Department of Pathology and Laboratory Medicine, Tulane University School of Medicine, New Orleans, Louisiana, USA.
Department of Pathology and Laboratory Medicine, Tulane University School of Medicine, New Orleans, Louisiana, USA Department of Medicine, Gastroenterology and Hepatology, Tulane University School of Medicine, New Orleans, Louisiana, USA.
J Virol. 2015 Jan;89(1):626-42. doi: 10.1128/JVI.02492-14. Epub 2014 Oct 22.
Ribavirin (RBV) continues to be an important component of interferon-free hepatitis C treatment regimens, as RBV alone does not inhibit hepatitis C virus (HCV) replication effectively; the reason for this ineffectiveness has not been established. In this study, we investigated the RBV resistance mechanism using a persistently HCV-infected cell culture system. The antiviral activity of RBV against HCV was progressively impaired in the persistently infected culture, whereas interferon lambda 1 (IFN-λ1), a type III IFN, showed a strong antiviral response and induced viral clearance. We found that HCV replication in persistently infected cultures induces an autophagy response that impairs RBV uptake by preventing the expression of equilibrative nucleoside transporter 1 (ENT1). The Huh-7.5 cell line treated with an autophagy inducer, Torin 1, downregulated membrane expression of ENT1 and terminated RBV uptake. In contrast, the autophagy inhibitors hydroxychloroquine (HCQ), 3-methyladenine (3-MA), and bafilomycin A1 (BafA1) prevented ENT1 degradation and enhanced RBV antiviral activity. The HCV-induced autophagy response, as well as treatment with Torin 1, degrades clathrin heavy chain expression in a hepatoma cell line. Reduced expression of the clathrin heavy chain by HCV prevents ENT1 recycling to the plasma membrane and forces ENT1 to the lysosome for degradation. This study provides a potential mechanism for the impairment of RBV antiviral activity in persistently HCV-infected cell cultures and suggests that inhibition of the HCV-induced autophagy response could be used as a strategy for improving RBV antiviral activity against HCV infection.
The results from this work will allow a review of the competing theories of antiviral therapy development in the field of HCV virology. Ribavirin (RBV) remains an important component of interferon-free hepatitis C treatment regimens. The reason why RBV alone does not inhibit HCV replication effectively has not been established. This study provides a potential mechanism for why RBV antiviral activity is impaired in persistently HCV-infected cell cultures and suggests that inhibition of the HCV-induced autophagy response could be used as a strategy to increase RBV antiviral activity against HCV infection. Therefore, it is anticipated that this work would generate a great deal of interest, not only among virologists but also among the general public.
利巴韦林（RBV）仍然是无干扰素治疗丙型肝炎方案的重要组成部分，因为 RBV 单独使用并不能有效抑制丙型肝炎病毒（HCV）复制；其无效的原因尚未确定。在这项研究中，我们使用持续感染 HCV 的细胞培养系统研究了 RBV 耐药机制。在持续感染的培养物中，利巴韦林对 HCV 的抗病毒活性逐渐受损，而干扰素 λ1（IFN-λ1），一种 III 型干扰素，表现出强烈的抗病毒反应并诱导病毒清除。我们发现，持续感染培养物中的 HCV 复制会诱导自噬反应，通过阻止平衡核苷转运体 1（ENT1）的表达来阻止 RBV 的摄取。用自噬诱导剂 Torin 1 处理的 Huh-7.5 细胞系下调了 ENT1 的膜表达并终止了 RBV 的摄取。相比之下，自噬抑制剂羟氯喹（HCQ）、3-甲基腺嘌呤（3-MA）和巴弗洛霉素 A1（BafA1）可防止 ENT1 降解并增强 RBV 的抗病毒活性。HCV 诱导的自噬反应以及 Torin 1 的治疗会降解肝癌细胞系中的网格蛋白重链表达。HCV 降低网格蛋白重链的表达可防止 ENT1 向质膜的再循环，并迫使 ENT1 进入溶酶体进行降解。本研究为持续 HCV 感染细胞培养物中 RBV 抗病毒活性受损的潜在机制提供了依据，并表明抑制 HCV 诱导的自噬反应可能是提高 RBV 抗 HCV 感染抗病毒活性的一种策略。
这项工作的结果将允许对 HCV 病毒学领域抗病毒治疗发展的竞争理论进行审查。利巴韦林（RBV）仍然是无干扰素治疗丙型肝炎方案的重要组成部分。单独使用 RBV 不能有效抑制 HCV 复制的原因尚未确定。本研究提供了一个潜在的机制，解释了为什么 RBV 抗病毒活性在持续感染 HCV 的细胞培养物中受损，并表明抑制 HCV 诱导的自噬反应可以作为提高 RBV 抗 HCV 感染抗病毒活性的一种策略。因此，预计这项工作不仅会引起病毒学家的极大兴趣，也会引起公众的极大兴趣。
