African trypanosomes. Cultivation of animal infective Trypanosoma brucei in vitro

Trypanosoma brucei grew in the presence of bovine fibroblast-like cells in Hepes-buffered RPMI 1640 medium with 20 percent fetal bovine serum for more than 220 days at 37°C. The organisms grown in this system were infective to mammalian hosts, retained the morphological and biochemical characteristics of long slender bloodstream forms, and displayed variant-antigen on their surfaces.