Abstract
Three thousand Danish porcine field sera were tested for the possible presence of neutralizing antibodies for Hog Cholera (HC) and Bovine viral Diarrhea (BVD). The technique used was a microplate neutralization test read by peroxidase-linked antibody assay (NPLA) in the HG examination, and by cytopathogenic effect in the BVD examination. The initial dilution of the test sera was 1:2. BVD-antibodies were demonstrated in 6.4 % of the sera, while all the sera were found to be free from antibodies to HG-virus.