Vaccination with live epimastigotes of Trypanosoma rangeli protects mice against Trypanosoma cruzi lethal infection

RESUMO

Trypanosoma cruzi and Trypanosoma rangeli share geographical areas, vectors and hosts. Although both parasites are antigenically similar, T. rangeli is not pathogenic for humans. In consequence, T. rangeli have been experimentally employed as immunogen to protect against T. cruzi infection. The aim of this work was to analyze the evolution of T. cruzi infection in mice previously vaccinated with live epimastigotes of T. rangeli obtained from cultures, and to measure TNF-alfa, IL12 and IL-18 productions. The evolution of the T. cruzi (Tulahuen strain) infection was evaluated by parasitemia levels, survival of Balb/c mice, tissue lesions and/or the presence of parasites. Cytokine levels were measured by an immuno-enzyme assay technique. The mice that were not vaccinated, died in the acute stage of infection with high parasitemias, nests of amastigotes and inflamatory foci in heart and skeletal muscle tissues, associated with high TNF-alfa levels. On the order hand, mice that were previously infected with T. rangeli, survived the acute stage of T. cruzi infection with low TNF-alfa level and high IL-18 level. In conclusion, this work describes a new model of immunization with T. rangeli associated with resistance to T. cruzi infection with modulation of proinflammatory TNF-alfa and increased IL-18 serum level.