An indirect activator of STING signaling; induces IRF3- and IFN-dependent transcription in human fibroblasts, PBMCs, and HUMECs; prevents replication of chikungunya and Venezuelan equine encephalitis alphaviruses (IC90s = 8.01 and 24.57 μM, respectively); increases phosphorylation of IRF3 when used at a concentration of 100 μM but not in cells lacking STING