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| Adaptive evolution analysis of hepatitis B virus epidemic strains in China |
| (Institute of Life Sciences, Jiangsu University, Zhenjiang Jiangsu 212013, China) |
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Abstract Objective: To detect evolution of hepatitis B virus(HBV), its genotypes B and C circulating in China, and to evaluate the association of positive selection on four HBV gene regions \[S, C, X, and reverse transcriptase (RT)\] with immune escape. Methods: All available fulllength genomic sequences (884 sequences) of HBV genotypes B and C in China were downloaded from GenBank. Four gene segments of S, C, X, and RT were obtained from the genomic sequences according to HBV reference sequence. Positively selected sites occurring in HBV genome were detected by HyPhy method. Results: A total of 101 and 125 positively selected sites were identified in genotype B and C respectively. Interestingly, in genotype B,37 positively selected sites were located in 32 Tcell epitopes, and in genotype C, 48 positively selected sites were located in 43 Tcell epitopes, suggesting an association of positive selection with viral immune escape. In addition, three known drug resistance sites 180, 181, and 223 in HBV genotype B RT gene, and four known drug resistance sites 173, 180, 181, and 223 in genotype C RT gene were also identified under positive selection, suggesting an association of positive selection with drug resistance. Conclusion: Drug resistance mutation and immune escape of HBV might be one major factor driving the adaptive evolution of HBV.
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2012, Vol. 22 
