Porcine Respiratory Disease Complex (PRDC) is a significant economic problem for swine producers.Development of diagnostic tests that are able to rapidly and simultaneously detect multiple pathogens offer an important tool for disease surveillance and control measurements.In this study,we have developed a multiplexed fluorescent microsphere immunoassay (FMIA) for the simultaneous detection of specific antibodies in oral fluid and serum samples from animals infected with porcine reproductive and respiratory syndrome virus (PRRSV),swine influenza virus (SwlV),and porcine circovirus (PCV2).Recombinant nucleocapsid proteins of PRRSV,SwlV,PCV2 were generated and used as antigens that were covalently coupled to Luminex fluorescent microspheres with a distinct spectral address.