The amino-terminal region of dense granule protein 6 of Toxoplasma gondii stimulates IFN-γ production by microglia

We examined activities of dense granule proteins (GRAs), which Toxoplasma gondii secretes within infected cells, to stimulate microglial IFN-gamma production in vitro. We identified that the N-terminal region (amino acids 41-152) of GRA6 (GRA6Nt) stimulates IFN-gamma 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-gamma 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-gamma production for facilitating the protective immunity to control the pathogen. (C)20 Institut Pasteur. Published by Elsevier Masson SAS. All rights reserved.