Immunization of mice against Trypanosoma cruzi: the effect of chemical treatment or immune serum on an epimastigote vaccine.

Groups of long Evans and CD-1 mice were immunized with vaccines prepared from epimastigotes of Trypanosoma cruzi, strains Y and Tulahuen, modified by various chemical means, or by the addition of immune sera. Freeze-thawed epimastigotes were used as a control antigen. Freeze-thawed epimastigotes, with and without saponin as adjuvant, gave significant protection against challenge with homologous trypomastigotes. Similar levels or protection were obtained in mice vaccinated with living epimastigotes. Treatment of epimastigotes by various chemical means, including sodium perchlorate failed to increase their immunogenicity, but did not reduce it. The addition of immune serum to the antigen may have slightly increased its immunogenicity.