chimeric dy comprises a human variable domain and a constant domain from an animal ed from a mouse or rat; in a specific embodiment, the mouse or rat is selected from the family Cricetidae and the family e. in one embodiment, the chimeric antibody comprises a human heavy chain variable domain, a human light chain variable domain and a constant region sequence derived from a rodent selected from mouse and rat, wherein the human heavy chain variable domain and the human light chain are cognate. In a specific embodiment, cognate includes that the human heavy chain and the human light chain variable domains are from a single B cell that expresses the human light chain variable domain and the human heavy chain variable domain together and present the le domains together on the surface of an individual B cell.

In one embodiment, the chimeric antibody is sed from an immunoglobulin locus. in one embodiment, the heavy chain variable domain of the chimeric antibody is expressed from a rearranged endogenous immunoglobulin heavy chain locus. In one ment, the light chain variable domain of the ic antibody is expressed from a nged endogenous immunoglobulin light chain locus. in one embodiment, the heavy chain variable domain of the chimeric antibody and/or the light chain le domain of the chimeric antibody is expressed from a rearranged transgene (e.g., a rearranged nucleic acid sequence derived from an unrearranged nucleic acid sequence integrated into the animal’s genome at a locus other than an endogenous immunoglobulin locus). in one embodiment, the light chain variable domain of the chimeric antibody is expressed from a rearranged transgene (e.g., a rearranged nucleic acid sequence derived from an unrearranged nucleic acid sequence integrated into the animal’s genome at a locus other than an endogenous immunoglobulin locus).

In a specific embodiment, the transgene is expressed from a transcriptionally active locus, e.g., a ROSA26 locus, 6.9., a murine (e.g., mouse) ROSA26 locus.

In one aspect, a non—human animal is provided, comprising a humanized immunoglobulin heavy chain locus, wherein the humanized globulin heavy chain locus comprises a non-human ADAMS sequence or ortholog or homolog thereof.

In one embodiment, the non-human animal is a rodent selected from a mouse, a rat, and a hamster. 2] In one embodiment, the non-human ADAMS ortholog or homolog is a ce that is orthologous and/or homologous to a mouse ADAMS sequence, wherein the ortholog or homolog is functional in the non-human animal.

In one embodiment, the non-human animal is selected from a mouse, a rat, and a hamster and the ADAMS ortholog or homolog is from a non-human animal selected from a mouse, a rat, and a hamster. In a specific embodiment, the non—human animal is a mouse and the ADAMS og or homolog is from an animal that is selected from a ent mouse species, a rat, and a hamster. In specific embodiment, the non-human animal is a rat, and the ADAMS ortholog or homolog is from a rodent that is selected from a different rat species, a mouse, and a hamster. In a specific embodiment, the non-human animal is a hamster, and the ADAMS ortholog or homolog is form a rodent that is selected from a different hamster species, a mouse, and a rat.

In a specific ment, the non—human animal is from the suborder Myomorpha, and the ADAMS sequence is from an animal selected from a rodent of amily Dipodoidea and a rodent of the superfamily Muroidea. In a specific embodiment, the rodent is a mouse of superfamily Muroidea, and the ADAMS ortholog or homolog is from a mouse or a rat or a hamster of amily Muroidea.

In one embodiment, the humanized heavy chain locus comprises one or more human VH gene segments, one or more human DH gene segments and one or more human JH gene ts. In a specific embodiment, the one or more human VH gene segments, one or more human DH gene segments and one or more human JH gene segments are operably linked to one or more human, chimeric and/or rodent (e.g., mouse or rat) constant region genes. In one embodiment, the constant region genes are mouse.

In one embodiment, the constant region genes are rat. In one embodiment, the constant region genes are hamster. In one ment, the constant region genes comprise a ce selected from a hinge, a CH2, a CH3, and a combination thereof. In specific embodiment, the constant region genes comprise a hinge, a CH2, and a CH3 sequence.

In one ment, the non-human ADAMS sequence is contiguous with a human immunoglobulin heavy chain sequence. In one embodiment, the man ADAMS sequence is positioned within a human immunoglobulin heavy chain sequence. In a specific ment, the human immunoglobulin heavy chain sequence comprises a V, D and/or J gene t.

In one embodiment, the non-human ADAM6 sequence is positioned between two V gene segments. In one ment, the man ADAM6 sequence is juxtaposed n a V and a D gene t. In one embodiment, the mouse ADAM6 sequence is positioned between a V and a J gene t. In one embodiment, the mouse ADAM6 sequence is juxtaposed between a D and a J gene t.

In one aspect, a genetically modified non-human animal is provided, comprising a B cell that expresses a human VH domain cognate with a human VL domain from an immunoglobulin locus, wherein the non-human animal expresses a non-immunoglobulin non-human protein from the immunoglobulin locus. In one embodiment, the non- immunoglobulin non-human protein is an ADAM protein. In a specific ment, the ADAM protein is an ADAM6 protein or homolog or ortholog or functional fragment thereof.

In one embodiment the non—human animal is a rodent (e.g., mouse or rat). In one embodiment, the rodent is of family Muridae. In one embodiment, the rodent is of subfamily Murinae. In a specific embodiment, the rodent of subfamily Murinae is selected from a mouse and a rat.

In one ment, the non-immunoglobulin non-human protein is a rodent protein. In one ment, the rodent is of family Muridae. In one embodiment, the rodent is of subfamily Murinae. In a specific embodiment, the rodent is selected from a mouse, a rat, and a hamster.

In one embodiment, the human VH and VL domains are attached directly or h a linker to an immunoglobulin constant domain sequence. In a speciﬁc embodiment, the constant domain sequence comprises a sequence selected from a hinge, a CH2 a CH3, and a combination f. In a specific embodiment, the human VL domain is selected from a VK or a V?» domain.

In one aspect, a genetically modified non-human animal is provided, comprising in its germline a human immunoglobulin sequence, wherein the sperm of a male non- human animal is characterized by an in vivo migration defect. In one embodiment, the in vivo migration defect comprises an inability of the sperm of the male non—human animal to e from a uterus through an oviduct of a female non-human animal of the same species. In one embodiment, the non-human animal lacks a nucleotide sequence that encodes and ADAM6 protein or functional fragment thereof. In a specific embodiment, the ADAM6 protein or functional fragment thereof includes an ADAM6a andi’or an ADAMBb n or functional fragments thereof. In one embodiment, the non-human animal is a rodent. In a specific embodiment, the rodent is selected from a mouse, a rat, and a hamster.

In one , a non—human animal is provided, comprising a human immunoglobulin sequence contiguous with a non-human sequence that encodes an ADAMS n or ortholog or homolog or onal nt thereof. In one embodiment, the non-human animal is a rodent. In a specific embodiment, the rodent is selected from a mouse, a rat, and a hamster.

In one embodiment, the human immunoglobulin sequence is an gtobulin heavy chain sequence. In one embodiment, the globulin sequence comprises one or more VH gene segments. In one embodiment, the human immunoglobulin sequence comprises one or more DH gene ts. In one ment, the human immunoglobutin sequence comprises one or more JH gene segments. In one embodiment, the human immunogIobuIin sequence comprises one or more VH gene segments, one or more DH gene segments and one or more JH gene segments.

In one embodiment, the immunogIobuIin sequence comprises one or more VH gene segments have a high frequency in natural human repertoires. In a specific embodiment, the one or more VH gene segments comprise no more than two VH gene ts, no more than three VH gene segments, no more than four VH gene segments, no more than five VH gene ts, no more than six VH gene segments, no more than seven VH gene segments, no more than eight VH gene segments, no more than nine VH gene segments, no more than 10 VH gene segments, no more than 11 VH gene segments, no more than 12 VH gene segments, no more than 13 VH gene segments, no more than 14 VH gene segments, no more than 15 VH gene segments, no more than 16, VH gene segments, no more than 17 VH gene segments, no more than 18 VH gene segments, no more than 19 VH gene segments, no more than 20 VH gene ts, no more than 21 VH gene segments, no more than 22 VH gene segments or no more than 23 VH gene segments.

In a specific embodiment, the one or more VH gene ts comprise five VH gene segments. In a specific embodiment, the one or more VH gene segments comprise VH gene segments. In a specific embodiment, the one or more VH gene segments comprise 15 VH gene segments. In a specific embodiment, the one or more VH gene segments comprise 20 VH gene segments.

In various embodiments, the VH gene segments are selected from VH6-1, VH1~2, VH1-3, VH2-5, VHS-7, VH1-8, VH3-9, VH3-11, VH3-13, VH3—15, VH3-16, VH1-18, VH3-20, VH3— 21, VH3-23, VH1-24, VH2-26, VH4-28, VH3-30, VH4—31, VH3-33, VH4-34, VH3—35, VH3-38, VH4-39, VH3-43, VH1-45, VH1-46, VH3-48, VH3—49, VHS-51, VH3-53, VH1-58, VH4-59, , VHS-64, VHS-68, VH1-69, VH2-70, VH3—72, VHS—73 and VH3—74.

In various embodiments, the VH gene segments are selected from VH1-2, VH1—8, , VH1-46, VH1-69, VHS—7, VHS-9, VH3-11, VH3—13, VH3-15, VHS-21, , VH3—30, VHS-33, VHS-43, VH3-48, , VH4-34, VH4-39, VH4—59, VHS—51 and VH6-1. 9] In various embodiments, the VH gene segments are selected from VH1-18, VH1- 46, VH1-69, VH3-7, VH3-11, VH3-15, VHS-21, VH3-23, , VH3-33, VH3—48, VH4-34, VH4- 39, VH4-59 and VHS-51.

In various embodiments, the VH gene segments are selected from VH1—18, VH1- 69, VH3-7, VHS-11, VH3—15, VHS-21, VH3—23, , , VH3-48, VH4-39, VH4-59 and VHS—51.

In various ments, the VH gene segments are selected from VH1-18, VH3— 11, VH3-21, , VH3—30, VH4-39 and VH4-59. 2] In various embodiments, the VH gene segments are selected from VH1-18, VH3- 21, VHS-23, VH3—30 and VH4—39.

In s embodiments, the VH gene segments are selected from VH1—18, VH3- 23 and VH4-39. 4] In various embodiments, the VH gene segments are selected from VHS-21, VH3- 23 and VH3-30.

In various embodiments, the VH gene segments are selected from VH3-23, VH3— and VH4-39.

In a specific embodiment, human immunoglobuIin sequence comprises at least 18 VH gene segments, 27 DH gene segments and six JH gene segments. In a specific embodiment, the human immunoglobuIin sequence ses at Ieast 39 VH gene segments, 27 DH gene segments and six JH gene segments. In a specific embodiment, the human globuIin sequence comprises at least 80 VH gene segments, 27 DH gene segments and six JH gene segments.

In one embodiment, the non-human animal is a mouse, and the mouse comprises a replacement of endogenous mouse VH gene segments with one or more human VH gene segments, wherein the human VH gene segments are operably Iinked to a mouse CH region gene, such that the mouse rearranges the human VH gene segments and expresses a reverse chimeric immunoglobuIin heavy chain that comprises a human VH domain and a mouse CH. In one embodiment, 90—100% of unrearranged mouse VH gene segments are ed with at least one unrearranged human VH gene segment. In a specific embodiment, all or substantially all of the endogenous mouse VH gene segments are replaced with at Ieast one unrearranged human VH gene segment. In one embodiment, the ement is with at Ieast 19, at least 39, or at least 80 or 81 unrearranged human VH gene segments. In one embodiment, the replacement is with at least 12 functionai unrearranged human VH gene segments, at least 25 functional unrearranged human VH gene segments, or at least 43 functional unrearranged human VH gene ts. In one embodiment, the mouse comprises a replacement of all mouse DH and JH segments with at least one unrearranged human DH segment and at least one unrearranged human JH segment. In one embodiment, the at least one unrearranged human DH segment is selected from 1-1, 1—7, 1-26, 2-8, 2-15, 3-3, 3-10, 3-16, 3-22, 5-5, 5- 12, 6-6, 6—13, 7-27, and a combination thereof. In one embodiment, the at least one unrearranged human JH segment is selected from 1, 2, 3, 4, 5, 6, and a combination thereof. In a specific embodiment, the one or more human VH gene segment is selected from a 1—2, 1—8, 1-24, 1-69, 2-5, 3—7, 3—9, 3—1 1, 3-13, 3-15, 3-20, 3—23, 3-30, 3-33, 3-48, 3- 53, 4—31, 4-39, 4—59, 5-51, a 6-1 human VH gene segment, and a combination f.

In various ments, the human immunoglobulin sequence is in operable linkage with a constant region in the germline of the non-human animal (e.g., the rodent, e.g., the mouse, rat, or hamster). In one embodiment, the constant region is a human, ic human/mouse or ic human/rat or chimeric human/hamster, a mouse, a rat, or a hamster constant region. In one embodiment, the constant region is a rodent (e.g., mouse or rat or hamster) constant region. In a specific embodiment, the rodent is a mouse or rat. In various embodiments, the constant region comprises at least a CH2 domain and a CH3 domain.

