Isolation of Genetic Suppressor Elements Against Hepatitis C Virus

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DESCRIPTION (provided by applicant): Hepatitis C virus (HCV) infection is a major public health problem, putting infected individuals (~180 million worldwide) at risk of developing cirrhosis, hepatocellular carcinoma, and liver failure. Chronic hepatitis C is the leading cause for liver transplantation. Current standard interferon-based therapy, a costly and time-consuming process, has only a ~50% cure rate, and no anti-HCV drugs have yet been approved for hepatitis C therapy. Despite the promise shown by HCV-specific proteases and polymerases as drug targets, the rapid emergence of viral resistance indicates that additional targets and combinations of antivirals will be necessary for effective treatment. We propose to isolate genetic suppressor elements (GSEs) from a library comprising a fragmented HCV genome which could be used both as potent anti-HCV therapeutic agents and as probes to identify and validate new targets for further drug screening. GSEs are nucleic acid or protein/peptide molecules derived from a gene or genome that act as transdominant inhibitors of a particular biological function through a variety of mechanisms, which includes binding to and blocking essential interaction surfaces for protein activity. In order to identify GSEs from within the HCV genome that exert inhibitory activity against HCV, a novel function-based selection system will be developed and implemented. Briefly, a fragmented HCV genome will be delivered to a hepatoma derivative cell line that is sensitive to a cytopathic effect exerted by HCV. The cells containing the HCV-derived genetic fragments will be subjected to a cytopathic challenge by exogenously administered cell culture-derived HCV (HCVcc) infectious particles, and cells surviving this HCV challenge will be enriched in GSEs that exert an inhibitory effect against HCV. Iterative application of this selection procedure will result in the identification of highly potent GSEs that protect cells against HCV infection and cytotoxicity. Preliminary studies will evaluate the degree of the protective effect conferred by the identified GSEs against HCV-mediated cytotoxicity, and the stage in the HCV life cycle at which the anti-HCV effect of the GSEs is exerted. Future studies originating from the identified GSEs are expected to reveal the molecular basis of the anti-HCV GSE activity, thus providing new leads for anti-HCV drug development. It is expected that the GSEs identified from the proposed research, and molecular mimetics derived therefrom, will inhibit HCV infection/propagation through diverse mechanisms, including the inhibition of virus-host cell interactions, thus contributing to the urgent quest for new and effective HCV antivirals on multiple fronts. PUBLIC HEALTH RELEVANCE: Infection by hepatitis C virus is a serious global health problem that causes numerous debilitating liver conditions. The current treatment regime for hepatitis C is time-consuming, expensive, and often ineffective, creating an urgent need for new and effective drugs. Novel anti-hepatitis C genetic suppressor elements isolated from this research will serve both as hepatitis C drugs, and as keys to open doors to new avenues of research in hepatitis C antiviral development.