Biology subjects

Mbaisi, L.

Publications and source records attributed to Mbaisi, L..

3 recordsLinked to original sources

bioRxiv2026

Suppression of Plasmodium falciparum infection by Microsporidia MB in wild Anopheles arabiensis populations

Symbiont-based approaches offer a promising strategy for reducing malaria transmission by suppressing Plasmodium development in Anopheles mosquitoes. Microsporidia MB, a naturally occurring microsporidian symbiont of Anopheles arabiensis, inhibits Plasmodium falciparum development in the laboratory, but its efficacy under natural transmission conditions is unknown. Here we monitored Microsporidia MB in wild An. arabiensis over 30 months in western Kenya and identified distinct low- and high-intensity infection phenotypes consistent with horizontal and vertical transmission, respectively. Overall, Microsporidia MB was associated with approximately 50% lower odds of P. falciparum infection. This association strengthened with symbiont intensity: high-intensity infections were associated with approximately 60% lower odds of Plasmodium infection compared with approximately 34% for low-intensity infections, identifying symbiont intensity as a key determinant of parasite-blocking efficacy. These findings provide evidence that Microsporidia MB suppresses P. falciparum infection in wild Anopheles populations, providing a key component of the field validation needed to advance Microsporidia MB as a candidate for malaria-control applications.

microbiology↗

bioRxiv2025

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

Microsporidia MB is an endosymbiotic microbe found in Anopheles mosquito populations. This symbiont can block Plasmodium transmission in mosquitoes, and it can spread through mosquito populations and be sustained over generations by vertical and horizontal transmission. These characteristics make Microsporidia MB a potential candidate for symbiont-based malaria vector control. However, the mechanistic basis of interactions between Microsporidia MB and Anopheles arabiensis is poorly characterized. We investigated how the presence of Microsporidia MB affects 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. arabiensis mosquitoes. We observed that mosquito infection with Microsporidia MB upregulated farnesoic acid O-methyltransferase, a gene linked to juvenile hormone biosynthesis in the non-blood-fed mosquitoes. In addition, blood feeding in Microsporidia MB positive mosquitoes was associated with an activation of immune-related genes 24 hours after a blood meal, where several genes including the lipopolysaccharide tumor necrosis factor gene were upregulated. Interestingly, we also observed that Microsporidia MB positivity was associated with a microbiota shift to favor the proliferation of microbes including Pseudomonas and Serratia 24 hours post blood meal. There were indications of immune system activation in Microsporidia MB positive mosquitoes up to 48 hours after a blood meal where factors such as the peptidoglycan recognition SC2-like and lysozyme c-1 were upregulated. Notably, an upregulated immune system at this time point was associated with downregulation of genes associated with metabolism and the restoration of Serratia, Pseudomonas and other key microbes to relative abundances similar to those recorded in non-blood-fed mosquitoes. At the 72-hour time point, Microsporidia MB positive mosquitoes exhibited a downregulation of genes associated with immunity, including cecropins and defensins, while metabolic processes were predominantly upregulated. Our results provide insights into the effect of Microsporidia MB infection on the An. arabiensis gene expression and gut microbiota profiles. This work will contribute to mechanistic insights into symbiont-mediated malaria transmission blocking.

systems biology↗

bioRxiv2019

A Microsporidian blocks Plasmodium falciparum transmission in Anopheles arabiensis mosquitoes

Malaria imposes an enormous burden on sub-Saharan Africa, and evidence that incidence could be starting to increase again1 suggests the limits of currently applied control strategies have now been reached. A possible novel control approach involves the dissemination in mosquitoes of inherited symbiotic microbes to block transmission. This strategy is exemplified by the use of transmission-blocking Wolbachia in Aedes aegypti against dengue virus2-7. However, in the Anopheles gambiae complex, the primary African vectors of malaria, there limited reports of inherited symbionts with transmission-blocking capacity8-10. Here we show that a newly discovered vertically transmitted species of Microsporidia symbiont in the An. gambiae complex blocks Plasmodium transmission. Microsporidia MB is present at moderate prevalence in geographically dispersed populations of An. arabienesis in Kenya, localized to the mosquito midgut and ovaries, and is not associated with significant reductions in adult host fecundity or survival. Field collected Microsporidia MB-infected An. arabiensis were never found to harbor P. falciparum gametocytes and on experimental infection with P. falciparum no sporozoites could be detected in Microsporidia MB-infected mosquitos. As a Plasmodium transmission-blocking microbe that is non-virulent and vertically transmitted, Microsporidia MB could be exploited as a novel malaria control tool.

microbiology↗