Silva N M, Gazzinelli R T, Silva D A, Ferro E A, Kasper L H, Mineo J R
Laboratory of Immunology, Department of Pathology, Universidade Federal de Uberlandia, Uberlandia 38400-902, Minas Gerais, Brazil.
Infect Immun. 1998 Aug;66(8):3959-63. doi: 10.1128/IAI.66.8.3959-3963.1998.
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.
在慢性感染刚地弓形虫ME-49株的C57BL/6小鼠中研究了缓殖子和速殖子之间的阶段转换。为了促进缓殖子向速殖子的转换，给小鼠体内注射中和剂量的抗γ干扰素（IFN-γ）或抗肿瘤坏死因子α（TNF-α）抗体。通过免疫细胞化学在中枢神经系统中观察寄生虫特异性抗原SAG-1、SAG-2和热休克蛋白70（Hsp-70）的表达，并通过光度测定法进行测量。抗IFN-γ或抗TNF-α治疗的免疫抑制作用是即时的，导致寄生虫阶段转换，这表现为速殖子特异性抗原（SAG-1和SAG-2）表达增加以及寄生虫快速复制。我们还观察到在缓殖子向速殖子短暂转换期间高水平Hsp-70的表达。我们的数据表明，Hsp-70可能在慢性弓形虫病再激活过程中的缓殖子-速殖子转换过程中起重要作用。
