Expression and characterization of hepatitis C virus core protein fused to hepatitis B virus core antigen

Recombinant plasmids were constructed by fusing the gene fragments encoding the full-length (1-191aa) and the truncated (1-40aa and l-69aa) HCV core proteins (HCc) respectively to the core gene of HBV at the position of amino acid 144 and expressed inE. coli. The products were analyzed by ELISA, Western blotting as well as the immunization of the mice. The results showed that those fusion proteins (B144C191, B144C69, B144C40) possessed the dual antigenicity and immunogenicity of both hepatitis B virus core antigen (HBcAg) and hepatitis C virus core protein (HCc). Analysis by electron microscopy and CsCI density gradient ultra-centrifugation revealed that similar to the HBcAg itself, all fusion proteins were able to form particles. Comparison of the antigenicity and immunogenicity of those fusion proteins showed that the length of HCc gene fused to HBcAg had no much effect on the antigenicity and immunogenicity of HBcAg, however, B144C69 and B144C40 induced higher titres antibodies against HCc than B144C191. Using those fusion proteins, ELISA for screening of antibodies against both HBV and HCV in human sera was also established.