Control of Antigenic Variation in African Trypanosomas

Trypanosomes are unicellular organisms belonging to the Kinetoplastida, a group of protozoa that diverged early from the eukaryotic lineage (Sogin et al. 1989). The African trypanosomes, such as Trypanosoma brucei (Fig. 1), are parasites of mammals that cause a low-grade innocuous chronic infection of wild life in central Africa. T. brucei is transmitted between mammals by the tsetse fly. Most African trypanosome species, including T. brucei brucei, cannot infect primates. However, host-range mutants of T. brucei, called T. brucei gambiense and T. brucei rhodesiense, have adapted to humans and cause sleeping sickness.