[Comparative study of chronic congenital toxoplasmosis and re-infection in an animal model [MICE]]

ABSTRACT

Toxoplasma gondii is a coccidian parasite and has, as intermediate hosts, many warm-bloodedanimals, including mammals and birds. Congenital toxoplasmosis is one of the most important infectiousdiseases seen in fetuses and infants born from mothers infected with Tox.gondii during pregnancy. Congenitalinfection, which may occur if a mother is infected for the first time during pregnancy, is often serious, resultingin abortion or severe neurological and ophthalmological disorders. Information on human cases of neonataltoxoplasmosis makes it unquestionable that Toxoplasma crosses the placenta and invades the fetus in utero ineach of the two cases.Tox. gondii infection in newborn rat litters was detected by a bioassay and parasitological method. Ratlitters were billed and where possible, separated from their mothers in order to prevent feeding. Their tissueswere separately homogenized in normal saline or PBS and inoculated intraperitoneally in 3 mice. The tissuesused for bioassays were brain, hearts, lungs, livers, and spleen of pups, which were killed on the day of birth. Inaddition, control infected rat were sacrificed and their different tissues were evaluated for parasite burden at eachtime point of reinfection and chronic infection.Data in the occurrence of congenital transmission from chronically infected mother rats given similarlygraded inoculums of the RH strains [1[106 to 5[106] presented that none of the 36 pups was infected withTox.gondii. The occurrence of congenital transmission in rats reinfected with Toxoplasma shows that none ofthe 14 pups was infected with Tox.gondii. Rats were reinfected intra- peritoneally with 1[106 parasite at 1,2and 4 months after primary infection, respectively.Thus, this study demonstrated that Rats chronically infected with Tox.gondii, have immunitycapable of protecting their embryos from congenital infection, even if they are reinfected during pregnancy andthe immunity systems of these mothers can fully protect the fetus from such infections