Ribavirin regulates hepatitis C virus replication through enhancing interferon-stimulated genes and interleukin 8.

BACKGROUND The manner in which ribavirin (RBV) enhances the antiviral effects of interferon (IFN) against hepatitis C virus (HCV) remains unknown. We investigated whether RBV modifies IFN-stimulated genes (ISGs) in vivo and in vitro. METHODS We measured the messenger RNA (mRNA) levels of ISGs in T lymphocytes from patients with HCV infection who were receiving IFN-α therapy with or without RBV. We added RBV and/or IFN-α to a plasmid-based HCV replication system containing a full-length HCV genotype 1a sequence in HepG2 and Huh7 cell lines and the JFH-1 HCV genotype 2a sequence in Huh7 cell lines and measured levels of ISGs and autocrine IFN-β. RESULTS The expression of protein kinase R and myxovirus resistance A mRNA was enhanced more with IFN-α and RBV than by IFN-α alone in assays in vivo and in vitro. Such enhancement depended on autocrine IFN-β being enhanced by RBV. RBV upregulated interleukin 8 (IL-8) in the absence of IFN-α. The IL-8 upregulation induced by RBV was responsible for the activation of activator protein 1 (AP-1). CONCLUSIONS Ribavirin augments the anti-HCV effects of IFN-α induced by ISGs through enhancing autocrine IFN-β. Moreover, RBV can enhance IL-8 through activating AP-1. Improved understanding of ISG modulation by RBV would help to establish a means of eliminating HCV.