Strain specific protective immunity against Trypanosoma cruzi.

Swiss albino, C57BL/10J, and B10.A mice previously inoculated with an LD50 dose of T. cruzi Y strain were protected against subsequent challenge with the homologous strain, but had a parasitemia comparable to that of control mice when challenged with F strain trypomastigotes, although they were protected against mortality. In contrast, animals previously inoculated with an LD50 of T. cruzi F strain were protected both against a subsequent challenge with the homologous strain and the Y strain.