1. An HBV core antigen particle comprising at least one capsid binding immunogen, said capsid binding immunogen comprising at least one HBV capsid binding peptide component and at least one immunogenic component. 2. The HBV core antigen particle according to claim 1, wherein said capsid binding immunogen is oriented on said particle such that it permits said immunogenic component to elicit an immune response when said particle is administered to an individual. 3. The HBV core antigen particle according to claim 1, wherein said capsid binding immunogen is linked to said particle through any amino acid residue of said HBV capsid-binding peptide component. 4. The HBV core antigen particle according to claim 1, wherein said capsid binding immunogen is linked to said particle through any amino acid residue or other residue of said immunogenic component. 5. The HBV core antigen particle according to claim 4, wherein said other residue of said immunogenic component is a carbohydrate. 6. The HBV core antigen particle according to claim 1, wherein said capsid binding immunogen is linked to said particle through the amino terminus of said HBV capsid-binding peptide component. 7. The HBV core antigen particle according to claim 1, wherein said capsid binding immunogen is linked to said particle through the carboxy terminus of said HBV capsid-binding peptide component. 8. The HBV core antigen particle according claim 1, wherein said capsid binding immunogen is crosslinked to said particle by a crosslinker. 9. The HBV core antigen particle according to claim 1, wherein said immunogenic component is linked to said HBV capsid-binding peptide component directly or through a linker sequence. 10. The HBV core antigen particle according to claim 1, wherein said immunogenic component is linked to the amino terminus of said HBV capsid-binding peptide component directly or through a linker sequence. 11. The HBV core antigen particle according to claim 1, wherein said immunogenic component is linked to the carboxy terminus of said HBV capsid-binding peptide component directly or through a linker sequence. 12. The HBV core antigen particle according to any one of claims 9-11, wherein said immunogenic component is linked to said HBV capsid-binding peptide component by a crosslinker. 13. The HBV core antigen particle according to claim 8, wherein said crosslinker is a multifunctional crosslinker. 14. The HBV core antigen particle according to claim 12, wherein said crosslinker is a multifunctional crosslinker. 15. The HBV core antigen particle according to claim 14, wherein said multifunctional crosslinker is selected from the group consisting of 1-ethyl-3 (3-dimethylaminopropyl) carbodiimide hydrochloride and N-hydroxy-sulphosuccinimide. 16. The HBV core antigen particle according to claim 1, wherein said immunogenic component comprises one or more epitopes selected from the group consisting of immunologic epitopes, immunogenic epitopes and antigenic epitopes. 17. The HBV core antigen particle according to claim 16, wherein said epitopes are selected from the group consisting of linear epitopes, conformational epitopes, single epitopes and mixed epitopes. 18. The HBV core antigen particle according to claim 1, wherein said immunogenic component is selected from the group consisting of antigens, allergens, antigenic determinants, proteins, glycoproteins, antibodies, antibody fragments, peptides, peptide mimotopes which mimic an antigen or antigenic determinant, polypeptides, glycopeptides, carbohydrates, oligosaccharides, polysaccharides, oligonucleotides and polynucleotides. 19. The HBV core antigen particle according to claim 1, wherein said immunogenic component is targeted to or derived from a pathogenic agent selected from the group consisting of viruses, parasites, mycobacteria, bacteria, bacilli, fungi, protozoa, plants, phage, animal cells and plant cells. 20. The HBV core antigen particle according to claim 19, wherein said virus is selected from the group consisting of retroviruses, herpesviruses, orthomyoxoviruses, paramyxoviruses, hepadnaviruses, flaviviruses, picornaviruses, papoviruses, adenoviruses, baculoviruses, hantaviruses, parvoviruses, enteroviruses, rhinoviruses, tumor viruses, DNA viruses, RNA viruses, togaviruses, rhabdoviruses and poxviruses. 21. The HBV core antigen particle according to claim 20, wherein said virus is selected from the group consisting of human immunodeficiency type 1 virus, human immunodeficiency type 2 virus, T cell-leukemia virus, herpes simplex type 1 virus, herpes simplex type 2 virus, varicella-zoster virus, cytomegalovirus, Epstein-Barr virus, influenza A virus, influenza B virus, influenza C virus, respiratory syncytial virus, measles-like virus, mumps virus, parainfluenza virus, hepatitis B virus, hepatitis C virus, hepatitis A virus, hepatitis E virus, yellow fever virus, malaria, dengue virus, tick-borne encephalitis virus, oncovirus, poliomyelitis virus, papillomavirus, rubella virus, rabies virus and vaccinia virus. 