Figure 3

Glycosylation sites and amino acid substitution positions in the HA1 domain contributing to the antigenic diversity of Chilean H1 swine IAVs. Trimeric HA 3D structures with surface representation of one of their monomers, in which HA1 domain is in blue and HA2 domain is in light blue. A side view is shown on the left and a top view is shown on the right. Conserved glycosylation sites present in reference swine IAV vaccine strains are highlighted in yellow; while unique or not-conserved glycosylation sites, which are not present in reference swine IAV strains from current commercial vaccines, are highlighted in magenta. The absolute HA numbering (starting at the first methionine position) are provided in parentheses since some studies have used this nomenclature to designate glycosylation sites. Residues of the antigenic sites (Sa, Sb, Ca1, Ca2 and Cb) are colored light orange, and unique amino acid substitutions in the antigenic sites of antigenic variants are colored red. (a) Representative HA of ChH1A cluster using the HA structure of A/Thailand/CU44/2006(H1N1) strain (PDB ID: 4edb). (b) Representative HA of ChH1B cluster using the HA structure of the A/Thailand/CU44/2006(H1N1) strain. (c) Representative HA of the A(H1N1)pdm09-like cluster was based on the HA structure of the A/California/04/2009(H1N1) strain (PDB ID: 3lzg).