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https://www.arca.fiocruz.br/handle/icict/14757
SPECIFIC IMMUNIZATION OF MICE AGAINST LEISHMANIA MEXICANA AMAZONENSIS USING SOLUBILIZED PROMASTIGOTES
Affilliation
Fundação Gonçalo Moniz. Centro de Pesquisas Gonçalo Moniz. Salvador, BA, Brasil / Universidade Federal da Bahia. Salvador, BA, Brasil / Cornell University Medical College. New York, NY
Fundação Gonçalo Moniz. Centro de Pesquisas Gonçalo Moniz. Salvador, BA, Brasil / Universidade Federal da Bahia. Salvador, BA, Brasil / Cornell University Medical College. New York, NY
University of Louisville. School of Medicine. Department of Microbiology and Immunology. Louisville, KY
University of Louisville. School of Medicine. Department of Microbiology and Immunology. Louisville, KY
Fundação Gonçalo Moniz. Centro de Pesquisas Gonçalo Moniz. Salvador, BA, Brasil / Universidade Federal da Bahia. Salvador, BA, Brasil / Cornell University Medical College. New York, NY
University of Louisville. School of Medicine. Department of Microbiology and Immunology. Louisville, KY
University of Louisville. School of Medicine. Department of Microbiology and Immunology. Louisville, KY
Abstract
Successful immunization of highly susceptible BALB/c mice against progressive infection
by Leishmania mexicana amazonensis, using whole solubilized promastigotes was
achieved. The best immunization schedule consisted of three weekly injections of 5 x 107
parasite equivalents. Intravenous was superior to intraperitoneal or subcutaneous
immunization. Protection persisted for up to 2 months after immunization, and beneficial
effects could be observed in long-term follow-up (24 weeks after infection). Immunized
mice exhibited marked reduction in primary lesion size, as well as reduction of the number
of parasites in the spleen, and developed less metastases. High titres of specific anti-L. m.
amazonensis IgG antibodies resulted from immunization, but titres did not correlate with
protection. Groups with widely differing pre-infection antibody titres were equally
protected, and similar antibody titres resulted in different levels of protection. Immunization
alone did not induce significant serum interferon-gamma levels and specific delayedtype
hypersensitivity (DTH) reactions, but resulted in the persistence of positive (DTH)
reactions after infection, at a time when infected control animals had suppressed
responses. Resistance to leishmaniasis appears to depend on cell mediated immune
mechanisms, and the possibility of immunization with a solubilized antigen without
adjuvant is intriguing and opens new perspectives in this area.
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