WO1998028004A1

WO1998028004A1 - Hepatitis delta particle containing a fusion protein immunogen

Info

Publication number: WO1998028004A1
Application number: PCT/AU1997/000884
Authority: WO
Inventors: Eric James Gowans; Thomas Bernard Macnaughton
Original assignee: The Crown In The Right Of The Queensland Department Of Health (Sir Albert Sakzewski Virus Research Centre)
Priority date: 1996-12-24
Filing date: 1997-12-24
Publication date: 1998-07-02
Also published as: AUPO434196A0

Abstract

The present invention provides a virus-like particle for use in the treatment or prevention of at least a microorganism infection wherein said particle comprises: at least an antigenic and/or immunogenic polypeptide or part thereof from the microorganism, fused to at least the last 19 amino acid of the COOH terminal sequence of the large protein from Hepatitis D virus (L-HDAg), wherein the fusion protein is at least partially enveloped by Hepatitis B surface antigen (HBsAg).

Description

HEPATITIS DELTA PARTICLE CONTAINING A FUSION PROTEIN IMMUNOGEN

The present invention relates to an improved therapeutic delivery system and in particular to virus-like particles which may be used to ameliorate or prevent infections. For example, the invention relates to virus-like particles which may be used to ameliorate or protect against infections caused by hepatitis B virus and/or at least another hepatitis virus.

Background Art

The immune response to infection with a micro-organism (eg bacteria or viral) is divided into a specific and a non-specific response. The non-specific response becomes effective soon after infection and serves to inhibit spread of the invading organism during the time it takes the host to mount the specific response. In turn, the specific immune response is also divided into 2 components viz. the humoral (antibody) and the cellular immune responses. In general terms, these different responses are effected by different cells of the immune system and although the system involves complex multimolecular interactions, B lymphocytes produce antibodies whereas T lymphocytes are a major component of the cellular response. However, T lymphocytes are also important for the antibody response to infection by providing T cell help.

In the case of antibody production, the specific antigen is recognised by soluble antibody or by immunoglobulin (receptors) on the B cell; the immunogenic activity of the antigen is most often but not exclusively dependent on the conformation of the protein that is recognised in solution. T lymphocyte help is necessary for specific B cell expansion; antigen is taken up by antigen presenting cells (APCs), viz. macrophages and dendritic cells, or by B lymphocytes, presented in context with MHC (major histocompatibility complex) Class II to T helper lymphocytes (CD4+) which then stimulate B cell division. MHC antigens are cell surface glycoproteins which control the recognition of cell and foreign proteins in a complex system of intracellular signalling. The immune response is dependent on the expression of the MHC, sometimes called the human leukocyte antigen (HLA) system.

If the antigen recognised by the antibody is displayed on the surface of for example a virus particle, then one effect of antibody binding to specific antigen is to neutralise the virus and this in turn results in protection of the host.

In some cases, a viral or bacterial antigen displayed on the surface of a cell can be recognised by antibody and this can result in elimination of the infected cell by a process of antibody dependent cellular cytotoxicity (ADCC). However, the elimination of virus infected cells is most commonly and readily accomplished by CD8+ cytotoxic T cell (CTL). In contrast to the recognition of exogenous soluble antigen, usually processed and presented in a MHC Class ll-restricted manner, CTL recognise short (8-11 residues long) antigenic sequential peptides which are MHC Class 1 restricted and which are generally derived from endogenous expression. During cell synthesis, peptides are processed by the cell proteosome machinery then transported to the lumen of the endopiasmic reticulum (ER) by a family of transporter proteins which are encoded in the HLA locus. There, the peptides are examined for the presence of HLA allele-specific binding motifs by MHC Class I molecules. Peptides containing the appropriate motifs are then bound by the MHC Class I protein which then associates with B2-microglobulin and the complex is then transported to the cell surface to be displayed as an integral membrane protein. This complex is then recognised by a CD8+ cell with the appropriate specific T cell receptor (TCR). If, during natural sampling of peptides in the ER, the peptide antigen which interacts with the Class I MHC molecule is derived from a virus or bacterial protein, then this peptide is seen as foreign and the CTL proceeds to eliminate the target cell. In order for this to occur, the target peptide/MHC Class I interaction with the specific TCR is stabilised by several accessory interactions. Elimination of the target cell may be the result of the direct transfer of cytotoxic molecules from the effector cell or by the indirect action of cytokines thought to be TNF-a and IFN-g secreted by the cell. Although it is possible to recognise MHC Class I binding motifs from the sequence of a protein, it is still not possible to predict precisely if the peptides which encompass these motifs represent antigenic epitopes recognised by a CTL. Furthermore, CTL epitopes, like antibody epitopes, often require T cell help for activity and it is not always possible to recognise T helper epitopes in the amino acid sequence of a protein.

At the present time, 3 types of vaccines are commonly used to prevent infections, namely: i) live attenuated vaccines; ii) killed particle vaccines; and iii) subunit vaccines. The choice can depend on several factors including a knowledge of the specific microorganisms pathogenesis.

Individuals who receive live attenuated vaccines generally require a single injection of the vaccine whereas the use of killed or subunit vaccines requires multiple injections. A major disadvantage of live vaccines is the need for an effective cold chain, otherwise the potency of the vaccine may be diminished, particularly in tropical countries.

In the case of viruses, it is thought that live attenuated virus vaccines are most efficient because humoral and cell-mediated immune responses become activated, although the relative contribution of each has not been determined. In contrast, after vaccination with the latter two preparations, only a humoral immune response usually results because there is no de novo synthesis of viral antigens which can enter the endogenous pathway necessary to generate a cellular immune response.

Recent research has shown that vaccination with live attenuated virus will elicit humoral (antibody) and cell mediated immunity (CMI) (ie T cell dependent) and although there are no licenced vaccines at present that are designed solely to elicit CMI, there are a number of examples of successful experimental vaccines which are able to do so. In each case challenge of the vaccinated animal showed complete protection. The appearance of neutralising antibodies to the envelope proteins of viruses is generally thought to result in the clearance of virus and/or provide a marker of convalescence. In some cases like Hepatitis C virus (HCV) infections neutralising antibodies have not been detected. It is likely that the high mutation rate associated with HCV results in the appearance of antibody-resistant strains of virus that accounts for the co-expression of virus and antibody to the envelope proteins. A practical application of these findings is that passive vaccination with high titre HCV immunoglobulin prepared by cold ethanol fractionation to inactivate residual HCV fails to protect chimpanzees against challenge. These data help to explain why individuals can be re-infected with HCV and lead to the suggestion that a vaccine which is based on a neutralising antibody response is unlikely to be successful against a range of HCV genotypes. Nevertheless, immunisation of chimpanzees with a vaccine based on recombinant E1/E2 protected 5/7 animals from challenge with homologous virus and the disease was ameliorated in the remaining 2 animals (Choo et al., (1994) Proc Natl Acad Sci, USA 91 ; 1294-1298). However, the chimpanzees were injected on 15 occasions in order for the vaccine to be effective and were only protected against 10 CID₅₀ a relatively small challenge dose, but not 100

CID₅₀ (1 CID₅₀ is the dose which infects 50% of chimpanzees in a given experiment). Moreover, the duration of protection was very limited. No data are available on the results of challenge of the animals with heterologous virus.

Since the need for and the potential of a vaccine for viruses like HCV that is based on a cellular immune response has been recognised, other workers have chosen to develop a DNA vaccine, based on the finding that direct injection of DNA into animals results in immunisation. Most of these studies reported the development of antibody to the protein encoded by the DNA. Some studies have also reported the development of CTL activity that was able to prevent the growth of a plasmacytoma resulting from injection of a myeloma cell line which constitutively expressed an antigenic protein. While a lot of research has been carried out into what constitutes an effective prophylactic there remains a need for improved therapeutic agents which are capable of modifying microorganism (including bacterial and viral) infections and which are relatively easy to produce.

Throughout this specification, unless the context requires otherwise, the word "comprise", or variations such as "comprises" or "comprising" will be understood to imply the inclusion of a stated integer or group of integers, but not the exclusion of any other integer or group of integers including method steps.

