Structural models of influenza A virus H5 proteins complexed with 3′SLeX. A) Clade 1 H5 (H5N11 of A/Vietnam/1194/2004) complexed with 3′SLeX (PDB 3ZNM0 (29). B) H5N12.3.4 and C) H5N8 hemagglutinins were modeled into the structure shown in panel A as detailed in Materials and Methods. Key amino acids are indicated and shown in a stick representation. C (gray), O (red), and N (blue) in the side chains are colored. SIA, Gal, GlcNAc, and Fuc moieties of 3′SLeX are shown in purple, yellow, blue, and red, respectively. Hydrogen bonds are indicated by dotted lines. H5N12.3.4, novel H5N1 virus clade 2.3.4; H5N11, H5N1 virus clade 1.