Viral infection triggers host innate immune responses that result in the production of various cytokines including type I interferons (IFN), activation of inflammasomes, and programmed cell death of the infected cells. Tight control of inflammatory cytokine production is crucial for the triggering of an effective immune response that can resolve the infection without causing host pathology. In examining the inflammatory response of Asc and Casp1 macrophages, we found that deficiency in these molecules resulted in increased IFN production upon DNA virus infection, but not RNA virus challenge. Investigation of the underlying mechanism revealed that upon canonical and non-canonical inflammasome activation, caspase-1 interacted with cyclic GMP-AMP (cGAMP) synthase (cGAS), cleaving it and dampening cGAS-STING-mediated IFN production. Deficiency in inflammasome signaling enhanced host resistance to DNA virus in vitro and in vivo, and this regulatory role extended to other inflammatory caspases. Thus, inflammasome activation dampens cGAS-dependent signaling, suggesting cross-regulation between intracellular DNA-sensing pathways.

Highlights d Deficiency in apoptotic caspases leads to elevated IFN production by virus infection d Caspase-3 cleaves cGAS, MAVS, and IRF3 to keep apoptosis immunologically silent d Caspase-7 is differently involved in mouse and human cells to cleave cGAS and MAVS d MAVS is cleaved at alternative sites to ensure caspasemediated negative regulation

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