A Descriptive Study of Lectin Histochemistry of the Placenta in Cattle following Inoculation of Neospora caninum

Abstract

The aim of this study was to describe the lectin-binding pattern in the placentas of cows infected experimentallywith Neospora caninum. Four cows were inoculated intravenously with 1 ×108 tachyzoites of the NC-1 strain ofN. caninum at 150 7 days of pregnancy. Two control cows were administered a placebo. An indirect fluorescenceantibody test (IFAT) was performed on serum samples obtained before and after the inoculation. Thecows were killed at 30 and 37 days post inoculation. Samples of placenta were taken for histopathology andlectin histochemistry. Fetal tissues and fluids were collected for histopathology and IFAT, respectively. All infectedcows had high antibody titres. All fetuses had characteristic histopathological lesions, including nonsuppurativemeningoencephalitis, myocarditis, hepatitis and myositis, suggesting N. caninum infection. Onlytwo infected fetuses developed specific antibodies. Mild non-suppurative inflammatory infiltrates were recordedin the placentae. Differences in the lectin-binding pattern were observed between infected animalsand controls in the glycocalyx (CON-A and WGA) and apical cytoplasm (RCA-I and CON-A) of the trophoblasticcells; giant trophoblastic cells (CON-A and DBA); glycocalyx (PNA, WGA) and apical cytoplasm(CON-A, WGA, PNA, DBA and RCA-I) of endometrial cells; trophoblast of the interplacentomal region(WGA); endothelium (CON-A, SBA, RCA-1 and WGA); and finally, mesenchyme (CON-A, RCA-1, SBA,PNA and DBA). These findings indicate that there is a distinctive pattern of lectin binding in the placentaof cattle infected with N. caninum. The direct effect of the presence of the protozoa as well as the altered expressionof cytokines could explain these changes in the maternofetal interface.