Induction of CD8(+) T cell-mediated protective immunity against Trypanosoma cruzi

Trypanosoma cruzi was transformed with the Plasmodium yoelii gene encoding the circumsporozoite (CS) protein, which contains the well-characterized CD 8(+) T cell epitope, SYVPSAEQI, In vivo and in vitro assays indicated that cells infected with the transformed T, cruzi could process and present this malaria parasite-derived class I MHC-restricted epitope, Immunization of m ice with recombinant influenza and vaccinia viruses expressing the SYVPSAEQ I epitope induced a large number of specific CD8(+) T cells that strongly s uppressed parasitemia and conferred complete protection against the acute T : cruzi lethal infection. CD8(+) T cells mediated this immunity as indicate d by the unrelenting parasitemia and high mortality observed in immunized m ice treated with anti-CD8 antibody. This study demonstrated, for the first time, that vaccination of mice with vectors designed to induce CD8(+) T cel ls is effective against T: cruzi infection.