MAVS and viral infectious disease: TRIM21 also serves as a negative regulator of IFN-β during Japanese encephalitis virus (JEV) infection in human microglial cells (19).Recently, Xue et al. report that TRIM21 is upregulated upon RNA virus infection and promotes K27-linked polyubiquitination of MAVS to upregulate type-I interferon signaling, thereby inhibiting viral infection (20).