Dual oxidase geneDuoxand Toll-like receptor 3 geneTLR3in the Toll pathway suppress zoonotic pathogens through regulating the intestinal bacterial community homeostasis inHermetia illucensL.

Abstract

AbstractBlack soldier fly (BSF;Hermetia illucensL.) larvae can convert fresh pig manure into protein and fat-rich biomass, which can then be used as livestock feed. Currently, it is the only insect approved for such purposes in Europe, Canada, and the USA. Pig manure is rich in zoonotic pathogens (e.g.,Staphylococcus aureusandSalmonellaspp.). BSF larvae inhibit these zoonotic pathogens; however, the mechanism is unclear. We employed RNAi, qRT-PCR, and Illumina MiSeq bacterial 16S rDNA high-throughput sequencing molecular techniques to study the interaction between the two immune genes (Duoxin Duox-reactive oxygen species [ROS] immune system andTLR3in the Toll signaling pathway) and zoonotic pathogens to determine the mechanisms resulting in pathogen suppression.Results indicated thatBsf Duox-TLR3RNAi increased bacterial load but decreased the relative abundance ofProvidenciaandDysgonomonasintestinal symbionts. Concurrently,Bsf Duox-TLR3RNAi inactivated the NF-κ B signaling pathway, downregulated the expression of antimicrobial peptides, and diminished inhibitory effects on zoonotic pathogen. The resulting dysbiosis stimulated an immune response by activatingBsfDuoxand promoting ROS, which regulated the composition and structure of the gut bacterial community.Thus,BsfDuoxandBsfTLR3are important factors in regulating the gut key bacteriaProvidenciaandDysgonomonashomeostasis while inhibiting target zoonotic pathogens.