Trypanosoma cruzi: requirements for induction and maintenance of protective immunity conferred by immunization |
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Authors: | Paiva Cláudia N Pyrrho Alexandre S Ribeiro Liane J Gonçalves Renata Costa Deise A Araujo-Jorge Tania C Soares Milena B P Gattass Cerli R |
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Institution: | 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 |
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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. |
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