Study of inhibition of interferon inducible genes by dephosphorylation of E2 envelope gene of HCV genotype 1a

Background: Interferon is considered as the first line of defense against all infections including HCV. Unfortunately 50% of the patients do not respond to the existing treatment. Envelope protein 2 of HCV interacts with the interferon-inducible protein kinase (PKR) protein. This protein contains a sequence identical with phosphorylation sites of the PKR and the translation initiation factor eIF2alpha, a target of PKR. Inhibition of the kinase activity of PKR by this interaction is postulated as a mechanism for the resistance to interferon (IFN) therapy. Objective: This research work is aimed to determine the role of envelope E2 protein causing interferon resistance and also to investigate the correlation between phosphorylation of envelope protein, PKR protein and interferon response which is useful to find out the role of envelope genes in mediating interferon resistance. Results: A hybrid in-silico and wet laboratory approach has pointed out serine 75 and 277 of the HCV E2 gene as a potential candidate for the serine phosphorylation. Interferon a-2a response was checked and it was observed that with increase in interferon concentration a significant decrease in number of viable cells was observed in envelope 2 gene mutated at positions S75 and S277 as compared to normal envelope 2 gene containing Huh-7 and CHO ceil lines. Conclusion: It is suggested that these phosphorylation sites of HCV E2 gene exhibit a key role in interferon resistance. The results of this study suggest that serine residues as predicted have a significant role in interferon resistance, especially at position S75.