Computational analysis of adaptive antigenic mutations of the human influenza hemagglutinin for vaccine strain selection

The adaptive evolution of the hemagglutinin (HA) segment of the human influenza H1N1 and H3N2 viruses is not well understood due to antigenic mutations under selection pressures. This paper identified significant antigenic selection sites and discussed the structural relevance of these mutations. We discovered four positively selected sites for H1N1 (position 206 for the 1A lineage - 2009 swine influenza, and positions 144, 190, and 192 for the 1B lineage), and eight positively selected sites for H3N2 with the loop regions near residues 157 and 225 as the latest antigenic mutations, which may be targeted for vaccine development.