Lectin mediated establishment of midgut infections of Trypanosoma congolense and Trypanosoma brucei in Glossina morsitans.

D+Glucosamine, which has been shown in vitro to specifically inhibit tsetse midgut lectin activity, when fed to Glossina morsitans morsitans with the infective feed significantly increased midgut infection rates of Trypanosoma congolense and T. brucei rhodesiense. All flies infected with T.b. rhodesiense and maintained on a diet of blood with D+Glucosamine throughout their lives developed midgut infections. Midgut extracts from flies bred for refractoriness to infection with trypanosomes showed significantly greater erythrocyte agglutinating activity and were more trypanocidal in vitro than flies bred for susceptibility to trypanosome infection. It is concluded that susceptibility to trypanosome infection in tsetse is mediated through midgut lectins.