WO1993006843A1

WO1993006843A1 - Peptides corresponding to antigenic determinants of htlv

Info

Publication number: WO1993006843A1
Application number: PCT/US1992/008405
Authority: WO
Inventors: Thomas J. Palker; Barton F. Haynes
Original assignee: Duke University
Priority date: 1991-10-08
Filing date: 1992-10-08
Publication date: 1993-04-15
Also published as: EP0618804A1; JPH07502493A; AU2879292A; EP0618804A4

Abstract

The present invention relates to immunogenic preparations of peptides comprising amino acid sequences corresponding to antigenic determinants of the envelope glycoprotein of HTLV-I or HTLV-II covalently coupled, directly or through a spacer molecule, to carrier molecules suitable for vaccination of mammals. The invention also relates to the use of such peptides in diagnostic assays.

Description

PEPTIDES CORRESPONDING TO ANTIGENIC DETERMINANTS OF HTLV BACKGROUND OF THE INVENTION

1. Technical Field

The present invention relates, in general, to immunogenic preparations and, in particular, to synthetic peptides having amino acid sequences corresponding to antigenic determinants of the envelope proteins of human T-cell leukemia virus (HTLV) types I or II, and immunogenic compositions comprising same.

2. Background Information

HTLV-1 and -II are exogenous, naturally occurring human retroviruses that preferentially infect thymus-derived (T) lymphocytes. HTLV-1 and -II are causative agents of adult T-cell leukemias and lymphomas (ATLL) (Poiesz et al. Proc. Natl.

Acad. Sci. USA 77:7415, 1980; Kalyanaraman et al. Science 218:571, 1982). HTLV-1 infection in man can be associated with a "smoldering" pre-leukemic condition that can progress to an overt aggressive ATLL or can remain unchanged for years (Yamaguchi et al. Blood 62:758, 1983). The apparent long latency period prior to onset of ATLL presents a major epidemiological problem in containing the spread of infection by healthy, HTLV-I+ carriers and in identifying those exposed to the virus. HTLV-I can be transmitted by sexual intercourse, shared

intravenous drug-abuse equipment, breast milk, and in utero or peripartum exposure (Wong-Staal and Gallo Nature 317:395, 1985). Currently, there is no way to eliminate HTLV-I from infected humans or to prevent viral transmission or development of

disease. In addition to ATLL, HTLV-I infection has also been associated with tropical spastic

paraparesis (Gessain et al. Lancet 11:698, 1986), chronic progressive myelopathies (Osame et al. Ann. Neurol. 21:117, 1987), multiple sclerosis (Koprowski et al. Nature 318:154, 1985), non-Hodgkin's

lymphomas (Gibbs et al. Assoc. Intern, ed. 106:361, 1987), and B-cell chronic lymphocytic leukemia (CLL) (Mann et al. Science 236;1103, 1987). HTLV-II has been associated with a rare form of chronic leukemia called T-cell variant of Hairy Cell Leukemia

(Kalyanaraman et al. Science 218:471, 1982).

While HTLV-I has a worldwide distribution, localized endemic regions have been identified in southern Japan (Hiruma et al. Int. J. Cancer 29:631, 1983), the Caribbean basin (Blattner et al. Lancet II:61, 1983), southeastern United States (Blayney et al. J. Am. Med. Assoc. 250:1048. 1983), Africa

(Biggar et al. Int. J. Cancer 34:215, 1984), and other regions. The epidemiology of HTLV-II is less well known, although the prevalence of HTLV-II seropositivity is increasing (Rosenblatt et al. New Engl. J. Med. 315:372, 1986). Similarly, rates of seropositivity for HTLV-I are increasing in

intravenous drug abusers from New York City (9%, (Robert-Guroff et al. J. Am. Med. Assoc. 255:3133, 1986)) and New Orleans (49% (Weiss et al. Proc. Am. Soc. Clin. One. 6:5, 1987)) and in subjects

receiving transfusions of blood products from New York City (9% (Robert-Guroff et al. J. Am. Med.

Assoc. 255:3133, 1986)) and Chapel Hill, North

Carolina (13%, (Haynes et al. Clin. Res. 33:342A, 1985)).

Recently, a cluster of 6 individuals from Raleigh, NC was identified with antibodies to HTLV- I (Weinberg et al. Centers for Disease Control.

Morbidity and Mortality Weekly Report. Dec. 18, 1987). These individuals also had abnormal

circulating lymphocytes, indicative of a preleukemic syndrome. One patient has subsequently died of adult T-cell leukemia, all 6 were

seronegative for HIV. The finding of this cluster, as well as increasing rates of seropositivity in New York City and New Orleans, underscore an immediate need for both reliable diagnostic assays for HTLV-I and for a protective vaccine for non-infected individuals.

Currently, there are no vaccines available for HTLV-I, although results of a number of studies indicate that a vaccine incorporating envelope gene products of HTLV-I is likely to have protective value. The envelope gene of HTLV-I encodes a 63-67 kilodalton (kd) glycoprotein precursor that is proteolytically processed to give rise to a mature gp46 external envelope glycoprotein and a 21kd transmembrane protein (Lee et al. Proc. Natl. Acad. Sci. USA 81:3856, 1984).

Kiyokawa et al (Proc. Natl. Acad. Sci. USA 81:6202, 1984) have expressed in E. coli the entire gp63 envelope precursor molecule of HTLV-I as two fragments, an N-terminal portion containing all but 12 amino acids of the external gp46 envelope

molecule and a C-terminal portion consisting almost entirely of the gp21 transmembrane molecule. Using rabbit antisera to the N- and C-terminal portions of HTLV-I gp63 envelope precursor, Kiyokawa et al have neutralized both American and Japanese HTLV-I pseudotypes. Hoshino et al (Int. J. Cancer 36:761, 1985) have confirmed this finding with anti-gp21 antiserum. Collectively, these data indicate the presence of at least 2 neutralizing sites on HTLV-I envelope, one associated with the external gp46 envelope glycoprotein and a second associated with the gp21 transmembrane glycoprotein. Moreover, since these HTLV-I recombinant proteins produced in E. coli are not glycosylated, carbohydrate is not an essential component of these neutralizing sites.

