Viral and host genetic determinants of hepatitis C virus persistence and interferon resistance

by Sumpter, Rhea Myers

Approximately 170 million people worldwide are chronically infected with hepatitis C virus (HCV), which is an important cause of cirrhosis and hepatocellular carcinoma. HCV replicates through an error-prone process that may support the evolution of genetic variants resistant to the host cell antiviral response and interferon (IFN)-based therapy. The development of the HCV RNA replicon system has allowed the study of persistent HCV RNA replication in tissue culture. We evaluated HCV/IFN interactions within a long-term culture system of Huh7 cell lines harboring different variants of an HCV genotype 1b subgenomic RNA replicon that differed only at two sites within the NS5A coding region. A replicon with a lysine (K) insertion at HCV codon 2040 (K2040) replicated efficiently and exhibited sequence stability in the absence of host antiviral pressure. In contrast, a replicon with an leucine (L) to serine (S) point mutation at HCV codon 2198 (L2198S) replicated poorly and triggered a cellular response characterized by IFN-! production and low-level interferon-stimulated gene (ISG) expression. When maintained in long term-culture, the L2198S RNA evolved into a stable high passage (HP) variant with 6 additional point mutations throughout the HCV protein-coding region that enhanced viral replication. The