Geographic Distribution, Clinical Relevance Of Hepatitis B Virus Genotypes In Mainland China

Though HBV prevailed in China by a high infection rate and causes considerable morbidity, the geographical distributions and clinical relevance of HBV genotypes in this area remain unknown. This study aimed to investigate the distribution, clinical and virological characteristics of HBV genotypes in Chinese chronic carriers. Using a polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) method, we studied 1096 Chinese chronic HBV carriers from 9 provinces covered the Mainland China. Four major genotypes A, B, C and D were found in this study and the ratios were 1.2%, 39.3%, 50.2%, 8.1%, respectively. In northern China, genotype C is predominant by a ratio of 81 .6%, while genotype B is more popular in the south (55%). A younger mean age was observed in patients with genotype B, while genotype C was more popular and with higher HBeAg positive rate in patients older than 30 years compared with genotype B. However, there were no significant differences between genotypes B and C in sex, level of ALT and total bilirubin, positive rate of HBeAg, disease distributions, and pathological index. Phylogenetic analysis showed that all HBV strains of genotype B and C prevailed in China had consensus preC/C sequences. This study illustrated the geographical distributions of HBV genotypes in Mainland China, and suggested that there may be lack of clinical differences between HBV genotype B and C, which may relate to the molecular characteristic of HBV strains. So, if stratification for HBV genotypes should be included in the clinical evaluation in this area needs further studies.In addition, to study the divergence of Polymerase gene (P gene) within HBV genotypes and provide some useful references for further studies on HBV genotype, P gene mutations, replication and nucleoside analogues resistance, 202HBV complete sequences obtained from the GeneBank and P genes of them were analyzed using computer soft-wares. There were some genotype-related characteristics of HBV P gene. As rt domain was concerned, there were more amino acid divergences in genotype C and D compared with genotype A. There were also amino acid substitutions in the conserved regions of the rt domain within HBV genotypes. These results suggested that there were divergences of P gene within HBV genotypes, which should be considered when amino acid changes were claimed or proposed to be drug-resistance mutations. Moreover, these divergences might affect the antiviral effect of nucleoside analogues on HBV with different genotypes.