Thus, synthetic peptides, as nonglycosylated constructs, are likely to be suitable for raising neutralizing antisera to HTLV-I

envelope. Since human or animal antisera to

Japanese and American HTLV-I envelope will cross- neutralize in pseudotype assays, it is also likely that the. envelope antigens of HTLV-I represent a single serotype worldwide (Nagy et al. Int. J.

Cancer 32:321, 1983). Thus, unlike the isolatespecific neutralizing epitopes of HIV, a synthetic vaccine against one HTLV-I isolate should protect against other HTLV-I isolates. In fact, Tochikuro et al. (Int. J. Cancer 36:1, 1985) have demonstrated that HTLV-I or specific antibodies can suppress viral antigen expression when added to cultures of HTLV-I+ lymphocytes, suggesting a mechanism whereby anti-HTLV-I antibodies might protect in vivo.

While these data provide strong support for the proposal that portions of HTLV-I envelope glyco-proteins can be used as a vaccine to elicit protective antibody titers to HTLV-I in humans, these studies do not identify the sequence of the critical epitope(s). Elucidation of the sequence(s) should also facilitate identification of the

epitope(s) of HTLV-II envelope glycoproteins that would be important for inclusion in a vaccine for HTLV-II, due to the sequence homology that exists between HTLV-I and HTLV-II envelope glycoproteins. OBJECTS OF THE INVENTION

It is an object of the present invention to provide synthetic peptides that either alone, or when linked to a carrier molecule, and/or

polymerized to form molecular aggregates, are capable of inducing in mammals the production of high titers of neutralizing antibodies against HTLV-I or HTLV-II.

It is another object of the invention to provide an immunogenic conjugate comprising a peptide having an amino acid sequence corresponding to an antigenic determinant of the HTLV-I envelope protein that is capable of inducing protective immunity in a mammal against HTLV-I.

It is a further object of the invention to provide an immunogenic conjugate comprising a peptide having an amino acid sequence corresponding to an antigenic determinant of the HTLV-II envelope protein that is capable of inducing protective immunity in a mammal against HTLV-II.

It is an additional object of the invention to provide a method of detecting the presence of anti-HTLV-I or anti-HTLV-II antibodies in a biological test sample.

These, and other objects that will be clear to those skilled in the art from the following detailed description, have been accomplished by providing synthetic peptides useful in producing an immunogenic response to the viral causative agents of HTLV-I and HTLV-II. SUMMARY OF THE INVENTION

The invention relates to immunogenic preparations and vaccines made therefrom. Synthetic peptides having amino acid sequences corresponding to antigenic determinants of the envelope proteins of either HTLV-I or HTLV-II are covalently coupled, either directly or through spacer molecules, to suitable carrier molecules to form immunogenic conjugates. Vaccines comprising one or more such conjugates are disclosed.

In one embodiment, the present invention comprises a synthetic peptide having an amino acid sequence corresponding to an antigenic determinant of the envelope glycoprotein of HTLV-I (or HTLV- II), which peptide is capable, either alone or when covalently linked to a carrier molecule, of inducing in a mammal high titers of protective antibodies against HTLV-I ( or HTLV-II). The peptide of the instant invention corresponds to an antigenic determinant present in a hydrophilic region (Kyte and Doolittle J. Mol. Biol. 157:105, 1982) of an HTLV-I (Seiki et al. Proc. Natl. Acad. Sci. USA

80:3618, 1983) or HTLV-II (Sodroski et al. Science 225:421, 1984)) envelope glycoprotein.

In another embodiment, the present invention comprises an immunogenic conjugate capable of inducing in a mammal high titers of protective antibodies against HTLV-I (or HTLV-II), said

conjugate comprising: (i) a carrier molecule

covalently attached to (ii) a synthetic peptide having an amino acid sequence corresponding to an antigenic determinant of the envelope glycoprotein of HTLV-I (or HTLV-II). In yet another embodiment, the present invention comprises a method of producing immunity to HTLV-I (or HTLV-II) comprising administering the above-described HTLV-I (or HTLV-II) specific

conjugate to a mammal in an immunogenically

effective amount.

In another embodiment, the present

invention comprises a method of detecting the presence of anti-HTLV-I (or HTLV-II) antibodies in a biological test sample comprising contacting a peptide of the instant invention with the sample, allowing antibodies in the sample to complex with the peptide, and measuring the formation of the complex.

FIGURE 1: Reactivity of antibodies from

HTLV-I+ patients to gp46 envencoded synthetic peptides.

FIGURE 2: Reactivity of anti-synthetic peptide antisera to gp46 and gp63 envelope glycoproteins of

HTLV-I in an immunoblot assay. FIGURE 3: Specific inhibition of antipeptide antibody reactivity to HTLV-I gp46 in an immunoblot assay.

FIGURE 4A and 4B: Mapping of an epitope of HTLV-I gp46 that is

recognized by an HLD-DR2

restricted cytotoxic T cell line P-10 from patient A with HTLV-I associated tropical spastic paraparesis (TSP).

FIGURE 5: Absorption of neutralizing

anti-peptic antisera with synthetic peptide SP-2. FIGURE 6: Peptide absorption of

neutralizing antibodies to HTLV-I.

FIGURE 7: HTLV-I T-Cell/B-Cell Peptide. DETAILED DESCRIPTION OF INVENTION

The present invention relates to peptides corresponding to immunogenic epitopes of HTLV-1 and to peptides corresponding to immunogenic epitopes of HTLV-II, and to synthetic vaccines against HTLV-I and HTLV-II, respectively, made therefrom. These novel immunogenic agents are prepared by chemically synthesizing peptides sharing antigenic determinants with the gp46 envelope protein of HTLV-I or HTLV- II. The peptides are linked to carrier molecules, thus, forming immunogenic conjugates (and/or are polymerized), rendering them suitable as vaccines. These vaccines are useful for immunization against HTLV-I- or HTLV-II-related diseases when

administered in an immunogenically effective amount to a mammal, for example, by the parenteral route.

