Performance of hepatitis B surface antigen tests with the first WHO international hepatitis B virus genotype reference panel

Background: Standardization of hepatitis B surface antigen (HBsAg) tests is indispensable for consistent quality and comparability. Ideally, the assays should detect all known hepatitis B virus (HBV) genotypes equally well. Objective: Development of an HBV genotype reference panel for HBsAg assays representing the most prevalent HBV subgenotypes to address commutability and traceability of the heat-inactivated 2nd WHO International Standard (IS) for HBsAg in relation to native HBsAg and to HBV genotypes. Study design: An HBV panel of 15 non-inactivated lyophilized specimens representing the subgenotypes A1, A2, B1, B2, C2, D1-D3, E, F2, and H was evaluated in parallel to the IS by 15 laboratories using 19 different HBsAg tests and tree unitages. The virus content of the samples was reduced by ultracentrifugation and dilution to <2 x 10(4) IU HBV DNA/mL. Results: Twenty-two qualitative and 6 quantitative data sets were evaluated. Overall, the results demonstrated consistent detection of HBV genotypes by the majority of tests with a mean potency variability relative to the IS of 36%. Some assays showed significant genotype-dependent differences in analytical sensitivity. Some tests were more sensitive with the IS, others less. On average, one IU HBsAg corresponded to 0.88 +/- 0.20 ng HBsAg protein. Conclusions: The panel was accepted by the WHO as the 1st International Reference Panel for HBV genotypes for HBsAg-based assays. The panel is a helpful complementation to the IS to validate HBV genotype specific analytical test sensitivities. (C) 2013 Elsevier B. V. All rights reserved.