Distribution and Epidemiologic Trends of HBV Genotypes and Subtypes in 14 Countries Neighboring China

BACKGROUND The number of cases of HBV infection reported by the WHO for each district and country is positively correlated with the number of HBV sequences in the database isolated from the corresponding district and country. OBJECTIVES This study determined distribution characteristics of HBV genotypes and subtypes in 14 countries neighboring China. The progress made in genomic research involving HBV was also reviewed. MATERIALS AND METHODS Nine hundred fifty-one complete genome sequences of HBV from 14 countries neighboring China were selected from NCBI. The sequence-related information was analyzed and recorded. One hundred seventy-two sequences of HBV genotype B were screened for alignment using DNA star and MEGA 5.1. RESULTS Dominant HBV genotypes in the countries neighboring China were genotypes B, C and D and dominant subtypes were adw2 and adrq+. The association between genotype and serotype of HBV in these countries was shown to differ from previous research results. As shown by sequence alignment, the sequence divergence between five subgenotypes (B3, B5, B7, B8 and B9) was below 4%. The B subgenotypes shared six common specific amino acid sites in the S region. CONCLUSIONS The B3, B5, B7, B8 and B9 subgenotypes can be clustered into quasi-sub-genotype B3 and the open reading frame of HBV has a start codon preference; however, whether a mutation in the start codon in the pre-S2 region has an impact on survival and replication of HBV remains to be determined.