It was determined that peptides that should be studied for immunogenic potential included those corresponding to hydrophilic, charged regions of the HTLV-I and HTLV-II gp46 envelope

glycoproteins. It was further determined that, of such peptides, those with predicted beta turns would likely be of particular importance. It was

recognized that the formation of intrapeptide

disulfide bonds would be useful in establishing native configurational determinants. Also, it was recognized that formation of interchain disulfide bonds would be useful in polymerizing peptide molecules so as to form larger, more immunogenic peptide aggregates.

Computer analysis of the predicted amino acid sequences of the envelope proteins of HTLV-I and HTLV-II established the secondary structure and location of hydrophilic regions. Secondary

structure was determined from the computer analysis using the method of Chou and Fasman (Biochemistry 13:211 and 13:222, 1974; Advances in Enzymolocry

(47:45, 1978). Potential areas of beta turns were localized using the method of Rose (Nature 272:586, 1978). Hydrophilic regions of the envelope protein were identified by the technique of Rose and Roy (Proc. Natl. Acad. Sci. USA 77:4643, 1980) and Kyte and Doolittle (J. Mol. Biol. 157:105-132, 1982).

The peptides of the instant invention include peptides that correspond to, or are

homologous with, B-cell epitopes present within the gp46 envelope glycoprotein of HTLV-I. These

peptides are about 25 amino acids (units) or less in length, are hydrophilic, and when conjugated to an appropriate carrier molecule, evoke the production in a mammal of high titers (1:1000) of anti-peptide antibodies that can react with the native gp46 envelope glycoprotein of HTLV-I. Other peptides of the instant invention correspond to, or are

homologous with, B-cell epitopes present within the gp46 envelope glycoprotein of HTLV-II. These peptides are about 25 amino acids (units) or less in length, are hydrophilic, and when conjugated to an appropriate carrier molecule, should evoke the production in a mammal of high titers (1:1000) of anti-peptide antibodies that can react with the native gp46 envelope glycoprotein of HTLV-II. The synthetic peptides of the present invention can have an amino acid sequence as shown in Table 1, or a sequence which is similar enough to one of the sequences shown in Table l so as to be treated in the same manner by an antibody which bonds with the epitope represented by the specific sequence given in the table (that is, an

immunogenically comparable sequence). An example of such a similar sequence is WTKKPNRNGGG (amino acid numbers 88-98 of HTLV-I envelope; designated SP 2L-1). Such synthetic peptides are hereinafter

designated "HTLV-I-specific peptides."

TABLE 1

Synthetic Peptides for Use in Diagnosis

and Vaccination Against HTLV-I

Peptide # Envelope¹ Amino Acid Sequence^2,3,4

Amino Acid #

1 33 - 47 VSSYHSKPCNPAQPV

2 86 - 107 (C) PHWTKKPNRNGGGYYSASYSDP

3 176 - 189 (C)LNTEPSQLPPTAPP(Y)

4 129 - 149 SSPYWKFQHDVNFTQEVSRLN(C) 4A 190 - 209 (C)LLPHSNLDHILEPSIPWKSK(Y)

5 269 - 280 (Y) LPFNWTHCFDPQ(C)

6 296 - 312 (C)PPFSLSPVPTLGSRSRR

7 374 - 392 YAAQNRRGLDLLFWEQGGL(C)

8 400 - 415 CRFPNITNSHVPILQE

9 411 - 422 (C)PILQERPPLENR

10 462 - 480 CILRQLRHLPSRVRYPHYS

11 475 - 488 (C)RYPHYSLIKPESSL

1 According to Seiki, M. et al. Proc. Natl.

Acad. Sci. USA 80:3618-3622, 1983; N- terminal methionine of leader sequence = 1.

Sequence of synthetic peptides 1-11 are listed sequentially from N- to C- terminus of the HTLV-I gp63 envelope precursor molecule with the exception of peptide 4. Sequences in peptides 1-6 are from gp46 external envelope glycoprotein while sequences in peptide 7-11 are derived from gp21 transmembrane glycoprotein. Amino acid numbers begin with the initiation methionine = 1. (See Palker et al J.

Immunol (1989) Vol. 142 (Feb. 1.) Amino acids in parentheses were added to facilitate coupling to carrier protein (C) and iodination (Y) of peptide. Cys can be either at N- or C- terminus.

Each amino acid is represented by its single - letter code, which is the first letter of its name, except for arginine

(R), aspartic acid (D), asparagine (N), glutamine (Q), glutamic acid (E), lysine (K), phenylalanine (F), tryptophan (W), and tyrosine (Y). Similarly, other synthetic peptides of the instant invention can have an amino acid sequence as shown in Table 2, or a sequence similar enough to one of the sequence shown in Table 2 so as to be treated in the same manner by an antibody which bonds with the epitope represented by the specific sequence given in the table (that is, an

immunogenically comparable sequence). An example of such a similar sequence is PHWIKKPNRQGLGYYS(C)

(amino acid numbers 82-97 of HTLV-II envelope;

designated DP-90). Such synthetic peptides are hereinafter designated "HTLV-II-specific peptides."

TABLE 2

Synthetic Peptides for Use in Diagnosis

and Vaccination Against HTLV-II

Peptide # Envelope¹ Amino Acid Sequence^2,3,

Amino Acid #

1 30 - 44 SSYHSSPCSPTQPVC

2 44 - 63 CTWNLDLNSLTTDQRLHPPC

3 83 - 104 HWIKKPNRQGLGYYSPSYNDPC

4 125 - 140 (C) SSPSWKFHSDVNFTQE

5 174 - 194 (C) SEPTQPPPTSPPLVHDSDLEH

6 295 - 308 (C) SLAPVPPPATRRRR

1 According to Sodroski et al. Science

225:421-424, 1984. Methionine of leader sequence = 1.

2 Amino acids in parentheses were added to facilitate coupling to carrier protein (C) and iodination (Y) of peptide. Cys can be either at N- or C-terminus.

3 Each amino acid is represented by its

single - letter code, which is the first letter of its name, except for arginine (R), aspartic acid (D), asparagine (N), glutamine (Q), glutamic acid (E), lysine (K), phenylalanine (F), tryptophan (W), and tyrosine (Y).

