FIGURE 2.

Hemagglutinin head and stem and their conserved regions. Structure view of trimerized hemagglutinin proteins of influenza virus. A homotrimer shown as a sphere model. HA1 and HA2 are colored in green and blue, respectively. The other polypeptides of HAs are depicted as a ribbon model. Conserved amino acids among group 1 influenza viruses are colored in gold overlaid on the model on the left. Amino acids of the C179 binding region are colored in red. These views were generated by Protean 3D using the structure PDB 4HLZ