Pseudorabies Virus US3 Protein Inhibits IFN-β Production by Interacting With IRF3 to Block Its Activation

Pseudorabies virus is a typical swine alphaherpesvirus, which can cause obvious neurological disorders and reproductive failure in pigs. It is capable of evading host antiviral immune response. However, the mechanism by which many PRV proteins assist the virus to evade innate immunity is not fully understood. This study identified PRV US3 protein as a crucial antagonistic viral factor that represses interferon beta (IFN-β) expression. A in-depth study showed that US3 protein restricted type I IFN production by targeting interferon regulatory factor 3 (IRF3), a key molecule required for type I IFN induction. Additionally, US3 protein interacted with IRF3, degraded its protein expression to block the phosphorylation of IRF3. These findings suggested a novel strategy utilized by PRV to inhibit IFN-β production and escape the host innate immunity.