Roles for hepatitis C virus-derived circular RNAs in infected cells

虽然针对丙型肝炎病毒的新型直接作用抗病毒药物(DAA)对许多患者有效，如抗聚合酶和抗蛋白酶化合物，但这些治疗方法仍然非常昂贵，全球1.7亿丙型肝炎病毒感染者中的大多数人都无法获得这些治疗方法。此外，目前还不知道是否每个患者群体都会对目前的DAA治疗产生反应。因此，继续寻找针对丙型肝炎病毒和病毒宿主易感因子的新化合物以对抗病毒感染具有重要意义。我们实验室最近的一项惊人发现显示，丙型肝炎病毒基因组RNA在病毒感染过程中被处理，产生数百种不同的病毒来源的环状RNA(CircRNAs)。这些CircRNA是从10,000个核苷酸的病毒RNA基因组的所有部分产生的，包括包含病毒内部核糖体进入位点(IRES)的CircRNAs。据推测，这些CircRNA代表了一类新的病毒RNA物种，可能在感染和未感染的旁观者细胞中显示新的功能。由于这些病毒CircRNA被预测为长期存在，它们也可能作为生物标记物发挥重要作用。因此，探索丙型肝炎病毒来源的环状RNA的亲病毒和抗病毒作用是一个重要的研究场所，并将指出RNA病毒的新阿喀琉斯跟腱。这项应用的长期目标是探索已识别的病毒CircRNAs在亲病毒和抗病毒反应中的作用。为实现这些目标，提出了两个具体目标。首先，正在研究病毒CircRNA的产生机制。假设是，丙型肝炎病毒颠覆了一种细胞剪接机制，该机制调节内质网中未折叠的蛋白质反应。其次，将检测高度丰富的CircRNAs和含有IRES的CircRNAs是否对感染细胞中的丙型肝炎病毒基因表达具有功能作用。IRES-CircRNA翻译产物在病毒感染周期中的功能将在培养的肝细胞和可能感染自体丙型肝炎的人肝器官中进行检测。这项应用的预期结果将解决有关新型环状丙型肝炎病毒衍生RNA在病毒感染周期中功能的基本方面。这项拟议的研究具有创新性，因为它将检查新的病毒来源的CircRNAs是否可以在RNA病毒感染的细胞中作为抗病毒方法的靶点。

While novel direct-acting antivirals (DAA) against hepatitis C virus (HCV), such as anti-polymerase and anti- proteinase compounds are effective in many patients, these treatments are still very expensive and not available to most of the 170 million people world-wide infected with HCV. In addition, it is not known whether every patient population will respond to the current DAA treatments. Thus, it is significant to continue to search for new compounds that target both HCV and viral host susceptibility factors to combat virus infection. An astonishing recent discovery made by our laboratory revealed that the HCV genomic RNA is processed during viral infection to yield hundreds of different virus-derived circular RNAs (circRNAs). These circRNAs are generated from all parts of the 10,000-nucleotide viral RNA genome, including circRNAs that contain the viral internal ribosome entry site (IRES). It is hypothesized that these circRNAs present a novel class of viral RNA species that likely display novel functions in infected and uninfected bystander cells. Because these viral circRNAs are predicted to be long-lived they could also have important roles as biomarkers. Thus, exploring the pro- and anti-viral effects of the HCV-derived circular RNAs is a significant venue of research and will point to new Achilles’ heels in RNA viruses. The long-term goals of this application are to explore the roles for the identified viral circRNAs in pro- and anti-viral responses. Two specific aims are proposed to accomplish these goals. First, the mechanism by which the viral circRNAs are generated is being investigated. The hypothesis is that HCV subverts a cellular splicing mechanism that modulates the unfolded protein response in the endoplasmic reticulum. Secondly, it will be examined whether highly abundant circRNAs and IRES-containing circRNAs have functional roles on HCV gene expression in infected cells. The functions of IRES-circRNA translation products in the viral infectious cycle will be examined both in cultured liver cells and human liver organoids that can be infected with autologous HCV. The expected outcomes of this application will address fundamental aspects about the functions of novel circular HCV-derived RNAs in the viral infectious cycle. This proposed research is innovative because it will examine whether novel virus-derived circRNAs can be targeted in antiviral approaches in RNA virus-infected cells.