Immune response against Trypanosoma cruzi antigens in Cebus apella monkeys

The american primate Cebus apella has been used as an experimental model for the study of acute and chronic Chagas' disease. The antibody response elicited by 4 x 10(6) blood trypnomastigotes injected into four monkeys was analysed. Peak titres of IgM and IgG of anti-Trypanosoma cruzi antibodies were found at day 22, and between days 20 and 40 post-infection (p.i.), respectively. The ability of a Mr 37kDa (T37K) glycoprotein purified from T. cruzi epimastigotes to generate IgG anti-T. cruzi antibodies in monkeys, and protect them against a challenge with trypomastigotes, was also studied. Monkeys non-immunized with T37K reached peak values of parasitaemia between days 18 and 21 post-infection, whereas immunized monkeys had lower parasitaemias without important variation. Anti-T37K antibodies in immunized monkeys decreased from day 2 with the lowest titres between days 14 to 22 p.i., coincident with the peak of parasitaemia in control non-immunized monkeys. These results suggest that anti-T37K antibodies could be responsible for the low parasitaemia detected in immunized monkeys.