Cantón, G.J., Katzer, F., Benavides, J., Maley, S.M., Palarea Albaladejo, J., Pang, Y.P., Bartley, P., Rocchi, M.S., Innes, E.A. and Chianini, F.
||Despite Neospora caninum being a major cause of bovine abortion worldwide, its pathogenesis is not completely understood. Neospora infection stimulates host cell-mediated immune responses, which may be responsible for the placental damage leading to abortion. The aim of the current study was to characterize the placental immune response following experimental infection at day 210 of gestation. Cows were culled at 14, 28, 42 and 56 days post inoculation. Placentomes were examined by immunohistochemistry using antibodies against macrophages, T-cells, natural killer cells and B cells. Macrophages were labeled mainly at 14 days post inoculation. Inflammation was generally mild and mainly characterized by CD3+, CD4+ and γδ T-cells labelled cells; whereas CD8+ and NK cells were less numerous. The immune system cell subset distribution observed in this study was similar to those seen at early gestation. However, cellular infiltrates were less severe than those seen during the first trimester Neospora infections and more severe when compared to third trimester infections. This may explain the milder clinical outcome observed when animals are infected late in gestation.