Department of Pharmacology and Center for Cancer Research and Diagnostic Medicine, IBST, School of Medicine, Konkuk University, Seoul, South Korea.
Department of Pharmacology and Center for Cancer Research and Diagnostic Medicine, IBST, School of Medicine, Konkuk University, Seoul, South Korea Institute of Functional Genomics, Konkuk University, Seoul, South Korea.
J Virol. 2014 Jun;88(12):6805-18. doi: 10.1128/JVI.00635-14. Epub 2014 Apr 2.
The emergence of drug-resistant hepatitis B virus (HBV) is a major problem for antiviral treatment in chronic hepatitis B infection. In this study, we analyzed the evolution of drug-resistant mutations and characterized the effects of the rtA181T and rtI233V mutations on viral replication and drug resistance. We performed a clonal analysis of the HBV polymerase gene from serum samples during viral breakthrough treated with antiviral agents. A series of mutant clones containing rtA181T and/or rtI233V mutations were constructed and determined the effect of these mutations on the replication ability and drug resistance. An in vitro study revealed that the effect of the rtA181T mutation on viral replication and drug resistance is dependent on the mutations in the overlapping surface gene. Compared to the rtA181T surface missense mutation (rtA181T/sW172S), the introduction of rtA181T surface nonsense mutation (rtA181T/sW172*) resulted in decreased viral replication and increased drug resistance. Complementation assay revealed that the truncated PreS1 is responsible for reduced replication of rtA181T/sW172* mutant. Moreover, the rtA181T/sW172* mutant exhibited a defect in viral particle secretion. The rtI233V mutation that emerged during adefovir therapy reduced viral replication and conferred resistance to adefovir. Our data suggest that the impact of the rtA181T mutation on replication and drug resistance differs based on the mutation status of the corresponding surface gene. The rtI233V mutation also affects replication ability and drug resistance. This observation suggests the need for genotypic analysis of overlapping surface genes to manage antiviral drug resistance if clinical isolates harbor the rtA181T mutation.
The emergence of drug-resistant HBV that are no longer susceptible to nucleos(t)ide analogues is a major problem for antiviral treatment in chronic hepatitis B infection. Among drug-resistant mutations, the single rtA181T mutation is known to confer cross-resistance to antiviral drugs. This mutation causes intermediate or reduced susceptibility to tenofovir. Moreover, the clinical occurrence of the rtA181T mutation during antiviral therapy is also high. Our study revealed that the effect of the rtA181T mutation on viral replication and drug resistance is dependent on the mutations in the overlapping surface gene. This observation suggests the need for genotypic analysis of overlapping surface genes to manage antiviral drug resistance if clinical isolates harbor the rtA181T mutation. We believe that our study will not only extend the understanding of the drug resistance mechanism, but it will also ultimately provide new treatment options for patients with multidrug resistant HBV.
耐药乙型肝炎病毒（HBV）的出现是慢性乙型肝炎感染抗病毒治疗的主要问题。在本研究中，我们分析了耐药突变的演变，并对 rtA181T 和 rtI233V 突变对病毒复制和耐药性的影响进行了特征描述。我们对抗病毒药物治疗期间病毒突破时的血清样本中的 HBV 聚合酶基因进行了克隆分析。构建了一系列含有 rtA181T 和/或 rtI233V 突变的突变体克隆，并确定了这些突变对复制能力和耐药性的影响。体外研究表明，rtA181T 突变对病毒复制和耐药性的影响取决于重叠表面基因中的突变。与 rtA181T 表面错义突变（rtA181T/sW172S）相比，rtA181T 表面无义突变（rtA181T/sW172*）导致病毒复制减少和耐药性增加。互补实验表明，缩短的 PreS1 负责减少 rtA181T/sW172突变体的复制。此外，rtA181T/sW172突变体表现出病毒粒子分泌缺陷。阿德福韦治疗期间出现的 rtI233V 突变降低了病毒复制并赋予阿德福韦耐药性。我们的数据表明，rtA181T 突变对复制和耐药性的影响因相应表面基因的突变状态而异。rtI233V 突变也会影响复制能力和耐药性。如果临床分离株携带 rtA181T 突变，则需要对重叠表面基因进行基因型分析以管理抗病毒药物耐药性，这一观察结果表明了这一点。
耐药乙型肝炎病毒（HBV）对核苷（酸）类似物不再敏感的出现是慢性乙型肝炎感染抗病毒治疗的主要问题。在耐药突变中，单一的 rtA181T 突变被认为对抗病毒药物具有交叉耐药性。该突变导致替诺福韦的中间或降低敏感性。此外，rtA181T 突变在抗病毒治疗期间的临床发生频率也很高。我们的研究表明，rtA181T 突变对病毒复制和耐药性的影响取决于重叠表面基因中的突变。这一观察结果表明，如果临床分离株携带 rtA181T 突变，则需要对重叠表面基因进行基因型分析以管理抗病毒药物耐药性。我们相信，我们的研究不仅将扩展对耐药机制的理解，而且最终将为多药耐药 HBV 患者提供新的治疗选择。