Disclosure of the invention

The present invention consists of a virus-like particle for use in the treatment or prevention of at least a microorganism infection wherein said particle comprises: at least a antigenic and/or immunogenic polypeptide or part thereof from the microorganism, fused to at least the last 19 amiπo acid of the COOH terminal sequence of the large protein from Hepatitis D virus (L-HDAg), wherein the fusion protein is at least partially enveloped by Hepatitis B surface antigen (HBsAg).

The antigenic and or immunogenic polypeptide or part thereof used in the invention should be at least capable of eliciting a humoral and/or a T cell response. The T-cell response may be either a T helper cell response or a cytotoxic T-cell (CTL) response. Preferably the polypeptide or part thereof displays a plurality of epitopes. An epitopic region on a polypeptide is generally relatively small - typically 8 to 10 amino acids or less in length. Fragments of as few as 5 amino acids may characterize an epitopic region. Most preferably, some of the epitopes on the polypeptide should be capable of eliciting a humoral response and/or some should be capable of eliciting a T cell response.

In the case of viruses it is generally presumed that a hosts response to viral antigens is almost entirely T-cell dependant. Even the antibody response requires T-cell help. Thus susceptability to virus infection is particularily associated with T-cell dysfunction. Therefore, when the invention is used as a prophylactic or therapeutic for viral infections the polypeptide should incorporate at least a range of epitopes which contribute to T-cell activity. Preferably, the polypeptide includes epitopes capable of eliciting a CTL response. Most preferably these epitopes are also substantially conserved between members of the species from which the polypeptide or part thereof was initially selected.

The polypeptide or part thereof used in the invention may correspond to part of a natural protein produced by a microorganism or it may be a recombinant protein which contains at least a antigenic and/or immunogenic peptide. Preferably, the polypeptide or part thereof consists of a plurality of antigenic and/or immunogenic peptides linked together. Most preferably, the polypeptide is selected from regions in a protein or is composed of peptides which have a variety of antigenic and/or immunogenic epitopes and which are substantially homologous between members of the species of microorganism from which the regions or peptides were selected.

In addition, the polypeptide or part thereof used in the invention may be selected from any protein from any microorganism (including but not limited to bacteria, protozoa and viruses), provided that the polypeptide or part thereof displays antigenic and or immunogenic properties. By varying the polypeptide or part thereof, different virus-like particles may be produced to treat different microorganism infections without departing from the substance of the invention. Preferably the polypeptide or part thereof is derived from a virus, such as a Hepatitis causing virus.

By way of example only, virus-like particles may be generated against Hepatitis C Virus (HCV). Since peptides with lipid tails (lipopeptides) are well known to stimulate cellular immune responses, it is expected that the lipid component of the HBsAg will have a similar effect, perhaps by enhancing the intracellular delivery of the sub-viral particle. On the other hand, individuals who are already anti-HBs positive may respond most favourably to the sub-viral particle vaccine because the particles will be targeted by the antibody to antigen presenting cells. Furthermore, because L-HBsAg is known to be more immunogenic than S-HBsAg, incorporation of L-HBsAg into the particles will mimic the second generation of HBV vaccines and lead to improved rates of response to the HBV component of the vaccine.

When HCV is the virus of choice, the polypeptide or part thereof is preferably derived from either the HCV core protein or the NS3 protein. These proteins, in contrast to other HCV proteins, are highly conserved amongst HCV isolates and are known to contain both CTL and T-helper epitopes that are recognised by a range of HLA types. Some examples of CTL epitopes are described in table 1 , below.

Table 1: HCV CTL epitopes in the core protein

HLA CTL Reference Class epitope location

A11 aa2-9 Koziel et al., (1993) J Virol 67; 7522 - 7532

B60 aa28-37 Kaneko et al., (1996) J Gen Virol 77; 1305 - 1309

A2.1 aa35-44 Battegay et al., (1995) J Virol 69; 2462 - 2470

B44 aa81-100 Kita et al., (1993) Hepatology 18; 1039 - 1044

A2 aa131 -140 Battegay et al., (1995) J Virol 69; 2462 - 2470

A2 aa178-187 Battegay et al., (1995) J Virol 69; 2462 - 2470

DRB1 ^* aa111-130 Kaneko βt al., (1996) J Gen Virol 77; 1305 - 1309

DRB1 ^* aa161-180 Kaneko et al., (1996) J Gen Virol 77; 1305 - 1309

^* CTL epitopes are generally HLA Class I restricted but HLA Class ll-restricted CTL have been described (see Kaneko et al, 1996).

In a particularly preferred embodiment of the invention the HCV core protein is selected from any peptide or polypeptide that may be produced from amino acids 1 to 191 of the HCV core protein (wherein the amino acid numbering starts at the first amino acid in the core protein). The peptide or polypeptide must, however, be capable of inducing a T cell response against at least one major subtype of HCV. Preferably the core protein is between about 120 and about 160 amino acids in length. Most preferably the sequence is about 140 amino acids in length.

The length of the polypeptide or part thereof that may be used in the invention is dictated by (i) the length of the amino acid sequence used from L-HDAg and (ii) the overall length of fusion protein which can be efficiently enveloped by HBsAg. Thus, it will be appreciated that the polypeptide or the length of the amino acid sequence used from L-HDAg may be varied depending on the purpose for which the virus-like particles are being used and the method of construction used. Preferably the amino acid sequence used from L-HDAg is the last 19 amino acids at the COOH terminus of that protein. In such instances the number of amino acids in the polypeptide or part thereof should at least be greater than about 5 amino acids and more particularly about 5 to 500 amino acids in length. Preferably, the polypeptide sequence or part thereof is about 50 to 200 amino acids long. Most preferably the sequence is about 100 to about 160 amino acid long.

If, for example, the polypeptide or part thereof is selected from HCV, the fusion protein which is produced preferably consists of entire core of HCV together with the complete L-HDAg. More preferably the fusion protein contains amino acids 1 to 140 from HCV core. In an alternative form of the invention part or all of the HCV core protein may be inserted into an internal site within L-HDAg. For example amino acids 1 to 40 may be inserted into the nuclear localisation site for L-HDAg or into the proline/glycine rich domain.

Preferably the fusion protein is selected from SEQ ID NO 1 to SEQ ID NO 3. The fusion protein selected for use in the invention need not, however, be identical to those described. The fusion protein should, however, be substantially homologous to SEQ ID NO 1 to SEQ ID NO 3, while still maintaining substantially all of the biological activity of the fusion proteins described herein.

By "biological activity" is meant at least the ability of the fusion protein to be released inside or from a host cell and the respective polypeptides or parts thereof ability to bind to an appropriate MHC molecule and induce a CTL response against at least one major subtype of HCV. By CTL response is meant a CD8+ T Lymphocyte response specific for an HCV antigen of interest, wherein CD8+, MHC class l-restricted T Lymphocytes are activated. Various modifications can be effected at non-critical amino acid positions within a polypeptide without substantially disturbing its biological activity. Such modifications include but are not limited to, substitutions (either conservative or non-conservative), deletions and additions.

In another embodiment of the invention the polypeptides or parts thereof used in the invention may be modified to enhance substantially their CTL inducing activity. For example it may be desirable to increase the hydrophobicity of the N terminal of a polypeptide or part thereof, particularly where the second residue of the N terminal is hydrophobic and is implicated in binding to the HLA restriction molecule.

With respect to the large form of HDAg, this protein is generated during Hepatitis D virus (HDV) replication. Initially a 195 amino acid protein known as small HDAg (S-HDAg) is expressed that is required for HDV replication and at a later stage, a 214 amino acid protein, the large HDAg (L-HDAg), is expressed that is required for HDV packaging and export. The only molecular difference between S- and L-HDAg is that L-HDAg contains an additional 19 amino acids. The 4 amino acids at the carboxy terminus of L-HDAg represent an isoprenylation site. This site and the preceeding 15 amino acids are however, vital for the interaction between HDAg and HBsAg to permit the packaging event to occur.

While the present invention requires at least the last 19 amino acids of the L- HDAg to be present for the packaging by HBsAg, it will be appreciated that larger forms of the L-HDAg may be present in the fusion protein. Thus any length of amino acids from the L-HDAg may be used in the invention. Preferably, the entire L-HDAg is used in the fusion protein.