In one embodiment, the human immunoglobulin heavy chain sequence is located at an immunoglobulin heavy chain locus in the germline of the non-human animal (e.g., the rodent, e.g., the mouse or rat or r). In one embodiment, the human immunoglobulin heavy chain sequence is located at a non-immunoglobulin heavy chain locus in the germline of the non—human , wherein the non-heavy chain locus is a riptionally active locus. In a specific embodiment, the non-heavy chain locus is a ROSA26 locus.

In various aspects, the non-human animal further comprises a human immunoglobulin light chain sequence (e.g., one or more ranged light chain V and J sequences, or one or more nged VJ sequences) in the germline of the non-human animal. In a specific embodiment, the immunoglobulin light chain sequence is an immunoglobulin x light chain sequence. In one embodiment, the human immunoglobulin light chain sequence comprises one or more VL gene segments. In one embodiment, the human immunoglobulin light chain sequence ses one or more JL gene segments. In one ment, the human immunoglobulin light chain sequence comprises one or more VL gene segments and one or more JL gene segments. In a specific embodiment, the human immunoglobulin light chain ce comprises at least 16 VK gene segments and five JK gene segments. In a specific embodiment, the human immunoglobulin light chain sequence comprises at least 30 VK gene segments and five JK gene segments. In a specific embodiment, the human immunoglobulin light chain sequence comprises at least 4O VK gene segments and five JK gene segments. in various embodiments, the human immunoglobulin light chain sequence is in operable linkage with a constant region in the germline of the non-human animal (e.g., rodent, e.g., mouse or rat or hamster). In one embodiment, the nt region is a human, chimeric human/rodent, mouse, rat, or hamster nt region. In a specific embodiment, the constant region is a mouse or rat constant region. in a specific embodiment, the constant region is a mouse K constant (mCK) region or a rat K nt (rCK) region. ln one embodiment, the non-human animal is a mouse and the mouse comprises a replacement of all or substantially all VK and JK gene segments with at least six human VK gene segments and at least one JK gene t. in one embodiment, all or substantially all VK and JK gene segments are replaced with at least 16 human VK gene segments (human VK) and at least one JK gene t. ln one embodiment, all or substantially all VK and JK gene segments are replaced with at least 30 human VK gene segments and at least one JK gene segment. in one embodiment, all or substantially all VK and JK gene segments are replaced with at least 40 human VK gene segments and at least one JK gene segment. in one embodiment, the at least one Jic gene segment comprises two, three, four, or five human JK gene segments. 2] in one embodiment, the human VK gene segments comprise VK4—1,Vi<5-2, VK7-3, VK2-4, VK1-5, and VK1-6. in one embodiment, the VK gene segments comprise VK3-7,VK1-8,VK1-9,VK2-10,VK3-11,VK1-12,VK1-13,VK2-14,VK3-15 and VK1-16. in one embodiment, the human VK gene segments comprise VK1-17, VK2-18, VK2-19, VIC?)- , VK6-21, VK1-22, VK1-23, VK2-24, VK3-25, VK2-26, VK1—27, VK2-28, VK2-29, and VK2- . in one embodiment, the human VK gene segments comprise VK3-31, VK1-32, VK1-33, VK3-34, VK1-35, VK2-36, VK1-37, VK2-38, VK1-39, and VK2-40.

In a specific embodiment, the VK gene ts comprise contiguous human immunoglobulin K gene ts spanning the human immunoglobulin K light chain locus from VK4-1 through VK2-40, and the JK gene segments comprise contiguous gene segments spanning the human immunoglobulin K light chain locus from JK1 through JK5.

In one embodiment, the human immunoglobulin light chain sequence is d at an immunoglobulin light chain locus in the germline of the man . in a specific ment, the immunoglobulin light chain locus in the germline of the non- human animal is an immunoglobulin K light chain locus. in one embodiment, the human immunoglobulin light chain sequence is located at a munoglobulin light chain locus in the germline of the non-human animal that is transcriptionally active. In a ic embodiment, the non-immunoglobulin locus is a ROSA26 locus.

] In one aspect, a method of making a human dy is provided, wherein the human antibody comprises variable domains d from one or more variable region nucleic acid sequences encoded in a cell of a non-human animal as bed herein. 6] in one aspect, a pharmaceutical composition is provided, comprising a polypeptide that comprises antibody or dy fragment that is derived from one or more variable region c acid ces isolated from a non-human animal as described herein. In one embodiment, the polypeptide is an antibody. In one embodiment, the polypeptide is a heavy chain only antibody. In one embodiment, the polypeptide is a single chain variable fragment (e.g., an scFv).

In one aspect, use of a non-human animal as described herein to make an antibody is provided. In various embodiments, the antibody comprises one or more variable domains that are derived from one or more variable region nucleic acid sequences isolated from the non—human . in a specific embodiment, the variable region nucleic acid sequences comprise immunoglobulin heavy chain gene segments. In a specific ment, the variable region nucleic acid sequences comprise immunoglobulin light chain gene segments.

EXAMPLES The following examples are provided so as to describe how to make and use methods and compositions of the invention, and are not intended to limit the scope of what the inventors regard as their invention. Unless indicated otherwise, temperature is indicated in Celsius, and pressure is at or near atmospheric.

Example 1 Humanization of Mouse lmmunoglobulin Genes Human and mouse bacterial artificial chromosomes (BACs) were used to engineer 13 different BAC targeting vectors (BACvecs) for humanization of the mouse globulin heavy chain and K light chain loci. Tables 1 and 2 set forth descriptions of the steps performed for construction of all BACvecs employed for the humanization of mouse immunoglobulin heavy chain and K light chain loci, respectively.

Identification of human and mouse BACs. Mouse BACs that span the 5’ and 3’ ends of the immunoglobulin heavy chain and K light chain loci were identified by hybridization of filters spotted with BAC library or by PCR ing mouse BAC library DNA pools. Filters were hybridized under standard ions using probes that corresponded to the regions of interest. Library pools were screened by PCR using unique primer pairs that flank the targeted region of interest. Additional PCR using the same primers was performed to deconvolute a given well and isolate the corresponding BAC of interest. Both BAC s and library pools were generated from 129 SVJ mouse ES cells (lncyte cs/lnvitrogen). Human BACs that cover the entire immunoglobulin heavy chain and K light chain loci were identified either by hybridization of filters spotted with BAC library (Caltech B, C, or D libraries & RPCl-11 library, Research Genetics/lnvitrogen) through screening human BAC library pools (Caltech library, lnvitrogen) by a PCR-based method or by using a BAC end ce database (Caltech D library, TIGR).

Construction of BACvecs by bacterial homologous recombination and ligation. Bacterial homologous recombination (BHR) was performed as bed (Valenzuela et al., 2003; Zhang et al., 1998, A new logic for DNA engineering using recombination in Escherichia coli, Nat Genet 20:123-128). in most cases, linear nts were generated by ligating nerated homology boxes to cloned cassettes followed by gel isolation of on ts and electroporation into BHR-competent bacteria harboring the target BAC. After selection on appropriate antibiotic petri dishes, correctly ined BACs were identified by PCR across both novel junctions ed by restriction anaiysis on pulsed-field gels (Schwartz and Cantor, 1984, Separation of yeast chromosome-sized DNAs by pulsed field gradient gel electrophoresis, Cell 75) and spot-checking by PCR using primers distributed across the human sequences. [0003221 A 3hVH BACvec was ucted using three sequential BHR steps for the initial step of humanization of the immunoglobulin heavy chain locus ( and Table 1). In the first step (Step 1), a cassette was introduced into a human parental BAC upstream from the human VH1-3 gene segment that ns a region of homology to the mouse immunoglobulin heavy chain locus (H81), a gene that confers kanamycin resistance in bacteria and G418 resistance in animals cells (kanR) and a site-specific recombination site (9.9., onP). In the second step (Step 2), a second cassette was introduced just downstream from the last JH segment that contains a second region of homology to the mouse immunoglobulin heavy chain locus (H82) and a gene that confers resistance in bacteria to spectinomycin (specR). This second step included ng human immunoglobulin heavy chain locus sequences downstream from JH6 and the BAC vector chloramphenicol resistance gene (cmR). in the third step (Step 3), the doubly modified human BAC (B1) was then linearized using l—Ceul sites that had been added during the first two steps and integrated into a mouse BAC (82) by BHR through the two regions of homology (H81 and H82). The drug selections forfirst (cm/ken), second (spec/kan) and third (cm/ken) steps were designed to be specific for the d products. Modified BAC clones were analyzed by pulse-filed gel electrophoresis (PFGE) after digestion with restriction enzymes to determine appropriate construction (FlG. 4B).

In a similar fashion, 12 additional BACvecs were engineered for humanization of the heavy chain and K light chain loci. In some instances, BAC ligation was performed in lieu of BHR to conjoin two large BACs through introduction of rare restriction sites into both parental BACvecs by BHR along with careful placement of selectable markers. This allowed for the survival of the desired ligation t upon selection with specific drug marker combinations. inant BACs obtained by ligation after digestion with rare restriction enzymes were identified and screened in a similar fashion to those obtained by BHR (as described above).

Table 1 BACvec Step Description Process Insert upstream mouse homology box Into human 1 BHR proximal BAC OTB—257202 Insert downstream mouse homology box Into human proximal BAC OTB-257202 Insert 3hVH/27hDH/9hJH into mouse proximal BAC CT7— 3 BHR 302a07 to create .3th BACvec Insert cassette at distal end of mouse IgH locus using Insert specR marker at downstream end of 3hVH insertion using human BAC OTB-257202 Insert l-Ceul and Not sites flanking puroR at upstream and of 3hVH ion Insert Not site at downstream end of 08p02 BAC (JO BHR (=10 kb downstream of VH2-5) Insert l—Ceul site at upstream end of Rel2-408p02 BAC (=23 kb upstream of VH1-18) gigate 1842kb fragment from step 4 into 153kb vector on 18th r°.m Step n—.=85kb and leaving 65kb homology to 3hVH Insert cassette and Not site at distal end of mouse IgH locus in 3i20 BAC nSubclone mouse distal homology arm for insertion on upstream from human BACs a Insert 20 kb mouse arm upstream of Rel2-408p02 Swap selection cassette from hng to neoR to create 18th BACvec Insert I-Ceul and Pl-Scel sites flanking hng into distal end of human BAC 34n10 Insert CmR at proxrmal end of CTD—2534n10 BAC to 39th allow for selection for ligation to RP11-72n10 BAC Insert PI-Scel site into RP11—72n10 BAC for on to CTD—2534n10 BAC of RP11—72n10 BAC construct of step 2 repIacmg hng —-distalhomologyarm usrng CT7-253i20 BAC Insert specR and l-Ceul srte at distal end of mouse distal homology arm Ligate mouse distal homology arm onto human insert L'iga iont' from step 5 Swap selection cassette from neo to hyg usrng UbCp and pA as homology boxes to create 39hVH BACvec Insert specR at proximal end of human 74b5 1 BHR Insert Ascl site at distal end of human CTD-3074b5 2 BHR Insert hng and Ascl site at al end of mouse 53ml” BHR distal homology arm using CT7-253i20 BAC Ligate mouse distal homology arm onto construct from A L''gat'onl step 2 Swap selection cassette from hyg to neo using UbCp BHR and pA as homology boxes to create 53hVH BACvec Insert Pl-Scel and l-Ceul sites flanking spec at distaI 1 BHR end of human CTD-2195p5 BAC insert l—Ceul site at proximal end of RP11-926p12 BAC for ligation to CTD-2195p5 BAC 70hVH-—-926p12 BAC for ligation of mouse arm -Ligate mouse distal gy arm onto construct from A Ligation step 3 Ligate mouse distal homology arm and hIgH fragment from RP11—926p12 BAC onto CTD-2195p5 BAC to Ligation create 70 hVH BACvec of CTD-Z313e3 BAC 8()th Ligate mouse distal gy arm onto human CTD— 2 Li9ation 2313e3 BAC from step 1 to create 80th BACvec Table 2 BACvec Step Description Process Insert loxP site within mouse J-C intron usrng CT7- I 9K'PC 1 BHR 254m04 BAC Insert onP site at distal end of mouse IgK locus usmg | 9“-DC 1 BHR . CT7-302912 BAG Insert PI—Scel site R400 bp downstream from hJK5 in 1 BHR 66j12 BAC Insert I Ceul and Ascl Sites flanking hng at distal- - BHR end of CTD-2366112 BAG - Insert I—Ceul and PI Scel sites flanking puroR 3 BHR downstream from mJK using CT7 254m04 BAC Insert hlgVK/JK upstream from mouse EHhK/CK using 6hVK 4 Ligation construct from step 3 Replace cmR in construct of step 4 With specR Insert Neo selection cassette at distal end of mouse ng locus using 2912 BAC Ligate mouse distal homology arm upstream of human insert in construct of step 6 to create 6th( BACvec 1 Insert NeoR at distal end of RP11-1061b13 BAC Replace cmR in construct of step 1 with SpecR Insert Hyg selection cassette at distal end of mouse 16an ng locus using 2912 BAG Ligate mouse distal homology arm upstream of human insert from uct of step 2 to create 1(5th 1 insert Hng at distal end of RP1 1-9996 BAG HR 2 Replace cmR in construct of step 1 with specR HR Insert Neo selection cassette at distal end of mouse 30hVK ng locus using CT7-302g12 BAG Ligate mouse distal homology arm upstream of human insert from construct of step 2 to create 30hVK Insert NeoR at distal end of hIgH locus in CTD— 1 BHR 2559d6 BAC Replace cmR in construct of step 1 with specR HR 40hVK Ligate mouse distal homology arm upstream of 3 human Insert in construct of step 2 to create 4Oth( Ligation Modification of embryonic stem (ES) cells and tion of mice. ES cell (F1 H4) targeting was performed using the VELOCIGENE® genetic ering method as described (Valenzuela et al., 2003). Derivation of mice from modified ES cells by either blastocyst (Valenzuela et al., 2003) or 8-cell injection (Poueymirou et at, 2007, F0 generation mice fully derived from gene-targeted embryonic stem cells allowing immediate phenotypic analyses, Nat Biotechnol 25:91-99) was as described. Targeted ES cells and mice were confirmed by screening DNA from ES cells or mice with unique sets of probes and primers in a PCR based assay (e.g., , SB and 30). All mouse studies were overseen and approved by Regeneron’s institutional Animal Care and Use Committee (IACUC).

