Fig. 6

Amino acid (AA) substitutions in HAs of pH1N1 and H3N2 viruses circulated between 2009 and 2017. a Number of amino acid substitutions in HA head and stem domains of pH1N1 and H3N2 viruses. Amino acids are colored according to their location in head (red), stem (blue) and antigenic sites (dark red). b Amino acid substitutions identified in the antigenic sites of HAs of pH1N1 and H3N2 viruses in 2009 and 2016. The 3D crystal structures of A/California/04/2009 (PDB 3LZG) and for 2005 human H3N2 Virus (PDB 2YP7) are displayed using CLC genomic workbench version 11. The antigenic sites of H1 are colored: Sa (red), Sb (green), Ca (blue) and Cb (orange). The antigenic sites of H3 are colored: A (red), B (blue), C (green), D (orange) and E (purple). The inner site of H3 structure (2016) is shown to visualize D53N substitution in C1 epitope. Fixed substitutions developed during the evolution of the influenza viruses are labeled in bold. AA substitutions in RBS are shown in italics. AA substitutions that are associated with changes of potential glycosylation sites are framed