Cloning of anti-HBsAg single-chain variable fragments from hybridoma cells for one-step ELISA

Hepatitis B virus (HBV) infection is a worldwide health problem. More than 400 million people are chronic HBV carriers in the world. Infected individuals are at a high risk of developing liver cirrhosis and hepatocellular carcinoma as the main consequences of HBV. The discoveries of fast diagnostic systems and new therapeutic applications are crucial in the fight against viral hepatitis. In this paper we present the generation of a single-chain variable fragment (scFv) from a mouse monoclonal antibody specific to the HBV surface antigen (HBsAg) and demonstrate its expression as a bacterial alkaline phosphatase (AP) fusion protein. In this study, we constructed scFvs from hybridoma cells expressing HBsAg-specific antibody using phage display technology and expressed them in Escherichia coli. The anti-HBsAg scFvs were inserted into pQE-2 vector to produce scFv antibody genetically fused to bacterial AP. Reproducibility of the recombinant HBsAg-scFv fusion protein was tested using Enzyme-linked Immunosorbent Assay (ELISA). Present preliminary findings indicate that the anti-HBsAg-scFv AP conjugate could be further used for the development of one-step ELISA for the detection of HBV.