The general principle behind the the development of the therapeutic of the present invention is illustrated in Figure 1. Having regard to figure 1 it can be seen that a fusion protein consisting of a polypeptide which exhibits antigenic and or immunogenic properties is fused to at least the last 19 amino acid tail of the L-HDAg. The fusion protein is then packaged into virus-like particles through the interaction of the 19 amino acid moiety with HBsAg. This process occurs when the 19 amino acid moiety from the L-HDAg and HBsAg are co- expressed in the same cell.

The formation of virus-like particles using the method of the present invention provides a means of stimulating a hosts immune system against HBV and the polypeptide that is fused to the 19 amino acid tail of the L-HDAg. Thus a dual immunological effect is observed from using the method of the invention.

In another embodiment, there is provided in a method for producing virus-like particles containing an antigenic/immunogenic polypeptide or part thereof comprising: incubating host cells transformed with an expression vector containing a sequence encoding a fusion polypeptide containing the antigenic/immunogenic polypeptide or part thereof and at least the last 19 amino acid of the COOH terminal sequence of the large protein from Hepatitis D virus (L-HDAg); in the presence of HBsAg and under conditions which allow expression and packaging of said fusion polypeptide. Preferably the HBsAg is expressed in the same host cells as the fusion polypeptide. This may be acheived by co-tranfection of both expression vectors into the host cells.

The coding sequence for the antigenic/immunogenic polypeptide or part thereof used in the invention may be derived from any source which expresses the polypeptide or part thereof or a protein containing the polypeptide or part thereof. In the case of viruses, for example, the coding sequence for the polypeptide or part thereof or polypetide may be selected from the coding region for coat or envelope antigens, from core antigens or from non-structural proteins. Fragments encoding the desired polypeptides may be derived from cDNA clones or genomic clones using conventional restriction digestion or any other method known in the art. Alternatively the fragments may be obtained by synthetic methods. Once isolated the fragments are then ligated into vectors which contain the coding sequence for at least the last 19 amino acid of the COOH terminal sequence of the large protein from Hepatitis D virus. Virus-like particles produced according to the present invention may be expressed in a variety of different expression systems. The selection of the expression system which a researcher wishes to use will to a large extent be based on personal preference. Systems in which the virus-like particles may be expressed include Chinese hamster ovary cells (CHO cells), COS cells, HeLa and MRC-5 cells, all of which have been used in the past to produce vaccines or therapeutic products for use in humans, or any other suitable continuous cell line. The particles may also be synthesised in Escherichia coli, in yeast cells or in insect cells infected with recombinant baculovirus. Further, these cells may be used with alternative systems to transient transfection viz. stable transfected cell lines, constitutive or inducible expression, expression from a live recombinant virus. In a highly preferred example of the invention the particles are expressed from transient transfection of DNA into COS 7 cells.

The particles may be purified by any protein purification method known in the field. Purification may be achieved by techniques such as, for example, salt fractionation, chromatography on ion exchange resins, affinity chromatography, centrifugation, and the like. See, for example, Methods in Enzymology for a variety of methods for purifying proteins. Preferably they are purified by a combination of sucrose and caesium chloride gradient centrifugation using methods which are well described in the literature.

A number of methods to administer the virus-like particles to uninfected individuals or to infected patients are available. The method of choice to produce the most effective response will however need to be determined empirically and the methods described below are given as examples and do not limit the method of delivery.

Methods for the preparation of therapeutics which contain an immunogenic or antigenic polypeptide or part thereof as the active agent are known to those of ordinary skill in the field. The same preparations can be used with the virus-like particles of the present invention. Typically, therapeutics are prepared as injectables, either as liquid solutions or suspensions; solid forms suitable for solution in, or suspension in, liquid prior to injection may also be prepared. The preparation may also be emulsified, or the particles encapsulated in liposomes.

The virus-like particles may be formulated into therapeutics with excipients which are pharmaceutically acceptable and compatible with the active ingredient. Examples of excipients which may be used in such a formulation include, water, saline, ethanol, dextrose glycerol, or the like and combinations thereof. Further, if desired, the virus-like particle formulation may also contain minor amounts of auxiliary substances such as adjuvants, wetting, pH buffering agents, or emulsifying agents which enhance the effectiveness of the vaccine. Suitable adjuvants which may be include in such formulations for example, aluminium hydroxide, N-acetyl-muramy1-L-threonyl-D-isoglutamine (thr-MDP), N-acetyl-nor-muramy1 -L-alanyl-D-isoglutamine (nor-MDP), N-acetylmuramyl-L- alanyl-D-isoglutaminyl-L-alaπine-2-(r-2'-dipalmitoyl-sn-glycero-3- hydroxyphosphoryloxy)methylamine (MTP-PE), and RIBI, which contains three components extracted from bacteria, monophosphoryl lipid A trehalose dimycolate and cell wall skeleton (MPL+TDM+CWS).

Virus-like particles may also be formulated into therapeutics as neutral or salt forms. Pharmaceutically acceptable salts include, for example, the acid addition salts (formed with free amino groups of the peptide) and which are formed with inorganic acids such as, for example, hydrochloric or phosphoric acids, or such organic acids such as acetic, oxalic, tartaric, maleic, and the like. Salts formed with the free carboxyl groups may also be derived from in- organic bases such as, for example, sodium, potassium, ammonium, calcium, or ferric hydroxides, and such organic bases as isopropylamins, trimethylamine, 2-ethylamino ethanol, histidine, procaine, and the like.

Virus-like particle formulations may be administered in a manner compatible with the dosage formulation, and in such amount as will be prophylactically and/or therapeutically effective. The quantity of virus-like particles to be administered, will generally be in the range of 5 micrograms to 250 micrograms of particles per dose. However this will depend on the subject to be treated, the capacity of the subject's immune system to respond, and the degree of protection desired. Precise amounts of active ingredient required to be administered may depend on the judgment of the practitioner and may be peculiar to each subject.

Formulations may be administered by the intradermal, subcutaneous or intramuscular routes, or by other routes including oral, aerosol, parenteral, intravenous, iπtraperitoneal, rectal or vaginal administration. For example the virus-like particles may be administered parenterally, by injection, for example, either subcutaneously or intramuscularly. All the above formulations are commonly used in the pharmaceutical industry and are known to suitably qualified practitioners.

In the case of oral administration, the virus-like particles should be delivered with diluents (water, saline etc) and/or delivery vehicles (tablets, capsules) which do not interfere with the activity of the particles. Oral formulations may include such normally employed excipients as, for example, pharmaceutical grades of maπnitol, lactose, starch, magnesium stearate, sodium saccharine, cellulose, magnesium carbonate and the like. These compositions take the form of solutions, suspensions, tablets, pills, capsules, sustained release formulations or powders

Rectal or vaginal administration also requires specific formulation into acceptable forms that contain lubricants and or emulsifying agents. For example such formulations usually include, traditional binders and carriers such as, polyalkylene glycols or triglycerides.

Further, the therapeutic may be given in a single dose schedule, or preferably in a multiple dose schedule. A multiple dose schedule is one in which a primary course of delivery may be with 1-10 separate doses, followed by other doses given at subsequent time intervals required to maintain and or reinforce the immune response, for example, at I-4 months for a second dose, and if needed, a subsequent dose(s) after several months. The dosage regimen will also, at least in part, be determined by the need of the individual and be dependent upon the judgment of the practitioner.

In addition, the therapeutic containing the virus-like particles may be administered in conjunction with other immunoregulatory agents, for example, immunoglobulins.

Brief Description of Drawings

The present invention will now be described by way of example only with reference to the following non-limiting Figures and Examples.

Figure 1 illustrates the method by which virus-like particles, consistent with the present invention, are made.

Figure 2 illustrates the sequence of the HCV cDNA insert of pA2.

Figure 3 illustrates the sequence of the HCV cDNA insert of pA3.

Figure 4 illustrates the sequence of the HCV cDNA insert of pA10.

Figure 5 illustrates the PCR cloning strategy for clones pA2, pA3 and pA10.

