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An indirect enzyme-linked immunosorbent assay (ELISA) was developed for a screening test to detect antibodies against classical swine fever virus (CSFV). Viral glycoproteins, which were purified from swine kidney cells infected with CSFV ALD/A76 strain by the immunoaffinity purification using monoclonal antibody against E2 protein, were adsorbed on a microtiter plate as the antigen for the antibody detection. Each antibody titer of serum sample was expressed as a sample per positive value calculated with optical absorbance of each sample and that of a positive control. The advantage of this ELISA is its higher sensitivity: most sera containing more than 4 neutralization titers were determined to be positive. This ELISA is unable to discriminate between antibodies against CSFV and those against other ruminant pestiviruses, therefore positive sera in this ELISA should be evaluated by a cross-neutralization test using CSFV, bovine viral diarrhea virus, and border disease virus. Taken together, the indirect ELISA developed in this study is useful screening tool to detect antibodies against CSFV for the large-scale monitoring of classical swine fever.

All pestiviruses are important veterinary pathogens causing economic losses in cattle, sheep, and pigs. In this study, blood samples randomly collected from 465 sheep were analysed for the presence of antibodies to pestiviruses (bovine viral diarrhea virus, border disease virus) using an enzyme-linked immunosorbent assay in the province of Van and their towns. The seroprevalance were estimated as 75.9% and 60.0-82.5% in the sampled animals and sampled towns, respectively. The results revealed that pestiviruses are important abort pathogens in the province of Van and their towns.

There is a great need to establish effective tools to control border disease virus (BDV) in European dairy sheep flocks. Hence, our main aim was to investigate the accuracy of analyzing anti-BDV antibodies in bulk-tank milk (BTM) in detecting the real BDV seroprevalence in dairy sheep flocks. Furthermore, the relevance of BDV to reproductive performance of dairy sheep flocks prompted us to search for the association between BDV seroprevalence and reproductive parameters. For these purposes, 34 flocks were selected based on different percentages of antibody inhibition (AIP) values in BTM as estimated by ELISA. Serum samples from 10 replacement lambs older than 6 mo, 10 ewes 1 to 2 yr old, and 10 ewes > 2 yr old were collected and analyzed for the presence of anti-BDV antibodies by ELISA. A negative relationship between BDV AIP in BTM and within-flock seroprevalence was observed. Flocks with a high AIP (> 80%) had an average of 2.5% seropositive animals; flocks with a moderate AIP (46-79%) had 11.4% seropositive animals; and finally, flocks with an AIP < or = 45% showed a high flock seroprevalence (57.2%). Ten out of 34 flocks showed a high BDV seroprevalence in lambs, suggesting the presence of persistently infected animals in the flock. The observed AIP values in BTM from these likely BDV-infected flocks were indicative of a high seroprevalence. The analysis of reproductive-parameters data collected from these flocks showed no differences in fertility or prolificacy in relation to BDV circulation rates. Nonetheless, lamb mortality was significantly greater in flocks with low-moderate seroprevalence (10-30%), probably as a result of a first-time contact with BDV of previously naïve ewes. These findings suggest that testing of BTM samples may be useful in inferring the BDV seroprevalence in a flock., (2010 American Dairy Science Association. Published by Elsevier Inc. All rights reserved.)

An enzyme-linked immunosorbent assay (ELISA) has been developed to detect antibody to border disease virus (BDV) in sheep serum. A monoclonal antibody bound to 96-well microplates was used to capture antigen from detergent-solubilised BDV-infected cells. Single dilutions of test sera were then added to wells containing bound BDV antigen and control wells containing uninfected cell lysates. Specific antibody to BDV was detected by an anti-ovine IgG antiserum conjugated with horseradish peroxidase and the results expressed as ELISA units with reference to a standard curve. Sequential sera from 16 experimentally infected sheep and single sera from 103 sheep involved in a field outbreak were tested in the ELISA and for neutralising antibody. There was good qualitative correlation between the two tests.

An enzyme-linked immunosorbent assay (ELISA) was established for the rapid detection of specific antibodies against the causative agent of border disease in ovine sera. Polyethylene-glycol concentrated, equilibrium density gradient purified bovine virus diarrhea virus was used as test antigen. The optimal amount of antigen was 0.5 microgram/well, and the optimal concentration of conjugate was at 1/4,000 dilution. A total of 20 ovine serum samples, which had been collected from animals with or without border disease, were compared by ELISA and serum neutralization test for the detection of border disease-specific antibodies. ELISA was shown to be equally specific but less time-consuming and easier to perform than serum neutralization test. A positive correlation (r = 0.60) between the two tests was found.