] Karyotype Analysis and scent in situ ization (FISH).

Karyotype Analysis was performed by Coriell Cell Repositories (Coriell Institute for Medical Research, Camden, NJ). FISH was performed on targeted ES cells as described zuela etal., 2003). Probes ponding to either mouse BAC DNA or human BAC DNA were labeled by nick translation (Invitrogen) with the scently labeled dUTP nucleotides spectrum orange or spectrum green (Vysis). lmmunoglobulin Heavy Chain Variable Gene Locus. Humanization of the variable region of the heavy chain locus was achieved in nine sequential steps by the direct replacement of about three million base pairs (Mb) of contiguous mouse genomic sequence containing all VH, DH and JH gene ts with about one Mb of contiguous human genomic sequence containing the equivalent human gene segments ( and Table i) using VELOCIGENE® genetic engineering technology (see, 6.9., US Pat. No. 6,586,251 and Valenzuela et al., 2003), The intron between JH gene segments and constant region genes (the J—C intron) contains a transcriptional enhancer (Neuberger, 1983, sion and regulation of immunoglobulin heavy chain gene transfected into lymphoid cells, EMBO J 211373-1378) followed by a region of simple repeats required for recombination during e switching (Kataoka et al., 1980, ngement of immunoglobulin gamma 1-chain gene and mechanism for heavy-chain class switch, PNAS USA 77:919-923). The junction n human VH—DH-JH region and the mouse CH region (the proximal on) was chosen to maintain the mouse heavy chain intronic enhancer and switch domain in order preserve both efficient sion and class switching of the humanized heavy chain locus within the mouse. The exact nucleotide position of this and subsequentjunctions in all the replacements was possible by use of the VELOCIGENE® genetic engineering method (supra), which employed bacterial homologous recombination driven by synthesized oligonucleotides. Thus, the proximal junction was placed about 200 bp downstream from the last JH gene segment and the distal on was placed several hundred upstream of the most 5’ VH gene segment of the human locus and about 9 kb downstream from the mouse VH1-86 gene segment, also known as J558.55. The mouse VH1-86 55) gene segment is the most distal heavy chain variable gene segment, reported to be a pseudogene in C57BL/6 mice, but potentially active, albeit with a poor RSS sequence, in the targeted 129 allele. The distal end of the mouse heavy chain locus reportedly may contain control elements that regulate locus sion and/or ngement (Pawlitzky et al., 2006).

A first insertion of human immunoglobulin DNA sequence into the mouse was achieved using 144 kb of the proximal end of the human heavy chain locus containing 3 VH, all 27 DH and 9 JH human gene segments inserted into the proximal end of the mouse lgH locus, with a itant 16.6 kb deletion of mouse genomic sequence, using about 75 kb of mouse homology arms (Step A, FiG. 2A; Tables 1 and 3, 3hVH). This large 144kb insertion and accompanying 16.6 kb deletion was performed in a single step (Step A) that occurred with a frequency of 0.2% (Table 3). Correctly targeted ES cells were scored by a loss-of—native-allele (LONA) assay (Valenzuela et al., 2003) using probes within and flanking the deleted mouse sequence and within the inserted human sequence, and the integrity of the large human insert was verified using multiple probes spanning the entire insertion (FlG. 3A, 3B and 30). Because many rounds of sequential ES cell targeting were anticipated, targeted ES cell clones at this, and all subsequent, steps were subjected to karyotypic analysis (supra) and only those clones g normal karyotypes in at least 17 of 20 s were utilized for subsequent steps.

Targeted ES cells from Step A were re—targeted with a BACvec that ed a 19 kb deletion at the distal end of the heavy chain locus (Step B, FlG. 2A). The Step B BACvec contained a hygromycin resistance gene (hyg) in contrast to the in resistance gene (neo) contained on the BACvec of Step A. The resistance genes from the two BACvecs were designed such that, upon successful ing to the same chromosome, approximately three Mb of the mouse heavy chain le gene locus containing all of the mouse VH gene segments other than VH1~86 and all of the DH gene segments other than DQ52, as well as the two ance genes, were flanked by loxP sites; DQ52 and all of the mouse JH chain gene segments were deleted in Step A. ES cell clones doubly targeted on the same chromosome were identified by driving the 3hVH proximal cassette to homozygosity in high G418 (Mortensen et al., 1992, Production of gous mutant ES cells with a single targeting construct, Mo/ Celt Biol 12:2391-2395) and following the fate of the distal hyg cassette. Mouse segments up to four Mb in size, having been modified in a manner to be flanked by loxP sites, have been successfully deleted in ES cells by transient expression of CRE recombinase with high efficiencies (up to z11%) even in the absence of drug selection (Zheng et al., 2000, Engineering mouse chromosomes with Cre-loxP: range, ency, and somatic applications, Mol Cell Biol —655). ln a similar , the inventors achieved a three Mb deletion in 8% of ES cell clones following transient CRE expression (Step C, ; Table 3). The deletion was scored by the LONA assay using probes at either end of the d mouse sequence, as well as the loss of neo and hyg and the appearance of a PCR product across the deletion point containing the sole remaining loxP site. Further, the deletion was confirmed by fluorescence in situ hybridization (data not shown).

The remainder of the human heavy chain variable region was added to the 3hVH allele in a series of 5 steps using the GENE® genetic engineering method (Steps E-H, ), with each step ing precise ion of up to 210 kb of human gene sequences. For each step, the proximal end of each new BACvec was designed to overlap the most distal human sequences of the previous step and the distal end of each new BACvec contained the same distal region of mouse homology as used in Step A. The BACvecs of steps D, F and H contained neo selection cassettes, whereas those of steps E and G contained hyg selection tes, thus selections were alternated between G418 and hygromycin. Targeting in Step D was assayed by the loss of the unique PCR product across the distal loxP site of 23th Hybrid Allele. Targeting for Steps E through i was assayed by loss of the previous selection cassette. in the final step (Step I, ), the neo selection cassette, flanked by Frt sites (McLeod et a/., 1986, Identification of the crossover site during FLP-mediated recombination in the Saccharomyces cerevisiae plasmid 2 microns circle, Mol Cell Biol 6:3357-3367), was removed by transient FLPe expression (Buchholz et al, 1998, Improved properties of FLP recombinase d by cycling mutagenesis, Nat Biotechnol 162657—662). The human sequences of the BACvecs for Steps D, E and G were derived from two parental human BACs each, whereas those from Steps F and H were from single BACs. Retention of human sequences was confirmed at every step using multiple probes spanning the inserted human sequences (as described above, 9.9., FlG. 3A, 3B and 3C). Only those clones with normal karyotype and germline potential were carried forward in each step. ES cells from the final step were still able to contribute to the ne after nine sequential manipulations (Table 3). Mice gous for each of the heavy chain alleles were viable, appeared healthy and demonstrated an essentially wild-type humoral immune system (see Example 3).

Table 3 Hybrid Human Targeting Targeting % Total Functional Allele sequence construct efficiency usage VH VH 0) L0 53th 655 kb 186 kb 0.4% 65 70th 238 kb 05% 80th 940 kb 124 kb 0.2% “-100 Immunoglobulin K Light Chain Variable Gene Locus. The K light chain variable region was humanized in eight sequential steps by the direct replacement of about three Mb of mouse sequence containing all VK and JK gene segments with about 0.5 Mb of human sequence containing the proximal human VK and JK gene segments in a manner similar to that of the heavy chain (HS. 13; Tables 2 and 4).

The variable region of the human K light chain locus ns two nearly identical 400 kb repeats separated by an 800 kb spacer (Weichhold et at, 1993, The human immunoglobulin kappa locus consists of two copies that are organized in opposite polarity, Genomics 161503-511). e the repeats are so similar, nearly all of the locus diversity can be reproduced in mice by using the proximal repeat. Further, a natural human allele of the K light chain locus missing the distal repeat has been reported (Schaible et al., 1993, The immunoglobulin kappa locus: polymorphism and haplotypes of oid and non-Caucasoid individuals, Hum Genet -267). The inventors replaced about three Mb of mouse K light chain variable gene ce with about 0.5 Mb of human K light chain variable gene sequence to effectively replace all of the mouse VK and JK gene segments with the al human VK and all of the human JK gene segments (FlG. 2C and 2D; Tables 2 and 4). In contrast to the method bed in Example 1 for the heavy chain locus, the entire mouse VK gene region, containing all VK and JK gene segments, was deleted in a three-step process before any human sequence was added. First, a neo cassette was introduced at the proximal end of the variable region (Step A, FlG. 20). Next, a hyg cassette was inserted at the distal end of the K locus (Step B, ). Recombinase ition sites (e.g., loxP) were again situated within each selection cassette such that CRE treatment induced deletion of the remaining 3 Mb of the mouse VK region along with both resistance genes (Step C, FlG. 2C).

A human genomic nt of about 480 kb in size ning the entire immunoglobulin K light chain variable region was inserted in four sequential steps (; Tables 2 and 4), with up to 150 kb of human globulin K light chain ce inserted in a single step, using methods similar to those employed for the heavy chain (see Example 1). The final hygromycin resistance gene was removed by transient FLPe expression. As with the heavy chain, targeted ES cell clones were evaluated for integrity of the entire human insert, normal ype and germ-line potential after every step. Mice homozygous for each of the K light chain alleles were generated and found to be healthy and of normal appearance.

Table 4 Hybrid Human Targeting Targeting % Total Functional Allele sequence construct efficiency usage V1< VK “n—--— 6th 0.3% 14 16th 0.4% 47 16 11 Example 2 Generation of Fully Humanized Mice by Combination of Multiple Humanized immunoglobulin Alleles At several points, ES cells bearing a portion of the human immunoglobulin heavy chain or K light chain variable repertoires as described in Example 1 were microinjected and the resulting mice bred to create multiple versions of VELOCIMMUNE® mice with progressively larger fractions of the human germline immunoglobulin repertoires (Table 5; and 5B). VELOCIMMUNE® 1 (V1) mice s eighteen human VH gene segments and all of the human DH and JH gene segments combined with sixteen human VK gene segments and all the human JK gene segments. VELOClMMUNE® 2 (V2) and VELOCIMMUNE® (V3) mice have increased variable repertoires bearing a total of thirty—nine VH and thirty VK, and eighty VH and forty VK, respectively. Since the genomic regions encoding the mouse VH, DH and JH gene segments, and VK and JK gene segments, have been completely replaced, antibodies ed by all versions of VELOCIMMUNE® mice contain human variable regions linked to mouse constant regions.

The mouse k light chain loci remain intact in various embodiments of the VELOCIMMUNE® mice and serve as a comparator for efficiency of expression of the various VELOCIMMUNE® K light chain loci.