Figure 6 illustrates the DNA and Amino-Acid Sequence of pTBM-HBsAg (ayw3).

Figure 7 illustrates the sequence of the L-HDAg gene.

Figure 8 illustrates the DNA sequence of L-HDAg 19aa tail and alignment with other group 1 isolates of HDV.

Figure 9 illustrates the steps in the construction of plasmid pECE-C/d.

Figure 10 illustrates the general cloning strategy for the construction of the partial core protein expression vectors. Figure 11 illustrates the sequence of the chimeric insert of plasmid pCδ27core120a.

Figure 12 illustrates the HCV-HDV sequence in plasmid pCδ27core120.

Figure 13 illustrates the HCV-HDV sequence in plasmid pCδ27core140.

Figure 14 illustrates the HCV-HDV sequence in plasmid pCδ27core161.

Figure 15 illustrates that a product with a size consistent with the expected size of the core-delta fusion protein was detectable by SDS- PAGE.

Figure 16 provides a western blot of the product of in vitro translated RNA from pCδ27 corel 20a.

Figure 17 provides a western blot of secreted core/HDAg fusion protein. The figure shows that doublet bands that were identical in size to those detected in cell lysates could be detected in cell culture fluids (CCF) from COS7 cells transfected with pCδ27core140. No HCV core antigen was detected in the CCF from COS7 cells transfected with pCδ27core120 or pCδ27core161. HCV core antigen in the CCF was dependent on co- expression of HBsAg.

Figure 18 is a schematic representation of three HCV L-HDAg fusion constructs according to the invention.

Figure 19 is an imiηunoblot of secreted particles from Cos 7 (lanes 1 and

3) and Huh 7 (lane 2) cells transfected with genes for HCV core 140 full length HDAg fusion protein and HBsAg. Human anti-HDAg was used in lanes 1 and 2 and human anti-HCV was used in lane 3. The arrow indicates the position of the full length chimeric protein.

Figure 20 is an immunoblot, with human anti-HDAg, of secreted particles from Huh 7 cells transfected with genes for full length HCV core full length HDAg fusion protein and HBsAg. The arrow indicates the position of the full length chimeric protein.

Figure 21 is an immunoblot of secreted particles from Cos 7 cells co- transfected with genes expressing HBsAg and full length L-HDAg containing an internal insertion of a portion of the HCV core protein. The insertions were amino acids 1-40 of the HCV core and were made into the Apa1 (nt222) or Sma1 (nt490) sites of L-HDAg with (+) or without (-) wild type L-HDAg. Human anti-HDAg was used and the large and small arrows indicate secreted fusion protein and L-HDAg respectively.

Figure 22 provides a graph of BALB/c mice vaccinated with HBsAg-HCV core particle (HBsAg boost, Bs28 treated P815 in vitro restimulation).

Further features of the present invention are more fully described in the following Examples. It is to be understood, however, that this detailed description is included solely for the purposes of exemplifying the invention, and should not be understood in any way as a restriction on the broad description as set out above.

EXAMPLES

DNA sequencing.

All plasmid DNA sequences reported in this document were sequeπced using the Dye Terminator Cycle Sequencing Ready Reaction (Perkin Elmer). Unless stated otherwise, all sequences were derived from material cloned into pBluescript KS using the following forward and reverse primers:

primer M13-20-5'-GTAAAACGACGGCCAGT-3' reverse primer-5'-AACAGCTATGACCATG-3\

These primers recognise a sequence in pBluescript KS on either side of the multiple cloning site. The reaction was performed according to the manufacturer's instructions and the extension products ethanol precipitated. The DNA was dried and analysed with the Applied Biosystems 373 sequencer.

Cloning, sequencing and expression of the HCV core gene.

A serum sample from a bone marrow transplant patient with acute hepatitis C diagnosed as anti-HCV positive was used as the source of virus. Briefly, the RNA from the sample was prepared by the addition of guanidine isothiocyanate, sodium acetate and phenol-chloroform, as described (Chomczynski and Sacchi, Anal Biochem 162; 156-159, 1987), incubated on ice for 5-10min and the RNA precipitated by the addition of an equal volume of isopropanol. The sample was then centrifuged and the RNA dried then re-dissolved in distilled water. An aliquot of the RNA sample was mixed with random hexamer primers

(Pharmacia), heated to 95°C for 5min then cooled rapidly on ice. The first strand DNA was synthesised by reverse transcriptase (Superscript II, Gibco-

BRL) at 37°C for 2h. The second strand synthesis was performed by the addition of DNA polymerase 1 from Esch coli (Boehringer, Mannheim), RNaseH

(Boehringer, Mannheim) and DNA ligase from Esch coli (Boehringer, Mannheim) at 12°C for 1 h followed by 22°C for 1 h. The preparation was then treated with T4 DNA polymerase (Boehringer, Mannheim) to ensure that the final DNA product was completely double stranded. The sample was then phenol extracted, ethanol precipitated, air dried and re-dissolved in distilled water.

The dsDNA sample was then subjected to the sequence-independent single- strand amplification (SISPA) procedure (Reyes and Kim. Mol Cell Probes 5; 473-1991 ). Briefly, the dsDNA sample was ligated to a dsDNA molecule composed of 2 complementary synthetic oligonucleotides which, prior to re- annealing, were previously phosphorylated by the action of polynucleotide kinase at 37°C for 1 h, using T4 DNA ligase (Boehringer, Mannheim) at 15°C overnight then 65°C for 15min. The nucleotide sequence of the complementary primers is:

RT-A; 3'-TAGCGCCGGCGAGATCTCG-5' RT-B; 5'- ATCGCGGCCGCTCTAGAGCTG-3'

The ligation reaction may result in the formation of a dimer of the ds oligonucleotide resulting in reconstitution of an EcoRV site; thus, prior to SISPA amplification with primer RT-A, the product was digested with the restriction enzyme EcoRV. This step ensured that only ds DNA molecules generated by the reverse transcriptase that were ligated to the ds oligonucleotide were amplified.

An aliquot of this SISPA reaction was then amplified by conventional PCR with HCV-specific primers designed to amplify a major region of the core gene ; these primers were designed from the published sequence of the core gene (Okamoto et al., (1990) Jap J Exp Med 69; 167-177). The sequence of the primers is: sense primer (#156) 5' - GAGGTCTCGTAGACCGTGCA - 3' (-22 to -3 of 5' UTR) anti-sense primer (#155) 5' - CCGGTGCTCCCTGTTGCATAGTTCACG - 3' (residues 1-7 represent sequences designed to facilitate cloning while the remainder represent nt 501 - 482 of the HCV genome) NB. HCV nucleotide numbering is based on nucleotide number 1 representing the start of the long open reading frame.

The product of this reaction, a 531 nt amplicon, was blunt end cloned into pBluescript KS, that was previously linearised with Sma1 , and sequenced. This clone was named pA2 and the sequence of the HCV cDNA insert is shown in Figure 2.

Clone A3 was generated in a similar manner, using the SISPA product and primers #157 and #402. The sequence of these primers is: primer (#157) 5' - CCGGTGCTCGGTCGTCCCCACCACAAC - 3' (nt 1540 - 1559, excluding 7 nt at the 5' end to facilitate cloning) primer (#402) 5' - TGGCATGGGATATGATGATG - 3'

(nt 953 - 972).

Primer #157 was designed from an HCV RNA published sequence (Okamoto et al., (1990) Jap J Exp Med 60; 167-177), and primer #402 from a sequence published by Choo et al (Proc NatI Acad Sci, USA 88; 2451-2455, 1991 ). The product of this reaction, (614 bp) was blunt-end cloned into pBluescript KS linearised by Sma1 to generate clone pA3. The sequence of clone pA3 is shown in Figure 3.

Based on the sequences of clones A2 and A3, primers 1A and 2A respectively were designed to amplify a region corresponding to nt 358-1030. The sequence of these primers is;

primer (#2A) - 5'-TTTCTTGTGGGATCCGGAGT - 3' (1011-1030) primer (#1A) - 5'-GGTAAGGTCATCGATACCCT - 3' (358-367).

