Fig. 6.

The antigenic site of HA recognized by 98 mAbs that showed binding and neutralizing activity against H3 influenza viruses. Illustrations of the 3D model were constructed in the same way as described in Fig. 5(b). The amino acids that formed a receptor-binding site are marked in grey. When loss of Ab binding was observed in some chimaeric HA, the amino acids replaced in the chimaera were marked in the same way as in Fig. 1(b).