STING1 and influenza: Additionally, the STING agonist, bis-(3′,5′)-cyclic dimeric guanosine monophosphate (c-di-GMP or cdGMP), has been reported as a potent mucosal vaccine adjuvant that induces Th1 and Th17 cytokines in a plant-derived H5 influenza vaccine after intranasal vaccination (75).