by Jiazheng Quan, Xibao Zhao, Shaoying Chen, Hongrui Li, Wei Chen, Qianqian Di, Xunwei Li, Jiajing Zhao, Han Wu, Jin Chen, Yue Xiao, Zherui Wu, Weilin Chen RIG-I and STING are critical for mediating the RIG-I and cGAS-STING signaling pathways that guard against viral infection. Here, we report that ubiquitin-specific peptidase 39 (USP39) positively regulates the RIG-I and cGAS-STING pathways to induce antiviral innate immunity in vitro and in vivo. The USP39 deficiency impaired the antiviral immune response of macrophages, leading to low type I IFNs expression, and high RNA and (e.g., VSV, H1N1 PR8) DNA virus (e.g., HSV-1) replication. Moreover, USP39-deficient mice were more sensitive to VSV or HSV-1 infection than control mice. Conversely, USP39 overexpression promoted the antiviral immune response. Mechanistically, we found that USP39 regulates RIG-I protein expression by promoting pre-RIG-I mRNA splicing and maturation. In addition, we also revealed that USP39 interacts with and st