Utilization of RNA polymerase I promoter and terminator sequences to develop a DNA transfection system for the study of hepatitis C virus internal ribosomal entry site-dependent translation

Background: Hepatitis C virus (HCV) causes severe liver diseases in a large population worldwide. HCV protein translation is controlled by an internal ribosomal entry site (IRES) within the 5′-untranslated region (UTR). HCV IRES-dependent translation is critical for HCV-associated pathogenesis. Objective: To develop a plasmid DNA transfection system by using RNA polymerase I promoter and terminator sequences for studying HCV IRES-dependent translation. Study design: A gene cassette containing HCV 5′-UTR, Renilla luciferase reporter gene, and HCV 3′-UTR was inserted between RNA polymerase I promoter and terminator sequences. HCV IRES-directed translation was determined by luciferase assay after transfection. Results: Transfection of the RNA polymerase I-HCV IRES plasmid into human hepatoma Huh-7 and HepG2 cells resulted in luciferase gene expression. Deletion of the IIIf domain in HCV IRES dramatically reduced luciferase activity. Conclusion: Our results indicated that the plasmid vector system-based on RNA polymerase I promoter and terminator sequences represents an effective approach for the study of HCV IRES-dependent translation.