Abstract
Resistance-associated substitutions (RASs) of hepatitis C virus (HCV) in the NS5A region impair the efficacy of NS5A inhibitors. In this study, we evaluated the characteristics of the novel RASs observed in treatment-failure patients, A92K and a deletion at P32 (P32del), and the susceptibility of viruses with these RASs to various anti-HCV reagents by using JFH-1 based recombinant HCV with NS5A from a genotype 1b Con1 strain (JFH1/5ACon1). We introduced A92K or P32del solely or in combination with Q24K, L28M, R30Q or L31F into the NS5A of JFH1/5ACon1. Viruses harboring R30Q/A92K showed high extracellular core antigens and infectivity titers, whereas the other viruses with RASs showed low replication levels and infectivity titers. All the viruses with A92K or P32del were markedly resistant to ledipasvir, velpatasvir and elbasvir. Interestingly, viruses with R30Q/A92K were more susceptible to grazoprevir than viruses without RAS. All the viruses had a similar susceptibility to ribavirin and sofosbuvir. In conclusion, combination RASs R30Q/A92K enhanced virus production whereas other RASs impaired virus replication. Both A92K and P32del conferred severe resistance even to second generation NS5A inhibitors. However, these viruses were susceptible to grazoprevir, ribavirin and sofosbuvir. Thus, combination regimens with these reagents may eradicate viruses harboring A92K or P32del.
Highlights
Resistance-associated substitutions (RASs) of hepatitis C virus (HCV) in the NS5A region impair the efficacy of NS5A inhibitors
RASs of L31F/M/V/I and Y93H in the NS5A region are frequently observed in both direct-acting antiviral agents (DAAs) naïve and experienced patients infected with HCV genotype 1b strains[9,11,12,13]
Time-dependent increases of extracellular HCV core Ag levels were observed in these cells, but the levels were different between recombinant viruses (Fig. 1b)
Summary
Resistance-associated substitutions (RASs) of hepatitis C virus (HCV) in the NS5A region impair the efficacy of NS5A inhibitors. We evaluated the characteristics of the novel RASs observed in treatment-failure patients, A92K and a deletion at P32 (P32del), and the susceptibility of viruses with these RASs to various anti-HCV reagents by using JFH-1 based recombinant HCV with NS5A from a genotype 1b Con[1] strain (JFH1/5ACon[1]). Combination RASs R30Q/A92K enhanced virus production whereas other RASs impaired virus replication Both A92K and P32del conferred severe resistance even to second generation NS5A inhibitors. RASs of L31F/M/V/I and Y93H in the NS5A region are frequently observed in both DAA naïve and experienced patients infected with HCV genotype 1b strains[9,11,12,13] These RASs were reported to be associated with virologic failure of the DAA therapies including first generation NS5A inhibitors, such as daclatasvir (DCV), ledipasvir (LDV) and ombitasvir[9,14]. The current study used this system to evaluate the effects of the novel RASs A92K and P32del on the HCV life cycle and susceptibility to various anti-HCV reagents
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