Many microbial pathogens and toxins recognize animal cells via cell surface sialic acids
(Sias) that are α2–3-or α2–8-linked to the underlying glycan chain. Human influenza A/B
viruses are unusual in preferring α2–6-linked Sias, undergoing a switch from α2–3 linkage
preference during adaptation from animals to humans. This correlates with the expression of
α2–6-linked Sias on ciliated human airway epithelial target cells and of α2–3-linked Sias on
secreted soluble airway mucins, which are unable to inhibit virus binding. Given several …