Congenital toxoplasmic retinochoroiditis in the mouse--the use of the peroxidase anti-peroxidase method to demonstrate Toxoplasma antigen

Fundal white dots: observations from a murine model of congenital ocular toxoplasmosis

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Ultrastructural immunocytochemistry of the intact tissue cyst of Toxoplasma in the brains of mice with congenital toxoplasmosis

Electron immunocytochemistry, using rabbit polyclonal anti-Toxoplasma IgG as the primary layer in immunogold staining, was used to assess the distribution of Toxoplasma antigen within, and in relation to, intact tissue cysts in brain tissue from mice with congenital toxoplasmosis. Toxoplasma antigen was widely distributed in the matrix of the cyst, being most concentrated in the proximity of the inner surface of the parasitophorous vacuole membrane (PVM). Relatively little Toxoplasma antigen was detected directly associated with cystozoites. Small amounts of antigen were detected within the host cell components exterior to the PVM and in the host neuropil immediately adjacent to the tissue cyst.

The immunocytochemical demonstration of Toxoplasma antigen in the brains of congenitally infected mice

The peroxidase anti-peroxidase immunocytochemical staining method was used to identify Toxoplasma antigen in paraffin embedded sections of the brains of 22 mice congenitally infected with the parasite. Intact Toxoplasma tissue cysts were readily demonstrated in the brain in all cases. In 4 of the 22 infected mice there was evidence of rupture of the cyst wall and/or presence of extra-cystic Toxoplasma antigen. Further support for the extra-cystic location of Toxoplasma antigen was obtained by electron microscopy of reprocessed tissue which revealed endozoites in the area immediately surrounding a ruptured cyst. The possible implications of these findings in relation to the pathogenesis of congenital toxoplasmic meningo-encephalitis are discussed.