Leishmania transmission is disrupted in sandflies colonized by Delftia tsuruhatensis TC1 bacteria

Most human pathogenic Leishmania species are zoonotic agents; therefore, sandfly-based control strategies are essential to prevent parasite circulation. Here, we used a Delftia tsuruhatensis strain that inhibits the development of Plasmodium in mosquitoes, but in the context of Leishmania-infected sandflies. We show that D. tsuruhatensis TC1 colonizes the midgut of Phlebotomus duboscqi sandflies and impacts the development of L. major parasites, independently of the colonization timing. This phenotype is likely an indirect consequence of D. tsuruhatensis colonization, related with the induction of sandfly gut dysbiosis. Importantly, Leishmania-infected, bacteria-fed sandflies are less able to transmit L. major parasites and cause disease in mice. Modelling supports the disruption of disease endemicity in the field, highlighting D. tsuruhatensis as a promising agent for the control of leishmaniasis. These are 16S V34 rRNA data (primer sequences CCTAYGGGRBGCASCAG,GGACTACNNGGGTATCTAAT) corresponding to 42 samples. The primer and barcode sequences have been removed.