Molecular Mechanism Of Human Immunodeficiency Virus-I Rev Protein Activates Hepatitis C Virus Translation

Hepatitis C virus (HCV) infects approximately180million people while human immunodeficiency virus-1(HIV-1) infects approximately40million worldwide. Due to share the routes of transmission, infection with HCV is common among HIV-1-infected patients, and approximately4to5million patients are co-infected with HIV-1and HCV. HCV has been recognized as a major source of morbidity and mortality in HIV-1-infected patients. It has been suggested that HIV-1infection may enhance HCV replication because HCV RNA levels are significantly elevated in co-infected patients and HIV-1seroconversion was associated with sustained increases in HCV viral load. Patients with co-infection of HIV-1and HCV suffer from enhanced liver disease with accelerated fibrosis progression compared to those infected with HCV only. However, the precise molecular mechanism by which HIV-1interacts with HCV to increase HCV persistence and accelerate liver fibrosis is not well known.In this study, we investigated the role of HIV-1in the regulation of HCV gene expression. We co-transfected Huh7.5.1cells with a full-length HCV genome RNA and the mRNA of each of HIV-1genes, respectively. We showed for the first time that the Rev protein of HIV-1involved in the activation of HCV gene expression. In order to confirm the effect of Rev on HCV gene expression, two well-characterized dominant negative Rev mutants, were constructed. Results showed that the wild-tpye Rev gene activates the expression of HCV genes, but the two mutants of Rev failed to stimulate the expression of HCV genes. To gain more insight in the mechanism involved in the activation of HCV gene expression by HIV-1Rev protein, we investigate whether the Rev protein interacts with HCV RNA. We performed immunoprecipitation experiments and the results demonstrate that Rev can bind to HCVRNAs.Employing EMS A, we conclude that Rev binds directly to HCV5’-UTR RNA and the arginine-rich41-44amino acid region of Rev contributes to the binding activity of Rev. We generated a series mutants of HCV5’-UTR and analyzed the interactions of the mutants with Rev. Our results indicated that Rev binds to the Ⅲb internal loop of HCV5’-UTR.We also evaluated the function of Rev in the translation mediated by HCV IRES. Employing monocistronic reporter RNAs of HCV, we found that Rev specifically stimulates the translation mediated by HCV IRES. We have demonstrated that Rev directly bound to the Illb internal loop of HCV5’-UTR. We next investigate the role of this binding site in the activation of HCV IRES-mediated translation regulated by HIV-1Rev protein. We found that Rev stimulated the translation of HCV RNAs. And this stimulatory activity appears to be dependent on an intact internal loop Ⅲb of HCV5’-UTR. Thus, we conclude that Rev, by binding to the HCV5’-UTR, enhances HCV IRES-mediated translation.These results provide insights into our understanding the role of HIV-1in the HCV replication and the mechanism involved in the regulation of HCV gene expression mediated by HIV-1during co-infection of the two viruses.