Antigenic distance between North American swine and human seasonal H3N2 influenza A viruses as an indication of zoonotic risk to humans
Scripts and data related to the H3 pipeline manuscript:
Souza, C.K., Anderson, T.K., Chang, J., Venkatesh, D., Lewis, N.S., Pekosz, A., Shaw-Saliba, K., Rothman, R.E., Chen, K-F, Vincent, A.L. (2022). Antigenic distance between North American swine and human seasonal H3N2 influenza A viruses as an indication of zoonotic risk to humans. Journal of Virology 96(2): e01374-21. doi: https://doi.org/10.1128/JVI.01374-21
Human-to-swine transmission of influenza A virus (IAV) repeatedly occurs, periodically leading to sustained transmission and increased IAV diversity in swine; human seasonal H3N2 introductions occurred in the 1990s and 2010s and were maintained in North American swine. These swine H3N2 were subsequently associated with zoonotic infections, highlighting the need to understand the risk of endemic swine IAV to humans. We used antigenic cartography to quantify antigenic distances between swine H3N2 and human seasonal vaccine strains from 1973 to 2014 using a panel of monovalent antisera raised in pigs in hemagglutination inhibition (HI) assays. Swine H3N2 lineages retained closest antigenic similarity to human vaccine strains from the decade of incursion. Swine lineages from the 1990s were antigenically more similar to human vaccine strains of the mid-1990s but had substantial distance from recent human vaccine strains. In contrast, swine lineages from the 2010s were closer to human vaccine strains from 2011 and 2014 and most antigenically distant from human vaccine strains prior to 2007. HI assays using ferret antisera demonstrated that swine lineages from the 1990s and 2010s had significant fold-reduction compared with the homologous HI titer of the nearest pandemic preparedness candidate vaccine virus (CVV) or seasonal vaccine strain. The assessment of post-infection and post-vaccination human sera cohorts demonstrated limited cross-reactivity to swine H3N2 strains from the 1990s, especially in older adults born before 1970s. These studies identified swine strains to which humans are likely to lack population immunity or are not protected against by a current human seasonal vaccine or CVV to use in prioritizing future human CVV strain selection.
| file | description |
|---|---|
| phylogeny-figure | Files and data for phylogenetic analyses |
| figures | folder containing all generated figures |
| supplementary-data | folder containing HI data for the post exposure and post vaccination cohort |