Replicons from genotype 1b HCV-positive sera exhibit diverse sensitivities to anti-HCV reagents

Half of the population of genotype 1 HCV is resistant to current pegylated-interferon-α (PEG-IFN-α) and ribavirin therapy. The resistance to IFN therapy is an urgent problem, especially in patients with genotype 1 HCV infection. However, sensitivities among HCV strains to anti-HCV reagents including IFNs have not been thoroughly addressed. Here, we established three different subgenomic replicons (1B-4, 1B-5, and KAH5 strains) in addition to our previously established replicon (O strain). We comparatively examined the sensitivities of four replicons to IFN-α, IFN-γ, IFN-λ, cyclosporine A, and fluvastatin. Among the replicons, the 1B-4 and KAH5 replicons were the most sensitive and resistant, respectively to IFN-λ (EC50: 1.50 ng/ml vs. 8.50 ng/ml) and fluvastatin (EC50: 2.82 μM vs. 7.87 μM), although these replicons possessed similar features in terms of genetic distance from the O strain, HCV RNA expression levels, and sensitivity to IFN-α (EC50: 1.44 IU/ml vs. 1.37 IU/ml) and cyclosporine A (EC50: 0.71 μg/ml vs. 0.96 μg/ml). These replicons are thus useful tools for examining the mechanism of anti-HCV activity, especially in IFN-λ and statins.