Passive immunization of mice against Trypanosoma cruzi using convalescent mouse serum.

Groups of 10 mice were infected by the s.c. injection of blood trypomastigotes of Trypanosoma cruzi, strains "Y" and "Tulahuen". They were injected i.p. with convalescent mouse-anti-T. cruzi serum (CMATS) at various times. A single dose of CMATS (Y) was most effective when injected one day after homologous infection -31 of 40 mice survived the infection, whereas all controls, both untreated and injected with normal serum, died. CMATS was significantly less effective in treating mice infected with the Tulahuen strain. Sera from animals immunized with killed epimastigotes or trypomastigotes showed only very slight passive immunizing properties.