Corynebacterium parvum as an adjuvant for Trypanosoma cruzi epimastigote vaccines: a comparison with saponin and Bordetella pertussis.

The effect was compared in CBA mice of adding Corynebacterium parvum, saponin, and Bordetella pertussis to living or killed Trypanosoma cruzi (Y strain) epimastigote vaccines on the induction of protective immunity against subcutaneous (s.c.) challenge with blood trypomastigotes. The addition of C. parvum to a low dose of T. cruzi vaccine, which alone was non-protective, generated a greater degree of protection than did saponin or B. pertussis. C. parvum alone increased resistance to infection to a variable and usually weak extent. The addition of C. parvum to larger doses of T. cruzi vaccine, which were themselves sufficient to elicit some degree of protection, improved resistance when the challenge was given 1 or 12 weeks after immunization, but lowered it at 3 weeks. It is concluded that the comparative efficacy of adjuvants for T. cruzi vaccines needs to be assessed on 3 parameters: (1) the dose of antigen, (2) the dose of adjuvant and (3) the time interval between immunization and challenge.