Carrier molecules to which peptides of the invention are covalently linked (conjugated) are advantageously non-toxic, pharmaceutically

acceptable, and of a size sufficient to produce an immune response in a mammal. Examples of suitable carrier molecules include tetanus toxoid, and keyhole limpet hemocyanin (KLH). Other carrier molecules to which HTLV-I-specific and HTLV-II-specific peptides can be linked include peptides comprising sequences corresponding to T-cell

epitopes of the HTLV-I or HTLV-II gp63 envelope glycoprotein or p55 gag polyprotein having helical structures predicted by the algorithm of Margalit et al. (J. Immunol. 138:2213, 1987), specific examples of which are given in Table 3. The addition of

LASGKSL amino acids to the N-terminus of I-T1 result in a peptide identified by murine T-helper cells.)

TABLE 3

T Cell Epitopes of HTLV-I and HTLV-III

VIRUS GENE AMINO ACID # DESIGNATION SEQUENCE

HTLV-I Envelope 347-363 I-T1 LHEVDKDISQLTQIVK

HTLV-I Envelope 64-74 I-T2 QPPCPNLVSYS

Gag 184-200 I-T3 DLQDLLQYLCSSLVASL

Gag 79-87 I-T4 RVNEILHIL

HTLV-II Envelope 348-369 II-T4 KDISHLTQAIVKNHQNILRVAQ

Algorithm of Margalit et al. J. Immunol. 138:2213, 1987 used to protect amino acid sequences containing amphipathic a helical secondary structures.

HTLV-I predicted amino acid sequence from Seiki et al.

Prod. Natl. Acad. Sci. USA 80:3618, 1983.

HTLV-II predicted amino acid sequence from Sodorski et al.

Science 225:421, 1984.

HTLV-I and HTLV-II-specific peptides can also be administered with a pharmaceutically acceptable adjuvant, for example, alum, or

conjugated to other carrier molecules more

immunogenic than tetanus toxoid.

Linkage of a carrier molecule to HTLV-I or HTLV-II-specific peptides of the invention can be direct or through a spacer molecule. Spacer

molecules are, advantageously, non-toxic and

reactive. Two glycine residues added to the amino terminal end of an HTLV-I or HTLV-II-specific peptide can provide a suitable spacer molecule for linking the peptide to a carrier molecule;

alternatively, HTLV-I- or HTLV-II-specific peptides can, for example, be synthesized directly adjacent to, for example, another immunogenic HTLV-I or HTLV- II envelope sequence, for example, such as those sequences (or portions thereof) shown in Table 3. Cysteines can be added either at the N- or C- terminus of the HTLV-I or HTLV-II-specific peptides for conjugation to the carrier molecule, or to both ends to facilitate interchain polymerization via disulfide bond formation to form larger molecular aggregates.

Conjugation of the carrier molecule to the

HTLV-I- or HTLV-II-specific peptide is accomplished using a coupling agent. Advantageously, the

heterofunctional coupling agent M-maleimidobenzoyl-N-hydroxysuccinimide ester (MBS), or the water soluble compound m-maleimido-benzoylsulfosuccinimide este (sulfo-MBS), is used, as described by Green et al. (Cell 28:477, 1982) and by Palker et al.

(Proc. Natl. Acad. Sci. USA 84:2479. 1987).

Vaccines of the instant invention, which, when administered to a mammal, induce a protective immunogenic response against HTLV-I, comprise one or more immunogenic conjugate(s), each conjugate comprising an HTLV-I-specific peptide, wherein each HTLV-I-specific peptide corresponds to a different portion of the HTLV-I gp46 envelope protein.

Advantageously, one or more of the HTLV-I-specific peptides listed in Table 1 is conjugated to, or synthesized with, a predicted T-cell epitope of HTLV-I envelope or gag proteins, for example, those shown in Table 3. An example of such a "chimera" is LPPTAPPLLPHSNLDHILEPSIPWKSKWTKKPNRNGGG (amino acid numbers 183-209/88-98 of HTLV-I envelope; designated DP-91).

Similarly, vaccines of the present

invention capable of inducing a protective

immunogenic response against HTLV-II, comprise one or more immunogenic conjugate(s), each conjugate comprising an HTLV-II-specific peptide, wherein each peptide corresponds to a different portion of the HTLV-II gp46 envelope protein. Advantageously, one or more of the HTLV-II-specific peptides listed in Table 2 is conjugated to, or synthesized with, a predicted T-cell epitope, for example, those shown in Table 3.

In addition, a bivalent vaccine can be constructed whereby immunogenic conjugates as described above, comprising synthetic peptides from envelope proteins of HTLV-I and HTLV-II, are mixed to form a single inoculum such that protective antibodies will be simultaneously raised in a mammal to HTLV-I and HTLV-II.

The advantage of using, as a carrier molecule, a synthetic peptide reflecting a portion of HTLV-I or -II envelope or gag molecules

recognized by helper T cells, is that no other carrier molecule, such as tetanus toxoid, is required, and the B and T cell response to HTLV-I, or HTLV-II, is specific. HTLV-I and HTLV-II- specific peptides, alone or synthesized with a corresponding T cell epitope, can be treated with oxidizing agents to induce disulfide bond formation between peptide chain cysteines, to effect

polymerized and therefore, highly immunogenic antigens.

The ability of HTLV-I- and HTLV-II- specific peptides of the instant invention to produce neutralizing antibodies following

immunization is determined as described by Nagy et al (Int. J. Cancer 32:321, 1983).

In addition to the use of HTLV-I- and

HTLV-II-specific peptides as a vaccine, or as a component of a vaccine, these peptides can also be used for diagnostic purposes. The presence and titers of antibodies to HTLV-I or HTLV-II envelope proteins in biological samples can be detected using HTLV-I- and HTLV-II-specific peptides in a solid phase radioimmunoassay (RIA) (Palker et al J.

Immunol. 136:2393, 1986 - the entire contents of which document is hereby incorporated by reference; ibid. Proc. Natl. Acad. Sci. USA 84:2479, 1987)

HTVL-I- and HTLV-II-specific peptides of the instant invention can also be used in standard enzyme-linked immunosorbent assays (ELISA) to detect the presence of antibodies to HTLV-I or HTLV-II envelope

glycoproteins in biological samples.

