FIG 1.

Both mtDNA and Mtb DNA engage cytosolic DNA surveillance pathways to activate type I interferon expression. Mtb infection can stimulate type I IFN expression by activating both cGAS, via Mtb dsDNA, and STING, via secretion of cyclic-di-AMP. To date, mtDNA has been shown to engage cGAS and TLR9. While TLR9 has been shown to play a role in determining Mtb infection outcomes in vivo, it remains unclear whether the endosomal receptor actually directly binds to Mtb-derived dsDNA during Mtb infection of macrophages (represented by the question mark). The figure was created with BioRender.