Lack of protection against Trypanosoma cruzi by multiple doses of T. lewisi culture forms. A discussion on some strains of "lewisi"

No protection against Trypanosoma cruzi was afforded to mice by previously inoculating multiple doses of T. lewisi blood stream forms, strain RU or culture forms of the IMT strain.Since these results conflicted with those obtained by other authors, we secured a sample of the strain used by them. This strain, labeled “T. lewisi” and which we called “F”, was verified to be actually T. cruzi. It was characterized by its morphologic features in axenic cultures, its capability to infect HeLa cells where the intracellular cycle was completed, by its infectivity for white mice which had amastigotes in their heart muscle, and in which the strain has been maintained by serial passages, and by the completion of its biologic cycle in triatoma bugs.The necessity for carefully testing doubtful strains, and the criteria to be adopted in these cases are discussed.