Dash Srikanta, Prabhu Ramesh, Hazari Sidhartha, Bastian Frank, Garry Robert, Zou Weiping, Haque Salima, Joshi Virendra, Regenstein Fredric G, Thung Swan N
Department of Pathology and Laboratory Medicine, Tulane University Health Sciences Center, 1430 Tulane Avenue, New Orleans, LA 70112, USA.
Liver Int. 2005 Jun;25(3):580-94. doi: 10.1111/j.1478-3231.2005.01082.x.
Interferon (IFN)-alpha is the standard therapy for the treatment of chronic hepatitis C, but the mechanisms underlying its antiviral action are not well understood. In this report, we demonstrated that IFN-alpha, -beta and -gamma inhibit replication of the hepatitis C virus (HCV) in a cell culture model at concentrations between 10 and 100 IU/ml. We demonstrated that the antiviral actions each of each these IFNs are targeted to the highly conserved 5' untranslated region of the HCV genome, and that they directly inhibit translation from a chimeric clone between full-length HCV genome and green fluorescent protein (GFP). This effect is not limited to HCV internal ribosome entry site (IRES), since these IFNs also inhibit translation of the encephalomyocardititis virus (EMCV) chimeric mRNA in which GFP is expressed by IRES-dependent mechanisms (pCITE-GFP). These IFNs had minimal effects on the expression of mRNAs from clones in which translation is not IRES dependent. We conclude that IFN-alpha, -beta and -gamma inhibit replication of sub-genomic HCV RNA in a cell culture model by directly inhibiting two internal translation initiation sites of HCV- and EMCV-IRES sequences present in the dicistronic HCV sub-genomic RNA. Results of this in vitro study suggest that selective inhibition of IRES-mediated translation of viral polyprotein is a general mechanism by which IFNs inhibits HCV replication.
干扰素（IFN）-α是治疗慢性丙型肝炎的标准疗法，但其抗病毒作用的潜在机制尚未完全明确。在本报告中，我们证明了IFN-α、-β和-γ在细胞培养模型中，当浓度介于10至100国际单位/毫升时，可抑制丙型肝炎病毒（HCV）的复制。我们证明了这些干扰素的抗病毒作用均靶向HCV基因组高度保守的5'非翻译区，并且它们直接抑制全长HCV基因组与绿色荧光蛋白（GFP）之间的嵌合克隆的翻译。这种效应并不局限于HCV内部核糖体进入位点（IRES），因为这些干扰素也抑制脑心肌炎病毒（EMCV）嵌合mRNA的翻译，其中GFP通过IRES依赖性机制表达（pCITE-GFP）。这些干扰素对来自非IRES依赖性翻译克隆的mRNA表达影响极小。我们得出结论，IFN-α、-β和-γ通过直接抑制存在于双顺反子HCV亚基因组RNA中的HCV-和EMCV-IRES序列的两个内部翻译起始位点，在细胞培养模型中抑制亚基因组HCV RNA的复制。这项体外研究结果表明，选择性抑制IRES介导的病毒多聚蛋白翻译是干扰素抑制HCV复制的普遍机制。
