Deposition of beta-amyloid plaque in the brains of mice with or without <i>T. gondii</i> infection.

<p>Differences between β-amyloid deposit levels in <i>T. gondii</i>-infected and non-infected mice (PBS-treated mice) were examined in the cortex and hippocampus regions using Congo red and by immunohistochemical staining with 6E10 antibody. Congo red staining was performed on; uninfected (PBS-treated) wild type (A1), <i>T. gondii</i>-infected wild type (A2), uninfected Tg2576 (A3), and infected Tg2576 (A4) mouse groups. Wild type mice with or without <i>T. gondii</i> infection showed no amyloid plaque (A1, A2) at 9 mo after birth, whereas PBS-treated Tg2576 mice showed many Congo red-stained regions in the cortex (A3). However, no amyloid plaque was observed in <i>T. gondii</i> infected Tg2576 mouse brain tissues (A4). Immunostaining results of cortex and hippocampus concurred with Congo red findings (A5, A6, A7, A8). (×40, Scale bar = 200 µm).). In addition, numbers of plaques in cortex and hippocampus were counted using a color digital camera attached to a microscope and Image J software, and the results obtained showed that numbers of plaques were significantly less in the hippocampus and cortex of <i>T. gondii</i>-infected Tg2576 mice (B).