In-vitro studies in the human cell line Huh7 has shown that on exposure of the cells to Interferon 50 genes were up-regulated by at least twofold in control clones, whereas induction of 9 of the 50 genes was significantly reduced in those Huh7 clones expressing NS5A. Interferon-alpha activity has been found to be inhibited by the HCV protein NS5A. The strongest effect of NS5A on Interferon response was observed on the OAS-p69 gene with reduced expression. In addition, Huh7 cells expressing NS5A showed an up-regulation of interleukin-8 a proinflammatory cytokine. As a result this study postulated a mechanism for NS5A mediated interferon resistance (6).