Evolutionary perspective on hepatitis B virus with an expanded sampling strategy

- Our research provided greater information on mutation profiles.
- Viruses experiencing a stronger immune response had lower haplotype diversity.
- HBeAg seroconversion could serve as an indicator of HBV evolution.
- Our work provided a sampling strategy for researchers in future studies.

To investigate the role hepatitis B e antigen (HBeAg) plays in the evolution of hepatitis B virus (HBV), we sequenced the basic core promoter (BCP) and precore (preC) regions of 348 clones total from ten HBV Chinese patients. Eleven mutations were more frequent in HBeAg-negative patients than in HBeAg-positive patients. Further, the sequencing of dozens of variants was found to be necessary to obtain mutation profiles. Phylogenetic and median-joining network analyses suggested that variants from each patient had a single common ancestor (monophyly). Higher haplotype and nucleotide diversities were identified in HBeAg-negative patients. Analysis of dN/dS suggested that viruses experiencing a stronger immune response had lower haplotype diversity. Because HBeAg seroconversion was associated with viral diversity it served as an indicator of HBV evolution. Significantly, this study indicated a larger sampling of variants from each patient was required to understand effectively the properties of HBV.