Mice doubly homozygous for both immunoglobulin heavy chain and K light chain humanizations were generated from a subset of the alleles described in Example 1. All pes observed during the course of breeding to te the doubly homozygous mice occurred in roughly Mendelian proportions. Male progeny homozygous for each of the human heavy chain alleles demonstrated reduced fertility, which resulted from loss of mouse ADAM6 activity. The mouse heavy chain variable gene locus contains two embedded functional ADAM6 genes a and ). During zation of the mouse heavy chain variable gene locus, the inserted human genomic ce contained an ADAMS pseudogene. Mouse ADAM6 may be required for fertility, and thus lack of mouse ADAM6 genes in humanized heavy chain variable gene loci might lead to a reduction in fertility notwithstanding the presence of the human gene. Examples 7- 11 describe the reengineering of mouse ADAM6 genes into a humanized heavy chain variable gene locus, and restoration of wild-type level fertility in mice with a humanized heavy chain immunoglobulin locus.

Table 5 Version of Heavy Chain K Light Chain VELOCIMMUNE® Human 5 VH, Human 5 VK.

Allele Allele Mouse VH (D :5e VK gene Example 3 Lymphocyte Populations in Mice with Humanized Immunoglobulin Genes Mature B cell tions in the three different versions of VELOCIMMUNE® mice were evaluated by flow cytometry.

Briefly, cell suspensions from bone marrow, spleen and thymus were made using standard methods. Cells were resuspended at 5x105 cells/mL in BD Pharmingen FACS ng buffer, blocked with anti—mouse CD16/32 (BD Pharmingen), stained with the appropriate cocktail of antibodies and fixed with BD CYTOFIXTM all according to the manufacturer’s instructions. Final cell pellets were resuspended in 0.5 mL staining buffer and analyzed using a BD FACSCALIBURTM and BD CELLQUEST PROTM re. All antibodies (BD Pharmingen) were prepared in a mass dilution/cocktail and added to a final concentration of 0.5 mg/1O5 cells. dy cocktails for bone marrow (A—D) staining were as follows: A: anti— mouse lgMb—FlTC, anti—mouse lgMa—PE, anti—mouse CD45R(8220)-APC; B: ouse CD43(S7)-PE, anti-mouse CD45R(8220)-APC; C: anti-mouse CDZ4(HSA)-PE; anti—mouse CD45R(BZZO)—APC; D: anti-mouse BP—1-PE, anti—mouse B220)-APC.

Antibody cocktails for spleen and al lymph node (E—H) staining were as follows: E: anti-mouse lgMb-FITC, anti—mouse lgMa—PE, anti-mouse CD45R(B220)—APC; F: anti-mouse lg, M, x2, A3 Light Chain-FlTC, anti mouse lgx Light Chain-PE, ouse CD45R(8220)-APC; G: anti-mouse Ly6G/C—FlTC, anti-mouse CD49b(DX5)-PE, anti- mouse CDHb-APC; H: anti-mouse CD4(L3T4)—FlTC, anti-mouse CD45R(BZZO)-PE, anti— mouse CDBa-APC. Results are shown in FlG. 6.

Lymphocytes isolated from spleen or lymph node of homozygous VELOClMMUNE® mice were stained for surface expression of the markers 8220 and lgM and analyzed using flow cytometry (. The sizes of the 8220* IgM“ mature B cell populations in all versions of VELOClMMUNE® mice tested were virtually identical to those of wild type mice, regardless of the number of VH gene segments they ned. In addition, mice containing homozygous hybrid humanized immunoglobulin heavy chain loci, even those with only 3 VH gene segments but normal mouse immunoglobulin K light chain loci or mice containing homozygous hybrid humanized K light chain loci with normal mouse immunoglobulin heavy chain loci, also had normal numbers of 8220+ lgM" cells in their peripheral compartments (not shown). These results indicate that chimeric loci with human variable gene segments and mouse nt regions can fully populate the mature B cell compartment. Further, the number of variable gene segments at either the heavy chain or K light chain loci, and thus the theoretical diversity of the antibody repertoire, does not correlate with the y to te wild type tions of mature B cells. In contrast, mice with randomly integrated fully—human globulin transgenes and inactivated mouse immunoglobulin loci have reduced numbers of B cells in these compartments, with the severity of the deficit ing on the number of variable gene segments included in the transgene (Green and Jakobovits, 1998, Regulation of B cell development by variable gene complexity in mice reconstituted with human immunoglobulin yeast artificial chromosomes, J Exp Med 3—495). This demonstrates that the “in situ genetic humanization” gy results in a fundamentally different functional outcome than the randomly integrated transgenes achieved in the “knockout-plus—transgenic” approach.

Allelic ion and Locus Choice. The ability to maintain allelic exclusion was examined in mice heterozygous for ent versions of the humanized immunoglobulin heavy chain locus.

The zation of the immunoglobulin loci was carried out in an F1 ES line (F1 H4, Valenzuela et al., 2003), derived from 129$6/SvaTac and C57BL/6NTac zygous embryos. The human heavy chain germline variable gene sequences are targeted to the 12936 allele, which carries the lgMa haplotype, s the fied mouse C57SBL/6N allele bears the lgMb haplotype. These allelic forms of lgM can be distinguished by flow cytometry using antibodies specific to the polymorphisms found in the lgMa or lgMb alleles. As shown in (bottom row), the B cells identified in mice heterozygous for each n of the humanized heavy chain locus only express a single allele, either lgMa (the humanized allele) or lgMb (the wild type alleie). This demonstrates that the mechanisms involved in allelic exclusion are intact in VELOCIMMUNE® mice. in addition, the relative number of B cells positive for the humanized allele (lgMa) is roughly proportional to the number of VH gene segments present. The humanized immunoglobulin locus is expressed in approximately 30% of the B cells in VELOCIMMUNE® 1 heterozygote mice, which have 18 human VH gene segments, and in 50% of the B cells in VELOCIMMUNE® 2 and 3 (not shown) heterozygote mice, with 39 and 80 human VH gene segments, respectively. Notably, the ratio of cells expressing the humanized versus wild type mouse allele (0.5 for VELOCIMMUNE® 1 mice and 0.9 for MMUNE® 2 mice) is greater than the ratio of the number of le gene segments contained in the humanized versus wild type loci (0.2 for VELOCIMMUNE® 1 mice and 0.4 for VELOCIMMUNE® 2 mice). This may indicate that the probability of allele choice is ediate between a random choice of one or the other chromosome and a random choice of any particular V segment RSS. Further, there may be a fraction of s, but not all, in which one allele becomes accessible for recombination, completes the process and shuts down recombination before the other allele becomes accessible. In addition, the even distribution of cells that have surface lgM (slgM) derived from either the hybrid zed heavy chain locus or the wild type mouse heavy chain locus is ce that the hybrid locus is operating at a normal level. in contrast, randomly integrated human immunoglobulin transgenes compete poorly with wild type mouse immunoglobulin loci emann et al., 1989, A repertoire of monoclonal antibodies with human heavy chains from transgenic mice, PNAS 86:6709-6713; Green etal., 1994; Tuaillon etal., 1993, Human immunoglobulin heavy-chain minilocus recombination in transgenic mice: gene— segment use in mu and gamma transcripts, PNAS USA 90:3720-3724). This further demonstrates the immunoglobulins produced by VELOCIMMUNE® mice are functionally different than those produced by randomly integrated transgenes in mice made by “knockout—plus—transgenic” approaches.

Polymorphisms of the CK regions are not available in 12986 or CSYBL/GN to examine allelic exclusion of humanized versus non-humanized K light chain loci. However, VELOClMMUNE® mice all possess wild type mouse it light chain loci, therefore, it is le to observe whether rearrangement and expression of zed K light chain loci can t mouse x light chain expression. The ratio of the number of cells expressing the humanized K light chain relative to the number of cells expressing mouse A light chain was relatively unchanged in VELOClMMUNE® mice compared with wild type mice, regardless of the number of human VK gene segments inserted at the K light chain locus ( third row from top). in addition there was no increase in the number of double positive (K plus A) cells, ting that productive recombination at the hybrid K light chain loci results in appropriate suppression of recombination of the mouse A light chain loci. in contrast, mice containing randomly integrated K light chain transgenes with inactivated mouse K light chain loci—but wild type mouse x light chain loci—exhibit ically increased MK ratios (Jakobovits, 1998), implying that the uced K light chain transgenes do not on well in such mice. This further demonstrates the different functional outcome observed in immunoglobulins made by VELOClMMUNE® mice as compared to those made by “knockout-plus-transgenic” mice.

B cell Development. Because the mature B cell populations in VELOClMMUNE® mice resemble those of wild type mice (described above), it is possible that defects in early B cell differentiation are compensated for by the ion of mature B cell populations. The s stages of B cell differentiation were examined by analysis of B cell populations using flow cytometry. Table 6 sets forth the ratio of the fraction of cells in each B cell lineage defined by FACs, using specific cell surface s, in VELOClMMUNE® mice compared to wild type littermates.

Early B cell pment occurs in the bone marrow, and different stages of B cell differentiation are characterized by changes in the types and amounts of cell surface marker expression. These differences in surface expression correlate with the molecular changes occurring at the globulin loci inside the cell. The pro-B to pre-B cell transition requires the successful rearrangement and expression of functional heavy chain protein, while transition from the pre-B to mature B stage is governed by the correct rearrangement and expression of a K or k light chain. Thus, inefficient transition between stages of B cell differentiation can be detected by s in the relative populations of B cells at a given stage.

Table 6 Bone Marrow Spleen Version of pro-B pre-B Immature Mature Emerging Mature MMUNE® , . . Bzzom Mice CD43” 0024‘“ 3220'° 8220'" BZZOhi 3220“) 3220'° g lgM” lgM" igivr No major s were observed in B cell entiation in any of the VELOClMMUNE® mice. The introduction of human heavy chain gene segments does not appear to affect the pro-B to pre—B transition, and uction of human K light chain gene segments does not affect the pre-B to B tion in VELOCIMMUNE® mice. This demonstrates that ”reverse chimeric” globulin molecules possessing human le regions and mouse constants function normally in the context of B cell signaling and co-receptor molecules leading to appropriate B cell differentiation in a mouse environment. in st, the balance between the different populations during B cell differentiation are perturbed to varying extents in mice that contain randomly integrated immunoglobulin transgenes and inactivated endogenous heavy chain or K light chain loci (Green and Jakobovits, 1998).

Example 4 Variable Gene oire in Humanized Immunoglobulin Mice Usage of human variable gene segments in the humanized antibody repertoire of VELOCIMMUNE® mice was analyzed by reverse transcriptase—polymerase chain reaction (RT—PCR) of human variable regions from multiple sources including splenocytes and hybridoma cells. Variable region sequence, gene segment usage, somatic hypermutation, and junctional diversity of rearranged variable region gene segments were determined. 8] Briefly, total RNA was extracted from 1x107 — 2x107 splenocytes or about 104 -— 105 hybridoma cells using TRlZOLTM (lnvitrogen) or Qiagen RNEASYTM Mini Kit (Qiagen) and primed with mouse constant region ic primers using the SUPERSCRIPTTM l|| One-Step RT-PCR system (lnvitrogen). Reactions were carried out with 2-5 pL of RNA from each sample using the aforementioned 3’ constant specific primers paired with pooled leader primers for each family of human variable regions for both the heavy chain and K light chain, separately. Volumes of reagents and primers, and RT-PCR/PCR conditions were performed according to the manufacturer’s instructions. Primers sequences were based upon multiple sources (Wang and r, 2000, Human immunogiobulin variable region gene analysis by single cell RT-PCR, J l Methods 244:217-225; Ig-primer sets, Novagen). Where appropriate, nested secondary PCR reactions were carried out with pooled family-specific framework primers and the same mouse 3’ immunoglobulin constant—specific primer used in the primary reaction. Aliquots (5 uL) from each reaction were ed by e electrophoresis and on products were purified from agarose using a MONTAGETM Gel Extraction Kit pore). Purified products were cloned using the TOPOTM TA Cloning System rogen) and transformed into DH1OB E. coli cells by electroporation. individual clones were selected from each transformation reaction and grown in 2 mL LB broth cultures with antibiotic selection overnight at 37°C. Plasmid DNA was purified from bacterial cultures by a kit—based approach (Qiagen). immunogiobulin Variable Gene Usage. Plasmid DNA of both heavy chain and K light chain clones were sequenced with either T7 or M13 e primers on the ABl 3100 c Analyzer ed Biosystems). Raw sequence data were imported into SEQUENCHERTM (v4.5, Gene Codes). Each sequence was assembled into contigs and aligned to human immunogiobulin sequences using IMGT V-Quest (Brochet et al., 2008, IMGTN-QUEST: the highly customized and integrated system for IG and TR standardized V—J and V-D-J sequence analysis, Nucleic Acids Res 362W503-5O8) search function to identify human VH, DH, JH and VK, JK segment usage. Sequences were ed to germline sequences for somatic hypermutation and recombination junction analysis.

