Center of Infectious Diseases, West China Hospital, Sichuan University, Chengdu 610041, China.
Division of Infectious Diseases, State Key Laboratory of Biotherapy and Cancer Center, West China Hospital, Sichuan University, Chengdu 610041, China.
Sci Rep. 2016 Dec 15;6:39260. doi: 10.1038/srep39260.
The hepatitis B virus(HBV) polymerase rtA181T mutation is selected during long-term antiviral therapy. As the polymerase gene completely overlaps with the envelope (S) gene, HBV rtA181T mutation also carries sW172 mutations. In this study, we investigated whether there were biological differences between rtA181T/sW172* (coding truncated HBsAg) and rtA181T/sW172L (coding substituted HBsAg) mutants. In cell experiments, a slight decline of viral replication was observed in both two mutants as compared to wild-type strains, but the levels of supernatant HBsAg and HBV DNA in rtA181T/sW172* were significantly lower than those in rtA181T/sW172L transfected cells. In animal experiments, we were amazed to find that viral replication in rtA181T/sW172* mutant increased and maintained significantly longer than that in rtA181T/sW172L mutant, while no significant difference was observed between rtA181T/sW172L and wild-type strains. Compared with wild-type strains, there were intracellular accumulations of HBsAg and HBcAg in rtA181/sW172* but none in rtA181/sW172L mutant strains. Importantly, we also found that truncated HBsAg could increase the activity of HBV core promoter, but substituted HBsAg could not. In summary, the characteristics of above two rtA181T mutants mentioned above were significantly different, and it is necessary and important for us to distinguish sW172* truncated mutation from sW172L substituted mutation.
乙型肝炎病毒(HBV)聚合酶 rtA181T 突变是在长期抗病毒治疗中选择的。由于聚合酶基因与包膜(S)基因完全重叠，HBV rtA181T 突变还携带 sW172 突变。在这项研究中，我们研究了 rtA181T/sW172*（编码截短的 HBsAg）和 rtA181T/sW172L（编码取代的 HBsAg）突变体之间是否存在生物学差异。在细胞实验中，与野生型菌株相比，两种突变体的病毒复制都略有下降，但 rtA181T/sW172上清液 HBsAg 和 HBV DNA 的水平明显低于 rtA181T/sW172L 转染细胞。在动物实验中，我们惊讶地发现，rtA181T/sW172突变体的病毒复制增加并维持的时间明显长于 rtA181T/sW172L 突变体，而 rtA181T/sW172L 与野生型菌株之间没有观察到显著差异。与野生型菌株相比，rtA181/sW172* 但 rtA181/sW172L 突变体株内 HBsAg 和 HBcAg 有细胞内积累。重要的是，我们还发现截短的 HBsAg 可以增加 HBV 核心启动子的活性，而取代的 HBsAg 则不能。综上所述，上述两种 rtA181T 突变体的特征明显不同，区分 sW172* 截断突变和 sW172L 取代突变是必要且重要的。
