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Published on: December 3, 2011
Probability of PRRS virus detection in pooled processing fluid samples
Will A López1, Phillip C Gauger2, Karen M Harmon2
1Veterinary Diagnostic and Production Animal Medicine Department, College of Veterinary Medicine, Iowa State University, Lloyd Veterinary Medical Center, 1809 S Riverside Dr., Ames, IA 50011-3619, United States; PIC North America, 100 Bluegrass Commons Blvd #2200, Hendersonville, TN 37075, United States.
Pooling processing fluids (PF) from multiple litters for porcine reproductive and respiratory syndrome virus (PRRSV) RNA testing is effective. This strategy maintains a high probability of detecting PRRSV, even at low prevalence, supporting widespread diagnostic monitoring in swine.
Area of Science:
- Veterinary Virology
- Swine Health Management
- Diagnostic Assay Development
Background:
- Population-based diagnostic monitoring and surveillance are increasingly vital for swine health.
- Processing fluids (PF) offer a promising matrix for screening breeding herds for porcine reproductive and respiratory syndrome virus (PRRSV).
- A key question is the optimal sample pooling strategy to maintain diagnostic sensitivity for PRRSV RNA detection.
Purpose of the Study:
- To model the impact of pooling processing fluid samples on the probability of detecting porcine reproductive and respiratory syndrome virus (PRRSV) RNA.
- To determine the maximum number of litters that can be pooled while preserving a high likelihood of PRRSV detection in low-prevalence scenarios.
Main Methods:
- A PRRSV-positive processing fluid (PF) sample was serially diluted with negative PF to simulate pooling.
- Dilutions represented increasing numbers of PRRSV-naïve pigs contributing to the sample.
- Samples were tested for PRRSV RNA using reverse transcription-quantitative polymerase chain reaction (RT-qPCR), and data analyzed with regression models.
Main Results:
- Each two-fold dilution resulted in an average increase of 1.37 in cycle threshold (Ct) values.
- The probability of detecting PRRSV RNA was estimated at 43%, 80%, and 95% when one positive piglet was present among 784, 492, and 323 negative piglets, respectively.
- These findings demonstrate that pooling PF samples maintains high detection probability.
Conclusions:
- The study validates the use of pooled processing fluid samples for PRRSV RNA detection in swine.
- Aggregating PF from multiple litters is a viable and effective strategy for herd surveillance.
- This supports enhanced diagnostic efficiency and cost-effectiveness in PRRSV monitoring programs.
