Can oral fluid ELISA tests give false positive PRRS results if weaned piglets are fed with whey or plasma powder?
Oral Fluid ELISA tests: false positive PRRS results.
Answered by: Andrea Ladining I Published on: August 29, 2017
Experiences from experimental studies and the field have shown that ELISA tests for the detection of antibodies against porcine reproductive and respiratory syndrome virus (PRRSV) in oral fluid samples can give false positive results (Sattler et al. 2015; De Regge and Cay 2016).
One possible explanation can be an exogenous source of PRRSV antibodies, for example included in the feed. The best described example is the use of spray-dried porcine plasma incorporated into the diet of nursery piglets which has been shown to cause false positive results in PRRSV oral fluid ELISA tests (Johnson et al. 2012).
No reports on the use of whey in pig diets influencing the results of PRRSV oral fluid ELISA tests have been published. Feral and domestic swine represent the only known host of PRRSV (Zimmerman et al. 2012). Since cattle are not expected to support PRRSV replication or produce antibodies against the virus whey is a very unlikely exogenous source of PRRSV antibodies.
If seemingly contradictory diagnostic results are obtained by oral fluid PRRSV ELISA tests, feedstuffs can be tested for the presence of exogenous PRRSV antibodies (Johnson et al. 2012).
- De Regge, N., Cay, B., 2016. Comparison of PRRSV Nucleic Acid and Antibody Detection in Pen-Based Oral Fluid and Individual Serum Samples in Three Different Age Categories of Post-Weaning Pigs from Endemically Infected Farms. PLoS ONE 11(11): e0166300.
- Johnson, J.K., Main, R., Zimmerman, J., 2012. Exogenous source of PRRSV antibody in positive oral-fluid ELISA results. Journal of Swine Health and Production 20, 215.
- Sattler, T., Wodak, E., Schmoll, F., 2015. Evaluation of the specificity of a commercial ELISA for detection of antibodies against porcine respiratory and reproductive syndrome virus in individual oral fluid of pigs collected in two different ways. BMC Veterinary Research (2015) 11:70.
- Zimmerman, J., Benfield, D., Dee, S.A., Murtaugh, M.P., Stadejek, T., Stevenson, G.W., Torremorell, M., 2012. Porcine Reproductive and Respiratory Syndrome Virus. In: Zimmerman J, Karriker L, Ramirez A, Schwartz K, Stevenson GW (Eds.). Diseases of Swine. 10th ed. West Sussex: John Wiley & Sons, Inc., 461-486.