Biology of Tsetse Symbionts

Wigglesworthia. Mutualistic bacteria enable tsetse to survive on a single diet-vertebrate blood. Wigglesworthia is an intracellular enteric bacterium with a reduced genome size of 700kb and reside in the bacteriome organ in anterior midgut. Also, extracellular Wigglesworthia cells reside in tsetse’s milk gland organ and are transmitted to the intrauterine larva in milk secretions. Our phylogenetic studies indicate that tsetse-Wigglesworthia interaction is ancient. Wigglesworthia WGS shows retention of various vitamin metabolic pathways and a functional flagellum. and displays congruence. In addition to host nutritient, Wigglesworthia plays a role in host immunity through activation of Pathogen Recognition Protein (PGRP-LB), which has putative antitrypanosomal functions.

Tsetse’s commensal symbiont Sodalis has wider tissue distribution and less integration with host biology. Sodalis is also transmitted to tsetse’s progeny through mother’s milk secretions. Sodalis genome size is similar to enteric microbes but it has many pseudogenes--indicative of an active process of functional erosion. Our studies suggest that Sodalis outer membrane protein (OmpA) plays a crucial role in symbiosis.

Parasitic Wolbachia is also present in some tsetse populations. The functional biology of Wolbachia in tsetse is under investigation in our group.