A microsporidian impairs Plasmodium falciparum transmission in Anopheles arabiensis mosquitoes

Abstract

A possible malaria control approach involves the dissemination in mosquitoes of inherited symbiotic microbes to block Plasmodium transmission. However, in the Anopheles gambiae complex, the primary African vectors of malaria, there are limited reports of inherited symbionts that impair transmission. We show that a vertically transmitted microsporidian symbiont (Microsporidia MB) in the An. gambiae complex can impair Plasmodium transmission. Microsporidia MB is present at moderate prevalence in geographically dispersed populations of An. arabiensis 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 tested negative for P. falciparum gametocytes and, on experimental infection with P. falciparum, sporozoites aren't detected in Microsporidia MB infected mosquitoes. As a microbe that impairs Plasmodium transmission that is non-virulent and vertically transmitted, Microsporidia MB could be investigated as a strategy to limit malaria transmission.

Mosquito Mycobiota: An Overview of Non-Entomopathogenic Fungal Interactions

“…It was shown that the number of oocysts in microsporidian-infected mosquitoes is strongly reduced compared to uninfected ones (58% vs. 81%) [63]. Similarly, Microsporidia MB, which is another example of microsporidia with non-deleterious effects, is found in the midgut and ovaries of Anopheles arabiensis and alters the development of Plasmodium falciparum by stimulating the expression of genes encoding digestive enzymes such as serine proteases, as well as the immune response (cecropins and gambicins) [64]. Strains of W. anomalus unable to produce killer toxins reduce the intensity of P. berghei infection in Anopheles mosquitoes by 38% probably through the activation of the mosquito immune system [57].…”

Biopesticide Research and Product Development in Africa for Sustainable Agriculture and Food Security – Experiences From the International Centre of Insect Physiology and Ecology (icipe)

“…transmission. As a microbe that is nonvirulent and vertically transmitted, Microsporidia MB could be investigated as a strategy to limit malaria transmission (Herren et al, 2020).…”

Vector-Focused Approaches to Curb Malaria Transmission in the Brazilian Amazon: An Overview of Current and Future Challenges and Strategies

“…More recently, a symbiont microsporidian (Microsporidia MB) that colonizes An. arabiensis from Kenya, was shown capable of blocking P. falciparum development and transmission, providing a new prospect for malaria control [201]. Host-baited traps, odour-baited traps, resting traps, and sugar-baited traps have been proposed as possible ways of delivering these agents to mosquitoes [202].…”