Submitted to: Clinical and Diagnostic Laboratory Immunology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: January 28, 1997
Publication Date: N/A
Interpretive Summary: Neosporosis is a parasitic disease of many species of domestic animals caused by the protozoan Neospora caninum. In cows, the parasite can be transmitted to the fetus via the placenta and cause a variety of clinical effects including abortion. Calves born from Neospora-infected cows may exhibit neurological symptoms and die within one week after birth or may be infected with the parasite and show no clinical signs of disease. There is an urgent need control transmission of the Neospora to offspring by identifying cows infected with the parasite and removing these animals from the breeding population. The present study describes the use of a recombinant antigen-based serological assay to identify cows infected with Neospora. The level of antibodies specific for Neospora remained high in cows for at least one year after a primary neosporosis infection. Also, calves born from parasite-infected cows had high levels of Neospora-specific antibodies in their serum which remained high during the course of the study. Serum from cows which aborted a fetus due to nesoporosis had much higher levels of Neospora-specific antibodies than cows which aborted a fetus due to other causes. These results indicate that the recombinant antigen-based immunoassay is suitable for identifying Neospora-infected cows and may be useful for controlling neosporosis in the field.
Technical Abstract: Recombinant Neospora caninum tachyzoite antigens were evaluated in an ELISA for diagnostic potential in natural Neospora infections in bovines. Serum samples were obtained every 2-3 wks for 1-1.5 years from 10 cows who had a history of Neospora-associated abortion. Serum was also obtained from offspring of these animals and from a large number of cows that had aborted a fetus due to infection by Neospora or other pathogens at various times during gestation. In general, antibody (Ab) titers to both recombinant Neospora tachyzoite antigens remained high prior to and after parturition. Calves born of Neospora-positive cows also had a high Ab titer to the recombinant tachyzoite antigens and these titers remained elevated for at least 4 months after birth. A portion of the serum immunoglobulin in calves may have been derived from colostrum of infected cows. A calf born from a seronegative mother exhibited a positive ELISA titer only after being fed colostrum from a seropositive cow. The recombinant tachyzoite antigens were also useful for corroborating a clinical diagnosis of Neospora-induced abortion. A significant difference (P < .05) in the anti-recombinant antigen Ab titers was found in cows that aborted due to Neospora compared to cows that aborted from other causes.