Persistence of Strain-Specific Behavior in Two Strains of Trypanosoma cruzi after Prolonged Transfer through Inbred Mice

Abstract

Two lethal, immunologically cross-reactive, and morphologically indistinguishable strains of T. cruzi, originally isolated from human patients, were maintained for 28 and 41 mos., respectively, by serial transfer through mice. By the use of genetically homogeneous hosts (homozygosity over 98%) of the same sex and comparable age kept on a standardized diet and infected at regular intervals with uniform inocula, the majority of variables, which enter into determining virulence levels, were controlled. The more virulent WBH strain showed a pronounced rhythmic response to seasonal temp. fluctuations, and was more susceptible to the quinoline derivative Bayer 7602 than the B-strain. These differences in behavior are interpreted as brought about entirely by the parasite''s inherent strain-specific physiol. pattern, rather than by environmental variables.