Mice were generated from ES cells containing the initial heavy chain modification (3hVH-CRE Hybrid Allele, bottom of HG. 2A) by RAG compiementation (Chen et al., 1993, RAG-Z-deficient blastocyst complementation: an assay of gene function in lymphocyte development, PNAS USA 8-4532), and cDNA was prepared from spienocyte RNA. The cDNA was amplified using primer sets (described above) specific for the ted chimeric heavy chain mRNA that would arise by V(D)J recombination within the inserted human gene ts and subsequent splicing to either mouse lgM or lgG constant domains. Sequences derived from these cDNA clones (not shown) demonstrated that proper V(D)J recombination had occurred within the human variable gene sequences, that the rearranged human V(D)J gene segments were properly spliced in-frame to mouse constant domains, and that class-switch recombination had occurred. Further sequence analysis of mRNA ts of uent hybrid immunogiobulin loci was performed. {000351} in a similar experiment, B cells from non—immunized wild type and VELOCIMMUNE® mice were separated by flow try based upon surface expression of 8220 and IgM or IgG. The 8220* lgM‘” or surface lgG+ (slgG+) cells were pooled and VH and VK ces were obtained ing RT—PCR amplification and cloning (described above). Representative gene usage in a set of RT-PCR amplified cDNAs from unimmunized VELOCIMMUNE® 1 mice (Table 7) and VELOCIMMUNE® 3 mice (Table 8) was ed (*defective RSS; Tmissing or pseudogene). Asterisk: gene segments with defective RSS. T: gene segment is missing or pseudogene.

Table 7 VH Observed DH Observed VK Observed 'P00 lt.”co 9" ...\ O 9“? 4.4 NA JK Observed _.4. N .A L A -_ —.4 O ‘F‘P'?’ .44.; \IQU‘I .- -._\ O-_ u 09 .A CO ‘3"? mmAm 40: ll NN mmu T'N\l__\ o Table 8 Observed Observed VK Observed ..3321334418747.7.20 4 90 _ .an. 7.8 98 3 O 0 21263464664444240047309874.?0 O 3. 4r 3. 4| 3. 1. 4| 4.. 4.! 76521 1 . 4... 303331 3. 47| 11111.11 493. 9 ..n 8 O Q...5 7 4M. 22 3Qw 23 L13131131154111114436644 2 1 4m0 5 2 6 2 Jx ObmWd 6-1 .- As shown in Tables 7 and 8, nearly all of the functional human VH, DH, JH, VK and JK gene segments are utilized. Of the functional variable gene segments described but not detected in the VELOClMMUNE® mice of this experiment, several have been reported to possess defective recombination signal sequences (RSS) and, thus, would not be expected to be sed (Feeney, 2000, Factors that influence ion of B cell repertoire, Immunol Res 212195—202). Analysis of several other sets of immunoglobulin sequences from various MMUNE® mice, isolated from both naive and immunized repertoires, has shown usage of these gene segments, albeit at lower frequencies (data not shown). Aggregate gene usage data has shown that all onal human VH, DH, JH, VK, and JK gene segments ned in VELOClMMUNE® mice have been observed in various naive and immunized repertoires (data not shown). Although the human VH7—81 gene segment has been identified in the analysis of human heavy chain locus sequences (Matsuda et al., 1998, The te nucleotide sequence of the human globulin heavy chain variable region locus, J Exp Med 188:2151-2162), it is not present in the MMUNE® mice as confirmed by re-sequencing of the entire VELOClMMUNE® 3 mouse genome.

Sequences of heavy and light chains of antibodies are known to show exceptional ility, especially in short polypeptide segments within the rearranged variable domain. These regions, known as hypervariable regions or complementary ining regions (CDRs), create the binding site for antigen in the structure of the antibody molecule. The intervening ptide sequences are called framework regions (FRs). There are three CDRs (CDR1, CDR2, CDR3) and 4 FRs (FR1, FR2, FR3, FR4) in both heavy and light chains. One CDR, CDR3, is unique in that this CDR is created by recombination of both the VH, DH and JH and VK and JK gene segments and generates a significant amount of repertoire diversity before antigen is encountered. This joining is imprecise due to both nucleotide deletions via lease activity and non—template encoded additions via terminal deoxynucleotidyl transferase (TdT) and, thus, allows for novel sequences to result from the recombination process. Although FRs can show substantial somatic mutation due to the high mutability of the le region as a whole, variability is not, however, distributed evenly across the variable region. CDRs are concentrated and localized regions of high variability in the surface of the antibody molecule that allow for antigen binding. Heavy chain and light chain ces of selected antibodies from VELOClMMUNE® mice around the CDR3 junction demonstrating junctional diversity are shown in HS. 7A and 78, respectively.

As shown in , mplate encoded nucleotide additions (N-additions) are observed at both the VH—DH and DH—JH joint in antibodies from VELOCIMMUNE® mice, indicating proper function of TdT with the human ts. The endpoints of the VH, DH and JH segments relative to their germline counterparts indicate that exonuclease activity has also occurred. Unlike the heavy chain locus, the human K light chain rearrangements exhibit little or no TdT additions at CDR3, which is formed by the recombination of the VK and JK segments (). This is ed due to the lack of TdT expression in mice during light chain rearrangements at the pre-B to B cell transition. The diversity observed in the CDR3 of rearranged human VK regions is introduced predominantly through exonuclease activity during the recombination event.

Somatic hypermutation. Additional diversity is added to the variable regions of nged immunoglobulin genes during the germinal center on by a process termed somatic hypermutation. B cells expressing somatically mutated variable regions compete with other B cells for access to antigen presented by the follicular dendritic cells.

Those B cells with higher affinity for the antigen will further expand and undergo class ing before exiting to the periphery. Thus, B cells expressing switched isotypes typically have encountered antigen and one germinal center reactions and will have sed numbers of mutations relative to naive B cells. Further, variable region sequences from predominantly naive slgM" B cells would be expected to have vely fewer mutations than variable sequences from slgG+ B cells which have undergone antigen selection. 6] Sequences from random VH or VK clones from slgM+ or slgG+ B cells from non- immunized VELOCIMMUNE® mice or slgG+ B cells from immunized mice were compared with their germline variable gene segments and changes relative to the ne sequence annotated. The resulting nucleotide sequences were translated in silica and mutations leading to amino acid changes also annotated. The data were collated from all the variable regions and the percent change at a given position was calculated (.

As shown in human heavy chain variable s derived from slgG" B cells from non-immunized VELOCIMMUNE® mice exhibit many more nucleotides relative to slgM+ B cells from the same splenocyte pools, and heavy chain variable regions derived from immunized mice exhibit even more changes. The number of changes is increased in the complementarity—determining regions (CDRs) relative to the framework regions, indicating n selection. The corresponding amino acid sequences from the human heavy chain variable regions also exhibit significantly higher numbers of mutations in lgG versus lgM and even more in immunized lgG. These mutations again appear to be more frequent in the CDRs compared with the framework sequences, suggesting that the dies were antigen-selected in vivo. A similar increase in the number the tide and amino acid mutations are seen in the VK sequences derived from lgG+ B cells from immunized mice.

The gene usage and somatic hypermutation ncy observed in VELOClMMUNE® mice demonstrate that essentially all gene segments present are capable of rearrangement to form fully functionally reverse chimeric antibodies in these mice. Further, VELOClMMUNE® antibodies fully participate within the mouse immune system to undergo affinity selection and maturation to create fully mature human antibodies that can effectively neutralize their target antigen. VELOClMMUNE® mice are able to mount robust immune responses to multiple classes of antigens that result in usage of a wide range of human antibodies that are both high affinity and suitable for eutic use (data not shown).

Example 5 Analysis of Lymphoid Structure and Serum lsotypes The gross structures of spleen, inguinal lymph nodes, Peyer’s patches and thymus of tissue samples from wild type or VELOClMMUNE® mice stained with H&E were examined by light microscopy. The levels of immunoglobulin isotypes in serum collected from wild type and MMUNE® mice were analyzed using LUMlNEXTM logy.

Lymphoid Organ Structure. The structure and function of the lymphoid tissues are in part dependent upon the proper development of hematopoietic cells. A defect in B cell development or function may be exhibited as an alteration in the structure of the lymphoid s. Upon analysis of stained tissue sections, no signiﬁcant difference in appearance of ary lymphoid organs between wild type and VELOClMMUNE® mice was identified (data not shown). 1] Serum lmmunoglobulin Levels. The level of expression of each isotype is similar in wild type and VELOClMMUNE® mice (, QB and QC). This demonstrates that humanization of the variable gene segments had no nt adverse effect upon class ing or immunoglobulin sion and secretion and ore apparently maintain all the endogenous mouse sequences necessary for these functions.

Example 6 zation and Antibody Production in Humanized Immunoglobulin Mice Different versions of VELOClMMUNE® mice were immunized with antigen to examine the humoral response to foreign antigen challenge.

Immunization and Hybridoma Development. VELOClMMUNE® and wild- type mice can be immunized with an antigen in the form of protein, DNA, a combination of DNA and protein, or cells expressing the antigen. Animals are lly boosted every three weeks for a total of two to three times. Following each antigen boost, serum samples from each animal are collected and analyzed for antigen-specific dy responses by serum titer determination. Prior to fusion, mice ed a final pre-fusion boost of 5 pg protein or DNA, as desired, via intra-peritoneal and/or intravenous injections. Splenocytes are harvested and fused to A98.653 myeloma cells in an electrofusion chamber according to the manufacture’s suggested protocol (Cyto Pulse es lnc., Glen Burnie, MD). Ten days after e, hybridomas are screened for antigen specificity using an ELISA assay (Harlow and Lane, 1988, Antibodies: A Laboratory Manual, Cold Spring Harbor Press, New York). atively, antigen specific B cells are isolated directly from immunized VELOClMMUNE® mice and ed using standard techniques, including those described here, to obtain human antibodies specific for an antigen of interest (9.9., see US 2007/0280945A1, herein orated by reference in its entirety).

Serum Titer Determination. To monitor animal anti-antigen serum response, serum samples are collected about 10 days after each boost and the titers are determined using antigen ic ELlSA. Briefly, Nunc MAXISORPTM 96 well plates are coated with 2 pg/mL antigen overnight at 4° C and blocked with bovine serum albumin (Sigma, St. Louis, MO). Serum samples in a serial 3 fold dilutions are allowed to bind to the plates for one hour at room temperature. The plates are then washed with PBS containing 0.05% Tween-20 and the bound lgG are detected using HRP-conjugated goat anti-mouse Fc (Jackson lmmuno Research Laboratories, lnc., West Grove, PA) fortotal lgG titer, or biotin-labeled isotype specific or light chain specific polyclonal antibodies (Southern Biotech lnc.) for isotype specific , respectively. For biotin—labeled antibodies, following plate wash, HRP—conjugated streptavidin (Pierce, Rockford, IL) is added. All plates are developed using colorimetric substrates such as BD OPTElATM (BD Biosciences Pharmingen, San Diego, CA). After the reaction is stopped with 1 M phosphoric acid, optical absorptions at 450 nm are recorded and the data are analyzed using M software from Graph Pad. Dilutions required to obtain two-fold of background signal are d as titer.

In one experiment, VELOClMMUNE® mice were immunized with human eukin-6 receptor (hlL-6R). A representative set of serum titers for VELOClMMUNE® and wild type mice zed with hlL-6R is shown in FlG. 10A and 108.

VELOClMMUNE® and wild-type mice mounted strong responses towards lL-6R with similar titer ranges (A). Several mice from the VELOClMMUNE® and wild- type cohorts reached a maximal response after a single antigen boost. These s indicate that the immune response strength and kinetics to this antigen were similar in the VELOClMMUNE® and wild type mice. These antigen-specific antibody responses were r analyzed to examine the particular isotypes of the antigen—specific antibodies found in the sera. Both VELOClMMUNE® and wild type groups predominantly ed an IgG1 response (8), ting that class switching during the humoral response is similar in mice of each type.

Affinity Determination of Antibody Binding to Antigen in Solution. An ELISA-based solution competition assay is typically designed to determine dy- binding afﬁnity to the antigen.

Briefly, antibodies in conditioned medium are premixed with serial dilutions of antigen protein ranging from O to 10 mg/mL. The solutions of the antibody and antigen mixture are then incubated for two to four hours at room temperature to reach binding equilibria. The s of free antibody in the mixtures are then measured using a quantitative sandwich ELISA. Ninety-six well MAXISORBTM plates (VWR, West Chester, PA) are coated with 1 ug/mL antigen protein in PBS on overnight at 4°C followed by BSA nonspecific blocking. The antibody-antigen mixture solutions are then transferred to these plates followed by one-hour incubation. The plates are then washed with washing buffer and the plate-bound antibodies were detected with an HRP—conjugated goat anti- mouse IgG polyclonal antibody reagent (Jackson lmmuno Research Lab) and developed using colorimetric substrates such as BD TM (BD Biosciences Pharmingen, San Diego, CA). After the reaction is stopped with 1 M phosphoric acid, optical absorptions at 450 nm are recorded and the data are analyzed using PRISMTM software from Graph Pad.

