Inhibition on IFN-β Expression by HCV NS3 and NS5A in HepG2 Cells

Objective To observe the effects of HCV protein,NS3 and NS5A on IFN-βin HepG2 cells and its regulation mechanism.Methods Human liver hepatocellular carcinoma cells HepG2 were transfected with recombinant eukaryotic plasmid pcDNA3.1/myc-His-core,NS3 or NS5A to overexpress these proteins,and the expression of IFN-βwere detected by qRT-PCR,Western blotting and ELISA.Luc2P reporter plasmids pGL4.10-IFNβ-P were constructed and transfected into HepG2 cells,and the activity of IFN-βpromoter were determined through luciferase assay for regulation mechanism study.Results Both mRNA level and protein expression of IFN-βwere significantly decreased(P<0.05)in the presence of NS3 or NS5A protein.Luciferase assay revealed that NS3 or NS5A protein downregulated IFN-βpromoter activity(P<0.05).Meanwhile,HCV core protein had little effect on IFN-βexpression.Conclusions HCV protein NS3 and NS5A could inhibit innate IFN-βexpression and thus escape immune selection and hinder the host immune responses.0129-3