Assays for RNA synthesis and replication by the hepatitis C virus

At least six major genotypes of Hepatitis C virus (HCV) cause liver diseases worldwide. The efficacy rates with current standard of care are about 50% against genotype 1, the most prevalent strain in the United States, Europe and Japan. Therefore more effective pan-genotypic therapies are needed. HCV RNA replication provides a number of validated targets for virus-specific and potentially pan-genotypic inhibitors. In vitro assays capturing the different steps of RNA synthesis are needed not only to identify new inhibitors, but also to examine their mechanisms of action. This review attempts to provide a comprehensive summary of the biochemical, cell-based and animal model systems to assess HCV polymerase activity and HCV RNA replication that should be useful for both basic research and applied studies.