Immunization and enhancement properties of the circulating antigens of Trypanosoma cruzi

Circulating antigens or exoantigens of trypanosomal origin were first demonstrated in the serum of rats infected with Trypanosoma brucei by WEITZ (1960). Subsequently the presence of these types of antigens has been demonstrated in hosts infected with T. vivax by GRAY (1961), with T. Iewisi by D’ALESSANDRO (1972), and with T. cruzi by SIQUEIRA et al. (1966), DZBENSKI (1974) and ARAUJO (1976). The nature and the role of these antigens in the course of the infection are not yet clear. WEITZ (1960) reported that rats can be immunized by repeated injection of exoantigens of T. brucei, and that exoantigens of this trypanosome are able to enhance an infection when added to the trypanosome inoculum just before inoculation into rats (WEITZ, 1963). In this paper we present results of experimental investigations of the immunizing and enhancing activities of exoantigens of T. cruzi.