Microsporidia MB mediated transcriptomics and gut microbiota shift in Plasmodium falciparum exposed Anopheles arabiensis mosquitoes

Background Microsporidia MB is a vertically and horizontally transmitted endosymbiont of Anopheles mosquitoes with the potential to impair Plasmodium falciparum transmission in malaria endemic regions. However, despite its ability to block Plasmodium transmission, the mechanistic basis underpinning this effect remains unknown. Methods We profiled gene expression and gut microbiota in Microsporidia MB -infected (positive) and -uninfected (negative) mosquitoes exposed to Plasmodium -infected and -uninfected blood from mosquito guts, across three time points 24-, 48-, and 72-hours post–blood meal. Results Microsporidia MB -negative mosquitoes exposed to P. falciparum infection exhibited suppressed immune signaling, followed by an upregulation of lipolytic and cellular stress related genes, suggesting parasite-driven immune evasion and host resource exploitation. In contrast, Microsporidia MB -positive mosquitoes exposed to Plasmodium -negative blood exhibited a sustained immune activation and lipid depletion, suggesting that Microsporidia MB infection contributes to a more sustained activation of immunity in mosquitoes exposed to Plasmodium- negative blood. In Microsporidia MB -positive mosquitoes exposed to P. falciparum- positive blood, gene expression indicated several possible routes by which parasite establishment could be disrupted. We observed indications of hormonal remodeling and nutrient restriction and suppression, which could potentially create an inhospitable environment for Plasmodium parasite development in Microsporidia MB -positive mosquitoes. Microbiota profiling further revealed the proliferation of taxa such as Serratia and Enterobacter , previously associated with parasite inhibition, in Microsporidia MB -positive mosquitoes. Conclusion Together, our data suggests that Microsporidia MB induces systemic changes in host metabolism, immunity, and gut microbial ecology to create an inhospitable environment for Plasmodium , supporting its potential as a sustainable transmission-blocking strategy.