The Investigation of Drug Resistance Substitutions in NS3 Protease Sequence of Hepatitis C Virus from Non-Responder Patients

Abstract

Background: Even with the fantastic successes of direct-acting antivirals (DAA) in the treatment of Hepatitis C<br />Virus (HCV) infection, natural drug resistance remains a challenging obstacle for their impacts. The data regarding<br />protease inhibitors (PIs) resistance in Iran population are limited. The aim of this study was to investigate the variations<br />in NS3 protease of HCV from non-responder patients. Methods: In this cross-sectional study, 14 HCV infected patients<br />with genotype 1(N=5) and 3(N=9) who have not responded to Interferon-related regime were enrolled from Liver<br />Clinic, Shiraz. The NS3 protease region was amplified by Nested-PCR followed by product gel extraction. Besides,<br />some amplified protease regions were cloned into a cloning vector to improve the sensitivity of mutation detection.<br />Both crude and cloned sequences were then introduced into sequencing. The obtained sequences were compared with<br />the NS3 reference sequences and analyzed by Geno2pheno available software to find possible substitutions. In the<br />end, the phylogenetic tree was constructed. Results: Among variations responsible for PIs resistance, only one out of<br />14 (7%) sample who was infected with genotype 1a, harbored R117C+N174S double mutation, which causes reduced<br />susceptibility to Telaprevir. Any another resistance mutation was not found among the studied population. The most<br />frequent substitutions were determined as I52M(N=9), S102A(N=9), S166A(8) and V170I(8) for genotype 3a, and<br />F147S/A(4) for genotype 1. However, some uncharacterized substitutions on scored position, including I132L(N=1),<br />I170V(N=3) and N174S(N=2) were also determined among sequences. Phylogenetic analysis demonstrated that the<br />protease region has enough power to correctly classify enrolled samples into relevant clusters on the tree. There were 2,<br />3 and 9 cases of sub-genotypes 1a, 1b, and 3a, respectively. Conclusion: A low frequency of PIs resistance mutations<br />in our HCV infected population is a hopeful point of starting these drugs in HCV infected patients.