In one embodiment of the HTLV-I diagnostic assay of the present invention, a mixture of

synthetic peptides from HTLV-I gp46 envelope and HTLV-I p19 gag proteins are used, advantageously peptide 4A of Table 1 and a peptide containing the following carboxy-terminal sequence of HTLV-I pl9: Pro-Tyr-Val-Glu-Pro-Thr-Ala-Pro-Gln-Val-Leu. In combination, these two peptides are recognized by antibodies in 95% of sera from HTLV-I+ subjects having antibodies to pl9 or gp46 (Palker et al. J. Immunol. 136:2393, 1986, and Figure 1). A

combination of these two peptides can be used in an ELISA or a RIA to detect antibodies in sera from HTLV-I+ patients.

In view of the foregoing, it will be clear to those of ordinary skill in the art that HTLV-I and HTLV-II specific test kits can be constructed for detecting antibodies to HTLV-I and HTLV-II in biological samples using techniques for detection that include ELISA, RIA, indirect immunofluorescence and Western blot analysis.

It will also be clear to those of ordinary skill in the art that antibodies produced in

response to immunization with the HTLV-I- or

HTLV-II-specific peptides of the instant invention can be used in an antigen diagnostic assay using standard techniques.

The following nonlimiting Examples

illustrate the invention in more detail: EXAMPLE 1

Synthesis of HTLV-I and HTLV-II-Specific

Peptides and Preparation of Conjugates

Synthetic essentially pure peptides containing hydrophilic amino acid sequences from HTLV-I gp46 (Seiki et al Proc. Natl. Acad. Sci. USA 80:3618-3622, 1983) and HTLV-I gp46 (Sodroski et al. Science 225:421-424, 1984) were synthesized on a Dupont 2100 peptide synthesizer using chemicals and program cycles supplied by the manufacturer.

Sequences are given in Tables 1 and 2.

Peptides were conjugated to the carrier molecule tetanus toxoid (TT) with MBS, as described by Green et al. (Cell, 28:447, 1982; Palker et al. Proc. Natl. Acad. Sci. USA 84:2479, 1987). For the coupling procedure, 24 mg of tetanus toxoid in 0.5 ml of phosphate buffered saline, pH 7.2, was incubated with 1 mg of MBS dissolved in 100μl f dimethylformamide for 1 hr. at 23°C. Tetanus toxoid treated with MBS (TT-MBS) was then subjected to sieving chromatpgraphy on a PD-10 (Pharmacia) column to remove unreacted MBS from TT-MBS, and fractions containing TT-MBS were recovered in the void volume of the column as determined by spectrophotometric assay at an optical density of 280 nm. TT-MBS was then incubated with rocking at 23°C for 3 hr. with 6-9 mg of synthetic peptide (molar ratio 30:1, peptide carrier protein) in PBS containing reduced cysteine at either the carboxyl or amino terminus. TT-peptide conjugates were dialyzed overnight at 4°C against PBS or again desalted on a PD-10 column and were used as an immunogen.

Conjugation of peptides to carrier molecule toxoid was monitored by subjecting

conjugates to sodium dodecylsulfate-polyacrylamide gel electrophoresis (SDS-PAGE) and by measuring the increase in apparent molecular weights over that of carrier molecule polyacrylamide gel electrophoresis (SDS-PAGE) any by measuring the increase in apparent molecular weights over that of carrier molecule treated with MBS. Coupling efficiencies, also monitored by trace iodination of peptides, varied from 10-30% depending on the peptide. EXAMPLE 2

Reactivity of Antibodies from HTLV-I

Seropositive Subjects to HTLV-I gp46

Synthetic Peptides. Synthetic peptides derived from hydrophilic regions of HTLV-1 gp46 (HTLV-I-synthetic peptides) were dissolved or suspended in 0.1M NaHCO buffer, pH 9.6 and 50μg/well were incubated in

Immulon 2 microtiter wells (Dynatech) overnight at 4°C. Wells were emptied, and 200μl of 5% nonfat dry milk (Carnation) in phosphate buffered saline (PBS) and 0.1% sodium azide were added to wells and incubated for 2 hr. Wells were emptied, washed once with PBS containing 5% nonfat dry milk and 0.05% Tween 20 (wash buffer) and incubated further with 1:50 dilutions of sera from either HTLV-I+ patients or normal subjects in wash buffer for 1 hr. Wells were washed X3 in wash buffer, further incubated with a 1:150 dilution of rabbit anti-human IgG (H & L chain specific, Cooper Biomedical, Malvern, PA) whole serum in wash buffer (50μl) for 30 min, washed as before and further incubated with 10⁵ cpm of 125I-labeled protein A (Sigma) in 50μl wash buffer for 30 min at 23°C. Wells were washed as before, and radioactivity bound to wells was measured in a gamma counter. As shown in Figure (E/C) of mean cpm values (duplicate wells) obtained with experimental (E) HTLV-I+ patient sera and normal serum controls (C). Ratios greater than 2.0 were considered positive. EXAMPLE 3

Detection of Antibodies to HTLV-I and HTLV-II

HTLV-I encoded synthetic peptides SP-71 (Pro-Tyr-Val-Glu-Pro-Thr-Ala-Pro-Gln-Val-Leu) from the C-terminus of pl9 or portions thereof and synthetic peptide SP-4A of Table 1 from gh46 can be mixed, added to microtiter wells (10-50μg of each peptide per microtiter well) in the RIA described above and used to detect antibodies to HTLV-I.

Also, the peptide

Pro-Tyr-Val-Glu-Pro-Thr-Thr-Thr-Gln-Cys-Phe or portions thereof containing an amino acid sequence from the C-terminus of HTLV-II pl9 can be added to microtiter wells (10-50μg/well) as described above and used to detect antibodies to HTLV-II.

