CGAS and viral infectious disease: cGAS/STING was initially found as an innate immune sensor that responds to cytosolic DNA in the context of bacterial and viral infections; Initially cGAS binds to cytosolic double-stranded DNA (dsDNA) to form 2′,3′-cyclic guanosine monophosphate–adenosine monophosphate (cGAMP), which then signals through STING (12, 13).