Submitted to: American Association of Veterinary Parasitologists Proceedings
Publication Type: Abstract Only
Publication Acceptance Date: 5/20/2004
Publication Date: 7/20/2004
Citation: Almeria, S., Araujo, R., Tuo, W., Dubey, J.P., Gasbarre, L.C. 2004. Experimental infection of pregnant cows with neospora canium: histological analysis and parasite detection in dam and fetus [abstract]. American Association of Veterinary Parasitologists Proceedings. p. 24
Technical Abstract: The present study was performed to define the lesions and transplacental infection patterns in heifers infected intravenously with 107 cattle strain culture derived Neospora caninum tachyzoites early in the second trimester of pregnancy (110 days of gestation). Animals were euthanized 3 weeks after infection (wai)(group 1), at 6 wai (group 2) and at 9 wai (group 3). Blood samples were collected weekly until the end of the experiment and total antibodies levels analyzed by ELISA. At the time of necropsy, sections of the placenta(cranial, medial and caudal from caruncle and cotyledonal areas), brain, spinal chord, lung, and liver from the dams, and brain, spinal chord, lung, (heart) and liver from the fetuses were aseptically collected and analyzed for lesions and for the presence of parasites by immunohistochemistry (IHQ). Samples of placental sections (cranial, medial and caudal from the caruncle and cotyledonal areas), brain and spinal chord from the dams, and brain, spinal chord, lung, and liver from the fetuses were analyzed by Nc5 PCR. At 6 weeks after infection one dam had a dead fetus with initial signs of mummification, but the fetuses from all other dams were alive when the dams were euthanized. Transplacental infection had already occurred in all the fetuses in the study and parasite DNA was detected by PCR from at least one of the analyzed tissues in both dams and fetuses. All dams showed parasite DNA in their placental tissues. Spinal chord, lung and brain were the tissues showing the highest percentage positive for parasite DNA in the fetuses. Throughout the study, the highest levels of antibodies were observed in the dam that aborted. In this animal antibody levels reached the positive threshold at 2 weeks after infection. In the aborted foetus specific N. caninum antibodies were detected as well as high levels of IFN-gamma , conversly neither antibodies nor IFN-gamma production were observed in the other fetuses of group 2.