Effects of mutagenic and chain-terminating nucleotide analogs on enzymes isolated from hepatitis C virus strains of various genotypes
Effects of mutagenic and chain-terminating nucleotide analogs on enzymes isolated from hepatitis C virus strains of various genotypes
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DOI：
10.1128/aac.01496-07
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发表时间：
2008-06-01
影响因子：
4.9
通讯作者：
Frick, David N.
中科院分区：
文献类型：
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作者：
Heck, Julie A.;Lam, Angela M. I.;Frick, David N.
开发有效的丙型肝炎病毒（HCV）治疗方法必须考虑到HCV毒株之间的遗传变异。对基于干扰素的治疗（包括目前首选的聚乙二醇化α干扰素联合利巴韦林治疗）的应答率具有基因型特异性。在目前作为抗病毒药物开发的众多HCV抑制剂中，靶向保守的NS 5 B活性位点的核苷类似物似乎对不同的HCV毒株非常有效。为了验证这一假设，我们研究了一组核苷酸类似物，包括三磷酸利巴韦林（RTP）和几个链终止核苷三磷酸，对来自基因型1a，1b和2a株的纯化HCV NS 5 B聚合酶的活性的影响。与先前报道的非核苷抑制剂对NS 5 B活性的基因型特异性影响不同（F。Pauwels，W.莫斯特曼斯湖M.基吕嫩湖货车德尔赫尔姆角W. Boutton，A. S. Rueff，E. Cleiren，P. Raboisson，D.叙勒罗岛Nyanguile和K. A. Simmen，J. Virol. 81：6909-6919，2007），在各种基因型中仅观察到抑制的微小差异;因此，作为当前药物候选物的核苷类似物可能更有希望用于治疗更广泛种类的HCV株。我们还研究了RTP对HCV NS 3解旋酶/ATP酶的影响。与聚合酶一样，在1a-、1b-和2a-衍生的酶之间仅观察到微小的差异。RTP并不抑制NS 3解旋酶催化的DNA解旋速率，而是作为底物来促进解旋。NS 3添加到RNA合成反应中减轻了RTP对聚合酶的抑制，推测是由于RTP水解。这些结果表明，NS 3可以限制利巴韦林掺入病毒RNA，从而降低其抑制或致突变作用。
The development of effective therapies for hepatitis C virus (HCV) must take into account genetic variation among HCV strains. Response rates to interferon-based treatments, including the current preferred treatment of pegylated alpha interferon administered with ribavirin, are genotype specific. Of the numerous HCV inhibitors currently in development as antiviral drugs, nucleoside analogs that target the conserved NS5B active site seem to be quite effective against diverse HCV strains. To test this hypothesis, we examined the effects of a panel of nucleotide analogs, including ribavirin triphosphate (RTP) and several chain-terminating nucleoside triphosphates, on the activities of purified HCV NS5B polymerases derived from genotype 1a, 1b, and 2a strains. Unlike the genotype-specific effects on NS5B activity reported previously for nonnucleoside inhibitors (F. Pauwels, W. Mostmans, L. M. Quirynen, L. van der Helm, C. W. Boutton, A. S. Rueff, E. Cleiren, P. Raboisson, D. Surleraux, O. Nyanguile, and K. A. Simmen, J. Virol. 81:6909-6919, 2007), only minor differences in inhibition were observed among the various genotypes; thus, nucleoside analogs that are current drug candidates may be more promising for treatment of a broader variety of HCV strains. We also examined the effects of RTP on the HCV NS3 helicase/ATPase. As with the polymerase, only minor differences were observed among 1a-, 1b-, and 2a-derived enzymes. RTP did not inhibit the rate of NS3 helicase-catalyzed DNA unwinding but served instead as a substrate to fuel unwinding. NS3 added to RNA synthesis reactions relieved inhibition of the polymerase by RTP, presumably due to RTP hydrolysis. These results suggest that NS3 can limit the incorporation of ribavirin into viral RNA, thus reducing its inhibitory or mutagenic effects.