Figure 3. Cellular signalling pathways in response to pathogenic viral infection or mtDNA release.

Antiviral pathways can be stimulated by both RNA and dsDNA from receptor-mediated fusion events or endocytosis. These foreign nucleic acids interact with pattern recognition receptors, such as RIG-I like receptors (RLRs), or with cGAS (cyclic GMP-AMP synthase) which initiates the STING (Stimulator of Interferon Genes) antiviral response pathway. mtDNA acts as a ligand for many immune receptors so is capable of activating both cGAS and RLRs as well as the NLRP3 (nod-like receptor family pyrin domain containing 3) inflammasome for the up-regulation of cytokine release and a pro-inflammatory response.