ELISA for Quantitative Determination of Hepatitis B Virus Surface Antigen

Several studies have reported a good correlation between levels of serum hepatitis B virus surface antigen (HBsAg) and covalently closed circular DNA (cccDNA) before and after antiviral therapy. As a result, the quantification of HBsAg levels has attracted much attention in recent years as an important approach to evaluate viral activity. In this study, mAbs against HBsAg were generated and 9 mAbs (H17, H30, H31, H67, H73, H97, H101, H118, and H128) were investigated for optimization of HBsAg quantitation ELISA. Determination of the best combinations of mAbs for sandwich ELISA identified H17 and H31 mAbs as the ideal capture and horseradish peroxidase (HRP) conjugate mAbs, respectively. A standard curve for the current assay system exhibited linearity up to 40 ng/ml of HBsAg while a detection limit of approximately 1 ng/ml of HBsAg was also estimated, which was comparable to that of the other commercial ELISA kits. The ELISA system established in this study is particularly differentiated from other commercial kits in using mAbs for both capture and HRP conjugate, which provides a solution to inconsistency of quality and ethical issues in polyclonal antibodies production using laboratory animals.