Influenza virus–glycan interactions

•It has been known since the 1950s that influenza virus uses sialic acid as a receptor.•Development of glycan arrays has allowed an unprecedented analysis of the fine specificity of binding.•While the general rule is that avian viruses bind to sialic acids bound α2-3 to galactose while human viruses bind α2-6 linked sialic acid, avian viruses can infect people without a change in specificity.•The role of receptor specificity in transmission of influenza viruses is still unclear.

It has been known for many years that influenza viruses bind by their hemagglutinin surface glycoprotein to sialic acid (N-acetylneuraminic acid) on the surface of the host cell, and that avian viruses most commonly bind to sialic acid linked α2-3 to galactose while most human viruses bind to sialic acid in the α2-6 configuration. Over the past few years there has been a large increase in data on this binding due to technological advances in glycan binding assays, reverse genetic systems for influenza and in X-ray crystallography. The results show some surprising changes in binding specificity that do not appear to affect the ability of the virus to infect host cells.