The specificity of the influenza B virus hemagglutinin receptor binding pocket: what does it bind to?

The influenza surface glycoprotein hemagglutinin (HA) binds to sialylglycoproteins and sialylglycolipids on the surface of host cells. These sialyl-glycans, usually linked to galactose in either a2,6 or a2,3 configurations, are the receptors for the viral HA, the binding to which promotes viral attachment, membrane fusion, and internalization of the virus. This review examines all of the available receptor binding data on the influenza B HA and provides a structure recognition perspective for the receptor binding preferences of influenza B virus HA regional and egg-adapted variants. Overall, the review serves as an up-to-date compendium of the literature binding data, and the presented discussions assist the reader in reaching a consensus understanding of the receptor specificity determinants for the influenza B HA.