TRYPANOSOMA-RANGELI - INCREASE IN VIRULENCE WITH INOCULA OF DIFFERENTORIGINS IN THE EXPERIMENTAL-INFECTION IN MICE

We compared two murine models of Trypanosoma rangeli infection. The sa me inoculum dose and age-matched hosts were used in both cases. One gr oup was infected with trypomastigotes obtained from passages in mice a nd the other, with trypomastigotes obtained from cell culture after a passage in mice. We observed that trypomastigotes obtained from the in vitro cellular infection showed increased virulence in experimental a nimals, with a 70% rate of death being noted in experimental mice inst ead of the lack of mortality seen when in vivo-derived parasites were used. The greatest levels of parasitemia and tissual lesions in the pr esence of the parasite also occurred when in vitro-derived parasites w ere used. The very low levels of parasitemia caused by the parasite an d the briefness of its presence in experimental animals (Urdaneta-Mora les and Tejero 1985) have made the study of T. rangeli difficult. Also important is the scarcity of studies about the influence of several f actors involved in the infection, such as the parasite strain, the ino culum dose, and the hosts age, sex, and immune response. The present w ok describes a comparative murine model of infection using trypomastig otes obtained from mice and from cellular culture. The parasitemia ind uced in and mortality of the experimental animals as well as the histo pathology of different tissues from these infected animals were studie d.