Role of Interferons in Chronic Hepatitis C Infection

It is known that the production of and/or response to interferon (IFN) are deregulated during chronic hepatitis C virus (HCV) infection. In particular, several studies have shown that patients with chronic HCV infection who have a high natural level of IFN-stimulated genes (ISGs) do not achieve viral clearance and have a poor response to treatment with pegylated IFNα and ribavirin. The viral and/or host factors that are responsible for the higher endogenous ISGs expression in some HCV infected patients compared to others remain to be determined. However, type III IFNs, and in particular the new discovered IFN lambda (L) 4 Gene, appear to play a dominant role in driving ISGs response and in contributing to the establishment of HCV persistence. This review focuses on recent studies on how the ISGs response and the IFNλ genetic factors (interleukin-28B and IFNL4) affect the clinical outcome of HCV infection highlighting their impact in the current antiviral therapies with direct acting antiviral agents.