Use of tissue swabbing as an alternative to tissue dissection and lysis prior to nucleic acid extraction and real-time polymerase chain reaction detection of Bovine viral diarrhea virus and Porcine reproductive and respiratory syndrome virus.

The use of swabbing to sample tissue samples, prior to nucleic acid extraction and performance of a real-time polymerase chain reaction (PCR) assay, was investigated for the detection of the viral pathogens Bovine viral diarrhea virus (BVDV) and Porcine reproductive and respiratory syndrome virus (PRRSV). The tissue swabbing method involved swabbing recently cut tissues, eluting the swabbed material, and extracting nucleic acid from the eluate prior to PCR amplification. Parallel testing of this method with traditional nucleic acid extraction from tissues, where small pieces of tissue are dissected and digested (typically overnight) in lysis buffer prior to nucleic acid extraction, was carried out for 50 samples for each virus. The results demonstrated that equivalent PCR results were obtained with both methods. It was also shown on a smaller number of samples that equivalent PCR results were also obtained when the lysis step of the swabbing method was reduced to only 2 hr. The ability to remove the overnight step typically associated with processing tissue samples for PCR analysis offers the potential for same-day testing of tissue. Although the current study is preliminary in nature and further validation will be required before adoption for routine use, the results show that tissue swabbing is a promising approach. It offers a convenient, simpler, and less time-consuming alternative to tissue dissection and lysis and has potential advantages for routine laboratory operation and outbreak testing, including easier pooling and sampling of large areas of tissue and carcasses.