Variability of the S gene of hepatitis B virus in southeastern China

In a study of 315 HBV specimens obtained from southern China, 240 (76.9%) were assigned to genotype B, 72 (22.9%) were genotype C, two (0.6%) were genotype A and one (0.3%) was genotype D. Statistical analysis revealed that variables such as age, gender, HBV vaccination rate, hepatitis anamnesis rate, anti-HBs and HBeAg prevalence and virus load were insignificant between genotype B (n = 240) and genotype C cases (n = 72) (P > 0.05). However, the frequency of amino acid (aa) substitutions in the major hydrophilic region (MHR; aa 99–169) and the putative HLA class I-restricted cytotoxic T lymphocyte (CTL) epitope region of the S gene, as well as the overlapping polymerase/RT region (aa 32–212), were significantly higher in genotype C group than genotype B (P < 0.001). These results suggest that the higher variability within genotype C carriers may account for the pathogenic potential.