COMPARATIVE-STUDY OF SEROLOGICAL METHODS FOR THE DETECTION OF ANTIBODIES TO PORCINE REPRODUCTIVE AND RESPIRATORY SYNDROME VIRUS

A comparison was made of serological diagnostic methods used for the d etection of antibodies against porcine reproductive and respiratory sy ndrome (PRRS) virus. In the ''phase I'' PRRS test panel comparison, a panel of sera collected from 135 pigs of various ages, from North Amer ican herds with and without PRRS histories, were sent to 4 different l aboratories and tested by an indirect immunofluorescent assay (IFA), a n immunoperoxidase monolayer assay (IPMA) and an indirect enzyme-linke d immunosorbent assay (iELISA). In the ''phase II'' PRRS test panel co mparison, a panel of 382 sera collected from pigs of various ages, PRR S histories, and from various locations in North America and France, w ere divided into 2 panels (A & B) and sent to 3 Canadian laboratories and tested by the IFA and iELISA. In the phase I comparison, agreement between the IFA of laboratory 4 and the iELISA and IPMA of laboratory 3 was excellent (kappa values of 95% and 98%, respectively). This con trasted with the poor agreement between these laboratories and the IFA results of laboratories 1 and 2 in the phase I trial. In the phase II comparison, the results demonstrated good agreement between various t ests both within and between laboratories. The overall performance of the iELISA was superior in the combination of sensitivity (96.1%) and specificity (100%) relative to the reference classification of the ser um samples and repeatability (kappa value 98%). The iELISA is technica lly superior to IFA and IPMA, time efficient, cost effective and suita ble for testing of a large number of samples over a short period of ti me. Thus, the iELISA may be a better alternative to IFA or IPMA for ro utine detection of PRRS viral antibodies in swine sera.