Affiliation:
1. Department of Medicine, Division of Infectious Diseases,1 and
2. Department of Pathology, Division of Parasitology,2 Albert Einstein College of Medicine, Bronx, New York, and
3. Department of Biologic Sciences, Rutgers University, New Brunswick, New Jersey3
Abstract
ABSTRACT
Toxoplasma gondii
is a well-described ubiquitous Apicomplexan protozoan parasite that is an important opportunistic pathogen. The factors affecting the transition of tachyzoites to the latent bradyzoite stage remain to be defined. The induction of bradyzoite development in vitro has been linked to temperature, pH, mitochondrial inhibitors, sodium arsenite, and many of the other stressors associated with heat shock protein (hsp) induction. There is evidence for other organisms that hsps are developmentally regulated. Therefore, we examined whether hsp induction is an early event in bradyzoite differentiation. Extracellular and intracellular
T. gondii
cells, after exposure to pH 8.1 or 7.1, were analyzed for the expression of inducible hsp70 by using monoclonal antibody C92F3A-5 (specific to hsp70). Western blotting demonstrated that a 72-kDa protein reactive with C92F3A-5 (hsp70), which we believe is part of the hsp70 family, is induced during bradyzoite development. By immunofluorescence and immunoelectron microscopy, we were able to demonstrate that hsp70 staining colocalized to
T. gondii
expressing bradyzoite-specific antigens and the presence of hsp70 in bradyzoites isolated from mouse brain. Quercetin, a bioflavonoid which inhibits the synthesis of hsp90, hsp70, and hsp27, suppresses the induction of bradyzoite development in vitro. Reverse transcription-PCR with conserved hsp70 primers demonstrated an increase in hsp70 in
T. gondii
on exposure to conditions which induce bradyzoite formation. A
T. gondii
hsp70 was subsequently cloned and sequenced by using this amplified fragment. We believe our evidence suggests that hsps are important in the process of bradyzoite differentiation.
Publisher
American Society for Microbiology
Subject
Infectious Diseases,Immunology,Microbiology,Parasitology
Cited by
106 articles.
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