COMPARISON OF A COMMERCIAL ELISA AND AN IMMUNOPEROXIDASE MONOLAYER ASSAY TO DETECT ANTIBODIES DIRECTED AGAINST PORCINE RESPIRATORY AND REPRODUCTIVE SYNDROME VIRUS

A commercially available enzyme-linked immunosorbent assay (ELISA) for the detection of antibodies against porcine respiratory and reproduct ive syndrome virus (PRRSV) was compared to an immunoperoxidase monolay er assay (IPMA), Serum samples used were collected from pigs experimen tally infected with either the American or European antigenic type of PRRSV, and also from piglets born to sows that had been experimentally infected with the European antigenic type of PRRSV, In addition, thre e sets of European field sera (n = 275, n = 68, n = 349) were tested a nd evaluated using the IPMA as the gold standard, Results showed that both the IPMA and the ELISA were able to detect antibodies against the two antigenic types of PRRSV. When sera of experimentally infected pi gs were tested, the TPMA with homologous antigen detected antibodies 2 to 3 days earlier than the ELISA, and was more sensitive in detecting maternal antibodies. The ELISA was slightly more sensitive for detect ing antibodies against the American type than for the European type, W hen sets of field sera were tested, the relative sensitivity of the EL ISA ranged between 0.68 and 0.91, and the relative specificity ranged between 0.75 and 0.97, However, in two of these sets (n = 275, n = 349 ) we determined that a decrease of the threshold value of ELISA (from 0.4 to 0.3) increased sensitivity without loss of specificity. We conc luded that the ELISA is an easy, quick and reliable test to diagnose P RRSV infection in swine herds.