N protein, as an abundantly produced structural protein within CoV-infected cells, has multiple functions, including virus replication, transcription, and assembly [56,134]. PEDV N protein has been identified as an IFN antagonist that blocks the expression of IFN-β and ISGs by suppression of the IRF3 and NF-κB activities [58]. PEDV N protein inhibits the activation of the IFN-β promoter induced by TBK1 and its upstream RIG-I, MDA-5, VISA, and TRAF3, while not affecting the activation of the IFN-β promoter driven by IRF3. Further experiments confirm that N directly interacts with TBK1 to obstruct the association between TBK1 and IRF3, which inhibits TBK1-induced IRF3 phosphorylation and IFN-β production [58]. Moreover, the effect of PEDV N protein on type III IFN production has also been evaluated [168]. N protein inhibits polyinosinic-polycytidylic acid (poly(I:C))-induced IFN-λ3 production by blocking the nuclear translocation of NF-κB, but does not antagonize the type I or type II IFN expression induced by poly(I:C) in IPEC-J2 cells [168].