Characterization of the inflammatory response in the uteri of cows infected naturally by Neospora caninum.

Bovine neosporosis manifests during gestation, when the fetus may be vulnerable to pathogens. Experimental studies of Neospora caninum-infected cattle have been performed, but little is known about the in-utero inflammatory response. The aim of this study was to characterize the inflammatory response in the uteri of pregnant and non-pregnant cows infected naturally with N. caninum. Four groups of seven animals were studied. Two groups consisted of N. caninum-seropositive pregnant and non-pregnant cows and the other two groups contained N. caninum-seronegative pregnant and non-pregnant cows. Uterine and placental samples were subjected to immunohistochemistry using antibodies specific for N. caninum, CD4, CD8, CD14 and CD21. The non-pregnant seropositive and seronegative groups did not show a difference (P >0.05) in the types of cells present. There were more lymphocytes in the uteri of the seropositive pregnant animals (P <0.05) than in the seronegative pregnant animals, but this was not considered to be consistent with an inflammatory process. N. caninum cysts were detected in eight seropositive cows; five were non-pregnant and three were pregnant. CD4(+) T cells were distributed in the endometrium and myometrium of the non-pregnant cows and were sparse in the placentomes of pregnant cows. CD8(+) T cells were distributed in a similar manner, but were present in smaller number. There were no cells expressing CD14 or CD21. The results of the study suggest that there is no consistent uterine inflammatory response against N. caninum in naturally infected animals.