FIG 9.

Comparison of C585 and other antibodies targeting HA head (non-RBS) showing that C585 binds a unique epitope in the HA head domain. (A) Schematic view of the H3 influenza hemagglutinin (HA) protein showing the different motifs present in HA. The stalk domain can be further divided into the F prime (green) or F (red) subdomains, whereas the globular head consists of the receptor-binding (RB) subdomain (blue) and vestigial esterase (VE) subdomain (yellow), followed by the fusion peptide (magenta), transmembrane domain (orange), and cytoplasmic domain (black). (B) Comparison of the binding site of C585 (orange, cartoon) with structurally characterized H3-binding antibodies binding to the HA head. The parts of HA are colored the same as in panel A. The HAs from all these HA-antibody complexes are aligned. These antibodies include H3v-47 (PDB 5W42) (blue), HC45 (PDB 1QFU) (pink) and F005-126 (PDB 3WHE) (green) binding to the globular head below the receptor-binding site (RBS) (location indicated by arrows). (C) Comparison of the detailed epitopes recognized by C585, H3v-47, F005-126, and HC45. The boundaries of the epitopes are outlined by black dotted lines. The RBS location is indicated by arrows.