STING is a key driver of Japanese encephalitis virus induced inflammatory response

Interferon and inflammation are the key early defence mechanisms that combat pathogen infection. The cytosolic DNA sensor cGAS activates immune signalling via the STING protein. Emerging evidence suggests crosstalk between innate immune DNA and RNA sensing, implicating a role of STING protein in RNA virus infection. This study characterizes STING in the context of Japanese encephalitis virus , an RNA virus of the flaviviridae family. We observe that activation of type I IFN through MAVS is essential for cGAS and STING activation. Knockdown, null mutant and inhibitor studies confirmed that STING restricts JEV replication independently of IFN beta signalling and autophagy. Transcriptomic analysis of STING gt bone-marrow derived macrophages showed enhanced IFN response, but reduced activation of inflammatory cytokines and chemokines. Phosphorylated STING was recruited on the virus replication complex, marked by the non-structural protein NS1, subsequently triggering the assembly of the NLRP3 inflammasome and Gasdermin D on the RC. STING proton channel activity was essential for NLRP3 inflammasome activation, IL-1beta production, and activation of pyroptotic cell death markers. Sting gt mice, showed higher viremia, earlier disease onset, reduced survival, and decreased brain inflammation. These findings establish STING as a key regulator of JEV-induced inflammation and antiviral defence.