Differentiation between Trypanosoma cruzi and T. rangeli by their different complement sensitivity.

Four-day-old culture forms of T. cruzi strains (Col-83, Y, OPS-31, OPS-32, PF, V, P-60), T. cruzi-like strains (WA-301, CL, FL, MR, Castro Alves, Téhuantépéc, P), T. rangeli strain V and T. rangeli-like strain DA 3412 were tested with the following sera: mouse, NMRI-HAN, germ-free; rat, Wistar HAN, germ-free; guinea-pig, PBW:HAN, SPF; normal fresh guinea-pig, hen, rabbit and human sera, heat inactivated guinea-pig serum and normal fresh guinea-pig serum plus EDTA. Incubation of normal fresh guinea-pig, rabbit, rat and human sera lysed the epimastigote forms of T. cruzi and T. cruzi-like strains but not the culture forms of the T. rangeli and T. rangeli-like strains. Mouse serum did not lyse the culture forms of both trypanosome species while the hen serum lysed all culture forms of T. cruzi, T. cruzi-like as well as T. rangeli and T. rangeli-like. Using DEAE 52 cellulose it was possible to separate the metacyclic forms of T. cruzi and T. cruzi-like from the lysed epimastigote stages. A small number of epimastigote forms of T. cruzi and T. cruzi-like are lysis-resistant against normal fresh guinea-pig serum. Fresh normal guinea-pig, rat, rabbit and human sera can be used for the distinction between T. cruzi, T. cruzi-like and T. rangeli, T. rangeli-like.