IL28B inhibits hepatitis C virus replication through the JAK–STAT pathway

Background & Aims The combination of pegylated interferon (IFN) α and ribavirin (RBV) is the standard therapy for patients with chronic HCV infection. However, it produces a sustained virologic response (SVR) in only half of the treated individuals and is associated with significant side effects. Recently, several single-nucleotide polymorphisms (SNPs) near the IL28B locus, also known as IFNλ3 , were identified to be strong predictors of SVR in patients receiving PEG-IFN and RBV. We sought to determine whether IL28B was capable of inhibiting HCV replication and to determine the pathway by which IL28B exhibits anti-HCV activity. Methods Using the full-length HCV replicon OR6 and the infectious HCV clones JFH1 and Jc1, we assessed the anti-HCV effect of IL28B on HCV and characterized the key steps of the JAK–STAT pathway by real time PCR, luciferase assay, and Western blot. Finally, we evaluated the anti-HCV effect of IL28B in the presence of JAK–STAT pathway inhibitors such as blocking antibodies, a pharmacological inhibitor, and siRNAs. Results We found that IL28B inhibits HCV replication in a dose- and time-dependent manner. Like IFNα, IL28B induces the phosphorylation of STAT1 and STAT2, ISRE-driven transcription, and expression of known ISGs. The anti-HCV effects of IL28A, IL28B, and IL29 were abrogated by an IL10R2 blocking antibody, a pharmacological inhibitor of JAK1/TYK2, and by siRNA against IL28R1 , STAT1 , STAT2, and IRF9 . Conclusions Our data demonstrate that IL28A, IL28B, and IL29 signal through the JAK–STAT pathway to inhibit HCV. These data suggest possible applications of new approaches in HCV treatment.