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

Location: Virus and Prion Research

Title: Antigenic differences between the two N2 neuraminidase lineages of North American swine influenza A viruses

item KAPLAN, BRYAN - Oak Ridge Institute For Science And Education (ORISE)
item Anderson, Tavis
item SANTOS, JEFFERSON - University Of Georgia
item PEREZ, DANIEL - University Of Georgia
item LEWIS, NICOLA - Royal Veterinary College
item Baker, Amy

Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: 4/17/2019
Publication Date: 6/25/2019
Citation: Kaplan, B.S., Anderson, T.K., Santos, J., Perez, D., Lewis, N., Vincent, A.L. 2019. Antigenic differences between the two N2 neuraminidase lineages of North American swine influenza A viruses [abstract]. p. none assigned.

Interpretive Summary:

Technical Abstract: The neuraminidase (NA) protein of IAV is a surface glycoprotein, important for the release of nascent virus particles from the cell surface. Though not as protective as neutralizing antibodies against the hemagglutinin (HA), antibodies against the NA can reduce clinical disease and transmission. H3N2 and H1N2 viruses widely circulate in North American swine populations, but the N2 genes are divided into two distinct phylogenetic lineages resulting from introductions of human H3N2 in 1998 and 2002, with further genetic diversity within each lineage. Here, we assessed the antigenic differences between and among 1998 and 2002 N2 lineages of swine IAV using enzyme-linked lectin assay (ELLA) and antigenic cartography. Varying cross-reactivity was observed between subclades of the N2-98 and N2-02 lineages, respectively. Antisera raised against N2-98 antigens did not display cross-reactivity against N2-02 antigens, but antisera raised against N2-02 antigens had some cross-inhibitory activity against the limited panel of N2-98 antigens. Using antigenic cartography, we mapped the N2 antigens and calculated the antigenic distances between N2 lineages and sub-clades. Antigenic distances are routinely used to describe the antigenic relationships between IAV HA, where antigenic distances greater than 3 antigenic units signify a lack of cross-reactivity for antisera to heterologous HA antigens. Intra-clade antigenic distances were moderate (~2 AU) while interclade distances were much larger (>5 AU). These results show major antigenic differences exist between the two major N2 lineages circulating in North American swine populations. Swine N2 antisera show little to no reactivity with contemporary human N2 suggesting NA mediated immunity in humans may be lacking and vice versa. These data aid in vaccine strain selection and in the identification of specific residues contributing to antigenicity to further improve vaccine strain selection and development for control of IAV in swine and human hosts.