The detection of bovine viral diarrhoea virus in bulk milk samples by the use of a single-tube RT-PCR

A single step, single-tube reverse transcriptase-polymerase chain reaction (RT-PCR) test was developed to detect the presence of bovine viral diarrhoe a virus (BVDV) in somatic cells from bulk milk samples. The test was config ured using commercial kit-form RNA extraction and RT-PCR procedures. The te st was validated by examining bulk milk samples from similar to 80 herds wi th a history of BVDV and comparing results with those obtained from samples from a similar-sized control group. The test proved highly specific, givin g a positive result in 20.5% of herds with a history of BVDV, with no contr ol herds positive. Its sensitivity was likewise high, detecting, at its max imum, one persistently infected (PI) cow in a herd of 162 lactating animals . In 19 herds where follow-up blood tests were performed, the RT-PCR gave a positive result in all ten herds where at least one lactating PI animal wa s present. In control schemes involving the detection of PT cattle, the tes t provides a rapid and inexpensive alternative to individual animal testing for those cows in milk at the time of sampling. Crown Copyright (C) 1999 P ublished by Elsevier Science B.V.