Binding kinetics of influenza viruses to sialic acid-containing carbohydrates

To elucidate the molecular mechanisms of transmission of influenza viruses between different host species, such as human and birds, binding properties of sialic acid-containing carbohydrates that are recognized by human and/or avian influenza viruses were characterized by the surface plasmon resonance (SPR) method. Differences in the binding of influenza viruses to three gangliosides were monitored in real-time and correlated with receptor specificity between avian and human viruses. SPR analysis with ganglioside-containing lipid bilayers demonstrated the recognition profile of influenza viruses to not only sialic acid linkages, but also core carbohydrate structures on the basis of equilibrated rate constants. Kinetic analysis showed different binding preferences to gangliosides between avian and human strains. An avian strain bound to Neu5Ac alpha 2-3nLc(4)Cer with much slower dissociation rate than its sialyl-linkage analog, Neu5Ac alpha 2-6nLc(4)Cer, on the lipid bilayer. In contrast, a human strain bound equally to both gangliosides. An avian strain, but not a human strain, also interacted with GM(3) carrying a shorter carbohydrate chain. Our findings demonstrated the remarkable distinction in the binding kinetics of sialic acid-containing carbohydrates between avian and human influenza viruses on the lipid bilayer.