These primers were used to amplify DNA from the products of a SISPA reaction, performed as described above. The product of this reaction was a 673bp fragment that was blunt-end cloned into pBluescript KS that was previously linearised with Smal, to create clone A10. The sequence of the HCV cDNA insert of pA10 is shown in Figure 4. The HCV sequences in clones pA2 and pA10 were then ligated to form a continuous cDNA molecule representing nt -22 to 1030 of the HCV genome. This was performed by ligation of the Cla1 fragment from pA2 with linearised pA10. This created clone pA2-A10, the orientation of which was confirmed by restriction enzyme mapping.

The PCR and cloning strategy for clones pA2, pA3 and pA10 is summarised in Figure 5.

Cloning of the L- hepatitis B surface antigen gene.

A serum sample from a HBsAg-positive patient represented the source of virus.

The virus DNA was purified by protease digestion followed by phenol extraction and ethanol precipitation. Briefly, the virus was pelleted through a 20% sucrose cushion at 39000 rpm for 5h in a Beckman SW41 rotor and the pellet was then mixed with a solution of proteinase K and SDS, and incubated at 37°C for 4h. The solution was then extracted with an equal volume of phenol:chloroform:isopropanol (25:24:1 ) and the upper aqueous layer containing the virus DNA removed. The DNA was precipitated by the addition of sodium acetate to 0.4M and 2.5vol of absolute ethanol. The DNA was pelleted, dried and re-dissolved in distilled water. The gene for HBsAg was amplified by PCR using primers designed from a published sequence of HBV DNA (Galibert et al., J Virol 41 ; 51-65, 1982). The sequence of the primers is:

Upstream: 5' - ATGGAGAACATCACATCAGGA - 3"

Downstream: 5' - AATGTATGCCCAAAGACAAAA - 3"

This reaction produced a 681 bp product that was cloned into pBluescript KS to create pTBM-LHBsAg and sequenced. The sequence of the HBsAg gene is shown in Figure 6.

Expression of S-HBsAg.

The region corresponding to the S-HBsAg gene was then excised by digestion of the plasmid with Hind III and sub-cloned into the expression vector pSVL (Pharmacia) to created pSV-HBsAg. Plasmid pSV-HBsAg was transfected into COS7 and HuH7 cells using the DOTAP procedure. Five days later, the cell monolayers were examined for expression of HBsAg by immunofluorescence and the cell culture fluid for secreted HBsAg by ELISA. The immunofluorescence pattern of the HBsAg expressed in the cells was typically cytoplasmic and the ELISA was positive for HBsAg. These results proved that the HBsAg was not only expressed from pSV-HBsAg but was also secreted.

Expression of L-HBsAg

Coverslip cultures of COS7 and HuH7 cells transfected with pTBM-LHBsAg were examined by immunofluorescence using a monoclonal antibody specific for L-HBsAg. A staining pattern similar to that noted for HBsAg was seen in all transfected cells. Cell lysates were also examined by immunoblot using the same antibody. Two bands of a size consistent with the glycosylated and non- glycosylated forms of L-HBsAg (ie. gp42/p39) were observed in lysates from cells transfected with pSV-LHBsAg but not the control plasmid.

Cloning of the L-HDAg gene

A serum sample from a HDV RNA-positive patient represented the source of the virus; the RNA was purified by the GIT extraction method described above. The L-HDAg gene was amplified by RT-PCR. The RT step was performed using random hexamer primers (Pharmacia) and the cDNA amplified by PCR using the following primers which include BamHI restriction enzyme sites to facilitate cloning;

H1- 5' -AAAGGATCCGATGAGCCGGTCCGAGTCG - 3' H2- 5' -AAAGGATCCTCACTGGGGTCGACAACT - 3'

The product of this reaction was a 465bp amplicon. This was digested with BamHI and cloned into the BamHI site of pCDNA3 to create pC-LHDAgl The sequence of the L-HDAg gene is shown in figure 7. Expression of L-HDAg.

Coverslip cultures of COS7 and HuH7 cells were harvested 2-3 days after transfection with pC-LHDAg1 and examined by immunofluorescence using a polyclonal rabbit antibody specific for the 19aa terminus of L-HDAg. A characteristic nuclear staining pattern was observed in all transfected cultures. Immunoblot examination of cell lysates from pC-LHDAg1 -transfected cells were also positive.

Synthesis of the gene for the C-terminal 19aa of L-HDAg.

The gene for the C-terminal 19aa region of HDAg was assembled from overlapping primers which were designed from examination of the consensus nucleotide sequences of the genomes of group 1 isolates of HDV. The sequence of the primers including restriction enzyme sites to facilitate cloning is:

primer p27 up

-5'-AAAGGATCCTGGGATATACTCTTCCCAGCCGATCCGCCCTTTTCT-3' (BamHI site) primer p27 down

-5'-AAACTCGAGTCACTGGGGTCGACATCAGTCGGGAGAAAAGGGCGG-3'

(Xho site)

The primers were heated to 85°C for 5 min then allowed to re-anneal as the mixture was cooled to room temperature. The product of this reaction was end filled with T4 DNA polymerase (Boehringer, Mannheim) to ensure that the hybrid was completely double stranded. The DNA was double digested with BamHI and Xho1 and directionally cloned into the corresponding sites in pcDNA3 which was previously digested with these enzymes and this resulted in the construction of pCδ27basic.

The sequence of the gene for the 19aa region (L-HDAg 19a) and an alignment with other Group 1 isolates of HDV is shown in Figure 8.

Construction of HCV core-HDAg fusion proteins. i) Full-length HCV core-HDAg

The full length core gene was amplified using primers #156C and #WYH-5 from pA2-A10; the sequence of the primers including Bam H1 and EcoR1 restriction enzyme sites to facilitate cloning is:

#156C-5'-CGCGGATCCATCGAAGGTAGAATGAGCACGAATCCTAAA-3'

#WYH-5-GGGGAATTCCGGAAGCTGGGATGGTCAAA-3'

The 600bp product of this reaction was directionally cloned into pECE (Leland et al, (1986), Cell 45; 721-732) which was previously digested with Bgl II and EcoR1 to create pECE-HCVcore; this plasmid was then digested with EcoR1 , made blunt ended by the action of the Klenow component of DNA polymerase 1 (Boehringer, Mannheim) and then digested with Xba1. This was then ligated to the Sma1/Xba1 fragment from pECEδBE (Chang et al, (1988) J Virol 62; 2403- 2410) that encodes the 51 -COOH terminal aa of L-HDAg to create pECE-C/d. The steps in the construction of this plasmid are shown in Figure 9. The sequence of the junction of the HCV core gene with the HDV antigen gene in pECE-C/d was determined using primer #1A and the junction of the genes shown to be in-frame.

ii) Partial core sequences.

The general cloning strategy for the construction of the partial core protein expression vectors is shown in Figure 10.

a) HCV corel 20a-HDAg The region corresponding to aa1-120 of the HCV core protein was fused to the 19aa COOH terminus of the L-HDAg to produce a chimeric fusion protein. The expression plasmid was constructed in the following manner.

The region coding for core amino acids 1 - 120 was amplified by PCR from pA2- A10 using primers TM1 and TM2. The sequence of these primers including the underlined BamHI sites to facilitate cloning is: primer #TM1

-5'-CGCGGATCCATCCAAGGTAGAATGAGCACGAATCCTAAA-3' primer #TM2- 5'-AAAGGATCCACCCAAATTACGCGACCTACG-3'

The product of this PCR was then digested with BamHI and ligated into the BamHI site of pCδ27basic to yield pCδ27core120a. The sequence of this chimeric gene was determined and is shown in Figure 11.

b) HCV core 120-HDAg The core gene region 1-120 was also amplified from pA2-A10 using primers TM2 and TM3 then ligated to the gene for the 19aa tail of L-HDAg. Primer TM3 is a modified version of primer TM1 that was designed to eliminate a potential loop in the 5' end of the mRNA transcribed from the plasmid, as it was considered that this loop may reduce the efficiency of protein translation from the mRNA. The sequence of primer TM3 including a BamHI site to facilitate cloning is: primer TM3-5'-AAAGGATCCAAAATGAGTACTAACCCTAAACCCCAA-3'.

