Location: Virus and Prion ResearchTitle: Cross-reactivity of contemporary US swine H1NX viruses to current seasonal and candidate vaccine viruses as a measure of risk to humans
|KIMBLE, BRIAN - Orise Fellow|
|SOUZA, CARINE - Orise Fellow|
|HUFNAGEL, DAVID - Orise Fellow|
|ARENDSEE, ZEBULUN - Orise Fellow|
|YOUNG, KATHARINE - Orise Fellow|
|LEWIS, NICOLA - Royal Veterinary College|
|DAVIS, TODD - Centers For Disease Control And Prevention (CDC) - United States|
Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: 10/28/2020
Publication Date: 1/11/2021
Citation: Kimble, B.J., Souza, C.K., Anderson, T.K., Hufnagel, D.E., Arendsee, Z.W., Young, K.M., Lewis, N.S., Davis, T.C., Vincent, A.L. 2021. Cross-reactivity of contemporary US swine H1NX viruses to current seasonal and candidate vaccine viruses as a measure of risk to humans. Centers of Excellence for Influenza Research and Surveillance Annual Network Meeting [abstract]. Poster No. 74.
Technical Abstract: Influenza A viruses (IAV) containing hemagglutinin genes from 8 phylogenetic clades of H1 were detected cocirculating in US swine in 2019. Of the current endemic swine H1 clades, six have caused variant cases in humans over the last decade. The majority of these zoonotic events are restricted to a single spillover with no subsequent transmission, however, reassortment between swine H1 and human-seasonal H1N1 results in unique viruses emerging in swine that maintain human-origin genes and can be transmitted to humans. To prepare for the potential of a swine-origin IAV pandemic in people, candidate vaccine viruses (CVV) have been developed for use as vaccine seed strains. To assess the pandemic risk of contemporary US swine H1N1 or H1N2 strains, we quantified the diversity of swine H1 HA genes and selected representatives of each circulating clade. We then tested the swine isolates against human seasonal vaccine and CVV strains using ferret antisera in hemagglutination inhibition assays (HI) to gain insight into the risk swine H1 IAV pose to the human population. HI assays revealed that some clades (1A.3.3.2-pdm, 1B.2.1-delta2) had high levels of cross reactivity to human seasonal vaccines or CVVs. However, viruses from 3 clades that represent more than 50% of the detected swine IAVs in the USA showed significant reduction (8-32 fold) in cross reactivity compared to the closest CVV virus: 1A.1 (alpha), 1A.3.3.3-clade 3 (gamma), and 1B.2.2.1 (delta1a). Representative viruses from each of these three clades were further characterized in a pig-to-ferret transmission model. Taken together, these data highlight the risk that swine H1N1 and H1N2 pose to the human population and identify the efficacy and gaps in current pandemic CVV preparation strategies.