Expression of Toxoplasma gondii-Specific Heat Shock Protein 70 during In Vivo Conversion of Bradyzoites to Tachyzoites |
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| Authors: | Neide M. Silva Ricardo T. Gazzinelli Deise A. O. Silva Eloisa A. V. Ferro Lloyd H. Kasper Jose R. Mineo |
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| Affiliation: | Laboratory of Immunology, Department of Pathology, Universidade Federal de Uberlandia, Uberlandia 38400-902,1. Department of Biochemistry and Immunology, Universidade Federal de Minas Gerais, Belo Horizonte 31270-010,2. and Centro de Pesquisas Rene Rachou, FIOCRUZ, Belo Horizonte 30190-002,3. Minas Gerais, Brazil, and Department of Medicine (Neurology) and Microbiology, Dartmouth Medical School, Lebanon, New Hampshire 037564. |
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| Abstract: | Stage conversion between bradyzoites and tachyzoites was investigated in C57BL/6 mice chronically infected with the ME-49 strain of Toxoplasma gondii. In order to promote bradyzoite-tachyzoite conversion, mice were treated in vivo with neutralizing doses of anti-gamma interferon (IFN-γ) or anti-tumor necrosis factor alpha (TNF-α) antibodies. Expression of parasite-specific antigens SAG-1, SAG-2, and heat shock protein 70 (Hsp-70) was visualized in the central nervous system by immunocytochemistry and measured by photometric assay. The immunosuppressive effect of anti-IFN-γ or anti-TNF-α treatment was immediate, leading to parasite stage conversion as indicated by the increased expression of tachyzoite-specific antigens (SAG-1 and SAG-2) and by rapid parasite replication. We also observed expression of high levels of Hsp-70 during a short period of conversion of bradyzoites to tachyzoites. Our data suggest that Hsp-70 may have an important role in the process of bradyzoite-tachyzoite conversion during the reactivation of chronic toxoplasmosis. |
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