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

Document Type: Research Articles

Authors

1 Department of Bacteriology and Virology, School of Medicine, Shiraz University of Medical Sciences, Shiraz, Iran.

2 Gastroenterohepatology Research Center, Shiraz University of Medical Sciences, Shiraz, Iran.

3 Department of Genetics and Molcular Biology, School of Medicine, Isfahan University of Medical Sciences, Isfahan, Iran.

Abstract

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

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