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Infect Immun, August 1998, p. 3959-3963, Vol. 66, No. 8
0019-9567/98/$04.00+0
Copyright © 1998, American Society for Microbiology. All rights reserved.

Expression of Toxoplasma gondii-Specific Heat Shock Protein 70 during In Vivo Conversion of Bradyzoites to Tachyzoites

Neide M. Silva,1 Ricardo T. Gazzinelli,2 3 Deise A. O. Silva,1 Eloisa A. V. Ferro,1 Lloyd H. Kasper,4 and Jose R. Mineo1 *

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

Received 30 January 1998/Returned for modification 19 February 1998/Accepted 30 April 1998

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-gamma ) or anti-tumor necrosis factor alpha (TNF-alpha ) 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-gamma or anti-TNF-alpha 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.

* Corresponding author. Mailing address: Laboratory of Immunology, Department of Pathology, Federal University of Uberlandia, Campus Umuarama-Bloco 4C, Uberlandia-MG-38400-902, Brazil. Phone: 55-34-218-2195. Fax: 55-34-232-8620. E-mail: jrmineo{at}ufu.br.

Infect Immun, August 1998, p. 3959-3963, Vol. 66, No. 8
0019-9567/98/$04.00+0
Copyright © 1998, American Society for Microbiology. All rights reserved.


This article has been cited by other articles:

  • Cleary, M. D., Singh, U., Blader, I. J., Brewer, J. L., Boothroyd, J. C. (2002). Toxoplasma gondii Asexual Development: Identification of Developmentally Regulated Genes and Distinct Patterns of Gene Expression. Eukaryot Cell 1: 329-340 [Abstract] [Full Text]  
  • Silva, N. M., Rodrigues, C. V., Santoro, M. M., Reis, L. F. L., Alvarez-Leite, J. I., Gazzinelli, R. T. (2002). Expression of Indoleamine 2,3-Dioxygenase, Tryptophan Degradation, and Kynurenine Formation during In Vivo Infection with Toxoplasma gondii: Induction by Endogenous Gamma Interferon and Requirement of Interferon Regulatory Factor 1. Infect. Immun. 70: 859-868 [Abstract] [Full Text]  
  • Kirkman, L. A., Weiss, L. M., Kim, K. (2001). Cyclic Nucleotide Signaling in Toxoplasma gondii Bradyzoite Differentiation. Infect. Immun. 69: 148-153 [Abstract] [Full Text]  


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