Detection of swine vesicular disease virus RNA by reverse transcription polymerase chain reaction

Two polymerase chain reaction (PCR) assays are described for the detection of swine vesicular disease virus (SVDV) RNA, a reverse transcription PCR (RT-PCR) and a reverse transcription nested PCR (RT-nPCR). Both the RT-PCR and RT-nPCR were able to detect representative members of each of seven phylogenetically distinct groups of SVDV and gave negative results with a range of porcine enteroviruses and of viruses responsible for vesicular conditions in pigs. When combined with a commercial kit for rapid RNA extraction, the RT-PCR was useful for the detection of SVDV in samples of epithelium and faeces from animals with clinical SVD. The addition of a second amplification step to create a nested PCR (RT-nPCR) increased the sensitivity of the technique for the detection of viral RNA (vRNA) in SVDV infected tissue culture fluid by a factor of approximately 1000, from 100 TCID50 for the RT-PCR to 0.1 TCID50 for RT-nPCR. When combined with a more elaborate extraction procedure for RNA, the RT-nPCR was considerably more sensitive than virus isolation in tissue culture for detecting SVDV in nasal swabs, tissues, and faeces collected from pigs between 7 days and 176 days after infection with a recent European isolate of SVDV. However, stringent conditions are necessary for carrying out the RT-nPCR to minimise the possibility of contamination. (C) 1997 Elsevier Science B.V.