Evaluation of a new automated assay for hepatitis B surface antigen (HBsAg) detection VIDAS HBsAg Ultra

In a multicenter study a new automated screening assay, VIDAS HBsAg Ultra (long (L) and short (S) incubation protocol (Biomérieux, Marcy l'Etoile, France), was compared to a well established test (AxSYM HBsAg v2, Abbott Diagnostics, Wiesbaden, Germany) for the detection of hepatitis B virus (HBV) surface antigen (HBsAg). A total of 32 seroconversion panels, sera from the chronic phase of infection, dilution series of the WHO standard, S gene mutants (recombinant mutants and diluted and undiluted sera harbouring mutants with single or multiple amino acid (aa) substitutions, n = 40) and isolated anti-HBc positive samples were tested for the evaluation of sensitivity. Sera from HBsAg negative blood donors, pregnant women, hospitalized patients and potentially cross-reactive samples were investigated to determine the specificity of the new assay. The VIDAS HBsAg Ultra (L+S) had a higher sensitivity than the alternative assay for the detection of acute hepatitis B in seroconversion panels. The mean time of the diagnostic window was shortened with the VIDAS HBsAg Ultra (L) and (S) in comparison with the AxSYM HBsAg v2 by 1.06 and 0.66 days, respectively. The VIDAS HBsAg Ultra (L) did not detect one diluted sample out of six bearing the single aa G145R substitution, and two out of 12 diluted samples harbouring multiple aa substitutions. The analytical sensitivity of the assays varied from one surface mutant to another. While no false positive results were obtained with the VIDAS HBsAg Ultra (L+S) among potentially interfering samples, four false positives were detected with the AxSYM HBsAg v2. The respective values for sensitivity for the VIDAS HBsAg Ultra (L), (S) and the AxSYM HBsAg v2 were 99.07%, 97.87% and 94.14%. The specificities were 100% (VIDAS HBsAg Ultra L and S) and 99.6% (AxSYM HBsAg v2). In conclusion, the VIDAS HBsAg Ultra is highly sensitive and specific and represents an improvement for the detection of HBsAg in routine diagnostic laboratories.