Serum factors and the maturation of Trypanosoma congolense infections in Glossina morsitans.

Removal of certain components from pig or cow blood greatly reduces the maturation rate of Trypanosoma congolense infections in Glossina morsitans fed on such diets. In particular, delipidation of serum has the same effect as complete removal of dietary serum with few midgut infections reaching maturity. The addition of gamma-globulin to red cells partially restores the ability of immature infections to transform suggesting that serum lipids or other serum factors are not acting directly on midgut trypanosome metabolism but indirectly through interactions between dietary constituents and the flies' metabolic processes. As susceptibility to T. congolense infection is known to be maternally inherited in G. morsitans, it is suggested that serum factors act through the flies' symbionts to induce maturation in midgut infections.