The product was then digested with BamHI and ligated into the BamHI site of pCδ27basic to yield pCδ27core120. The HCV-HDV sequence in this plasmid is shown in Figure 12.

c) HCV corel 40-HDAg

Similarly, the region corresponding to aa1-140 of the HCV core protein was fused to the 19aa COOH terminus of the L-HDAg . The expression plasmid was constructed in the following manner:

The region coding for core amino acids 1-140 was amplified by PCR from pA2- A10 using primers TM3 and TM4 which include a BamHI site to facilitate cloning. The sequence of the primers is: primer #TM3-as above primer #TM4-5'-AAAGGATCCGACAAGCGGGATGTACCCCAT-3'. The product of this reaction was digested with BamHI and ligated into the BamHI site of pCδ27basic to yield pCδ27core140. The sequence of the chimeric HCV-HDAg gene in this plasmid is shown in Figure 13.

d) HCV corel 61 -HDAg The core protein aa1 -161 was fused to the 19aa L-HDAg COOH terminus using a similar strategy. The expression plasmid was constructed by amplifying the core gene coding for 1-161 from pA2-A10 using primers TM3 and TM5 which also contain a BamHI site for ease of cloning. The sequence of these primers is: primer #TM3-as above primer #TM5-5'-AAAGGATCCGCCGTCCTCCAGAACCCGGAC-3'

The product of this reaction was digested with BamHI and ligated into the BamHI site of pCδ27basic. This yielded plasmid pCδ27core161 and the sequence of the HCV-HDAg chimeric gene contained in this plasmid is shown in Figure 14.

Expression of core-HDAg fusion proteins incorporating 19 amino acid tail of L-HDAg.

a. Methods used for the transfection of DNA i). Calcium phosphate transfection of HuH7 cells. 6μg of DNA (3ug of each plasmid in the event of co-transfections) was mixed with calcium chloride to a final concentration of 0.12M and hepes buffered saline (HBS) pH7.00, then incubated overnight at room temperature. The solution was then sonicated for 60sec. The transfection mix was added to a 25cm² culture flask of HuH7 cells and incubated at 37°C overnight. The cell culture medium was changed the following day and the cells incubated for the desired period.

ii). DOTAP transfection of COS7 and THT1 cells. 10 μg of DNA (5ug of each plasmid) in 100μl of HBS was added to 50μl DOTAP (Boehringer Mannheim) and 50μl HBS, then incubated at room temperature for 10min. The cell culture medium in a 25cm² flask was replaced with DMEM+1 % FCS and the tranfection mixture then added. The cells were incubated at 37°C overnight then re-fed with DMEM+5% FCS and incubated for the desired period.

b. Results. i). Expression from pCECE-C/d and pCδ27core120a . Transfection of pECE- C/d or pCδ27core120a with or without pSV-HBsAg into HuH7, COS7 and THT1 cells resulted in only a few cells which were weakly positive for HCV core antigen. All cells were negative for HDAg. Neither antigen was detected in the cell culture fluid (CCF) after co-transfection with pSV-HBsAg.

It seemed likely that two possibilities accounted for the lack of protein expression in these experiments viz. inefficient translation of protein from mRNA or protein stability. To examine these possibilities, in vitro translation in rabbit reticulocyte lysates using in vitro transcribed, capped RNA from pCδ27core120a was performed.

A product with a size consistent with the expected size of the core-delta fusion protein was detected by SDS-PAGE in this experiment (Figure 15). This product was subsequently confirmed to be reactive with anti-HCV core by immunoblot. Thus the core-HDAg fusion protein encoded in plasmid pCδ27core120a could be translated normally, suggesting that the poor expression of this plasmid in cell cultures was probably related to protein instability.

ii). Expression from pCδ27core120, pCδ27core140 and pCδ27core161. After co-transfection of these plasmids with pSV-HBsAg into COS7 cells, the intact cells and cell lysates were examined 3 days and 5 days later for HCV core antigen expression by immunofluorescence and immunoblot respectively. The results of the immunofluorescence examination showed that pCδ27core120 expression resulted in weak staining with a diffuse nuclear localisation, while expression from pCδ27core161 was similar except that the antigen was also expressed in the cytoplasm. However, expression from pCδ27core140 showed strong nuclear and cytoplasmic staining. In comparison, HCV expressed from pECE-HCV core showed strong perinuclear staining. These results are summarised in Table 2. HDAg was not detected in any of the transfected cells.

These results were confirmed by immunoblot examination of cell lysates harvested on day 5 post transfection. No signal was detected after transfection with pCδ27core120 and only a weak signal detected from pCδ27core161. In contrast, a strong reactive band corresponding to the predicted size of the fusion protein was detected in cell lysates after transfection with pCδ27core140 (Figure 16 and Table 2).

Table 2 Summary of results with pCδ27core120-161

Note: no virus like particles detected if the HBsAg gene was ommitted from the transfection mixture

CCF from the transfected cells were then examined. The samples were clarified, then centrifuged through a 20% sucrose cushion at 38000 rpm for 5h at 4°C in a Beckman SW-41 rotor. The pellets were dissolved in SDS-PAGE loading buffer then examined by immunoblot to detect secreted HCV core antigen.

Weak doublet bands that were identical in size to those detected in cell lysates were detected in cell culture fluids from COS7 cells transfected with pCδ27core140 (Figure 17). No HCV core antigen was detected in the CCF from COS7 cells transfected with pCd27core120 or pCδ27core161. These results were reproducible. Moreover the data clearly showed that the appearance of the HCV core in the CCF was dependent on co-transfection with pSV-HBsAg. Thus this experiment provides strong evidence that the HCV core protein was secreted from the cells as virus-like particles.

The above recombinant DNA techniques are in common use and are described in detail in Sambrook et al (Cold Spring Harbor Laboratory Press, 1989).

Virus-like particles constructed according to the examples using a fusion HCV/HDV protein and HBsAg were immunogenic with respect to HCV and HBV. That is the virus-like particles are capable of stimulating HLA class I restricted CTL responses against the core protein for HCV and the surface antigen of HBV.

Constructs including full length L-HDAg with and without insertions

Schematic representations of the following constructs are illustrated in Figure 18.

(a) pCc140FLδ

The gene encoding aa 1-140 of HCV core was excised by PCR from plasmid pCδ27c140 (aa 1 -140 fused to C-terminal 19aa of L-HDAg) by BamHI digestion and ligated into the BamHI site of a pCDNA derived plasmid containing full length L-HDAg cloned between BamHI and Xba1 sites. The HDAg insert for the latter plasmid (pCδ27/FL) was amplified by PCR (template pSV27 = complete L- HDAg gene inserted into the Sma1 site of pSVL [Pharmicia]) using primers

(i) HDAg For

5'-AAAGGATCCGGAATGAGCCGGTCCGAGTCGAGG-3' (BamHI site underlined)

(ii) HDAg Rev

5'-AAATCTAGATCACTGGGGTCGACAACTCTG-3' (Xba1 site underlined) (b) pCFLcore+δ

The full length gene for HCV core was amplified by PCR from the Australian HCV isolate (in plasmid pECEcore) and blunt-end cloned into the BamHI site of plasmid pCδ27/FL (see above).

The upstream primer for the PCR was the same as for the C140 insert. The downstream primer was as follows:

5'GCGAATTCCGGATCCTGGGATGGTCAAACA-3' (EcoR1 site is underlined).

(c) pSV27-C40Apa1 and pSV27-C40Apa1

These plasmids contain aa 1-40 of HCV core (amplified by PCR) inserted into the Apa1 or the Sma1 sites respectively of full length L-HDAg in plasmid pSV27 (see above)

Primers

(i) Apa1 insertion

HCV-C40Apa1 For

5'-AAAGGGCCCGAATGAGCACGAATCCTAAACCT-3'

HCV-C40Apa1 Rev

5'-AAAGGGCCCTGCGCGGCAACAGGTAAAC-3'

Apa1 sites are underlined

(ii) Sma1 insertion

HCV-C40EcoR5 For

5'-CTGAGATATCATGAGCACGAATCCTAAAC-3' HCV-C40EcoR5 Rev

5'-TTAAGATATCGCCCCTGCGCGGCAACAGG-3'

EcoR5 sites are underlined.