EXAMPLE 4

Reactivity of Anti-Synthetic Peptide

Antisera to Synthetic Peptides and

HTLV-I Envelope Glycoproteins HTLV-I env-encoded synthetic peptides

(HTLV-I-specific peptides) were covalently linked to tetanus toxoid (TT) as previously described, and used to immunize rabbits. After 1 immunization with 5mg of peptide-TT conjugate in Freunds complete adjuvant followed by 2 additional weekly boosts with conjugate in Freunds incomplete adjuvant, sera were collected and tested for reactivity to the

immunizing peptide (Table 4). TABLE 4

Rabbit Sera Reactivity to HTLV-I Synthetic

Peptides (SP) 1-6

Antibody Antigen

SP-1 SP-2 SP-3 SP-4 SP-4A SP-5 SP-6

α SP-1 58.1 0.5 2.1 0.4 0.9 1.3 0.4

α SP-2 1.3 40.3 6.6 2.3 0.8 5.0 1.1

α SP-3 2.0 0.4 45.6 2.0 0.9 0.9 0.9

α SP-4 0.4 0.5 0.7 20.9 0.6 0.4 1.1

α SP-4A 0.7 0.9 1.0 3.0 229.5 12.1 2.8

α SP-5 0.5 1.6 0.9 3.2 2.5 285.4 2.0

α SP-6 1.5 0.8 2.4 0.7 1.4 2.5 105.5

Reactivity of anti-peptide antisera to synthetic peptides was determined in radioimmunoassay (duplicate wells) and results were expressed as a ratio of mean cpm values obtained with immune and pre-immune sera. Anti-peptide antisera had a high degree of specificity to the immunizing peptide

(underlined values).

Antisera to HTLV-I synthetic peptides 1-6 reacted with a high degree of specificity to the immunizing peptide with minimum titers of 1:2000 in RIA. When tested in immunoblot assay, antisera to peptides 1, 3, 4, 4A and 6 reacted with HTLV-I gp46 and/or gp63 (lanes 2, 4, 6, 8, 10, respectively), while pre-immune sera (lanes 1, 3, 5, 8, 9) did not react; anti-HTLV-I envelope monoclonal antibody 1C11, used as a positive control, also reacted with gp46 and gp63 (line 12) whereas negative control ascites fluid (P3X63) did not react (lane 11).

(Figure 2.) The reactivity of anti-peptide

antiserum to gp46 in immunoblot assay could be specifically inhibited by pre-incubating antiserum with the corresponding peptide (Figure 3). To evaluate the specificity of anti-peptide antibody binding to gp46, antiserum to HTLV-I gp46 peptide SP-6 was pre-incubated with 200μg of either SP-6 (lane 1) or SP-5 (lane 2) and then reacted with gp46 in immunoblot assay. Synthetic peptide SP-6

completely inhibited anti-SP-6 antibody binding to gp46 (lane 1), while SP-5 did not (lane 2). Shown in lane 3 is the lack of reactivity of normal rabbit serum antibodies (plus peptide SP-6) to gp46. The data indicate that peptides from HTLV-I gp46

(HTLV-I- specific peptides) when coupled to carrier molecules can be used to raise antibodies to HTLV-I gp46.

EXAMPLE 5

Mapping of an Epitope of HTLV-I GP46

Recognized by an HLA-DR2 Restricted Cytotoxic T

Cell Line P-10 from Patient A with HTLV-I Associated Tropical Spastic Paraparesis (TSP).

The results shown in Figure 4A and Figure 4B were obtained using the method of Jacobson et al. (Viral Immunol. (1987/1988) 1:153-162))

Figure 4A: EBV-transformed B cells from patient A were incubated with HTLV-I env-encoded synthetic peptides 1-11 (Table 1), labelled with ⁵¹Cr and used as targets to assess peptide-specific killing by autologous, cloned, cytotoxic T cell line P-10. B cells coated with peptide SP-4A (A-A) and autologous T cells infected with HTLV-I (•-•) were both killed by the cytotoxic T cell line P-10 from patient A. Untreated autologous B cells (o-o) or B cells coated with any of the remaining 11 peptides (Δ-Δ) were not killed.

Figure 5B: Two heterologous B cell lines (•-•, ▲-▲) matched with the cytotoxic T cell line P-10 at HLA-DR2 and one B cell line mismatched at HLA-DR2 (o-o) coated with peptide SP-4A and used as targets in cytotoxicity assays as described above. B cells coated with peptide 4A and matched at HLA-DR2 were killed by T cell line P-10 while

substantially less killing was observed with HLA-DR2 mismatched B cells coated with SP-4A.

These indicate that the region of HTLV-I gp46 defined by peptide SP-4A (amino acids 198-209) contains an epitope identified by an HLA-DR2

restricted cytoxic-T cell line. EXAMPLE 6

Neutralization of Vesicular Stomatitis

Virus (VSV)/H/man T-Cell Leukemia Virus Type I

(HTLV-I) Pseudotype Particles with Antisera to

HTLV-I Env-Encoded Synthetic Peptides

A. Rabbits were immunized with 5mg of synthetic peptide - tetanus toxoid conjugates subcutaneously in Freund's complete (day 1) and incomplete (days 8, 15, 22, and 29) adjuvant.

Amino acid sequences of HTLV-I env gene encoded synthetic peptides are given in Table 1.

Data are given as the percent inhibition of VSV (HTLV-I) induced plaque formation.

Pseudotype particles containing the VSV genome and HTLV-I envelope glycoproteins were titered to give 150-200 plaques per assay. The assay was performed by Dr. Paul Clapham according to the procedure of Clapham et al. Proc. Natl. Acad. Sci. USA 81:2886, 1984, the entire contents of which document is hereby incorporated by reference.

