Figure 2. EpiMatrix Immunogenicity scale comparing the potential antigenicity of H7-HA to recent seasonal influenza A strain HA proteins. Using EpiMatrix and assessing each protein for overall T-cell epitope content, the protein scores are plotted on an immunogenicity scale that ranks the immunogenic potential of HA protein derived from recently-circulating strains of seasonal IAV (H1N1, H3N2) as compared with strains of avian-origin influenza. The set of avian-origin IAV strains have a low immunogenicity potential (below zero), EpiMatrix scores that are commonly associated with low immunogenicity proteins that do not effectively trigger IgG antibody responses. Scores are shown for H7-HA from several different sources, including the vaccines described in the text (refs. 22 and 23 [Anhui, scoring -6.49], 28 [mallard, –7.12], and 29 [chicken, –6.43]). In contrast, H1N1 California, H3N2 Victoria, and H2N3 Texas, rank +19.22, +16.23, and +14.25 respectively). The EpiMatrix Immunogenicity Scale is derived by analyzing more than 10 000 random protein sequences for T cell epitope content and producing a score that reflects the normal distribution of T cell epitope content per protein length. Proteins scoring higher than 10 on this scale are usually antigenic; proteins scoring lower than 10 are generally poorly antigenic. Details on the methodology are available in reference 13 and other publications by the group.