IFN-λ: A New Class of Interferon with Distinct Functions-Implications for Hepatitis C Virus Research

Pegylated interferon-α and ribavirin (PEG-IFN/RBV) is widely used to treat chronic hepatitis C virus infection with notorious adverse reactions since the broad expression of IFN-α receptors on all nucleated cells. Accordingly, a Type III IFN with restricted receptors distribution is much safer as an alternative for HCV therapy. In addition, single nucleotide polymorphisms (SNPs) near the human IFN-λ3 gene, IL-28B, correlate strongly with the ability to achieve a sustained virological response (SVR) to therapy with pegylated IFN-α plus ribavirin in patients infected with chronic hepatitis C. Furthermore, we also discuss the most recent findings: IFN-λ4 predicts treatment outcomes of HCV infection. In consideration of the apparent limitations of current HCV therapy, especially high failure rate and universal side effects, prediction of treatment outcomes prior to the initiation of treatment and developing new alternative drugs are two important goals in HCV research.