Porcine reproductive and respiratory syndrome virus (PRRSV): monoclonal antibodies detect common epitopes on two viral proteins of European and U.S. isolates

Sixteen hybridoma cell lines secreting monoclonal antibodies (mAbs) directed against two dutch isolates of the causative virus of Porcine Reproductive and Respiratory Syndrome (PRRSV) were produced. The hybridoma cells resulted from fusions of SP2/0 myeloma cells with splenocytes of STU mice immunized with purified PRRSV after induction of immunotolerance against host cell constituents. Screening of supernatant fluids was performed by an indirect immunofluorescence assay on PRRSV-infected porcine alveolar macrophages. Immunoblotting studies revealed that the mAbs had different protein specificities. One mAb reacted with a viral 15 kD protein, eleven were directed against a 40–50 kD protein, and four against a 30–40 kD protein. The mAb against the 15 kD putative nucleocapsid protein as well as five mAbs against the 40–50 kD protein recognized epitopes on these proteins which are conserved in various European U.S. isolates of PRRSV.