After three rounds of biopanning, eight individual phage clones were selected for target binding in ELISA as described in the manufacturer's instructions. Briey, 96-well plates were coated with 100 ng of purified mAb A9E8, or anti-porcine IFN-c mAb (Sigma, St Louis, MO, USA) as negative controls overnight at 4uC. The coated wells were blocked for 2 h at room temperature and then the phages (10 10 pfu/100 mL/well) diluted in blocking solution were added. The plates were incubated for 1 h at room temperature followed by washing ten times with TBST. Bound phages were subjected to reaction with horseradish peroxidase (HRP)-conjugated sheep anti-M13 antibody (Pharmacia, Piscataway, NY, USA), followed by color development with substrate solution containing o-phenylenediamine (OPD).