Figure 3. . Three-dimensional top view of the HA1 hemagglutinin structures for A) a representative A/Nepal/1648/04 virus and B) vaccine strain A/Wyoming/3/03. Most (24/26) of the Nepal isolates contain a lysine to asparagine substitution (shown in yellow) at position 145 (K145N). Magenta, residues 226 and 227; orange, residue 189; green, residues 155 and 156; yellow, residue 145. Hemagglutinin molecules were generated by using the respective amino acid sequences with MOLMOL (12). A/Nepal/1648/04 is available from GenBank under accession no. AY945264.