Publication Date

8-1-1995

Degree Program

Department of Biology

Degree Type

Master of Science

Abstract

It has been demonstrated that changes in environmental temperature can influence the resistance of mice to Trypanosoma cruzi (the causative agent of Chagas' disease in humans) infection. This increased resistance is not only reflected by decreased parasitemias and increased longevity but also by enhanced parasite-specific and nonspecific immune responsiveness in infected mice. The antibody response to heterologous antigen has been demonstrated to be greatly enhanced in infected mice held at elevated temperature. However, the parasite-specific antibody response was reported to be lower in infected mice maintained at 36°C than at room temperature (RT) during early stage of infection, although it could be elevated to higher levels through a boosting injection of parasites. It also has been demonstrated that T. cruzi produces abundant heat shock proteins (Hsp), typically Hsp90, Hsp70 and Hsp60, that are highly immunogenic. It was of interest, therefore, to determine whether different parasite antigens are produced by T. cruzi at different temperatures, and if so, whether these antigens would be recognized by antisera from mice held at either RT or 36°C. Trypomastigotes of T. cruzi were metabolically labeled with 35S-methionine/cysteine at 36, 39 and 42°C. Immunoprecipitation analysis was used to detect parasite antigens recognized by these antisera collected at various times post-infection. The results of this study indicated that 1) an elevated environmental temperature of 36°C provides a significant resistance to T. cruzi infection in infected mice. This temperature-related resistance to T. cruzi infection is effective during the first few days of hyperthermia; 2) the Hsp70 and Hsp90 heat inducible parasite proteins are highly immunogenic, recognized by antibodies very early in infection continuing with increasing intensity throughout infection; 3) the antibody response may play an important role in temperature-related resistance to T. cruzi infection very early in infection by targeting parasite Hsps whose increased production is induced at elevated temperature.

Disciplines

Medical Sciences

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