Investigation of the anti-Plasmodium properties of the Yeast Candida oleophila in the Malaria Mosquito, Anopheles gambiae

Plasmodium falciparum is a causative agent of malaria and a significant global health burden. The primary vector of P. falciparum in sub-Saharan Africa is the Anopheles gambiae species complex. Plasmodium species infect approximately 500 million people and cause nearly 1 million deaths annually. Current control efforts are hampered by drug resistant P.falciparum parasites and insecticide resistant mosquitoes. In the continuing effort to control malaria infection, microbes native to the midgut are being studied for species that can inhibit P. falciparum. While the bacteria of the mosquito microbiome have been well studied, few studies have explored fungi and yeast in the mosquito microbiome. Presented here is research on a Candida oleophila yeast isolated from the An. gambiae midgut that shows significant inhibitory effects on the P. falciparum parasite in vivo. We have assessed the inhibition of P. falciparum development in vivo and in vitro, as well as the impact of the presence of this yeast on the midgut bacterial flora and vector survival. This yeast isolate inhibits P. falciparum in a pre-oocyst stage through a secreted factor; numbers of oocysts are significantly reduced in those An. gambiae harboring yeast or supernatant filtrate in their midguts. An. gambiae harboring yeast in their midgut experience expansions in midgut bacteria populations, but no change in cohort survival was observed