Studies on hepatitis C virus resistance to inhibitors in replicon systems.

Viruses evolve under selection pressure from a particular antiviral agent, resulting in the emergence of organisms that are not susceptible to the drug. This process is referred to as "virus resistance induction." While conventional in vitro resistance studies are conducted using infectious viruses, the lack of a robust hepatitis C virus (HCV) infection system in cell culture makes such an approach impossible in this case. Instead, cell lines harboring a self-replicating HCV RNA (or HCV replicon) are used for this purpose. The protocols detailed in this unit describe methods for studying HCV resistance to inhibitors, including the selection of replicon variants resistant to HCV inhibitors, characterization of these variants for their phenotypes and genotypes, and determination of the role of the mutation(s) identified in their genomes. The results from such studies are not only important for lead identification and confirmation of drug targets, but also aid in monitoring the appearance of resistant variants in clinical settings.