Effects of resistance‐associated variants in genotype 2 hepatitis C virus on viral replication and susceptibility to antihepatitis C virus drugs

Aims Development of direct‐acting antivirals (DAAs) has made antihepatitis C virus (HCV) treatment highly safe and effective. However, the emergence of resistant‐associated variants (RAVs) after failure of DAA therapy affects retreatment outcomes. In particular, genotype 1 HCV with P32 deletion has been reported to be highly resistant to all approved non‐structural protein (NS)5A inhibitors. However, analysis of RAVs in genotype 2 HCV has been limited. Accordingly, in this study, we evaluated the roles of genotype 2 HCV variants in antiviral drug efficacy. Methods We utilized HCV‐2b/2a (JFH‐1) chimeric virus (genotype 2a), which replicates more robustly than JFH‐1. We constructed various genotype 2a JFH‐1‐based HCV cell culture systems with NS3 (D168E), NS5A (F28S, F28S/M31I, P32 deletion, and Y93H), and NS5B (S282 T) RAVs and analyzed the replication ability and sensitivity to various anti‐HCV reagents. Results Genotype 2a‐based HCV with NS5A–P32 deletion could not replicate even in long‐term cultures. Genotype 2a‐based HCV with NS5A‐F28S/M31I showed significantly higher replication ability than the wild‐type strain, and replication could not be suppressed, even with high concentrations of NS5A inhibitors, including pibrentasvir and velpatasvir (