The Properties of some Antigens of Trypanosoma brucei

Abstract

SUMMARY: A soluble trypanosomal antigen occurs in the serum of rats infected with Trypanosoma brucei. This ‘exoantigen’ is probably not a protein and is electrophoretically a slow-moving component in the serum. The exoantigen which is also present on the surface as an agglutinogen appears to protect the trypanosomes against adverse environment, preserving their infectivity for long periods in vitro. Rats and mice immunized with exoantigen are protected against infection with the homologous strain of T. brucei. Rabbits infected chronically with T. brucei form antibodies to exoantigen. On disintegration of the trypanosomes, in addition to exoantigen, ‘bound’ antigens are released. In the natural disease exoantigens induce antibodies which may be concerned with protection against further infection.