– Plays an essential role in viral RNA synthesis and also a role in suppressing innate immune signaling. Acts as a polymerase cofactor in the RNA polymerase transcription and replication complexes. Serves as nucleoprotein/NP monomer chaperone prior to the formation of the large oligomeric RNA-bound complexes. Regulates RNA synthesis by modulating NP-RNA interactions and interacting with DYNLL1. VP35-NP interaction controls the switch between RNA-bound NP and free NP and thus the switch between genome replication and genome packaging into the nucleocapsid. Prevents establishment of cellular antiviral state, thereby suppressing host DC maturation. Acts by inhibiting host DDX58/RIG-I activation both by shielding dsRNA from detection and by preventing PRKRA binding to DDX58. Blocks virus-induced phosphorylation and activation of interferon regulatory factor 3/IRF3, a transcription factor critical for the induction of interferons alpha and beta. This blockage is produced through the interaction with and inhibition of host IKBKE and TBK1, producing a strong inhibition of the phosphorylation and activation of IRF3. Also inhibits the antiviral effect mediated by the host interferon-induced, double-stranded RNA-activated protein kinase EIF2AK2/PKR. Increases PIAS1-mediated SUMOylation of IRF7, thereby repressing interferon transcription. Also acts as a suppressor of RNA silencing by interacting with host DICER1, TARBP2/TRBP and PRKRA/PACT. As a dimer, binds and sequesters dsRNA contributing to the inhibition of interferon production.