Heterogeneity across mammalian- and avian-origin A(H1N1) influenza viruses influences viral infectivity following incubation with host bacteria from the human respiratory tract.

Influenza A viruses (IAVs) are primarily transmitted between mammals by the respiratory route and encounter bacteria in the respiratory tract before infecting susceptible epithelial cells. Previous studies have shown that mammalian-origin IAV can bind to the surface of different bacterial species and purified bacterial lipopolysaccharides (LPS), but despite the broad host range of IAV, few studies have included avian-origin IAV in these assessments. Since IAVs that circulate in humans and birds are well adapted to replication in the human respiratory and avian gastrointestinal tracts, respectively, we investigated the ability of multiple human and avian A(H1N1) IAVs to associate with bacteria and their surface components isolated from both host niches. Binding interactions were assessed with microbial glycan microarrays, revealing that seasonal and avian IAV strains exhibited binding diversity to multiple bacterial glycans at the level of the virus and the bacterium, independent of sialic acid binding preference of the virus. Coincubation of diverse IAV with LPS derived from