Specificity assessment of an Elisa assay for detection of antibodies against porcine reproductive and respiratory syndrome virus (IDEXX HERDCHEK*PRRS 2XR)

The specificity of an indirect ELISA assay designed for the detection of antibody to Porcine Reproductive and Respiratory Syndrome Virus (IDEXX HERDCHEK* PRRS 2XR) was studied in a population of regularly controlled and negative selection and multiplication farms. Two subpopulations were studied: adult sows and young pigs (gilts between 80 and 150 days of age). A total of 641 adult pigs, out of 50 herd samplings and 1017 young pigs, out of 5 herd samplings were included. The observed specificity was significantly (p<0.02) higher in young pigs (99.51%, CI95: 99.03 - 99.99) than in adults (98.28 %, CI95: 97.20 - 99.37). The lower specificity in adults was not linked to a higher mean S/P ratio but to a higher variability of this ratio in this subpopulation.