We examined activities of dense granule proteins (GRAs), which Toxoplasma gondii secretes within infected cells, to stimulate microglial IFN-γ production in vitro. We identified that the N-terminal region (amino acids 41–152) of GRA6 (GRA6Nt) stimulates IFN-γ production by both a microglia cell line and primary microglia purified from the brains of uninfected adult mice. In contrast, neither of GRA1, GRA2, GRA5Nt, nor the carboxyl-terminal (amino acids 174–224) of GRA6 stimulated microglial IFN-γ production. GRA6Nt appears to be a target molecule of the sentinel function of microglia to detect cerebral proliferation of T. gondii and activate their IFN-γ production for facilitating the protective immunity to control the pathogen.

我们检测了弓形虫在感染细胞内分泌的致密颗粒蛋白 (GRA)在体外刺激小胶质细胞 IFN-γ的活性。我们发现 GRA6 (GRA6Nt) 的 N 端区域（氨基酸 41-152）刺激小胶质细胞系和从未感染的成年小鼠大脑中纯化的原代小胶质细胞产生 IFN-γ。相比之下，GRA1、GRA2、GRA5Nt 和 GRA6 的羧基末端（氨基酸 174-224）均不刺激小胶质细胞 IFN-γ 的产生。GRA6Nt 似乎是小胶质细胞哨兵功能的靶分子，可检测弓形虫的脑增殖并激活其 IFN-γ 产生以促进保护性免疫以控制病原体。