title: Trypanosoma cruzi: requirements for induction and maintenance of protective immunity conferred by immunization.
abstract: Immunization with CL-14-trypomastigotes generates efficient humoral and cellular responses against infective challenge. Herein, we investigated the relevance of these mechanisms in vivo. Immunization with live CL-14-trypomastigotes protected only part of beta2m(-/-) mice but efficiently protected perforin-knockout mice. Fixed CL-14-trypomastigotes could successfully immunize BALB/c, though live trypomastigotes lowered the requirements for doses and time intervals. Post-immune depletion of CD4 or CD8 subsets did not affect protection conferred by immunization, but switched the production of anti-Trypanosoma cruzi antibodies to IgG2a. Sublethal irradiation partially broke the resistance of immune mice, leading to development of late parasitemia. Passive serum transfer from immune mice conferred protection to nai;ve mice. Our results indicate that presentation of cytosolic antigens by MHC class I molecules is involved in the generation of immunity and suggest that the humoral response contributes to a great extent to keep CL-14-immunized mice protected against infective challenge.
authors.affiliation: Laboratório de Imunoparasitologia, Instituto de Biofísica Carlos Chagas Filho, Universidade Federal do Rio de Janeiro, 21941-900, RJ, Rio de Janeiro, Brazil. cnpaiva@iname.com
authors.forename: Cláudia N
authors.initials: CN
authors.lastname: Paiva
authors.forename: Alexandre S
authors.initials: AS
authors.lastname: Pyrrho
authors.forename: Liane J
authors.initials: LJ
authors.lastname: Ribeiro
authors.forename: Renata
authors.initials: R
authors.lastname: Gonçalves
authors.forename: Deise A
authors.initials: DA
authors.lastname: Costa
authors.forename: Tania C
authors.initials: TC
authors.lastname: Araujo-Jorge
authors.forename: Milena B P
authors.initials: MB
authors.lastname: Soares
authors.forename: Cerli R
authors.initials: CR
authors.lastname: Gattass
mesh_terms: D000818:Animals; D000913:Antibodies, Protozoan / Q000097:blood; D016026:Bone Marrow Transplantation / Q000276:immunology; D015496:CD4-Positive T-Lymphocytes / Q000276:immunology; D018414:CD8-Positive T-Lymphocytes / Q000276:immunology; D014355:Chagas Disease / Q000276:immunology / Q000517:prevention & control*; D005260:Female; D007111:Immunity, Cellular; D007114:Immunization; D007116:Immunization, Passive; D007074:Immunoglobulin G / Q000097:blood; D008221:Lymphoid Tissue / Q000276:immunology / Q000528:radiation effects; D008297:Male; D008562:Membrane Glycoproteins / Q000235:genetics; D051379:Mice; D008807:Mice, Inbred BALB C; D018345:Mice, Knockout; D018512:Parasitemia / Q000276:immunology / Q000517:prevention & control; D054353:Perforin; D052899:Pore Forming Cytotoxic Proteins; D014349:Trypanosoma cruzi / Q000276:immunology*; D014916:Whole-Body Irradiation; D001613:beta 2-Microglobulin / Q000235:genetics
chemical_list: D000913:Antibodies, Protozoan; D007074:Immunoglobulin G; D008562:Membrane Glycoproteins; D052899:Pore Forming Cytotoxic Proteins; D001613:beta 2-Microglobulin; D054353:Perforin