Document Type


Publication Date


Publication Title

Infection and Immunity


Geisel School of Medicine


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.

Original Citation

Silva NM, Gazzinelli RT, Silva DA, Ferro EA, Kasper LH, Mineo JR. Expression of Toxoplasma gondii-specific heat shock protein 70 during In vivo conversion of bradyzoites to tachyzoites. Infect Immun. 1998;66(8):3959-3963. doi:10.1128/IAI.66.8.3959-3963.1998