Expression of Toxoplasma gondii-specific heat shock protein 70 during In vivo conversion of bradyzoites to tachyzoites.
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.
Silva
N M
NM
Laboratory of Immunology, Department of Pathology, Universidade Federal de Uberlandia, Uberlandia 38400-902, Minas Gerais, Brazil.
Gazzinelli
R T
RT
Silva
D A
DA
Ferro
E A
EA
Kasper
L H
LH
Mineo
J R
JR
D000818:Animals; D000953:Antigens, Protozoan / Q000096:biosynthesis; D000954:Antigens, Surface / Q000096:biosynthesis; D005260:Female; D018840:HSP70 Heat-Shock Proteins / Q000096:biosynthesis*; D051379:Mice; D008810:Mice, Inbred C57BL; D015800:Protozoan Proteins / Q000096:biosynthesis; D051381:Rats; D014122:Toxoplasma / Q000254:growth & development / Q000378:metabolism*
D000953:Antigens, Protozoan; D000954:Antigens, Surface; D018840:HSP70 Heat-Shock Proteins; D015800:Protozoan Proteins; C047168:SAG1 antigen, Toxoplasma; C067547:surface antigen P22, Toxoplasma