Antigenic Mapping of H2 Influenza Viruses recognized by Ferret and Human Sera and Predicting Antigenically Significant Sites.

Influenza viruses cause hundreds of thousands of infections globally every year. In the past century, seasonal influenza viruses have included H1N1, H2N2 and H3N2 strains. H2N2 influenza viruses circulated in the human population between 1957-1968. Previously, our group demonstrated a lack of H2N2 influenza virus immunity in individuals born after 1968, as well as the effectiveness of hemagglutinin (HA) based vaccines for multiple influenza virus subtypes. In this study, H2 antigenic maps and radial graphs were generated using previously published data from H2 HA vaccinations of ferrets and seasonal influenza vaccinations of humans. The antigenic maps revealed a stark difference in clustering of HA antigens between the ferrets and humans, and the radial graphs showed specific antigen recognition varies greatly between different influenza preimmune ferrets. These maps also revealed the significant impact that different pre-existing immunities have on antigenic recognition and clustering of antigens after vaccine boost. From these data, we predicted two possible antigenically significant sites containing various mutations that have not been previously reported and showed that one of these sites is relevant using mouse anti-sera.