FIG 4.
Breadth of binding by head interface antibodies (Abs). (A) Dissociation constants from ELISA measurements. The pan-influenza A virus-binding stem-directed antibody FI6v3 (12) was used as a positive control, and an influenza B virus-specific RBS-directed antibody, CR8033 (31), was used as a negative control for influenza A virus isolates. Boxes are colored according to the key at the bottom. HAs used are as follows: H1 A/California/04/2009(H1N1), H2 A/Japan/305/1957(H2N2), H3 A/Hong Kong/JY2/1968(H3N2), H4 A/American black duck/New Brunswick/00464/2010(H4N6), H5 A/Viet Nam/1203/2004(H5N1), H6 A/Taiwan/02/2013(H6N1), H7 A/Taiwan/01/2017(H7N9), H8 A/northern shoveler/California/HKWF1204/2007(H8N4), H9 A/Beijing/1/2017(H9N2), H10 A/Jiangxi/IPB13/2013(H10N8), H13 A/gull/Maryland/704/1977(H13N6), A/mallard/Wisconsin/10OS3941/2010(H14N6), B-Phuket B/Phuket/3073/2013, H3-BK-79 A/Bangkok/01/1979(H3N2), and gHAshield (8). (B) Phylogram of 16 HA serotypes. The division of HA groups 1 and 2 is shown by a dotted line. (C) Structure of the 220 loop of A/Bangkok/01/1979(H3N2). The HA head is faded except for the 220 loop to emphasize this feature. Residues Arg220, Pro221, and Gly229 are shown in sticks. (D) Comparison with A/Aichi/02/1968(H3N2) (PDB accession number 2VIU) (gray), which has an Arg at position 229.