CTL assays

Transfected 2X 175cm² of Cos 7 cells with pCc140FLδ plus pSVHBsAg using DOTAP. Culture fluids were harvested 5 days post transfection and the VLPs centrifuged through a 20% sucrose cushion.

Transfected 2X 175cm² of Cos 7 cells each with pCc140FLδ (plus pSVHBsAg) and pCδ27c140 (plus pSVHBsAg) using DOTAP. Culture fluids and cell lysates were harvested 5 days post transfection. VLPs were prepared as above. Samples from transfection using pCc140FLδ were also analysed by western blot (Figure 19).

Transfected 2X 175cm² of Huh7 cells by Calcium Phosphate co-precipitation with pCFLcore+δ plus pSVHBsAg. Culture fluids were harvested 5 days post transfection. VLPs (prep as above) were examined by western blot (Figure 20).

internal insertions into HDAg

1x25cm² flasks each of Cos 7 cells were transfected with either pSV27- C40Apa1 or pSV27-C40Apa1 and pSVHBsAg. Culture fluids were harvested 5 days post transfection. VLPs (prep as above) were examined by western blot (Figure 21 ).

Virus-like particle vaccination results

Two groups of 3 mice were vaccinated with the virus-like particles, composed of 140 amino acids of HCV core fused with the 19 amino acid tail of HDAg, and enveloped by HBsAg. The particles were prepared by co-transfection of COS7 cells using DOTAP. The cell culture supernatant 5 days post transfection was then centrifuged over a 20% sucrose cushion and the particles resuspended in PBS 100μl of this preparation was injected by the intraperitoneal route, and 2 weeks later the mice were boosted.

After a further 2 weeks, the mice were sacrificed, the spleens removed and the cells stimulated and expanded in vitro with specific peptide. To determine the level of cytotoxic T cell activity, control P815 cells or peptide pulsed P815 cells were incubated with the expanded effector cells in a classical ⁵¹Cr release assay. The results are shown in figure 22; the level of background killing was high (approximately 40%), but there was a clear increase in cell killing in the HBsAg- and the HCV core-peptide pulsed cells. At an effectortarget ratio of 100:1 , 70.5% and 67% of the cells respectively were killed. Thus, there was a low but consistent CTL response to both HCV core peptides (amino acids 129- 140 and amino acids 132-140 respectively) and to the HBsAg peptide (amino acids 28-39). The sequence of the peptides used in these studies were: HCV core amino acids 129 - 140 GFADLMGYIPLV; HCV core amino acids 132 - 140 DLMGYIPLV;

HBsAg amino acids 28 - 39 IPQSLDSWWTSL

All the references cited herein, are hereby incorporated in their entirety by reference. Further while this invention has been described with an emphasis upon preferred embodiments, it will be obvious to those of ordinary skill that variations of the preferred embodiments may be used and that it is intended that the invention may be practiced otherwise than as specifically described herein.

Sequence listings

(1 ) SEQ ID NO: 1 10 20 30 40

* * * *

ATG AGT ACT AAC CCT AAA CCC CAA AGA AAA ACC AAA CGT AAC ACC AAC

TAC TCA TAG TTC GGA TTT GGG GTT TCT TTT TGG TTT GCA TTG TGG TTG

Met Ser Thr Asn Pro Lys Pro Gin Arg Lys Thr Lys Arg Asn Thr Asn

50 60 70 80 90 * * *

CGC CGT CCA CAG GAC GTC AAG TTC CCG GGC GGT GGT CAG ATC GTT GGT

GCG GCA GGT GTC CTG CAG TTC AAG GGC CCG CCA CCA GTC TAG CAA CCA Arg Arg Pro Gin Asp Val Lys Phe Pro Gly Gly Gly Gin lie Val Gly

100 110 120 130 140

* * * * *

GGA GTT TAC CTG TTG CCG CGC AGG GGC CCC AGG TTG GGT GTG CGC GCG CCT CAA ATG GAC AAC GGC GCG TCC CCG GGG TCC AAC CCA CAC GCG CGC

Gly Val Tyr Leu Leu Pro Arg Arg Gly Pro Arg Leu Gly Val Arg Ala

150 160 170 180 190 CTC AGG AAG ACT TCC GAG CGG TCG CAA CCT CGT GGA AGG CGA CAA CCT

GAG TCC TTC TGA AGG CTC GCC AGC GTT GGA GCA CCT TCC GCT GTT GGA Leu Arg Lys Thr Ser Glu Arg Ser Gin Pro Arg Gly Arg Arg Gin Pro

200 210 220 230 240 * * * * *

ATC CCC AAG GCT CGC CGA CCC GAG GGC AGG GCC TGG GCT CAG CCC GGG TAG GGG TTC CGA GCG GCT GGG CTC CCG TCC CGG ACC CGA GTC GGG CCC lie Pro Lys Ala Arg Arg Pro Glu Gly Arg Ala Trp Ala Gin Pro Gly 250 260 270 280

* * * *

TAC CCT TGG CCC CTC TAT GGC AAT GAG GGC ATG GGG TGG GCA GGA TGG ATG GGA ACC GGG GAG ATA CCG TTA CTC CCG TAC CCC ACC CGT CCT ACC Tyr Pro Trp Pro Leu Tyr Gly Asn Glu Gly Met Gly Trp Ala Gly Trp

290 300 310 320 330

* * * * *

CTC CTG TCA CCC CGT GGT TCT CGG CCT AGT TGG GGC CCC TCA GAC CCC

GAG GAC AGT GGG GCA CCA AGA GCC GGA TCA ACC CCG GGG AGT CTG GGG Leu Leu Ser Pro Arg Gly Ser Arg Pro Ser Trp Gly Pro Ser Asp Pro

340 350 360 370 380

* * + * *

CGG CGT AGG TCG CGT AAT TTG GGT GGA TCC TGG GAT ATA CTC TTC CCA GCC GCA TCC AGC GCA TTA AAC CCA CCT AGG ACC CTA TAT GAG AAG GGT

Arg Arg Arg Ser Arg Asn Leu Gly Gly Ser Trp Asp lie Leu Phe Pro

390 400 410 420

* * * * GCC GAT CCG CCC TTT TCT CCC CAG AGT TGT CGA CCC CAG TGA

CGG CTA GGC GGG AAA AGA GGG GTC TCA ACA GCT GGG GTC ACT

Ala Asp Pro Pro Phe Ser Pro Gin Ser Cys Arg Pro Gin *** (2) SEQ ID NO: 2

10 20 30 40

* * * * ATG AGT ACT AAC CCT AAA CCC CAA AGA AAA ACC AAA CGT AAC ACC AAC TAC TCA TAG TTC GGA TTT GGG GTT TCT TTT TGG TTT GCA TTG TGG TTG Met Ser Thr Asn Pro Lys Pro Gin Arg Lys Thr Lys Arg Asn Thr Asn

50 60 70 80 90 * * * * *

CGC CGT CCA CAG GAC GTC AAG TTC CCG GGC GGT GGT CAG ATC GTT GGT GCG GCA GGT GTC CTG CAG TTC AAG GGC CCG CCA CCA GTC TAG CAA CCA Arg Arg Pro Gin Asp Val Lys Phe Pro Gly Gly Gly Gin lie Val Gly 100 110 120 130 140

* * * * *

GGA GTT TAC CTG TTG CCG CGC AGG GGC CCC AGG TTG GGT GTG CGC GCG CCT CAA ATG GAC AAC GGC GCG TCC CCG GGG TCC AAC CCA CAC GCG CGC Gly Val Tyr Leu Leu Pro Arg Arg Gly Pro Arg Leu Gly Val Arg Ala

150 160 170 180 190

* * * * *

CTC AGG AAG ACT TCC GAG CGG TCG CAA CCT CGT GGA AGG CGA CAA CCT

200 210 220 230 240

* * * * *

ATC CCC AAG GCT CGC CGA CCC GAG GGC AGG GCC TGG GCT CAG CCC GGG TAG GGG TTC CGA GCG GCT GGG CTC CCG TCC CGG ACC CGA GTC GGG CCC lie Pro Lys Ala Arg Arg Pro Glu Gly Arg Ala Trp Ala Gin Pro Gly

