ANTIBODY-RESPONSES OF COWS DURING AN OUTBREAK OF NEOSPOROSIS EVALUATED BY INDIRECT FLUORESCENT-ANTIBODY TEST AND DIFFERENT ENZYME-LINKED IMMUNOSORBENT ASSAYS

Serum samples from 70 (33 aborting and 37 non-aborting) dairy cows fro m a herd in California were analyzed for Neospora caninum antibodies i n different laboratories by various serologic assays including enzyme- linked immunosorbent assay (ELISA) with recombinant antigens (Nc4.1 an d Nc14.1), kinetic ELISA, whole tachyzoite lysate ELISA, immunostimula ting complex (iscom) ELISA, antigen capture competitive inhibition ELI SA, and by the indirect fluorescent antibody test. Eighteen percent of pregnant cows in this herd had aborted within 2 mo of the index case. All 70 cows had antibodies to N. caninum by at least 1 of the tests. Antibody levels to N. caninum in aborting cows as a group were higher than in nonaborting cows. However, it was concluded that no serologica l test could be used to establish definitively that N. caninum caused the abortion in an individual cow.