To verify whether the identified motif represented an epitope recognized by the mAb A9E8, a DNA fragment coding for the motif SVQYHPL was expressed as a GST fusion protein (GST-H7wt) in E. coli. Western blot analysis showed that the fusion protein was recognized by the mAb A9E8 ( Figure 3A ) and REV-A infected chicken antiserum ( Figure 3B ), indicating that the motif represented a linear B-cell epitope.