Changes in the Anopheles arabiensis transcriptome and gut microbiota profiles associated with Microsporidia MB

Microsporidia MBis an endosymbiotic microbe found inAnophelesmosquito populations. This symbiont can blockPlasmodiumtransmission in mosquitoes, and it can spread through mosquito populations and be sustained over generations by vertical and horizontal transmission. These characteristics makeMicrosporidia MBa potential candidate for symbiont-based malaria vector control. However, the mechanistic basis of interactions betweenMicrosporidia MBandAnopheles arabiensisis poorly characterized. We investigated how the presence ofMicrosporidia MBaffects transcriptomics profiles and the gut microbiota composition and diversity in non-blood-fed and blood-fed (24, 48 and 72 hours post blood meal)An. arabiensismosquitoes. We observed that mosquito infection withMicrosporidia MBupregulatedfarnesoic acid O-methyltransferase,a gene linked to juvenile hormone biosynthesis in the non-blood-fed mosquitoes. In addition, blood feeding inMicrosporidia MBpositive mosquitoes was associated with an activation of immune-related genes 24 hours after a blood meal, where several genes including thelipopolysaccharide tumor necrosis factorgene were upregulated. Interestingly, we also observed thatMicrosporidia MBpositivity was associated with a microbiota shift to favor the proliferation of microbes includingPseudomonasandSerratia24 hours post blood meal. There were indications of immune system activation inMicrosporidia MBpositive mosquitoes up to 48 hours after a blood meal where factors such as thepeptidoglycan recognition SC2-likeandlysozyme c-1were upregulated. Notably, an upregulated immune system at this time point was associated with downregulation of genes associated with metabolism and the restoration ofSerratia,Pseudomonasand other key microbes to relative abundances similar to those recorded in non-blood-fed mosquitoes. At the 72-hour time point,Microsporidia MBpositive mosquitoes exhibited a downregulation of genes associated with immunity, includingcecropinsanddefensins, while metabolic processes were predominantly upregulated. Our results provide insights into the effect ofMicrosporidia MBinfection on theAn. arabiensisgene expression and gut microbiota profiles. This work will contribute to mechanistic insights into symbiont-mediated malaria transmission blocking.