Porcine reproductive and respiratory syndrome antibody detection on filter discs

Two enzyme-linked immunosorbent assay (ELISA) kits were evaluated for detection of porcine reproductive and respiratory syndrome (PRRS) antibodies in pooled sera and filter discs (FDs). Elution and incubation procedures and positive thresholds for both ELISAs were determined using FDs collected from sixty non-infected pigs and five pigs with low PRRS-antibody titres. Eighty paired samples (serum/FD) from infected pigs were titrated using both ELISAs. The authors thus showed that five sera or five FDs could be pooled in one test without significant loss of sensitivity. Compared to individual sera, method sensitivity was found to be 79% and specificity 97.5%, based on data from 200 pools of FDs collected on 15 PRRS-infected farms and 120 pools collected on 71 non-infected farms. To balance loss of sensitivity, two pools of five samples from sows and one pool of five samples from finishing pigs can be tested as an alternative to seven and five single sera, respectively.