Reactivity of genotypically distinct hepatitis B virus surface antigens in 10 commercial diagnostic kits available in Japan.

Hepatitis B virus (HBV) surface antigen (HBsAg) is one of the most important serological markers of current HBV infection. However, there are significant antigenic variations of HBsAg caused by genotypic diversity as well as mutation of the HBV genome. It is predictable that amino acid substitutions occurring in the HBsAg "a" determinant of a particular HBV genotype will affect the sensitivity of some diagnostic kits, since all the diagnostic kits currently available utilize monoclonal and/or polyclonal antibodies against the "a" determinant. One possible concern is that there may be a significant variation in the sensitivity of HBsAg diagnostic kits to HBsAg encoded by HBV of different genotypes, which might result in a failure to detect HBsAg of a particular HBV genotype. In this study, we assessed the reactivity of HBsAg specimens derived from three different HBV genotypes (A, B, and C) that are prevalent in Japan by 10 commercially available EIA (enzyme immunoassay), CLIA (chemiluminescent immunoassay), and CLEIA (chemiluminescent enzyme immunoassay) diagnostic kits. Specimens included both clinical samples and recombinant HBsAg. Our results showed that all the diagnostic kits evaluated were able to detect HBsAg irrespective of HBV genotypes. At the same time, it is apparent that some, but not all of the kits showed clear differences in sensitivity to the three HBV genotypes.