Glycosylation of classical swine fever virus E(rns) is essential for binding double-stranded RNA and preventing interferon-beta induction.

Host cells sense double-stranded RNA (dsRNA) produced during viral replication and initiate type I interferon (IFN-alpha/beta) production, leading to subsequent antiviral responses. Many viruses, including classical swine fever virus (CSFV), have developed strategies for counteracting the IFN-alpha/beta response. In this study, we explored the role of the CSFV E(rns) glycoprotein in the inhibition of IFN-beta production induced by dsRNA [poly(IC)]. Our results demonstrated that CSFV E(rns) could bind to exogenous dsRNA and inhibit dsRNA-induced IFN-beta production but failed to inhibit TRIF-triggered IFN-beta production. Our data suggest that the inhibition of IFN-beta induction occurred at the initial step of the TLR3 signaling pathway. We also showed that deglycosylation of E(rns) rendered it unable to bind to dsRNA, and thus unable to inhibit dsRNA-induced IFN-beta production. Taken together, these results indicated that N-glycan of CSFV E(rns) is essential for E(rns) blocking of IFN-beta induction.