The use of core antigen (HBcAg) of hepatitis B virus (HBV) to present peptide epitopes to the immune system has been shown to enhance immunogenicity of the peptide epitopes. HBcAg fused to the first 8 amino acid residues of β-galactosidase was exploited to serve as a carrier protein to present the epitopes from the S, preS_1 and preS_2 regions of HBV as its truncated C-terminus. The emergence of an HBV escape mutant carrying an amino acid substitution from glycine to arginine at amino acid residue 145 of the S domain suggests that it may be necessary to modify future HBV vaccines. The immunodominant region of HBAsAg carrying mutant sequence at amino acid residue 145 was also fused to HBcAg. These HBcAg fusion proteins were expressed in <i>E.coli</i> and produced in high yields, and assembled into core-like particles morphologically indistinguishable from HBcAg itself. The largest multiple fusion protein, containing a dimer of the HBs_(111-156) sequence as well as sequences from preS_1 and preS_2 regions carried a total of 165 amino acid residues attached to the C-terminus of truncated HBcAg, and could still be accommodated in core-like particles. The HBcAg fusion proteins displaced similar HBc antigenicity and immunogenicity to the full-length HBcAg. Immunisation of rabbits with the HBcAg fusion proteins elicited T-cell-proliferative responses to HBcAg, HBsAg and preS_1 peptides. The T-cell responses to HBcAg were much higher and more consistent than those to HBsAg or preS_1 peptide. The HBcAg fusion proteins induced antibodies against the corresponding peptides. The fusions carrying the immunodominant region of HBsAg, either wild-type or gly_145 mutant with arginine, glutamic acid or lysine substitution, showed HBs antigenicity in the immunoblot analysis and the antigen-capture sandwich radioimmunoassay, albeit at a lesser extent, using two antibodies with different specificity.
| Identifer | oai:union.ndltd.org:bl.uk/oai:ethos.bl.uk:661859 |
| Date | January 1993 |
| Creators | Shiau, Ai-Li |
| Publisher | University of Edinburgh |
| Source Sets | Ethos UK |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
| Source | http://hdl.handle.net/1842/14415 |
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