Lanford R E, Chavez D, Guerra B, Lau J Y, Hong Z, Brasky K M, Beames B
Department of Virology and Immunology, Southwest Regional Primate Research Center, Southwest Foundation for Biomedical Research, San Antonio, Texas 78227, USA.
J Virol. 2001 Sep;75(17):8074-81. doi: 10.1128/jvi.75.17.8074-8081.2001.
GB virus B (GBV-B) is the closest relative of hepatitis C virus (HCV) and is an attractive surrogate model for HCV antiviral studies. GBV-B induces an acute, resolving hepatitis in tamarins. Utilizing primary cultures of tamarin hepatocytes, we have previously developed a tissue culture system that exhibits high levels of GBV-B replication. In this report, we have extended the utility of this system for testing antiviral compounds. Treatment with human interferon provided only a marginal antiviral effect, while poly(I-C) yielded >3 and 4 log units of reduction of cell-associated and secreted viral RNA, respectively. Interestingly, treatment of GBV-B-infected hepatocytes with ribavirin resulted in an approximately 4-log decrease in viral RNA levels. Guanosine blocked the antiviral effect of ribavirin, suggesting that inhibition of IMP dehydrogenase (IMPDH) and reduction of intracellular GTP levels were essential for the antiviral effect. However, mycophenolic acid, another IMPDH inhibitor, had no antiviral effect. Virions harvested from ribavirin-treated cultures exhibited a dramatically reduced specific infectivity. These data suggest that incorporation of ribavirin triphosphate induces error-prone replication with concomitant reduction in infectivity and that reduction of GTP pools may be required for incorporation of ribavirin triphosphate. In contrast to the in vitro studies, no significant reduction in viremia was observed in vivo following treatment of tamarins with ribavirin during acute infection with GBV-B. These findings are consistent with the observation that ribavirin monotherapy for HCV infection decreases liver disease without a significant reduction in viremia. Our data suggest that nucleoside analogues that induce error-prone replication could be an attractive approach for the treatment of HCV infection if administered at sufficient levels to result in efficient incorporation by the viral polymerase.
GB病毒B（GBV-B）是丙型肝炎病毒（HCV）的近亲，是HCV抗病毒研究中一个有吸引力的替代模型。GBV-B可在绢毛猴中引发急性自限性肝炎。利用绢毛猴肝细胞的原代培养物，我们之前开发了一种能展现高水平GBV-B复制的组织培养系统。在本报告中，我们扩展了该系统在测试抗病毒化合物方面的用途。用人干扰素治疗仅产生了微弱的抗病毒效果，而聚肌胞苷酸分别使细胞相关病毒RNA和分泌型病毒RNA降低了>3和4个对数单位。有趣的是，用利巴韦林处理感染GBV-B的肝细胞会导致病毒RNA水平下降约4个对数。鸟苷可阻断利巴韦林的抗病毒作用，这表明抑制肌苷-5'-单磷酸脱氢酶（IMPDH）和降低细胞内鸟苷三磷酸（GTP）水平对于抗病毒作用至关重要。然而，另一种IMPDH抑制剂霉酚酸却没有抗病毒作用。从利巴韦林处理的培养物中收获的病毒粒子显示出特异性感染力显著降低。这些数据表明，三磷酸利巴韦林的掺入诱导了易出错的复制，同时感染力降低，并且掺入三磷酸利巴韦林可能需要降低GTP库。与体外研究相反，在GBV-B急性感染期间用利巴韦林治疗绢毛猴后，体内未观察到病毒血症有显著降低。这些发现与以下观察结果一致，即利巴韦林单药治疗HCV感染可减轻肝脏疾病，但不会显著降低病毒血症。我们的数据表明，如果以足够的剂量给药以使病毒聚合酶有效掺入，那么诱导易出错复制的核苷类似物可能是治疗HCV感染的一种有吸引力的方法。
