Placental transfer of specific antibodies during ovine congenital toxoplasmosis.

The passage of non-Toxoplasma antibodies from dam to fetus through damaged placenta was studied in sheep inoculated with Toxoplasma gondii. Six ewes were inoculated with chicken globulins and Leptospira bacterins 2 months before oral inoculation with Toxoplasma gondii oocysts. Ewes were euthanatized between 42 and 62 days after T gondii inoculation. Antibody titers against chicken globulins, Leptospira spp, Haemonchus contortus, Sarcocystis spp, and T gondii were measured in the maternal and fetal sera. All ewes became infected with T gondii and had grossly visible necrotic foci in the placentas, and T gondii antibodies were found in the fetuses and the ewes. Appreciable amounts of antibodies to Haemonchus contortus, Sarcocystis sp, Leptospira spp, and chicken globulins did not cross the placental barrier. Seemingly, serologic examination of the fetus was reliable for the diagnosis of ovine congential toxoplasmosis.