Abstract
Viperin is considered as an antiviral protein known to directly target a variety of viruses. However, whether and how Viperin affects virus infection by targeting intracellular immune signaling remain unexplored. Here, we reveal that Viperin inhibits type-I interferon (IFN-I) antiviral immune signaling by degrading STAT1. We found that IFN-I upregulates the ubiquitin E3 ligase ITCH to degrade UBR5, while Viperin subsequently recruits another ubiquitin E3 ligase UBE4A to promote STAT1 ubiquitination and degradation to attenuate IFN-I signaling. Moreover, the multifunctional interfering peptide VS-IP1 can block Viperin-mediated STAT1 degradation, thus enhancing IFN-I antiviral immune function. This study reveals that Viperin is a suppressor of IFN-I immune signaling, which could renew understanding of the biological function of Viperin, and provide a strategy for enhancing clinical IFN-I therapeutic efficacy.