The ency of the signals on the trations of antigen in solution are analyzed with a 4 parameter fit analysis and reported as |Cso, the n tration required to e 50% reduction of the signal from the antibody samples without the presence of antigen in solution.

In one experiment, VELOClMMUNE® mice were immunized with hIL—6R (as described above). A and 113 show a representative set of affinity measurements for lL6R antibodies from VELOClMMUNE® and wild-type mice.

After immunized mice receive a third n boost, serum titers are determined using an ELISA assay. Splenocytes are isolated from ed wild type and VELOClMMUNE® mouse cohorts and fused with Ag8.653 myeloma cells to form hybridomas and grown under selection (as described above). Out of a total of 671 anti—IL- 6R hybridomas produced, 236 were found to express antigen-specific antibodies. Media harvested from antigen positive wells was used to determine the antibody affinity of binding to antigen using a on competition ELISA. Antibodies derived from VELOClMMUNE® mice exhibit a wide range of affinity in binding to antigen in solution (A).

Furthermore, 49 out of 236 anti-IL—6R hybridomas were found to block lL-6 from binding to the receptor in an in vitro bioassay (data not shown). Further, these 49 anti-IL-6R blocking antibodies exhibited a range of high solution affinities similar to that of blocking antibodies derived from the parallel immunization of wild type mice (8).

Example 7 Construction of a Mouse ADAM6 Targeting Vector Due to replacement of mouse immunoglobulin heavy chain variable gene loci with human immunoglobulin heavy chain le gene loci, early versions of VELOCIMMUNE® mice lack expression of mouse ADAM6 genes. in particular, male VELOCIMMUNE® mice demonstrate a reduction in fertility. Thus, the ability to express ADAM6 was reengineered into VELOClMMUNE® mice to rescue the fertility defect. 2] A targeting vector for insertion of mouse ADAMGa and ADAM6b genes into a humanized heavy chain locus was ucted using VELOClGENE® genetic engineering technology (supra) to modify a Bacterial Artificial Chromosome (BAC) 929d24, which was obtained from Dr. Frederick Alt rd University). 929d24 BAC DNA was engineered to contain genomic fragments containing the mouse ADAM6a and ADAM6b genes and a hygromycin cassette for targeted deletion of a human ADAM6 pseudogene (hADAMGW) located between human VH1—2 and VHS—1 gene segments of a humanized heavy chain locus ().

First, a genomic fragment containing the mouse ADAM6b gene, ~800 bp of am (5’) sequence and ~4800 bp of downstream (3’) sequence was subcloned from the 929d24 BAC clone. A second genomic fragment containing the mouse ADAM6a gene, ~300 bp of upstream (5’) sequence and ~3400 bp of downstream (3’) sequence, was separately subcloned from the 929d24 BAC clone. The two genomic nts ning the mouse ADAM6b and ADAM6a genes were ligated to a ycin cassette flanked by Frt recombination sites to create the targeting vector (Mouse ADAM6 Targeting Vector, Figure 12; SEQ lD N023). Different ction enzyme sites were engineered onto the 5’ end of the targeting vector following the mouse ADAM6b gene and onto the 3’ end following the mouse ADAM6a gene (bottom of ) for ligation into the humanized heavy chain locus.

A separate modification was made to a BAC clone containing a replacement of mouse heavy chain variable gene loci with human heavy chain variable gene loci, including the human ADAM6 pseudogene BllJ) located between the human VH1-2 and VH6-1 gene segments of the humanized locus for the subsequent ligation of the mouse ADAM6 targeting vector ().

Briefly, a neomycin cassette d by onP recombination sites was engineered to contain homology arms containing human genomic sequence at positions 3’ of the human VH1-2 gene segment (5’ with respect to hADAMSLP) and 5’ of human VHS—1 gene segment (3’ with respect to hADAMSLlJ; see middle of ). The location of the insertion site of this targeting construct was about 1.3 kb 5’ and ~350 bp 3’ of the human ADAMS pseudogene. The targeting construct also included the same restriction sites as the mouse ADAMS targeting vector to allow for subsequent BAC ligation n the modified BAC clone ning the deletion of the human ADAMS pseudogene and the mouse ADAMS targeting vector.

Following digestion of BAC DNA derived from both constructs, the c fragments were ligated together to construct an ered BAC clone ning a humanized heavy chain locus containing an ectopically placed genomic sequence comprising mouse ADAMSa and ADAMSb nucleotide sequences. The final targeting construct for the deletion of a human ADAMS gene within a humanized heavy chain locus and insertion of mouse ADAMSa and ADAMSb sequences in ES cells ned, from 5’ to 3’, a 5’ genomic fragment containing ~13 kb of human c sequence 3’ of the human VH1—2 gene segment, ~800 bp of mouse genomic sequence ream of the mouse ADAMSb gene, the mouse ADAMSb gene, ~4800 bp of genomic sequence upstream of the mouse ADAMSb gene, a 5’ Frt site, a hygromycin cassette, a 3’ Frt site, ~300 bp of mouse genomic sequence downstream of the mouse ADAMSa gene, the mouse ADAMSa gene, ~3400 bp of mouse genomic sequence upstream of the mouse ADAMSa gene, and a 3’ c fragment containing ~30 kb of human genomic sequence 5’ of the human VHS-1 gene segment (bottom of ).

The engineered BAC clone (described above) was used to oporate mouse ES cells that contained a humanized heavy chain locus to created modified ES cells comprising a mouse genomic sequence ectopically placed that comprises mouse ADAMSa and ADAMSb sequences within a humanized heavy chain locus. Positive ES cells containing the ectopic mouse genomic fragment within the humanized heavy chain locus were identified by a quantitative PCR assay using TAQMAN TM probes (Lie and Petropoulos, 1998, Advances in quantitative PCR technology: 5’nuclease assays, Curr Opin Biotechno/ 9(1):43-48). The upstream and downstream regions outside of the modified portion of the humanized heavy chain locus were confirmed by PCR using primers and probes located within the modified region to confirm the presence of the ectopic mouse genomic sequence within the humanized heavy chain locus as well as the hygromycin cassette. The nucleotide sequence across the am insertion point included the following, which indicates human heavy chain genomic sequence upstream of the insertion point and an l-Ceul restriction site (contained within the heses below) linked contiguously to mouse genomic sequence present at the insertion point: (CCAGCTTCAT TAGTAATCGT GTGG TAAAAAGGCA GGATTTGAAG CGATGGAAGA TGGGAGTACG GGGCGTTGGA AGACAAAGTG CCACACAGCG CAGCCTTCGT CTAGACCCCC GGGCTAACTA TCCT AAGGTAGCGA G) GGGATGACAG ATTCTCTGTT CAGTGCACTC AGGGTCTGCC TCCACGAGAA TCACCATGCC CTTTCTCAAG ACTGTGTTCT GTGCAGTGCC CTGTCAGTGG (SEQ lD NO:4). The nucleotide sequence across the downstream insertion point at the 3’ end of the ed region included the following, which indicates mouse genomic sequence and a Pl-Scel restriction site (contained within the parentheses below) linked contiguously with human heavy chain genomic sequence downstream of the insertion point: (AGGGGTCGAG GGGGAATTTT AACA AAGAAGCGGG CATCTGCTGA CATGAGGGCC GAAGTCAGGC CAGC GGGAGCTCCA CCGCGGTGGC GCCATTTCAT TACCTCTTTC TCCGCACCCG ACATAGATAAAGCTT) ATCCCCCACC AAGCAAATCC CCCTACCTGG GGCCGAGCTT TGTG GGAAAATGAA TCCCTGAGGT CGATTGCTGC ATGCAATGAA ATTCAACTAG (SEQ ID NO:5).

Targeted ES cells described above were used as donor ES cells and introduced into an 8-cell stage mouse embryo by the VELOClMOUSE® mouse engineering method (see, eg., US Pat Nos. 7,6598,442, 7,576,259, 7,294,754). Mice bearing a humanized heavy chain locus containing an ectopic mouse genomic sequence comprising mouse ADAM6a and ADAM6b sequences were identified by genotyping using a modification of allele assay (Valenzuela et al., 2003) that ed the presence of the mouse ADAM6a and ADAM6b genes within the humanized heavy chain locus.

Mice g a humanized heavy chain locus that contains mouse ADAM6a and ADAM6b genes are bred to a FLPe deleter mouse strain (see, 9.9., Rodriguez et al., 2000, High-efficiency deleter mice show that FLPe is an alternative to Cre-onP. Nature Genetics 252139-140) in order to remove any Frt’ed hygromycin cassette introduced by the targeting vector that is not removed, e.g., at the ES cell stage or in the embryo. Optionally, the hygromycin te is retained in the mice.

Pups are ped and a pup heterozygous for a humanized heavy chain locus containing an ectopic mouse genomic fragment that comprises mouse ADAM6a and ADAM6b ces is selected for characterizing mouse ADAM6 gene expression and fertility.

Example 8 Characterization of ADAM6 Rescue Mice 1] Flow Cytometry. Three mice at age 25 weeks homozygous for human heavy and human K light chain variable gene loci (H+/+ +/+ K ) and three mice at age 18-20 weeks homozygous for human heavy and human K light chain having the ectopic mouse c fragment encoding the mouse ADAM6a and ADAM6b genes within both alleles of the human heavy chain locus (H+/+A6resK+/+) were sacrificed for fication and analysis of lymphocyte cell populations by FACs on the BD LSR ll System (BD Bioscience).

Lymphocytes were gated for specific cell lineages and analyzed for progression through various stages of B cell development. Tissues collected from the animals included blood, spleen and bone marrow. Blood was collected into BD microtainer tubes with EDTA (BD Biosciences). Bone marrow was collected from femurs by flushing with complete RPMI medium supplemented with fetal calf serum, sodium pyruvate, HEPES, 2—mercaptoethanol, non—essential amino acids, and gentamycin. Red blood cells from blood, spleen and bone marrow preparations were lysed with an ammonium chloride—based lysis buffer (e.g., ACK lysis buffer), followed by washing with complete RPMl medium.

For staining of cell populations, 1 x 106 cells from the various tissue sources were incubated with anti-mouse CD16/CD32 (2.4G2, BD Biosciences) on ice for 10 s, followed by ng with one or a combination of the following antibody cocktails for 30 s on ice.

Bone marrow: anti-mouse FlTC-CD43 (1 B1 1, BioLegend), PE-ckit (288, BioLegend), lgM (ii/41, eBioscience), PerCP-Cy5.5-lgD c.2a, BioLegend), APC-eFluor780-8220 (RA3-GBZ, eBioscience), A700-CD19 (1 DB, BD Biosciences).

Peripheral blood and : ouse FlTC-K (187.1, BD Biosciences), PE-A (RML-42, BioLegend), PeCy7-IgM (ll/41, eBioscience), PerCP-Cy5.5-lgD (11-260.2a, BioLegend), APC-CD3 (145-2011, BD), A700—CD19 (1D3, BD), APC—eFluor780-8220 (RA3-682, eBioscience), ing incubation with the labeled antibodies, cells were washed and fixed in 2% formaldehyde. Data acquisition was performed on an LSRll flow cytometer and analyzed with FlowJo (Treestar, lnc.). Results from a representative H+’*x*’*and H*’+A6‘esi<+’* mouse are shown in Fle. 14 -— 18.

The results demonstrate that B cells of H""‘A6“§SK"’+ mice progress through the stages of B cell development in a similar fashion to H*’+K+’+mice in the bone marrow and peripheral tments, and show normal patterns of maturation once they enter the periphery. H+I+A6reSK+/+ mice demonstrated an increased tCD19+ cell population as compared to H+14» +l+ K mice (HS. 168). This may indicate an accelerated igM expression from the humanized heavy chain locus containing an ectopic mouse genomic fragment comprising the mouse ADAM6a and ADAMGb sequences in H+’+A6resi<+’+mice. in the ery, B and T cell populations of H+/+A6resi<+’+mice appear normal and similar to H+’+K+’+mice.

Testis Morphology and Sperm Characterization. To determine if infertility in mice having humanized immunoglobulin heavy chain variable loci is due to testis and/or sperm production defects, testis logy and sperm content of the epididymis was examined.

Briefly, testes from two groups (n=5 per group; group 1: mice homozygous for human heavy and K light chain variable gene loci, H+/+K+/+ , group 2: mice heterozygous for human heavy chain variable gene loci and homozygous for K light chain variable gene loci H”K”) were dissected with the epididymis intact and weighed The specimens were then fixed, ed in paraffin, sectioned and stained with hematoxylin and eosin (HE) stain.

Testis ns (2 testes per mouse, for a total of 20) were examined for defects in morphology and evidence of sperm production, while epididymis sections were examined for presence of sperm.

In this ment, no ences in testis weight or morphology was observed between H+l+Kmmice and H+"K+’+mice. Sperm was observed in both the testes and the ymis of all genotypes. These s establish that the absence of mouse ADAM6a and ADAM6b genes does not lead to detectable changes in testis logy, and that sperm is produced in mice in the presence and absence of these two genes. s in fertility of male HHKmmice are therefore not likely to be due to low sperm production.

