Summary (continued)
In the neutralisation test, the paired serum samples showed a two- to fourfold increase in anti-BoHV1 antibody titre; in the cELISA, the paired samples were also found positive for anti-BoHV1 antibodies. Serum samples from 43 in-contact bulls were collected about day 22 after the first observation of clinical infection in the herd. Among these serum samples, a total of 30 were found positive for anti-BoHV1 antibodies in the VNT and a total of 30 were found positive in cELISA. Ten samples were positive in one test but not the other and 25 tested positive in both tests. In all, 35 serum samples from in-contact bulls tested positive in either one or both of the two types of test. An overall agreement of 76.74% was found in detection of anti-BoHV1 antibodies in the two tests. Sensitivity was higher than specificity in detection of anti-BoHV1 antibodies in the serum samples. The glycoprotein C region of the genomic DNA of BoHV1 was amplified from semen samples by polymerase chain reaction. The findings from the outbreak indicate that continuous monitoring of breeding bulls at frozen semen banks is warranted to avoid the risks associated with artificial insemination.