Prevalence of hepatitis C virus (HCV) variants resistant to NS5A inhibitors in naïve patients infected with HCV genotype 1 in Tunisia.

BACKGROUND: Hepatitis C virus (HCV) non-structural protein 5A (NS5A) inhibitors have been recently developed to inhibit NS5A activities and have been approved for the treatment of HCV infection. However the drawback of these direct acting antivirals (DAAs) is the emergence of resistance mutations. The prevalence of such mutations conferring resistance to HCV-NS5A inhibitors before treatment has not been investigated so far in the Tunisian population. The aim of this study was to detect HCV variants resistant to HCV-NS5A inhibitors in hepatitis C patients infected with HCV genotype 1 before any treatment with NS5A inhibitors. METHODS: Amplification and direct sequencing of the HCV NS5A region was carried out on 112 samples from 149 untreated patients. RESULTS: In genotype 1a strains, amino acid substitutions conferring resistance to NS5A inhibitors (M28V) were detected in 1/7 (14.2 %) HCV NS5A sequences analyzed. In genotype 1b, resistance mutations in the NS5A region (R30Q; L31M; P58S and Y93H) were observed in 17/105 (16.2 %) HCV NS5A sequences analyzed. R30Q and Y93H (n = 6; 5.7 %) predominated over P58S (n = 4; 3.8 %) and L31M (n = 3; 2.8 %). CONCLUSIONS: Mutations conferring resistance to HCV NS5A inhibitors are frequent in treatment-naïve Tunisian patients infected with HCV genotype 1b. Their influence in the context of DAA therapies has not been fully investigated and should be taken into consideration.

Natural prevalence of hepatitis C virus (HCV) variants resistant to protease and polymerase inhibitors in patients infected with HCV genotype 1 in Tunisia.

Hepatitis C virus (HCV) protease inhibitors (PIs) and polymerase inhibitors: nucleos(t)ide inhibitors (NS5B-NIs) and non-nucleos(t)ide inhibitors (NS5B-NNIs) have been recently developed to inhibit protease (NS3) or polymerase (NS5B) activities. The drawback of antiviral treatment is the emergence of resistance mutations to the drugs. The prevalence of such mutations conferring resistance to PIs, NS5B-NIs, and NS5B-NNIs before treatment has not been investigated so far in the Tunisian population. The aim of this study was to investigate the prevalence of known substitutions conferring resistance to HCV-PIs, NS5B-NIs, and NS5B-NNIs in 149 untreated patients naïve of any novel or investigational anti-HCV drugs and infected with HCV genotype 1 (genotype 1a = 7; genotype 1b = 142). Twelve sequences (9.2%) of the 131/149 HCV NS3 sequences analyzed showed amino-acid substitutions associated with HCV PIs resistance mutations (T54S, n = 4 (3%); V55A, n = 2 (1.5%); Q80K, n = 4 (3%); R155K, n = 1 (0.7%); A156V, n = 1 (0.7%)). One (1%) of the 95/149 HCV NS5B sequences analyzed showed the substitution V321I conferring resistance to NS5B-NIs, while 34 of 95 (35.8%) showed substitutions conferring resistance to NS5B-NNIs (C316N, n = 2 (2%); M414L, n = 1 (1%); A421V, n = 8 (8.5%); M423A, n = 1 (1%); M423T, n = 2 (2%); I424V, n = 5 (5.2%); C445F, n = 1 (1%); I482T, n = 2 (2%); V494A, n = 1 (1%); P496A, n = 1 (1%); V499A, n = 15 (16%); S556G, n = 5 (5.2%)). Naturally occurring substitutions conferring resistance to NS3 or NS5B inhibitors exist in a substantial proportion of Tunisian treatment-naïve patients infected with HCV genotype 1. Their influence on treatment outcome should be assessed.