FIG 1.

Structures of head interface antibodies bound to HA head domains. (A) HA trimer from A/Bangkok/01/1979(H3N2), shown with a yellow surface. The HA head domain of a single protomer is shown in a cartoon representation in gray. The H3 and H1 head constructs used for crystallization experiments are shown to the right. Fabs are colored according to the V_H (darker color) and V_L (lighter color) gene usage. HA heads are all shown in gray. H2214, S5V2-29, and FluA-20 have been previously reported, and their PDB accession numbers are indicated (9, 10). (B) The six antibodies (two columns of three) that do not use the IGκV1-39 gene. (C) One column showing the five antibodies that use IGκV1-39 (cyan). (D, left) Contact heat map on the HA head surface. The numbers of Fabs (from a total of 11) contacting each residue were tallied and are colored according to the key. Contacts for IGκV1-39 Fabs and non-IGκV1-39 Fabs and their relationship with conserved residues are shown in Fig. S1C in the supplemental material. (Right) Two key points of contact, the 220 loop (purple) and residues 99 to 105 (dark gray), are shown on the HA surface.