TRIM4 and infection: Our results revealed that nsp8 interacts with TRIM4 and suppresses TRIM4-mediated MDA5 K63-linked polyubiquitination for innate immune inhibition (Figs 5 and 6), and TRIM4 silencing almost completely abolishes nsp8-mediated inhibition of MDA5 K63-linked polyubiquitination and antiviral responses during infection with dsRNA viruses.