22. The HBV core antigen particle according to claim 19, wherein said immunogenic component is targeted to or derived from bacillus, enterobacteria, clostridium, listeria, mycobacterium, pseudomonas, staphylococcus, eubacteria, mycoplasma, chlamydia, spirochetes, neisseria or salmonella. 23. The HBV core antigen particle according to claim 19, wherein said immunogenic component is targeted to diptheria, tetanus, acellular pertussis, haemophilus influenza, polio, measles, mumps, rubella, varicella, hepatitis B virus, hepatitis A virus, pneumococcal pneumonia, yellow fever, malaria, hepatitis B virus, hepatitis A virus, typhoid fever, meningococcal encephalitis or cholera. 24. The HBV core antigen particle according to claim 18, wherein said immunogenic component is selected from the group consisting of animal allergens, insect allergens, plant allergens, atmospheric allergens and inhalant allergens. 25. The HBV core antigen particle according to claim 1, wherein said HBV core antigen is an HBV core antigen fusion protein. 26. The HBV core antigen particle according to claim 25, wherein said HBV core antigen fusion protein comprises an immunologic epitope, an immunogenic epitope or an antigenic epitope. 27. The HBV core antigen particle according to claim 26, wherein said HBV core antigen fusion protein comprises an immunologic epitope, an immunogenic epitope or an antigenic epitope fused to HBV core antigen directly or through a linker sequence. 28. The HBV core antigen particle according to claim 26, wherein said HBV core antigen fusion protein comprises an immunologic epitope, an immunogenic epitope or an antigenic epitope fused to the carboxy terminus of said HBV core antigen directly or through a linker sequence. 29. The HBV core antigen particle according to claim 26, wherein said HBV core antigen fusion protein comprises an immunologic epitope, an immunogenic epitope or an antigenic epitope fused to the amino terminus of said HBV core antigen directly or through a linker sequence. 30. The HBV core antigen particle according to claim 25, wherein said HBV core antigen fusion protein comprises truncated HBV core antigen. 31. The HBV core antigen particle according to claim 25, wherein said HBV core antigen fusion protein comprises HBV surface antigen or portions thereof. 32. The HBV core antigen particle according to claim 31, wherein said HBV core antigen fusion protein comprises a sequence selected from the group consisting of the pre-S1 region of HBV surface antigen, the pre-S2 region of HBV surface antigen, the immunodominant a region of HBV surface antigen and portions thereof. 33. The HBV core antigen particle according to claim 1, wherein said HBV core antigen is a full length HBV core antigen polypeptide, or portions, truncates, mutations or derivatives thereof which are capable of assembling in particulate form. 34. The HBV core antigen particle according to claim 1, wherein said HBV capsid-binding peptide component is selected from the group consisting of: SLLGRMKGA (SEQ ID NO: 6), GSLLGRMKGA (SEQ ID NO: 36), DGSLLGRMKGAA (SEQ ID NO: 37), ADGSLLGRMKGAAG (SEQ ID NO: 38), SLLGRMKG(beta-A)C (SEQ ID NO: 8), RSLLGRMKGA (SEQ ID NO: 9), HRSLLGRMKGA (SEQ ID NO: 10), ALLGRMKG (SEQ ID NO: 12), MHRSLLGRMKGA (SEQ ID NO: 40), RSLLGRMKGA(beta-A)C (SEQ ID NO: 11) and MHRSLLGRMKGAG(beta-A)GC (SEQ ID NO: 41). 35. A vaccine comprising a prophylactically effective amount of an HBV core antigen particle according to claim 1. 36. A pharmaceutical composition comprising a therapeutically effective amount of an HBV core antigen particle according to claim 1. 37. A method for producing an immune response in an individual comprising the step of administering to said individual an HBV core antigen particle according to claim 1 in an amount effective to produce an immune response. 38. The method according to claim 37, wherein said HBV core antigen particle is administered to said individual by parenteral route. 39. A method for increasing the immunogenicity of an immunogen by linking said immunogen to an HBV core antigen particle through an HBV capsid-binding peptide, characterized in claim 34. 40. The HBV core antigen particle according to claim 1, wherein said capsid binding immunogen comprises a diagnostic label or a chemical marker. 41. A method for detecting the presence of antibodies to an immunogen in a sample comprising the steps of: (a) contacting the sample with an HBV core antigen particle according to claim 40, for a time sufficient to permit any antibodies in said sample to form a complex with said capsid binding immunogen and; (b) using detection means to detect the complex formed between the capsid binding immunogen and said antibodies in said sample. 42. An HBV capsid-binding peptide immunogen comprising at least one capsid-binding peptide component and at least one immunogenic component. 43. The HBV capsid-binding peptide immunogen according to claim 42, wherein sa