Tsetse flies (Diptera: Glossinidae; Glossina spp.) are the sole vectors for African trypanosomiasis, which kills thousands of people and at least 3 million animals each year throughout subsaharan Africa. The causative agents are protozoan trypanosomes (Euglenozoa:Kinetoplastida; Trypanosoma brucei spp.) that are transmitted to humans by tsetse during blood feeding. Tsetse species vary in their ability to transmit the parasite (vector competence). Among factors influencing parasite transmission are physical barriers (e.g., peritrophic matrix), lectins, commensal bacteria, and the immune response (cellular and humoral). Within the morsitans species complex, G. pallidipes has been shown to be more refractory than closely related G. m. morsitans. Comparative analysis of the humoral immune-responsive pathways (i.e. to bacteria, to trypanosomes) between these tsetse species can give insight into the role of the immune system in refractoriness. Several genes integral to the imd pathway of the immune response (induced primarily against Gram-negative bacteria in Drosophila) were identified from a tsetse midgut EST library. The expression of these genes was investigated by Northern and RT-PCR analysis under various immunological states (normal, bacterial challenged, trypanosome challenged, midgut trypanosome infection) and from midgut and fat-body tissues. Although immune responses to artificial challenge with bacteria and trypanosomes were similar, the responses to established trypanosome infections were different between the two species. Genes typically involved in the antibacterial response (PGRP, relish, attacin) were transcriptionally activated in infected G. m. morsitans, yet were downregulated in infected G. pallidipes. The reason for these differences and their implications relative to vector competence will be discussed.
Back to Ten-Minute Papers, Section D. Medical and Veterinary Entomology
Back to Ten-Minute Papers, Section D. Medical and Veterinary Entomology
Back to The 2003 ESA Annual Meeting and Exhibition