Abstract
Most H1 influenza A viruses (IAVs) of swine are derived from past human viruses. As human population immunity against these IAVs gradually decreases, the risk of reintroduction to humans increases. We examined 549 serum samples from persons 0–97 years of age collected in Belgium during 2017–2018 for hemagglutination inhibiting and virus neutralizing antibodies against 7 major H1 swine IAV (swIAV) clades and 3 human progenitor IAVs. Seroprevalence (titers >40) rates were >50% for classical swine and European human-like swIAVs, >24% for North American human-like δ1a and Asian avian-like swIAVs, and <10% for North American human-like δ1b and European avian-like swIAVs, but rates were age-dependent. Antibody titers against human-like swIAVs and supposed human precursor IAVs correlated with correlation coefficients of 0.30–0.86. Our serologic findings suggest that European avian-like, clade 1C.2.1, and North American human-like δ1b, clade 1B.2.2.2, H1 swIAVs pose the highest pandemic risk.
Highlights
Humans and swine are susceptible to influenza A viruses (IAVs) of hemagglutinin (HA) subtypes H1 and H3, which are widespread in both species
In a previous seroprevalence study for H3 swine IAV (swIAV) in humans from Luxembourg, we demonstrated a correlation with the nature of the swIAV and its relation to human IAVs on the one hand and the persons’ birth year on the other [19]
We examined the relation between antibodies against human-like swIAVs and their presumed human seasonal ancestor IAV
Summary
Sample Collection During August 2017–January 2018, a total of 549 anonymized serum samples were collected from immunocompetent persons with unknown influenza vaccination or infection history born during 1920–2017 at Ghent University Hospital (Ghent, Belgium). Viruses Samples were evaluated for antibodies against 11 viruses representing 7 major H1 swIAV clades circulating in Europe, North America, and Asia; 2 human seasonal progenitor IAVs for European and North American human-like swIAVs; and 1 human seasonal IAV that circulated right before the pH1N1 virus (Table 1). We used epidemiologic data [10,11,12] and the H1 classification system [9] to select major H1 swIAV clades. We selected test viruses on the basis of amino acid homology and antigenic relatedness to currently circulating swIAVs of each clade. We determined the percent of amino acid homology between test viruses and numbers of identical amino acids in presumed antigenic sites [29] with MEGA7 and R version 3.2.2 [30].
Sign-in/Register to view highlights & summary 
Published Version (
Free)
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call