250 260 270 280 TAC CCT TGG CCC CTC TAT GGC AAT GAG GGC ATG GGG TGG GCA GGA TGG

ATG GGA ACC GGG GAG ATA CCG TTA CTC CCG TAC CCC ACC CGT CCT ACC Tyr Pro Trp Pro Leu Tyr Gly Asn Glu Gly Met Gly Trp Ala Gly Trp

290 300 310 320 330 * * * * *

CTC CTG TCA CCC CGT GGT TCT CGG CCT AGT TGG GGC CCC TCA GAC CCC GAG GAC AGT GGG GCA CCA AGA GCC GGA TCA ACC CCG GGG AGT CTG GGG Leu Leu Ser Pro Arg Gly Ser Arg Pro Ser Trp Gly Pro Ser Asp Pro 340 350 360 370 380

* * * * *

CGG CGT AGG TCG CGT AAT TTG GGT AAG GTC ATC GAT ACC CTT ACA TGC GCC GCA TCC AGC GCA TTA AAC CCA TTC CAG TAG CTA TGG GAA TGT ACG Arg Arg Arg Ser Arg Asn Leu Gly Lys Val lie Asp Thr Leu Thr Cys

390 400 410 420 430

* * + * *

GGC TTC GCC GAC CTC ATG GGG TAC ATT CCG CTC GTC GGA TCC TGG GAT

CCG AAG CGG CTG GAG TAC CCC ATG TAA GGC GAG CAG CCT AGG ACC CTA Gly Phe Ala Asp Leu Met Gly Tyr lie Pro Leu Val Gly Ser Trp Asp

440 450 460 470 480

* * * * *

ATA CTC TTC CCA GCC GAT CCG CCC TTT TCT CCC CAG AGT TGT CGA CCC TAT GAG AAG GGT CGG CTA GGC GGG AAA AGA GGG GTC TCA ACA GCT GGG lie Leu Phe Pro Ala Asp Pro Pro Phe Ser Pro Gin Ser Cys Arg Pro

CAG TGA

GTC ACT Gin *** (3) SEQ ID NO: 3

10 20 30 40

50 60 70 80 90 * * * * *

* * * * *

GGA GTT TAC CTG TTG CCG CGC AGG GGC CCC AGG TTG GGT GTG CGC GCG

CCT CAA ATG GAC AAC GGC GCG TCC CCG GGG TCC AAC CCA CAC GCG CGC

Gly Val Tyr Leu Leu Pro Arg Arg Gly Pro Arg Leu Gly Val Arg Ala

150 160 170 180 190

* * * * *

CTC AGG AAG ACT TCC GAG CGG TCG CAA CCT CGT GGA AGG CGA CAA CCT

200 210 220 230 240

* * * * *

250 260 270 280

* * * * TAC CCT TGG CCC CTC TAT GGC AAT GAG GGC ATG GGG TGG GCA GGA TGG

290 300 310 320 330

* * * * *

CGG CGT AGG TCG CGT AAT TTG GGT AAG GTC ATC GAT ACC CTT ACA TGC

GCC GCA TCC AGC GCA TTA AAC CCA TTC CAG TAG CTA TGG GAA TGT ACG

Arg Arg Arg Ser Arg Asn Leu Gly Lys Val He Asp Thr Leu Thr Cys

390 400 410 420 430

* * * * *

GGC TTC GCC GAC CTC ATG GGG TAC ATT CCG CTC GTC GGC GCC CCT CTA

CCG AAG CGG CTG GAG TAC CCC ATG TAA GGC GAG CAG CCG CGG GGA GAT Gly Phe Ala Asp Leu Met Gly Tyr He Pro Leu Val Gly Ala Pro Leu 440 450 460 470 480 *

GGG GGC GCC GCC AGG GCC CTG GCG CAT GGC GTC CGG GTT CTG GAG GAC CCC CCG CGG CGG TCC CGG GAC CGC GTA CCG CAG GCC CAA GAC CTC CTG Gly Gly Ala Ala Arg Ala Leu Ala His Gly Val Arg Val Leu Glu Asp

490 500 510 520 *

GGC GGA TCC TGG GAT ATA CTC TTC CCA GCC GAT CCG CCC TTT TCT CCC CCG CCT AGG ACC CTA TAT GAG AAG GGT CGG CTA GGC GGG AAA AGA GGG Gly Gly Ser Trp Asp He Leu Phe Pro Ala Asp Pro Pro Phe Ser Pro 30 540

CAG AGT TGT CGA CCC CAG TGA GTC TCA ACA GCT GGG GTC ACT Gin Ser Cys Arg Pro Gin ***

Claims

THE CLAIMS of the invention are as follows:

1. A virus-like particle for use in the treatment or prevention of at least a microorganism infection wherein said particle comprises: at least a antigenic and/or immunogenic polypeptide or part thereof from the microorganism, fused to at least the last 19 amino acid of the COOH terminal sequence of the large protein from Hepatitis D virus, wherein the fusion protein is at least partially enveloped by Hepatitis B surface antigen.

2. A virus-like particle according to claim 1 wherein the immunogenic polypeptide is capable of eliciting a T cell response.

3. A virus-like particle according to claim 1 wherein the immunogenic polypeptide is capable of eliciting a humoral response.

4. A virus-like particle according to claim 1 wherein the immunogenic polypeptide or part thereof expresses a plurality of epitopes.

5. A virus-like particle according to claim 1 wherein the immunogenic polypeptide or part thereof expresses a plurality of epitopes, which as a whole should be capable of eliciting a humoral response and a T cell response.

6. A virus-like particle according to any one of claims 1 , 2, 4 or 5 wherein the immunogenic polypeptide or part thereof expresses a plurality of epitopes wherein at least one of the epitopes is capable of stimulating a cytotoxic T lymphocyte response.

7. A virus-like particle according to any one of the previous claims wherein the immunogenic polypeptide is derived from hepatitis C virus.

8. A virus-like particle according to claim 7 wherein the immunogenic polypeptide is derived from HCV core protein.

9. A virus-like particle according to claim 7 wherein the immunogenic polypeptide is derived from HCV NS3 protein.

10. A virus-like particle according to claim 7 wherein the immunogenic polypeptide is derived from amino acids 1 to 191 of the HCV core protein.

11. A virus-like particle according to claim 8 wherein the immunogenic polypeptide is between about 120 and 160 amino acids in length.

12. A virus-like particle according to claim 1 wherein the fusion protein is selected from any one of SEQ ID NO 1 , SEQ ID NO 2 or SEQ ID NO 3.

13. A virus-like particle according to claim 1 wherein the fusion protein is substantially homologous to any one of SEQ ID NO 1 , SEQ ID NO 2 or SEQ ID NO 3.

14. A virus like particle according to any one of the preceding claims wherein the entire amino acid sequence of L-HDAg is used in the fusion protein.

15. A method for producing virus-like particles containing an antigenic and or immunogenic polypeptide or part thereof comprising the step of: incubating host cells transformed with an expression vector which includes a nucleotide sequence encoding a fusion polypeptide containing the antigenic and or immunogenic polypeptide or part thereof and at least the last 19 amino acid of the COOH terminal sequence of the large protein from Hepatitis D virus; in the presence of HBsAg, under conditions which allow expression and packaging of said fusion polypeptide.

16. A method according to claim 14 wherein HBsAg is expressed in the same host cells as the fusion polypeptide.

17. A method according to any one of claims 15 or 16 wherein the entire amino acid sequence of L-HDAg is used in the fusion protein.

18. A therapeutic for use in the treatment of a patient suffering from at least a microorganism infection, said therapeutic comprising: virus like particles according to any one of claims 1 to 13 in combination with a pharmaceutically acceptable carrier.

19. A therapeutic for aiding in the prevention of at least a microorganism infection in a patient, said therapeutic comprising: virus like particles according to any one of claims 1 to 13 in combination with a pharmaceutically acceptable carrier.

20. A therapeutic according any one of claims 18 or 19 wherein the entire amino acid sequence of L-HDAg is used in the fusion protein.