Eight phage clones were selected for reactivity with the mAb A9E8 after three rounds of biopanning and enrichment of the phages binding to the mAb A9E8. These selected clones were further evaluated by Phage ELISA for reactivity with the mAb A9E8 and a negative control mAb (anti-porcine IFN-c). As shown in Figure 2 , all the selected eight phage clones (A1-A8) showed specific reactivity with A9E8 (OD492 nm .1.10), but not with anti-porcine IFN-c mAb (OD492 nm ,0.15). The eight phage clones were sequenced, and were shown to display a consensus sequence SVQYHPL, which was identical to the motif 213 SVQYHPL 219 at the C-terminus of the gp90 protein of REV-A strain HLJ07I (Table 2) .