The behavior of three strains o/Trypanosoma cruzi, classijied according to their morphobiological, histopathological and isoenzymic characters, as Typel (Peruvian strain), Type II (21 SF strain) and TypelII (Colombian strain), was evaluated by the infection of six inbred strains of mice: A/J, AKR, Balb/c C3H, C57BL/10 and DBA. It was observed that the three strains of T. cruzi maintained their basic characteristic in respect to parasitemia, survival time, histopathological lesions and tissue tropism in all the mouse strains. The Peruvian strain (Type I) resulted in a high mortality in all the animals; on the other hand the infection with the 21 SF (Type II) and Colombian /Type III) strains displayed a variable pattem of mortality determining a singular spectrum of resistance to eachparasite strain. Early decrease of IgG1 and Progressive rise of IgG2a> IgG2b and IgM leveis, was observed, independently of the mouse or the parasite strain. There was a correlation between increased IgG2a leveis and intensity of the inflammatory process. Exudative lesions with polymorphonuclear neutrophils occurred in the resistant mice while a scarce infiltrate with predominance of mononuclear cells was observed in the more suceptible mouse strain. Our results suggest that the characteristics of T. cruzi strains are of the upmost importance in the course of the infection, but the host strain also plays a very important role in the process.
Trypanosoma cruzi; Strain of T. cruzi; Strain types; Isogenic mice