Study of the tsetse fly innate immunity to control the endosymbiotic bacterium Sodalis gossinidius and its impact on trypanosome transmission

Human African trypanosomiasis (HAT), also called sleeping sickness, and animal African trypanosomiasis (AAT) are vector-borne diseases occurring in sub-Saharan Africa. The causative agents of both diseases, African trypanosomes, are entirely dependent on the blood feeding tsetse fly (Glossina sp.) for their transmission. Tsetse flies also harbour three bacterial endosymbionts that influence the insect physiology, immune responsiveness and in turn, can affect trypanosome transmission2–4. In contrast to the anciently established obligate mutualist Wigglesworthia glossinidia, the impact of the more recently established commensal Sodalis glossinidius on tsetse biology is still very limited. Furthermore, our current knowledge on the molecular tripartite interactions between the bacterial symbiont Sodalis, the tsetse fly innate immune system and the trypanosome parasite represents a genuine black box. Therefore, the main goals of this PhD-project is to gain a deeper insight in the tsetse fly immune processes associated with the presence of the Sodalis endosymbiont, to identify specific immune components that tightly control the bacterial population and to evaluate their influence on trypanosome development and transmission.