Abstract
Hepatitis B can be initially diagnosed by hepatitis B core antibody - one of the earliest proteins of immune system detected after viral infection starts. Present study was aimed at the cloning, expression, refolding, purification and immunogenicity analysis of HBV core antigen protein of a local genotype D isolate from Pakistani population. The viral protein was expressed in BL21 (DE3) strain of E. coli using pET22 b (+) expression plasmid vector. Recombinant protein appeared as inclusion bodies constituting about 40 to 50% of total E. coli proteins with a molecular weight of 21IcDa. The misfolded inclusion bodies were solubilized, refolded in vitro and purified by anion exchange chromatography using DEAE-Sephadex. The immunogenicity of folded and purified antigen was determined and verified by antigen -antibody interaction reactions and ELISA. The recombinant antigen exhibited strong reaction against HBV positive and no reaction against HBVnegative sera. It gave a good response to the ELISA and indicated a great immune response in rabbit. The subject protein with considerably high immune response offers a useful marker for the early diagnosis of HBV and a candidate subject for vaccine development research.