Sperm Motility and ion. Mice that lack other ADAM gene family members are infertile due to defects in sperm motility or migration. Sperm migration is defined as the y of sperm to pass from the uterus into the oviduct, and is normally necessary for fertilization in mice. To determine if the deletion of mouse ADAM6a and ADAM6b affects this process, sperm migration and motility was evaluated in H+/+K+/+ mice.

Briefly, sperm was obtained from testes of (1) mice zygous for human heavy chain variable gene loci and homozygous for human K light chain variable gene loci (H+"K+’+); (2) mice homozygous for human heavy chain variable gene loci and homozygous for human K light chain variable gene loci (H+l+K+l+); (3) mice homozygous for human heavy chain variable gene loci and homozygous for wild-type K light chain (H+’+mK); and, (4) wild- type 057 BL/6 mice (WT). No significant abnormalities were observed in sperm count or overall sperm ty by inspection. For all mice, cumulus dispersal was observed, indicating that each sperm sample was able to penetrate the cumulus cells and bind the zona ida in vitro. These results establish that H+I+K+/+ mice have sperm that are capable of penetrating the cumulus and binding the zona pellucida.

Fertilization of mouse ova in vitro (lVF) was done using sperm from mice as described above A slightly lower number of cleaved embryos were observed for H+/+K+/+ mice the day following lVF as well as a reduced number of sperm bound to the eggs.

These results establish that sperm from H -I-/+K+/+ mice, once exposed'to an ovum, are capable of penetrating the cumulus and binding the zona pellucida in another experiment, the y of sperm from H+/+K+/+ mice to migrate from the uterus and through the oviduct was determined in a sperm migration assay.

Briefly, a first group of super-ovulated female mice (n=5) were set up with H“’+1<+’+ males (n=5) and a second group of super-ovulated female mice (n=5) were set up with H*"t<+f+ males (n=5). The mating pairs were observed for copulation, and five to six hours post-copulation the uterus and attached oviduct from all females were removed and d for analysis. Flush solutions were checked for eggs to verify ovulation and obtain a sperm count. Sperm migration was evaluated in two different ways. First, both oviducts were removed from the , flushed with saline, and any sperm identified were counted.

The presence of eggs was also noted as evidence of ovulation. , oviducts were left attached to the uterus and both tissues were fixed, embedded in paraffin, sectioned and stained (as described above). Sections were examined for presence of sperm, in both the uterus and in both oviducts.

For the females mated with the five “’+ males, very little sperm was found in the flush on from the oviduct. Flush solutions from oviducts of the females mated with the W5?” males exhibited a sperm level about 25— to 30—fold higher (avg, n = 10 oviducts) than present in flush solutions from the oviducts of the females mated with the H+I+K+’+males. A entative breeding comparison of mef’+ and H+I+A6resxw mice is shown in Table 9.

Histological sections of uterus and oviduct were prepared. The sections were ed for sperm presence in the uterus and the oviduct (the colliculus tubarius). inspection of histological sections of oviduct and uterus ed that for female mice mated with H+i+K+i+ mice, sperm was found in the uterus but not in the oviduct. Further, sections from s mated with H+/+ +H mice revealed K that sperm was not found at the uterotubal junction (UTJ). in sections from females mated with H+"1<”’+ mice, sperm was identified in the UTJ and in the oviduct.

These results establish that mice lacking ADAM6a and ADAM6b genes make sperm that exhibit an in vivo ion defect. in all cases, sperm was ed within the uterus, indicating that copulation and sperm release apparently occur as normal, but little to no sperm was observed within the oviducts after copulation as measured either by sperm count or histological observation. These results establish that mice g ADAM6a and ADAMBb genes produce sperm that exhibit an inability to migrate from the uterus to the oviduct. This defect apparently leads to infertility because sperm are unable to cross the uterine-tubule junction into the oviduct, where eggs are fertilized. Taken together, all of these results converge to the support the hypothesis that mouse ADAMS genes help direct sperm with normal ty to migrate out of the , through the uterotubal junction and the oviduct, and thus approach an egg to achieve the fertilization event. The mechanism by which ADAM6 achieves this may be directed by one or both of the ADAM6 ns, or through nate expression with other proteins, e.g., other ADAM proteins, in the sperm cell, as described below.

Table 9 Male Breeding .

. Duration of An'ma's “tiers. Oﬁsprlng_ Genotype Breeding (Male/Female) Mares ——— ADAM Gene Family Expression. A complex of ADAM proteins are known to be present as a complex on the surface of ng sperm. Mice lacking other ADAM gene family members lose this complex as sperm mature, and exhibit a reduction of multiple ADAM proteins in mature sperm. To determine if a lack of ADAM6a and ADAM6b genes affects other ADAM proteins in a similar manner, Western blots of protein extracts from testis (immature sperm) and epididymis (maturing sperm) were analyzed to determine the expression levels of other ADAM gene family members. 8] In this experiment, protein extracts were analyzed from groups (n=4 per group) of HW“and Hf“):“mice. The results showed that expression of ADAM2 and ADAM3 were not ed in testis extracts. However, both ADAM2 and ADAMS were dramatically d in epididymis extracts. This demonstrates that the absence of ADAM6a and ADAM6b in sperm of H+I+K+l+ mice may have a direct affect on the expression and perhaps on of other ADAM proteins as sperm matures (e.g., ADAM2 and ADAMS). This suggests that ADAM6a and ADAM6b are part of an ADAM protein complex on the surface of sperm, which might be critical for proper sperm migration.

Example 9 Human Heavy Chain Variable Gene Utilization in ADAM6 Rescue Mice Selected human heavy chain variable gene usage was determined for mice homozygous for human heavy and K light chain variable gene loci either lacking mouse ADAM6a and ADAM6b genes (H+/+K+/+) or containing an ectopic genomic fragment encoding for mouse ADAM6a and ADAM6b genes (H+’+A6’esi<+”) by a quantitative PCR assay using TAQMANTM probes (as described above).

Briefly, CD19 B cells were purified from the s of H+/+K*” and l8’esi<+’+ mice using mouse CD19 Microbeads (Miltenyi Biotec) and total RNA was purified using the TM Mini kit n). Genomic RNA was removed using an RNase-free DNase on-column treatment (Qiagen). About 200 ng mRNA was reverse-transcribed into cDNA using the First Stand cDNA Synthesis kit (lnvitrogen) and then amplified with the TAQMANTM Universal PCR Master Mix (Applied Biosystems) using the ABI 7900 Sequence Detection System (Applied Biosystems). Relative sion of each gene was normalized to the expression of mouse K light chain constant region (mCK). Table 10 sets forth the sense/antisensefl'AQMANTM MGB probe combinations used in this experiment.

Table 10 Human VH Sequence (5’—3’) SEQ ID NO: Sense: CAGGTACAGCTGCAGCAGTCA ense: GGAGATGGCACAGGTGAGTGA Probe: TCCAGGACTGGTGAAGC Sense: TAGTCCCAGTGATGAGAAAGAGAT ense: GAGAACACAGAAGTGGATGAGATC Probe: TGAGTCCAGTCCAGGGA Sense: AAAAATTGAGTGTGAATGGATAAGAGTG Anti—sense: AACCCTGGTCAGAAACTGCCA Probe: AGAGAAACAGTGGATACGT Sense: GCACAGAAGTTCCAGG Anti—sense: GCTCGTGGATTTGTCCGC Probe: CAGAGTCACGATTACC Sense: TGAGCAGCACCCTCACGTT Anti-sense: GTGGCCTCACAGGTATAGCTGTT Probe: ACCAAGGACGAGTATGAA In this experiment, expression of all four human VH genes was observed in the samples analyzed. Further, the expression levels were comparable between H+I+K+l+ and H+I+A6resxm mice. These results demonstrate that human VH genes that were both distal to the modification site (VH3-23 and VH1—69) and proximal to the modification site (VH1-2 and VHS-1) were all able to recombine to form a functionally expressed human heavy chain.

These results demonstrate that the ectopic genomic fragment comprising mouse ADAMGa and ADAM6b sequences inserted into a human heavy chain genomic sequence did not affect V(D)J recombination of human heavy chain gene segments within the locus, and these mice are able to ine human heavy chain gene ts in normal fashion to e functional heavy chain immunoglobulin proteins.

Example 10 Humoral Immune Response in ADAMS Rescue Mice The humoral immune se was determined for mice homozygous for human heavy and K light chain le gene loci either lacking mouse ADAM6a and ADAM6b genes +’*) or containing an ectopic genomic fragment encoding for mouse ADAM6a and ADAM6b genes (H+’+A6resx+’+) by a multi-antigen immunization scheme followed by antibody isolation and characterization. Results were compared for determination of any effect on V(D)J recombination involving the human globulin gene segments, assessment of serum titer progression, production of antibodies by hybridomas and affinity for antigen.

Immunization protocol. A human cell surface receptor (Antigen A), a human antibody specific for a human receptor tyrosine—protein kinase (Antigen B), a secreted human protein that functions in regulation of the TGF-B signaling pathway (Antigen C), and a human receptor tyrosine kinase (Antigen D) were employed for comparative immunizations in groups of mice. Serum was collected from groups of mice prior to immunization with the above antigens. Each antigen (2.3 pg each) was administered in an initial priming immunization mixed with 10 pg of CpG oligonucleotide as adjuvant (lnvivogen). The gen was administered via footpad (f.p.) in a volume of 25 pl per mouse. Subsequently, mice were boosted via f.p. with 2.3 pg of antigen along with 10 pg CpG and 25 pg Adju-Phos (Brenntag) as adjuvants on days 3, 6, 11, 13, 17, and 20 for a totai of six boosts. Mice were bled on days 15 and 22 after the fourth and sixth , tively, and antisera were assayed for dy titer to each specific antigen. dy titers were determined in sera of immunized mice using an ELISA assay. Ninety ll microtiter plates (Thermo ific) were coated with the tive antigen (2 pg/ml) in phosphate—buffered saline (PBS, lrvine Scientific) overnight at 4°C.

The following day, plates were washed with phosphate—buffered saline containing 0.05% Tween 20 (PBS—T, Sigma—Aldrich) four times using a piate washer (Molecular Devices).

Plates were then blocked with 250 pi of 0.5% bovine serum albumin (BSA, Sigma-Aldrich) in PBS and incubated for one hour at room temperature. The plates were then washed four times with PBS—T. Sera from immunized mice and pre-immune sera were serially diluted three-fold in 0.5% BSA—PBS ng at 1:300 or 1:1000 and added to the blocked plates in duplicate and incubated for one hour at room temperature. The last two wells were left blank to be used as secondary antibody control. The plates were again washed four times with PBS-T in a plate washer. A 1:5000/1:10,000 dilution of goat anti—mouse lgG-Fc-Horse Radish Peroxidase (HRP, n lmmunoresearch) or goat anti—mouse IgG-kappa-HRP (Southern Biotech) conjugated secondary antibody was added to the plates and incubated for one hour at room temperature. Plates were again washed eight times with PBS-T and developed using TMB/H202 as substrate. The ate was incubated for twenty minutes and the reaction stopped with 2 N VWR) or 1 N H3PO4 (JT Baker). Plates were read on a spectrophotometer (Victor, Perkin Elmer) at 450 nm. Antibody titers were calculated using ad PRlSM software.

] Serum titer was calculated as serum dilution within experimental titration range at the signal of n binding equivalent to two times above background. Results for the humoral immune response are shown in (Antigen A), FIG, 20 (Antigen B), en C), and HG. 22 (Antigen D). n positive score of hybridomas made using two spleens isolated from mice from each group of selected immunizations is shown in Table 11 (Antigen score is equal to 2X/background).

As shown in this Example, dy titers generated in Adam6 rescue mice (H+/+A6resK+/+) were comparable to those generated in mice lacking ADMA6a and ADAM6b and having humanized heavy chain (H+/+ +/+ K ). Further, spleens from H+I+A6'esx+’+ mice yielded antigen-positive hybridomas for all antigens tested, including antibodies of high affinity, at levels comparable to H+I+K+l+ mice. Thus, no impairment of V(D)J recombination of human immunoglobulin gene segments in Adam6 rescue mice is believed to exist given the production of antibodies with high affinity containing human immunoglobulin genes.

Table 11 Antigen Mouse Strain Antigen Score waxes?“ Example 11 Antigen Binding Affinity Determination Binding ties of antibodies showing specific binding to Antigen B were screened using a real—time surface plasmon resonance biosensor (BlAcore 2000).

