COMPARATIVE SEROLOGY OF PORCINE REPRODUCTIVE AND RESPIRATORY SYNDROMEIN 8 EUROPEAN LABORATORIES, USING IMMUNOPEROXIDASE MONOLAYER ASSAY AND ENZYME-LINKED-IMMUNOSORBENT-ASSAY

The members of a European Community Conceited Action participated in a study to compare in-house and commercial tests for the serodiagnosis of porcine reproductive and respiratory syndrome (PRRS). These tests i ncluded the immunoperoxidase monolayer assay (IPMA) and enzyme-linked immunosorbent assay (ELISA). The trials involved assays on experimenta lly-produced reference sera, a blind trial of sera of known status, an d a comparative study of negative and 'problem' field sera. The result s showed a high level of agreement among IPMA tests used in the partic ipating laboratories at the held level, with only minor inconsistencie s in resting early post-infection sera. A blocking ELISA, used in expe rimental work by one laboratory, was almost as sensitive as IPMA in as says of reference and validation trial sera. Commercial ELISAs were ge nerally less sensitive than IPMA when used to assay ten-day post-infec tion sera. Discrepant results among certain field sera are likely to b e doe to antigenic variation among PRRS viruses uses in Europe. This m ay lead to increasing instances of misdiagnosis using tests which rely solely on test antigens derived ft om single PRRS virus isolates.