Department of Internal Medicine, Konkuk University School of Medicine, Seoul, South Korea.
J Virol. 2010 May;84(9):4494-503. doi: 10.1128/JVI.02066-09. Epub 2010 Feb 17.
Clevudine (CLV) is a nucleoside analog with potent antiviral activity against chronic hepatitis B virus (HBV) infection. Viral resistance to CLV in patients receiving CLV therapy has not been reported. The aim of this study was to characterize CLV-resistant HBV in patients with viral breakthrough (BT) during long-term CLV therapy. The gene encoding HBV reverse transcriptase (RT) was analyzed from chronic hepatitis B patients with viral BT during CLV therapy. Sera collected from the patients at baseline and at the time of viral BT were studied. To characterize the mutations of HBV isolated from the patients, we subjected the HBV mutants to in vitro drug susceptibility assays. Several conserved mutations were identified in the RT domain during viral BT, with M204I being the most common. In vitro phenotypic analysis showed that the mutation M204I was predominantly associated with CLV resistance, whereas L229V was a compensatory mutation for the impaired replication of the M204I mutant. A quadruple mutant (L129M, V173L, M204I, and H337N) was identified that conferred greater replicative ability and strong resistance to both CLV and lamivudine. All of the CLV-resistant clones were lamivudine resistant. They were susceptible to adefovir, entecavir, and tenofovir, except for one mutant clone. In conclusion, the mutation M204I in HBV RT plays a major role in CLV resistance and leads to viral BT during long-term CLV treatment. Several conserved mutations may have a compensatory role in replication. Drug susceptibility assays reveal that adefovir and tenofovir are the most effective compounds against CLV-resistant mutants. These data may provide additional therapeutic options for CLV-resistant patients.
克来夫定（CLV）是一种具有强大抗慢性乙型肝炎病毒（HBV）感染活性的核苷类似物。在接受 CLV 治疗的患者中，尚未报道 CLV 耐药性。本研究旨在描述在接受 CLV 长期治疗过程中发生病毒突破（BT）的患者中 CLV 耐药性 HBV 的特征。从接受 CLV 治疗期间发生病毒 BT 的慢性乙型肝炎患者中分析了 HBV 逆转录酶（RT）的基因。研究了患者基线和病毒 BT 时采集的血清。为了描述从患者中分离的 HBV 突变体的特征，我们对 HBV 突变体进行了体外药物敏感性测定。在 RT 结构域中发现了几种保守突变，其中 M204I 最常见。体外表型分析表明，突变 M204I 主要与 CLV 耐药相关，而 L229V 是 M204I 突变体复制受损的代偿性突变。鉴定出一个四重突变体（L129M、V173L、M204I 和 H337N），其具有更强的复制能力，对 CLV 和拉米夫定均具有很强的耐药性。所有 CLV 耐药克隆均对拉米夫定耐药。它们对阿德福韦酯、恩替卡韦和替诺福韦敏感，除了一个突变体克隆。总之，HBV RT 中的突变 M204I 在 CLV 耐药中起主要作用，并导致长期 CLV 治疗过程中的病毒 BT。几种保守突变可能在复制中具有代偿作用。药物敏感性测定显示，阿德福韦酯和替诺福韦是针对 CLV 耐药突变体最有效的化合物。这些数据可能为 CLV 耐药患者提供额外的治疗选择。
