Macrophage expressed TRIM47 is required to control RNA virus infection by targeting MAVS

Abstract In the past half century, there have been multiple RNA virus pandemics (influenza 1957, 1968 and 2009; SARS-CoV and COVID-19), inhabiting 44% of all emerging contagious diseases. Innate immunity is the first line of defense against viral infection. Here we found that TRIM47, a member of the TRIM family E3 ligase, plays a pivotal role in positively regulating host innate immunity in response to Influenza A virus (IAV). Among immune cells, TRIM47 is highly expressed in macrophages. Compared with wild type, TRIM47 deficient bone marrow derived macrophages exhibited a significantly lower level of type I interferon (IFN-I) following RNA mimics infection, encompassing IAV and poly I: C. After in vivo IAV infection, TRIM47 knockout mice showed an extremely lower survival rate, along with a lower level of IFN-I, higher viral load and more inflammatory cell infiltration in lungs compared to wild-type mice. Mechanistically, TRIM47 induces K68-linked ubiquitination of mitochondrial antiviral-signaling protein (MAVS), a key adaptor in RNA-sensing pathway, leading to robust IFN-I production. This K68-linked ubiquitination by TRIM47 is essential for MAVS aggregation and activation in macrophage. These findings provide compelling evidence that TRIM47 interacts with MAVS, enhancing IFN-I production to effectively restrict IAV infection in macrophages. This research not only advances our understanding of influenza pathogenesis but also opens avenues for potential therapeutic interventions.