(C) Correlation between the OD415 nm values from ELISA with NcSAG1 and NcGRA7. in cattle, resulting in alarming economic losses to the livestock industry worldwide (7). Infected cows at any age may abort from 3 months of gestation to term, and most abortions occur at 5 to 6 months of gestation (5). Quantitative studies in the United States, New Zealand, The Netherlands, and Germany have indicated that 12 to 42% of aborted fetuses from dairy cattle were infected with and that up to 90% of cattle in some herds were infected (5). Many diagnostic methods have been developed to determine infection in animals and bovine abortion associated with infection. Although a definitive diagnosis of bovine abortion caused by is needed to demonstrate that there are parasites in the lesions and exclude other causes of abortion, serologic diagnosis, such as that with the enzyme-linked immunosorbent assay (ELISA), is important and widely used. A number of antigens have been evaluated as potential diagnosis antigens for the detection of an antibody to infection (7). Although has been found to be a major cause of bovine abortion, a marker for the serodiagnosis of infection in an aborting cow has not been identified. In this study, we compared ELISAs based on the recombinant antigens NcSAG1, NcSRS2, and NcGRA7 and the tachyzoite lysate antigen (NLA) for the detection of the as glutathione = 62), which were a gift from the Souya Livestock Hygiene Service Center, Hokkaido, Japan, and obtained from three Holstein dairy herds with a history of by IFAT. The serum samples were classified into three groups, i.e., group 1, 16 samples from aborting cows (gestation ranging from 3 to 7 months); group 2, 36 samples from nonaborting cows; and group 3, 10 samples from heifers. To detect the specific antibody associated with parasite-induced abortion, bovine sera from the above three groups were examined by ELISA with four antigens, NcSAG1, NcSRS2, NcGRA7, and NLA (Fig. ?(Fig.1).1). Among the three serum groups, the mean values of OD415 for group 1 were higher than those for groups 2 and 3 in the ELISA with recombinant antigens. The ELISA with recombinant antigens could discriminate between group 1 and group 3 ( 0.01), while there was no statistically significant difference among the groups by the ELISA with NLA. These results indicated that the specific antibodies against NcSAG1, NcSRS2, and NcGRA7 were produced in the aborting cows. However, in the ELISA with NcSAG1 and NcSRS2, there was no statistically significant difference between aborting and nonaborting hEDTP cows. More importantly, the ELISA with NcGRA7 could discriminate the aborting cows from the parasite-infected animals ( 0.01). Open in a separate window FIG. 1. Detection of antibody to by AVE 0991 ELISA with NcSAG1 (A), NcSRS2 (B), NcGRA7 (C), and the parasite lysates (NLA) (D). Group 1 includes serum samples from aborting cows. Group 2 includes samples from nonaborting cows. Group 3 includes samples from heifers. The mean AVE 0991 OD415 values are shown. Data were analyzed by analysis of variance, and the differences among the mean OD415 values were then analyzed using Turkey-Kramer multiple-comparison tests. *, statistically significant difference among the samples ( 0.05). The OD415 values were representative of at least three repeated experiments. In order to examine the distribution of the OD415 values between aborting and nonaborting cows, a further comparison of the ELISA with recombinant antigens was performed (Fig. ?(Fig.2).2). In Fig. ?Fig.2A,2A, positive correlations between the OD415 values of the ELISA with NcSAG1 and NcSRS2 in both aborting cows (= 0.68, 0.01) and nonaborting cows (= 0.732, 0.01) were found. However, when the difference in the correlation coefficients of the regression lines obtained from aborting and nonaborting cows was examined, no statistically significant difference was found. This result indicates that the patterns of production of antibodies against NcSAG1 and NcSRS2 in aborting and nonaborting cows were not different. We then tried to determine whether the production of antibodies against NcGRA7 and the other two molecules had a correlation among animals (Fig. 2B and C). A simple regression analysis revealed a correlation between the antibody responses against NcGRA7 and other recombinant antigens in aborting cows (NcGRA7 and NcSRS2, = 0.663, 0.01; NcGRA7 and NcSAG1, = 0.719, 0.01). In contrast, there was no correlation in the antibody responses from nonaborting cows. These results indicate that the production of the AVE 0991 anti-NcGRA7 antibody is upregulated in aborting cows. Open in a separate window FIG. 2. Comparison of the correlation between the OD415 values from ELISA with.