MxA is a positive regulator of type I IFN signaling in HCV infection.

Type I interferons (IFNs) are a family of primordial cytokines that respond to various pathogen infections including Hepatitis C virus (HCV). Type I IFNs signal through Jak/STAT pathway leading to the production of a few hundred interferon stimulated genes (ISGs). The aim of this study was to explore the role of one of these ISGs, MxA in HCV infection and type I IFN production. Plasmid encoding MxA was cloned into PcDNA3.1-3×tag vector and MxA expression was confirmed both at mRNA (RT-PCR) and protein (Western blot, WB) levels. IFNα and IFNβ productions were quantified by RT-PCR from cell lysate and by ELISA kit from culture medium following MxA over-expression in Huh7.5.1 cells. The activation status of Jak/STAT signaling pathway was examined at three levels: p-STAT1 (WB), interferon sensitive response element (ISRE) activity (dual luciferase reporter gene assay), and levels of ISG expression (RT-qPCR). J6/JFH1 HCV culture system was used to study the role of MxA in HCV replication. Our findings indicated that MxA over-expression inhibited HCV replication and potentiated the IFNα-mediated anti-HCV activity; MxA stimulated the production of IFNα, IFNβ, and enhanced IFNα-induced activation of Jak-STAT signaling pathway. We concluded that MxA is a positive regulator of type I IFN signaling in HCV infection.