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Research Project: Intervention Strategies to Control Influenza A Virus Infection in Swine

Location: Virus and Prion Research

Title: Antigenic distance from human vaccine strains as a measure of risk to human populations from currently circulating North American swine H1 viruses

Author
item VENKATESH, DIVYA - Royal Veterinary College
item KIMBLE, BRIAN - Orise Fellow
item KUNZLER-SOUZA, CARINE - Orise Fellow
item Anderson, Tavis
item CHANG, JENNIFER - Orise Fellow
item DETMER, SUSAN - University Of Saskatchewan
item MENA, IGNACIO - The Icahn School Of Medicine At Mount Sinai
item GARCIA-SASTRE, ADOLFO - The Icahn School Of Medicine At Mount Sinai
item LEWIS, NICOLA - Royal Veterinary College
item Vincent, Amy

Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: 5/5/2021
Publication Date: 5/5/2021
Citation: Venkatesh, D., Kimble, B., Kunzler-Souza, C., Anderson, T.K., Chang, J., Detmer, S., Mena, I., Garcia-Sastre, A., Lewis, N., Vincent, A.L. 2021. Antigenic distance from human vaccine strains as a measure of risk to human populations from currently circulating North American swine H1 viruses [abstract]. Applied Bioinformatics and Public Health Microbiology Conference. P. none assigned.

Interpretive Summary:

Technical Abstract: The first pandemic of the 21st century was caused by an H1N1 subtype influenza A virus (IAV) that was transmitted from pigs into humans, highlighting the importance of swine as reservoirs for pandemic viruses. In this project we have investigated the relationship between the evolution of the H1 subtype IAV in North American swine and the risk to human health. We quantified the antigenic distances between the HA of the swine H1 and human seasonal vaccine strains (1978-2015) using a panel of monovalent anti-sera raised in pigs using hemagglutination inhibition (HI) assays. Antigenic distances between viruses were calculated in antigenic units (AU), in which 1 AU is equivalent to a 2-fold loss in HI cross-reactivity. Two major lineages of swine H1 circulate in North America: 1A classical swine (including the 2009 pandemic H1N1), 1B: Human seasonal-like, which reflect multiple introductions from human seasonal strains. Broadly, we see a distinction between the distance of different swine H1 strains from the pre-pandemic vs post-pandemic human seasonal viruses. Viruses of the swine 1A lineage from which the pandemic strain arose are antigenically closer to the post-pandemic viruses (1.75 - 5.92 AU). This lineage includes pandemic viruses that have “spilled-back” into pigs. The 1B lineage strains, which arose from previously circulating human seasonal viruses are antigenically closer to those viruses (1.6 - 4.4 AU) (and distant from post-pandemic viruses (6.19 - 9.62 AU)). Notable exceptions result from distinct deletion mutations in one of the 1A sub-lineages (1A.1.1-3-del), and those strains highly distant from the post-pandemic viruses (8.34 - 11.86 AU). In human population immunity, as measured by cross-reactivity in HI assays to representative swine H1 strains, we see a very heterogenous response to most viruses, with a broad range of titres against each strain. Notable exceptions are representative viruses from the 1A.1.1-3-del and 1B.2.1 sub-lineages to which there appears to be almost no cross-reactivity in human sera at all. We propose these as specific lineages of concern to pandemic risk which should be characterised further.