Chen J, Liu B, Tang X, et al. - This study was sought to evaluate the role of core protein mutations in the development of occult hepatitis B virus infection. Researchers selected an occult hepatitis B virus infection (OBI) strain (SZA) carrying 9 amino acid (aa) substitutions in the core protein/capsid (Cp) by sequence alignment and Western blot analysis from 26 genotype B OBI samples to extensively evaluate the effect of Cp mutations on viral antigen production in vitro and in vivo. The findings demonstrated that during viral replication, W62R and its combination mutations in hepatitis B virus Cp might have a huge impact on HBcAg and HBeAg production, which, in turn, might contribute to the occurrence of OBI.