Objective      To identify the potent RNA interference suppressor encoded by hepatitis C virus (HCV).       Methods      The eukaryotic recombinant plasmids expressing various proteins encoded by HCV genes were constructed by inserting the corresponding DNA sequences into pcDNA3.1-3Flag

and the expression of the proteins in HepG2 cells were confirmed by immunofluorescence staining. The recombinant plasmids and the RNA interference system targeting firefly luciferase were co-transferred into HepG2 cells. The luciferase activity was assayed by dual luciferase assay system to identify the potent RNA interference suppressor

which was further confirmed using a RNA interference system targeting intrinsic GFP. The suppressing effect was observed in other two non-liver cell lines and the dose-dependent effect was studied. The effect of the potent suppressor on siRNA-mediated RNA interference was studied using a RNA interference system targeting firefly luciferase.       Results      The eukaryotic recombinant plasmids expressing various proteins encoded by HCV genes were constructed successfully. The core protein of HCV rescued both extrinsic luciferase activity and intrinsic GFP that were silenced by shRNA in HepG2 cells (P0.05)

in a dose-dependent manner. Similar results were observed in HEK293 and HeLa cells. However

HCV core protein did not rescue the luciferase activity silenced by siRNA (P0.05).       Conclusion      HCV core protein can act as a potent suppressor of shRNA-mediated RNA interference

but can not suppress siRNA-mediated RNA interference. This ability may contribute to the persistent infection and pathogenesis of HCV.