<i>Delftia tsuruhatensis</i> TC1 symbiont suppresses malaria transmission by anopheline mosquitoes

Abstract

Malaria control demands the development of a wide range of complementary strategies. We describe the properties of a naturally occurring, non-genetically modified symbiotic bacterium, <i>Delftia tsuruhatensis</i> TC1, which was isolated from mosquitoes incapable of sustaining the development of <i>Plasmodium falciparum</i> parasites. <i>D. tsuruhatensis</i> TC1 inhibits early stages of <i>Plasmodium</i> development and subsequent transmission by the <i>Anopheles</i> mosquito through secretion of a small-molecule inhibitor. We have identified this inhibitor to be the hydrophobic molecule harmane. We also found that, on mosquito contact, harmane penetrates the cuticle, inhibiting <i>Plasmodium</i> development. <i>D. tsuruhatensis</i> TC1 stably populates the mosquito gut, does not impose a fitness cost on the mosquito, and inhibits <i>Plasmodium</i> development for the mosquito's life. Contained field studies in Burkina Faso and modeling showed that <i>D. tsuruhatensis</i> TC1 has the potential to complement mosquito-targeted malaria transmission control.