RELATIONSHIPS BETWEEN HOST BLOOD FACTORS AND PROTEASES IN GLOSSINA-MORSITANS SUBSPECIES INFECTED WITH TRYPANOSOMA-CONGOLENSE

Host blood effects on Trypanosoma congolense establishment in Glossina morsitans morsitans and Glossina morsitans centralis were investigate d using goat, rabbit, cow and rhinoceros blood. Meals containing goat erythrocytes facilitated infection in G.m.morsitans, whereas meals con taining goat plasma facilitated infection in G.m.centralis. Goat blood effects were not observed in the presence of complementary rabbit blo od components. N-acetyl-glucosamine (a midgut lectin inhibitor) increa sed infection rates in some, but not all, blood manipulations. Cholest erol increased infection rates in G.m.centralis only. Both compounds t ogether added to cow blood produced superinfection in G.m.centralis, b ut not in G.m.morsitans. Midgut protease levels did not differ 6 days post-infection in flies maintaining infections versus flies clearing i nfections. Protease levels were weakly correlated with patterns of inf ection, but only in G. m. morsitans. These results suggest that physio logical mechanisms responsible for variation in infection rates are on ly superficially similar in these closely-related tsetse.