TABLE 5

Immunizations Antisera to Peptides

per rabbit

1 2 3 4 4A 5 6 7 8 9 10 11

Pre-immune

serum 0 0 0 0 0 0 0 0 0 0 0 0

4 50 50 50 0 0 0 0 ND ND ND ND ND

5 0 >80 >80 0 >80 0 0 0 0 0 0 0

B. Anti-peptide antisera were raised in two goats (#20, 21) to synthetic peptides SP-2

(containing HTLV-I envelope amino acids 86-107) and SP-3/4A (containing HTLV-I envelope amino acids 176- 209) coupled to tetanus toxoid. Antisera (but not pre-immune sera) from both goats inhibited the ability of HTLV-I infected cells to fuse with uninfected human T-cells (syncytium formation). To determine which peptide was responsible for inducing antibodies in goats 20 and 21 that neutralized HTLV- I, heat-inactived (56°C, 30 min) antisera were preincubated for 1 hr at 23°C with nanomolar amounts of either peptide SP-2, SP-3/4A or negative control peptide SP-7 (containing HTLV-I envelope amino acids 374-392). Ten microliters of antisera were then added to microtiter wells containing 5 × 10⁴ HTLV-I- infected C91PL cells and 5 x 10⁴ uninfected C8166 human T-cells in 90 μl of RPMI 1640 media containing 10% heat-inactivated fetal calf serum. Microtiter plates were incubated overnight at 37°C in a

humidified chamber with 5% CO₂. The microtiter wells were then evaluated for the presence of syncytia with an Olympus OM-2 inverted microscope at 200x magnification. Results were that peptide SP-2, but not SP-3/4A or SP-7, absorbed greater than 90% of the neutralizing antibodies from both #20 and 21 antisera in a dose dependent manner, as shown by the increased numbers of syncytia in wells containing antisera plus SP-2 peptide. Peptide SP-2 by itself did not induce syncytium formation with C8166 or C91PL cells (not shown). Results show that

neutralizing antibodies in #20 and 21 antisera were directed against peptide SP-2. (See Figure 5.)

Truncated peptides containing partial amino acid sequences of HTLV-I peptide SP-2 (envelope amino acids 86-107) were synthesized and used in absorption experiments as described above. Only peptides containing HTLV-I envelope amino acids 86-98, 88-98 and 90-98 could absorb neutralizing antibodies in goat antisera #20 and 21. Studies mapped the neutralizing site to HTLV-I envelope amino acids 90-98. (See Table 6.)

EXAMPLE 7

Mutational Analysis of Amino-Terminal

HTLV-I Neutralizing Doman

To determine which amino acids within HTLV-I envelope amino acids 88-98 were required for absorption of neutralizing anti-peptide antibodies to HTLV-I, 11 peptides (2L1.1 to 2L1.11) were synthesized in which sequential amino acids were each replaced by the amino acid alanine. These 11 mutated peptides, as well as peptide 2L-1 bearing the native HTLV-I sequence, were used to absorb neutralizing antibodies in three goat anti-SP-2 antisera (#20, 21 and 128), as described in Example 6.B. As shown in Table 7, peptides with alanine substitutions of asparagines in positions 91 and 93 (peptides 1.6 and 1.8) were not able to absorb neutralizing antibodies to HTLV-I in all 3 sera. Also, peptide 1.3 with an alanine substitution in position 90 was unable to absorb antibodies in sera #21 and 128, while peptide 1.5 (alanine in position 92) was unable to absorb neutralizing antibodies in serum #20. Results identified HTLV-I envelope amino acids #90 (K), #92 (P), #93 (N), and #95 (N) as being important for HTLV-I neutralization.

Depicted in Figure 6 are the results of the same experiments summarized in Table 7 except that Figure 6 shows numbers of HTLV-I induced syncytia obtained for each peptide absorption of antisera #20, 21 and 128. Results are

representative experiments performed 3 times with 20 and 21 antisera and twice with 128 antisera.

EXAMPLE 8

Neutralization of HTLV-I with Anti-Peptide Antisera

Antisera were raised in 2 goats to a peptide with an amino acid sequence (amino acids 82-97) of HTLV-II envelope that was homologous to the neutralizing region of HTLV-I envelope defined above. This HTLV-II peptide, designated DP-90, was coupled to tetanus toxoid, and conjugates were used to immunize goats #120 and 135. (See Table 8.) Sera from both of these goats (but not pre-immune sera), neutralized HTLV-II as determined in

syncytium assays performed as described in Example 6.B., except that HTLV-II infected Mo-T cells were substituted for HTLV-I infected C91PL cells.

Antisera to the HTLV-II peptide DP-90 did not neutralize HTLV-I, indicating that HTLV-II envelope amino acids 82-97 contained an HTLV-II type-specific neutralizing site.

EXAMPLE 9

Induction of Neutralizing Antibodies to HTLV-I with a Carrier and Free Synthetic Peptide Inoculum

In previous studies (Palker et al, J.

Immunol. 142:3612-3619, 1989; Hart et al, J.

Immunol. 145:2677-2685, 1990), it was demonstrated that synthetic peptides containing a site recognized by T-helper cells and a (B-cell) neutralizing site of human immunodeficiency virus type-1 (HIV-1) could elicit neutralizing antibodies to HIV-1 isolates without the need for coupling the peptide to a carrier molecule, such as tetanus toxoid. In order to circumvent the need to couple HTLV-I peptides to a carrier molecule such as tetanus toxoid, a

chimeric HTLV-I peptide containing HTLV-I envelope amino acids 183-209 synthesized amino-terminally to the HTLV-I envelope amino acids 183-209 contain a site recognized by murine T-helper cells (amino acids 190-209, Kurata et al, J. Immunol. 143:2024-2030, 1989), sites recognized by neutralizing monoclonal antibody 0.5 alpha (amino acids 186-195, Ralston et al, J. Biol. Chem. 264:16343-16346, 1989) and a neutralizing murine monoclonal antibody (amino acids 190-199, Tanaka et al, J. Immunol. 147:354-360), as well as a site (amino acids 196-209) recognized by CD4+, human cytotoxic T-cells

(Jacobson et al, J. Immunol. 146:1155-1162, 1991). (See Figure 6.) When used to immunize two goats, antisera were obtained that neutralized HTLV-I

(titer = 1/20). Neutralizing antibodies could be absorbed with peptide SP-2 (amino acids 86-107) but not by peptide SP-3/4A (amino acids 176-209), indicating that this chimeric peptide could induce neutralizing antibodies to HTLV-I without the need for coupling to a carrier molecule. Moreover, all neutralizing antibodies to HTLV-I elicited by this peptide were directed against the neutralizing domain described above, and not against other previously defined neutralizing sites contained within this peptide.

