Differentialin Vitroandin VivoBehavior of Three Strains ofTrypanosoma cruziin the Gut and Hemolymph ofRhodnius prolixus

Abstract

A comparison was made of the agglutination and lysis of three strains ofTrypanosoma cruziin gut extracts and hemolymph ofRhodnius prolixusand the results obtained were correlated with the success or failure of the parasite strain to infect the digestive tube or to survive in the hemocel after inoculation. BothT. cruzistrains Dm28c and Cl successfully infected the gut as evidenced by over 50% of adult insects having infective feces and urine 35 days after feeding with parasites. Concomitantly, both of these strains were agglutinated but not lysed by the crop extracts. In contrast,T. cruziY strain parasites rapidly disappeared from the gut and showed no agglutination, but some lysis, in the crop extract. Following inoculation into the hemocel, only the Cl strain survived at high levels and was also the only strain agglutinated significantly in the hemolymph. Both Dm28c and Y strains rapidly disappeared from the hemocel with the former parasite being removed more slowly than the latter, probably due to clearance by the cellular defenses. The rapid clearance of the Y strain was correlated with the presence of a high titer lysin in the hemolymph. Subsequent experiments using FITC-labeled lectins and FACS to probe the carbohydrates on the parasite surfaces showed significant differences between the three strains. Thus, only Dm28c was stained strongly byArachis hypogea(PNA) lectin, indicating the presence of galactose/N-acetylgalactosamine residues, and Dm28c and Y strains byPhytolaccalectin forN-acetyl glucosamine moieties. Finally, the fact that, in contrast to Dm28c and Y, the Cl strain strongly interacted withTriticum vulgaris(WGA) but not withPhytolaccalectin may be due to the presence ofN-acetyl neuraminic acid residues on these organisms. These surface carbohydrate differences may be correlated both to the behavior and agglutination variations between the three strains recorded in thiswork.