Novel HBsAg markers tightly correlate with occult HBV infection and strongly affect HBsAg detection

► HBsAg genetic markers correlated with occult HBV D genotype infection in vivo were studied. ► Twenty HBsAg-mutations significantly correlated for the first time with OBI were found. ► They localized in the major HBV B-cell-epitope, and in HBsAg-capsid interaction region. ► They strongly affect, up to abrogate, HBsAg detection. ► Thus, they can affect full-reliability of diagnostic-assays for HBsAg-detection.