Submitted to: American Journal of Veterinary Research
Publication Type: Peer reviewed journal
Publication Acceptance Date: 3/13/2003
Publication Date: 5/2/2003
Citation: O'Handley, R.M., Morgan, S.A., Parker, C.C., Jenkins, M.C., Dubey, J.P. 2003. Neospora vaccination in an ovine model for prevention of congenital transmission. American Journal of Veterinary Research 64:449-452. Interpretive Summary: Neosporosis is a parasitic disease that is a major cause of abortion in dairy cattle worldwide. The purpose of the present study was to determine if immunization of animals with a protein extract prepared from the causative organism, Neospora caninum, could prevent neosporosis. In this study, sheep were used as a ruminant model for dairy cattle. Prior to pregnancy, sheep were immunized with the N. caninum protein extract, while control sheep were injected with saline only. The sheep were mated and then challenged with live N. caninum during gestation. Lambs born from vaccinated ewes were negative by sensitive molecular assays for N. caninum, while lambs from control ewes were all positive. These results indicate that vaccination of sheep, and possibly cattle, may be an effective means of controlling neosporosis.
Technical Abstract: The purpose of the present study was to evaluate the immunological response of a killed Neospora caninum tachyzoite vaccine and its effectiveness in preventing vertical transmission of N. caninum in an ovine model. Dorset ewes were either immunized with a killed N. caninum tachyzoite preparation (vaccine) or injected with a mixture of sterile saline and adjuvant (control). The ewes were mated and then challenged during pregnancy with live N. caninum tachyzoites. Serum was collected every month from the ewes and from the lambs prior to suckling. Tissues were collected and examined for the presence of N. caninum antigen using immunohistochemistry and N. caninum DNA by PCR. Antibodies to N. caninum were elevated after N. caninum tachyzoite vaccine injection. Although both vaccinated and control ewes exhibited a heightened antibody titer after parasite challenge, only lambs born from vaccinated sheep were negative by PCR for N. caninum. However, lambs from both vaccinated and control ewes were positive by ELISA suggesting that partial protection against congenital infection was elicited.