Mice Intragastric Infected with Insect and Blood Trypomastigotes of Trypanosoma cruzi IV: Differences and Similarities on the Evolution Profile and Response to Etiological Treatment.

PURPOSE: Our goal was to analyze the outcome of infection and response to benznidazole (BZ) treatment in mice intragastrically inoculated with trypomastigotes forms of Trypanosoma cruzi from different origins. METHODS: Twenty-four Swiss mice were divided in two groups and inoculated, by gavage, with 1 × 104 blood trypomastigotes (BT) or insect-derived metacyclic trypomastigotes (IT) of AM14 strain (T. cruzi IV). Half of the animals of each group were treated with BZ (TBZ), from 10 to 30th days after the inoculation, and the other constituted the untreated control groups (NT). After the etiological treatment, all mice were immunosuppressed with cyclophosphamide for three weeks. Parasitological and molecular parameters, infectivity, cumulative mortality, and reactivation post-immunosuppression rates were obtained. RESULTS: Animals inoculated with BT showed lower pre-patent period and early day of the maximum parasitemia, as well as a higher maximum peak of parasitemia than the IT animals. However, both, BT and IT animals, did not respond to BZ treatment (0.0% of cure). CONCLUSION: We conclude that the infective form influences in the outcome of infection, but not the response to the etiological treatment in mice intragastrically infected with the T. cruzi IV strain studied.