Negative regulator of innate antiviral response. Blocks IRF3-dependent cytokine production such as IFNA, IFNB and TNF (PubMed:29802199). Interacts with IRF3 and inhibits IRF3 recruitment to type I IFN promoter sequences while also reducing nuclear levels of the coactivators EP300 and CREBBP (PubMed:29802199).