A novel role of classical swine fever virus Erns glycoprotein in counteracting the Newcastle Disease Virus (NDV)-mediated IFN-β induction

Abstract

Erns is an envelope glycoprotein of classical swine fever virus (CSFV) and has an unusual feature of RNase activity. In the present study, we demonstrate that Erns counteracts Newcastle disease virus (NDV)-mediated induction of IFN-β. For this purpose, Erns fused to the enhanced green fluorescent protein (EGFP) was transiently expressed in porcine kidney 15 (PK15) cells. In luciferase activity assay, E rns-EGFP was found to prevent IFN-β promoter-driven luciferase expression and block the induction of IFN-β promoter mediated by NDV in a dose-dependent manner. Through IFN-specific semi-quantitative RT-PCR detection, obvious decrease of IFN-β mRNA in NDV-infected PK15 cells was observed in the presence of Erns-EGFP. In contrast, EGFP alone showed none of this block capacity. In addition, Erns-EGFP mutations with RNase inactivation were also found to block NDV-mediated induction of IFN-β. These evidences establish a novel function for CSFV Erns glycoprotein in counteraction of the IFN-β induction pathway.