Production and characterization of clones of the Brazil strain of Trypanosoma cruzi

Abstract

Six clones and 4 subclones were isolated from the Brazil strain of Trypanosoma cruzi and were passaged in C3H(He) mice. Parasitemia levels and survival times of mice infected with 8 of the isolates were equivalent to the Brazil strain in virulence. Two clones, designated WFTc-5.1 and WFTc-6.1 (WFTc = Wake Forest Trypanosoma cruzi) were of lower virulence in C3H mice than the other isolates and the Brazil strain. C57BL/6 mice infected with WFTc-5.1 had significantly lower parasitemias and higher survival rates than C57BL/6 mice infected with the Brazil strain or a clone designated WFTc-3.2. Levels of anti-T. cruzi IgM and IgG antibodies were the same in mice infected with higher virulence or lower virulence isolates. Based on these results the Brazil strain of T. cruzi is composed of distinct subpopulations which are heterogeneous with respect to virulence.