STING-dependent autophagy suppresses Nosema bombycis infection in silkworms, Bombyx mori.

Nosema bombycis is a unicellular spore-forming obligate parasite, related to fungi, and causes infections in economically important animals and are opportunistic human pathogens. However, the mechanisms of host response to N. bombycis remain unclear. STING (stimulator of interferon genes) is an adapter protein involved in the innate immune response to pathogens. In this study, a transgenic gRNA vector containing BmSTING was constructed and microinjected to generate the transgenic line BmSTINGΔ6bp/WT and BmSTINGΔ5bp/WT in silkworms. The expression of BmSTING was significantly reduced in BmSTINGΔ5bp/WT compared to non-transgenic silkworm. The mortality and LC3 (microtubule-associated protein 1 light chain 3) level in BmSTINGΔ6bp/WT and BmSTINGΔ5bp/WT was significantly decreased in the early infection stage of N. bombycis, but the transgenic silkworms died rapidly in the later stage. Furthermore, both BmSTING and LC3 were increased in BmE cell lines after infection with N. bombycis. This study highlights the role of STING-dependent pathways response to microsporidia in silkworm, Bombyx mori.