SNP analysis of NS5B of HCV3a treated with sofosbuvir, peg-IFN, and ribavirin in Pakistani patients
Keywords:
HCV genotype 3a; sofosbuvir; peg-IFN; ribavirin; sustained viral responseAbstract
Hepatitis C virus (HCV) is a major cause of chronic liver disease, infecting about 3% of the world population. Chronic HCV infection may lead to liver cirrhosis and hepatocellular carcinoma. The prevalence of HCV infection is about 6% in Pakistan and predominant genotype is 3a. Nucleotide sequence variations in the NS5B region affect the therapeutic response of anti-HCV treatment such as sofosbuvir. The objective of current study is to analyze the nucleotide variation of NS5B of HCV 3a in Pakistani patients in the context of response to sofosbuvir. Twenty individuals, previously non responder to pegylated interferon (peg-IFN) and ribavirin (RBV), were enrolled. After blood samples collection, all patients were retreated with sofosbuvir, peg-IFN and RBV for three months. Sustained viral response (SVR) was monitored for six months after the completion of therapy. Out of 20 cases, 18 exhibited SVR, while 2 cases relapsed. To find possible variations in NS5B region responsible for SVR and relapse, viral RNA was isolated from serum followed by cDNA synthesis and amplification. The targeted region was sequenced by Sanger sequencing using 3500 Genetic Analyzer and phylogenetic analysis was carried out by MEGA software. Here, we did not find any of previously reported amino acid substitutions such as S282T, C316N, L320F, and V321I in NS5B gene responsible for the resistance of sofosbuvir in studied isolates. The study concludes that absence of amino acid variations in catalytic domain of NS5B polymerase improves the response of sofosbuvir, peg-IFN, and RBV against HCV genotype 3a in Pakistani patients.