Receptor specificity of subtype H1 influenza A viruses isolated from swine and humans in the United States

The evolution of classical swine influenza viruses receptor specificity preceding the emergence of the 2009 H1N1 pandemic virus was analyzed in glycan microarrays. Classical swine influenza viruses from the alpha, beta, and gamma antigenic clusters isolated between 1945 and 2009 revealed a binding profile very similar to that of 2009 pandemic H1N1 viruses, with selectivity for alpha 2-6-linked sialosides and very limited binding to alpha 2-3 sialosides. Despite considerable genetic divergence, the 'human-like' H1N1 viruses circulating in swine retained strong binding preference for alpha 2-6 sialylated glycans. Interspecies transmission of H1N1 influenza viruses from swine to humans or from humans to swine has not driven selection of viruses with distinct novel receptor binding specificities. Classical swine and human seasonal H1N1 influenza viruses have conserved specificity for similar alpha 2-6-sialoside receptors in spite of long term circulation in separate hosts, suggesting that humans and swine impose analogous selection pressures on'the evolution of receptor binding function. Published by Elsevier Inc.