Evaluation of a PCR Assay for PRRS Virus in Oral Fluids of Growing Pigs

Porcine Reproductive and Respiratory Syndrome (PRRS) virus RNA was detected in oral fluids from pigs viraemic with PRRS virus but the technique is currently too insensitive to be applied in the commercial setting, according to B. Strugnell in the final report for a BPEX project.

1 August 2010

3 minute read

The final report by B. Strugnell of the UK's Veterinary Laboratories Agency (VLA) in Thirsk has been published. It reports the evaluation of a PCR assay for Porcine Reproductive and Respiratory virus in oral fluids from growing pigs and its applications for diagnosis and surveillance in the UK pig industry.

Following reports from the US that oral fluids may prove a useful and convenient diagnostic measure of group disease status in pigs, the aim of this study was to investigate the potential of this methodology in the UK herd, using Porcine Reproductive and Respiratory Syndrome Virus (PRRSv) as the target pathogen.

Samples of oral fluid were obtained by suspending rope either in the corner or wall of the pen. The rope used was made from pure cotton and had a diameter of either 14mm or 18mm, depending on the size of the target pigs.

Proof of principle that PRRSv RNA can be detected in oral fluids from pigs viraemic with PRRSv was successfully achieved. However, the sensitivity of the technique needs to be improved before it can be more widely applied in the commercial setting.

Techniques for collection and handling of samples are described, along with the methods of optimising RNA extraction from oral fluids, and modification of the RT-PCR for PRRSv RNA for this diagnostic sample.

Some targets for further research and possible reasons for apparently sub-optimal test sensitivity are suggested.