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

Location: Virus and Prion Research

Title: Antigenic characterization of contemporary US swine H3N2 strains and transmission from swine to ferrets as an indication of risk to humans

item SOUZA, K, CARINE - Orise Fellow
item KIMBLE, BRIAN - Orise Fellow
item Anderson, Tavis
item ARENDSEE, ZEBULUN - Orise Fellow
item HUFNAGEL, DAVID - Orise Fellow
item YOUNG, KATHARINE - Orise Fellow
item LEWIS, NICOLA - Royal Veterinary College
item DAVIS, TODD - Centers For Disease Control And Prevention (CDC) - United States
item Baker, Amy

Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: 10/28/2020
Publication Date: 1/11/2021
Citation: Souza, K, C., Kimble, B.J., Anderson, T.K., Arendsee, Z.W., Hufnagel, D.E., Young, K.M., Lewis, N.S., Davis, T.C., Vincent, A.L. 2021. Antigenic characterization of contemporary US swine H3N2 strains and transmission from swine to ferrets as an indication of risk to humans [Abstract]. 2021 Centers of Excellence for Influenza Research and Surveillance Annual Network Meeting. Poster no. 76.

Interpretive Summary:

Technical Abstract: Interspecies transmission of influenza A virus (IAV) from humans into pigs occurs frequently, some leading to subsequent virus evolution in pig populations, and plays a critical role in swine IAV diversity. In the 1990s, human-to-swine seasonal H3N2 introductions (1990.1 and 1990.4) occurred in the US, of which the 1990.4 established and evolved in pig populations, diversifying into further clades. In the 2010s, two H3N2 human-to-swine spillovers were detected in the US (2010.1 and 2010.2). H3.1990.4 and H3.2010.1 lineages cocirculate in swine and have been associated with human variant cases, highlighting a public health concern. If variant viruses have substantially drifted from current human seasonal vaccine (HuVac) strains, they may be chosen as candidate virus vaccine (CVV) for pandemic preparedness purposes. However, not all swine IAV are systematically evaluated to address HuVac or CVV coverage. To assess the risk of contemporary US swine H3N2 strains to humans, we performed phylogenetic analyses of recent swine H3 HA genes to select clade consensus representatives to be evaluated in hemagglutination inhibition (HI) assays with CVV or HuVac using ferret antisera. Neither the H3.1990.1 nor H3.1990.4.B2 swine HA clades had a within-clade CVV and had significant decreases from the H3.1990.4 CVV A/Minnesota/11/2010 (MN/10). Contemporary H3.1990.4.A had a significant decrease from the within-clade CVV MN/10. Swine 2010.1 had significant decrease to the within-clade CVV A/Ohio/28/2016-like (OH/16). Swine 2010.2 do not have a within-clade CVV and also had a significant decrease to the 2010.1 CVV OH/16 and 8-fold decrease to HuVac A/Iowa/60/18. Representative contemporary US swine H3N2 strains from H3.1990.1, H3.1990.4A, and H3.1990.4B2 clades with significant loss in HI cross-reactivity to the nearest CVV or HuVac were selected for a swine-to-ferret transmission study. These results inform the zoonotic risk of contemporary circulating swine H3N2 viruses to humans.