Trypanosoma brucei brucei binds human complement regulatory protein C4BP

The uniflagellate protozoan parasite Trypanosoma brucei multiplies extracellularly in blood and escapes elimination by the complement system. Activated complement elicits potent biological activities including direct lysis of pathogens (Mollnes et al., 2002; Song et al., 2000; Walport, 2001). One strategy adopted by pathogens to avoid clearance and destruction by complement is to acquire host fluid-phase regulators, like C4b-binding protein or factor H. The acquisition of fluid-phase regulators on the surface of a given pathogen normally results in downregulation of complement activation.