Conditioned media from hybridomas isolated from two strains of mice immunized with Antigen B (H*’+K*’+ and resK+/+) were used during BlAcore screening. BlAcore sensor surface was ﬁrst derivatized with polyclonal rabbit anti—mouse antibody (GE) to e anti—Antigen B antibodies from conditioned media. During the entire screening method, HBST (0.01M HEPES pH 7.4, 0.15M NaCl, 3mM EDTA, 0.005% v/v tant P20) was used as the running buffer. Fab fragment of Antigen B was ed over the anti-Antigen B antibody captured surface at a flow rate of 50 pl/minute at 100nM concentration.

Antibody-antigen association was monitored for three minutes while the dissociation of antigen from the captured antibody was monitored for five minutes in HBST running buffer.

The experiment was performed at 25°C. c association (ka) and iation (kd) rate constants were determined by processing and g the data to a 1:1 binding model using Scrubber 2.0 curve fitting software. Binding dissociation equilibrium constants (KD) and dissociative half-lives (Tyz) were calculated from the kinetic rate constants as: KD (M) = kd / ka; and T72 (min) = (In2/(60*kd). Results for selected anti-Antigen B antibodies are shown in Table 12.

Table 12 Antibody Mouse strain KD (M) Ty, (min) 5D6 H+/+ +/+ 1 8 00 8G10 H+/+ +/+ 1 .20E-08 5 1OF10 H+/+ +/+ 1.09E—08 3 1F5 H+/+ +/+ 1.00E—07 0.3 1OG8V H+/+ +/+ 1.47E-07 0.3 1811 H+/+A6reSK+/+ 1.98E-08 _D11 H" +A6resi<+ + -5.6OE:E 704 H+/+A6resK+l+ 2.00E-06 0.05 H*’*A6"~‘SK*’* 2.31E—09 H+’*A6resx*’+ 3.47E-09 1034 H+I+A6reSK+I+ 3.60E-09 -23 H+/+A6’esr<+’+ 08 H*’*A6resl<+’+ 2.705-07 H*"‘Ac3“’3$t<+’+ 7.00E-10 H+’+A6'esi<””' 5.80E-10 In a similar experiment, kinetics of ent monoclonal antibodies present in hybridoma-conditioned media g to Antigen A was determined using a real-time surface plasmon resonance sor (BlAcore 4000) assay. All hybridoma clones used in this assay were produced in H+’+A6""si<+’+ mice.

Briefly, to capture the Antigen A-specific antibodies, polyclonal rabbit anti- mouse antibody (GE g# BR38) was first immobilized on the sensor chip.

BlAcore screening was med in two different buffers —- PBSP, pH7.2 and PBSP, pH6.0. Both the buffers were supplemented with 0.1 mg/ml BSA. Following the capture of anti-Antigen A antibodies from the conditioned media, 1 uM of n A monomer (prepared in respective running buffer) was injected over the captured antibody surface for 1.5 minutes at 30 ul/minute and the dissociation of bound Antigen A monomer was monitored for 1.5 minutes in the tive running buffer at 25°C. Kinetic association (ka) and dissociation (kd) rate constants were determined by processing and fitting the data to a 1:1 binding model using Scrubber 2.0 curve fitting software. Binding iation equilibrium constants (KD) and dissociative half-lives (Tyz) were calculated from the kinetic rate constants as: KD (M) = kd / ka; and T1/2 (min) = (ln2/(60*kd). Table 13 sets forth the binding kinetics parameters for selected anti-Antigen A dy binding to n A monomer at pH7.2 and pH6.0. NB: no binding detected under current experimental conditions.

Table 13 pH7.2 pH6.0 Antibody Kn (M) Ty; (mm) Kn (M) Ty: (min) — 2.98EB-09 2.06E-11 _Im- 6.-79E1 7,-42E11 .11:- -05E1 -197E0 _ 1. 58E—08 2.59E-09 _702E 11 14281 As shown above, high affinity antibodies were ed from both H*’*A6re‘°‘x*’+ and H+I+K+l+ mice in a comparable manner. Among the twenty~five antibodies represented in Table 12, twenty produced in H‘WAES’eSK”+ mice demonstrated an affinity range of 0.5 nM to 1 uM, while the five generated in H“"’K"’+ mice demonstrated an affinity range of 10 nM to 150 nM. Further, the ﬁfty-five antibodies shown in Table 13 trated an affinity range of 20 pM to 350 nM for g to Antigen A monomer.

As demonstrated in this Example, the reinsertion of mouse Adam6 genes into a humanized immunoglobulin heavy chain locus does not impair the y of the mouse to mount a robust immunize response to multiple antigens characterized by repertoires of human antibodies having diverse affinities in the subnanomolar range, which are derived from human gene segments rearranged from a engineered germline.

Claims

THE CLAIMS DEFINING THE INVENTION ARE AS FOLLOWS:

1. A genetically modified mouse whose genome: (i) lacks a functional endogenous ADAM6 locus; and (ii) includes an inserted nucleotide sequence encoding a mouse ADAM6 protein or functional nt f.

2. The genetically modified mouse of claim 1, wherein the mouse genome ses an endogenous ADAM6 locus that: (i) does not express an ADAM6 protein or onal fragment thereof; or (ii) expresses an ADAM6 protein or functional fragment thereof at a level that is insufficient to support essentially normal fertility of a male mouse.

3. The genetically ed mouse of claim 1 or 2, wherein the mouse genome comprises an endogenous ADAM6 locus has a modification in a gene selected from the group consisting of an ADAM6a gene, an ADAM6b gene, and the ation thereof.

4. The genetically modified mouse of any one of claims 1-3, wherein the mouse genome comprises an endogenous ADAM6 locus or fragment thereof has a modification in a regulatory region.

5. The genetically modified mouse of claim 4, wherein the regulatory region is selected from the group consisting of a region 5’ to ADAM6a, a region 3’ of ADAM6a, a region 3’ of ADAM6b, and combinations thereof.

6. The genetically ed mouse of any one of claims 1-5, wherein at least a portion of the endogenous ADAM6 locus has been removed.

7. The genetically modified mouse of claim 1 or 2, wherein the mouse genome lacks an endogenous ADAM6 gene.

8. The genetically modified mouse of claim 7, wherein the endogenous ADAM6 gene is an ADAM6a gene, an ADAM6b gene, or the combination thereof.

9. The genetically modified mouse of claim 7 or 8, wherein the endogenous ADAM6 gene has been removed.

10. The genetically modified mouse of claim 6 or 9, wherein the mouse genome includes a replacement of one or more endogenous heavy chain variable region gene segments with one or more human heavy chain le region gene segments, and n the replacement removed an endogenous ADAM6 gene or at least a portion of the endogenous ADAM6 locus.

11. The genetically modified mouse of any one of claims 1-10, wherein the inserted nucleotide sequence encoding a mouse ADAM6 protein or onal fragment thereof comprises a mouse ADAM6a gene, a mouse ADAM6b gene, or the combination thereof.

12. The genetically modified mouse of any one of claims 1-11, wherein the inserted nucleotide sequence encoding a mouse ADAM6 protein or functional fragment thereof is inserted into the mouse genome at a transcriptionally-permissive locus.

13. The cally ed mouse of any one of claims 1-12, wherein the inserted nucleotide ce encoding a mouse ADAM6 protein or functional fragment thereof is not found n the two endogenous mouse globulin variable region sequences that the endogenous ADAM6 locus is found between in a wild-type mouse.

14. The genetically modified mouse of any one of claims 1-13, wherein the mouse genome further comprises a human variable region sequence.

15. The genetically modified mouse of claim 14, wherein the inserted tide sequence encoding a mouse ADAM6 protein or functional fragment thereof is placed within the human variable region sequence.

16. The genetically modified mouse of claim 14 or 15, wherein the human variable region sequence includes one or more human VH gene segments.

17. The genetically modified mouse of claim 16, wherein one or more human VH gene segments comprise VH1-2 and VH6-1.

18. The genetically ed mouse of claim 17, wherein the inserted nucleotide sequence encoding a mouse ADAM6 protein or functional nt thereof is placed between the human VH1-2 and the human VH6-1 gene segments.

19. The genetically ed mouse of claim 18, wherein the ed nucleotide sequence encoding a mouse ADAM6 protein or onal fragment thereof has a direction of transcription opposite of that of the surrounding human variable gene segments.

20. The genetically modified mouse of any one of claims 14-19, wherein the human variable region sequence includes one or more human DH gene segments and one or more human JH gene segments.

21. The genetically modified mouse of any one of claims 14-20, n the human variable region sequence is operably linked to a human or mouse immunoglobulin constant region gene.

22. The genetically modified mouse of any one of claims 1-21, wherein the endogenous immunoglobulin loci are disabled.

23. The genetically modified mouse of any one of claims 1-22, whose genome ses a deletion of an endogenous immunoglobulin variable region sequence.

24. The genetically modified mouse of claim 23, wherein the deletion comprises a deletion of at least one mouse VH gene segment, at least one mouse DH gene segment, at least one mouse JH gene segment, or combinations thereof.

25. The genetically modified mouse of any one of claims 1-24, wherein the genetically modified mouse includes B cells that comprise a rearranged human immunoglobulin variable region sequence.

26. The mouse of claim 25, wherein the rearranged human immunoglobulin variable ce is selected from the group consisting of a rearranged human immunoglobulin heavy chain variable sequence and a rearranged human immunoglobulin light chain variable ce.

27. The mouse of claim 26, wherein the rearranged human immunoglobulin variable region is operably linked with a mouse constant region gene.

28. A method of making a genetically engineered mouse, the method comprising steps of: gestating in a ate mother a mouse embryo that comprises in its genome an inserted nucleotide sequence ng a mouse ADAM6 protein or functional fragment thereof.

29. The method of claim 28, wherein the step of gestating comprises: inserting into the mouse embryo a nucleotide sequence encoding a mouse ADAM6 protein or functional fragment thereof.

30. The method of claim 29, wherein the step of inserting into the mouse embryo comprises: inserting a nucleotide sequence ng a mouse ADAM6 protein or functional fragment thereof into a donor mouse ES cell; and introducing the donor mouse ES cell into the embryo.

31. The method of any one of claims 28-30, wherein the mouse into which tide sequence encoding a mouse ADAM6 protein or functional fragment thereof is inserted lacks an endogenous ADAM6 gene at an endogenous globulin heavy chain locus.

32. A method of increasing mouse fertility by: inserting into a mouse cell a nucleotide sequence encoding a mouse ADAM6 protein or functional fragment thereof.

33. The method of claim 32, wherein the mouse cell comprises a deletion of an endogenous immunoglobulin heavy chain variable region.

34. The method of claim 32 or 33, wherein the mouse cell comprises a replacement of an endogenous immunoglobulin heavy chain variable region.

35. The method of any one of claims 32-34, wherein the mouse comprises human VH gene segments.

36. The method of claim 35, wherein the human VH gene ts are within the endogenous mouse immunoglobulin heavy chain locus.

37. The method of claim 36, wherein the inserted nucleotide sequence encoding a mouse ADAM6 protein or functional fragment f is within the endogenous mouse immunoglobulin heavy chain locus ing the human VH gene segments.

38. The method of claim 35, wherein the human VH gene segments replaced one or more mouse variable region gene segments in the endogenous mouse immunoglobulin heavy chain locus.

39. A genetically modified mouse produced by the method of any one of claims 32-38.

40. A mouse immunoglobulin heavy chain locus that: (i) lacks a functional endogenous ADAM6 locus; and (ii) includes an inserted tide ce encoding a mouse ADAM6 protein or onal fragment thereof.

41. The mouse globulin heavy chain locus of claim 40, further comprising a sequence that includes one or more human VH gene segments.

42. The mouse immunoglobulin heavy chain locus of claim 41, wherein the sequence that includes one or more human VH gene segments replaced one or more endogenous VH gene segments.

43. The mouse immunoglobulin heavy chain locus of claim 42, wherein the replacement of the one or more endogenous VH gene segments with the sequence that includes one or more human VH gene segments removes the endogenous ADAM6 sequence.

44. The mouse immunoglobulin heavy chain locus of any one of claims 41-43, wherein inserted nucleotide sequence encoding a mouse ADAM6 protein or functional fragment thereof is placed between two human VH gene segments.

45. The mouse globulin heavy chain locus of any one of claims 41-44, wherein the one or more human VH gene segments are operably linked to one or more human or mouse DH gene segments, one or more human or mouse JH gene segments and a human or mouse globulin nt region gene.

46. A genetically modified mouse whose genome ses the mouse immunoglobulin heavy chain locus of any one of claims 40-45.

47. A mouse B cell whose genome comprises: a rearranged human immunoglobulin variable region sequence; and an inserted nucleotide sequence encoding a mouse ADAM6 n or functional fragment thereof.

48. The mouse B cell of claim 47, wherein the rearranged human immunoglobulin variable sequence is selected from the group consisting of an immunoglobulin heavy chain variable sequence and an immunoglobulin light chain variable sequence.

49. The mouse B cell of claim 47 or 48, wherein the rearranged human immunoglobulin variable region ce is operably linked with a mouse constant region gene.