* * * *

The foregoing invention has been described in some detail by way of examples for purposes of clarity and understanding. It will be obvious to those skilled in the art from a reading of the disclosure that a vaccine for HTLV-I can further comprise at least one synthetic peptide

corresponding to a hydrophilic envelope region of the transmembrane protein of HTLV-I (advantageously, YAAQNRRGLDLLFWEQGGFLC (amino acids 374-388 of gp21); CRFPNITNSHVPILQE (amino acids 399-415);

CPILQERPPLENR (amino acids 411-422);

CILRQLRHLPSRVRYPHYS (amino acids 462-480); or

(C)RYPHYSLIKPESSL (amino acids 475-488). It will also be obvious that various combinations in form and detail can be made without departing from the scope of the invention.

The entire contents of all documents cited hereinabove, are hereby incorporated by reference and relied upon.

Claims

WHAT IS CLAIMED IS:

1. A synthetic hydrophilic peptide consisting essentially of an amino acid sequence of up to about 25 units in length that corresponds to at least one antigenic determinant of the envelope glycoprotein of HTLV-I or HTLV-II recognized by a B lymphocytes, said peptide being capable, when covalently linked to a carrier molecule, of inducing in a mammal the production of high titers of

antibodies to the gp46 or gp63 envelope

glycoproteins of HTLV-I or HTLV-II.

2. The peptide according to claim

1, wherein said amino acid sequence corresponds to at least one antigenic determinant of the envelope glycoprotein of HTLV-I.

3. The peptide according to claim 1 wherein said amino acid sequence corresponds to at least one antigenic determinant of the envelope glycoprotein of HTLV-II.

4. The peptide according to claim

2, wherein said amino acid sequence is selected from the group consisting of VSSYHSKPCNPAQPV;

(C)PHWTKKPNRNGGGYYSASYSDP; (C) LNTEPSQLPPTAPP(Y); and SSPYWKFQHDVNFTQEVSRLN(C);

(C)LLPHSNLDHILEPSIPWKSK(Y); (Y) LPFNWTHCFDPQ(C);

(C)PPFSLSPVPTLGSRSRR; and sequences immunogenically comparable thereto.

5. The peptide according to claim

3, wherein said amino acid sequence in selected from the group consisting of SSYHSSPCSPTQPVC; CTWNLDLNSLTTDQRLHPPC; HWIKKPNRQGLGYYSPSYNDPC;

(C) SSPSWKFHSDVNFTQE; (C) SEPTQPPPTSPPLVHDSDLEH;

(C) SLAPVPPPATRRRR; and sequences immunogenically comparable thereto.

6. An immunogenic conjugate capable of inducing in a mammal the production of high titers of antibodies against gp46 or gp63 envelope glycoproteins of HTLV-I or HTLV-II, said conjugate comprising: (i) a carrier molecule covalently attached to (ii) a synthetic hydrophilic peptide consisting essentially of an amino acid sequence of up to about 25 units in length that corresponds to at least one antigenic determinant of the envelope glycoprotein of HTLV-I or HTLV-II recognized by B lymphocytes.

7. The conjugate according to claim 6, where said carrier molecule comprises an amino acid sequence corresponding to a T-cell epitope of HTLV-I or HTLV-II.

8. The conjugate according to claim 7 wherein said carrier molecule is selected from the group of peptides consisting of LHEVDKDISQLTQAIVK; QPPCPNLVSYS; DLQDLLQYLCSSLVASL; RVNEILHIL; and

KDISHLTQAIVKNHQNILRVAQ.

9. The conjugate according to claim 6, wherein said carrier molecule is tetanus toxoid.

10. The conjugate according to claim 6, wherein said carrier molecule is covalently linked to said peptide through at least one spacer molecule.

11. The conjugate according to claim 10, wherein said spacer molecule consists of the dipeptide glycine-glycine.

12. The conjugate according to claim 6 wherein said amino acid sequence corresponds to at least one antigenic determinant of the envelope glycoprotein of HTLV-I.

13. The conjugate according to claim 6 wherein said amino acid sequence corresponds to a hydrophilic region of the envelope glycoprotein of HTLV-II.

14. A method of producing immunity to HTLV-I in a mammal comprising administering to said mammal an immunogenically effective amount of at least one conjugate according to claim 12.

15. A method of producing immunity to HTLV-II in a mammal comprising administering to said mammal an immunogenically effective amount of at least one conjugate according to claim 13.

16. An immunogenic aggregate capable of producing a protective immune response in a mammal to HTLV-I comprising at least two conjugates according to claim 12, wherein each of said

conjugates is covalently bonded to at least one other of said conjugates.

17. An immunogenic aggregate capable of producing a protective immune response in a mammal to HTLV-II comprising at least two conjugates according to claim 13, wherein each of said conjugates is covalently bonded to at least one other of said conjugates.

18. A method of determing the presence and titer in a biological sample of antibodies against HTLV-I comprising the steps of:

(i) contacting a peptide according to claim 2, with said sample;

(ii) allowing an anti-HTLV-I antibody in said sample to complex with said peptide; and

(iii) measuring formation of a complex between said peptide and said antibody.

19. A method of determing the presence and titer in a biological sample of

antibodies against HTLV-II comprising the steps of:

(i) contacting a peptide according to claim 3, with said sample;

(ii) allowing an anti-HTLV-II

antibody in said sample to complex with said

peptide; and

(iii) measuring formation of a complex between said peptide and said antibody.

20. A method of determining the presence or titer in mammalian serum of antibodies against HTLV-II comprising the steps of:

(i) contacting the peptide Pro-Tyr-Val-Glu-Pro-Thr-Thr-Thr-Gln-Cys-Phe, or an

immunoreactive portion thereof, with said serum;

(ii) allowing a complex form between said antibodies and said peptide; and

(iii) measuring the formation of a complex between said peptide and said antibodies by radioimmunoassay or enzyme linked immunosorbent assay.

21. The peptide according to claim 4 wherein sid amino acid sequence is WTKKPNRNGGG.

22. The peptide according to claim 3 wherein said amino acid sequence is

PHWIKKPNRQGLGYYS(C).

23. The conjugate according to claim 7 wherein said carrier molecule has the amino acid sequence LPPTAPPLLPHSNLDHILEPSIPWKSK.