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A surface plasmon resonance assay for the binding of influenza virus hemagglutinin to its sialic acid receptor.

We have developed a sensitive microscale binding assay to study the interaction between influenza hemagglutinin and its cell surface receptor sialic acid using real-time surface plasmon resonance. The glycoprotein fetuin was bound to a carboxymethylated-Dextran sensor surface using N-hydroxysuccinimide and N-ethyl-N'-(dimethylaminopropyl) carbodiimide. Low-pH-induced BHA rosettes bind specifically to the fetuin-derivitized sensor surface, but not to an asialofetuin-derivitized sensor surface. Binding can be inhibited by preincubation of BHA rosettes with millimolar concentrations of inhibitors of the influenza hemagglutinin-sialic acid interaction. The association rate, dissociation rate, and dissociation constant for the multivalent interaction between BHA rosettes and the fetuin-derivitized sensor surface were also measured, allowing us to quantitate the tight binding achieved through the multivalent interaction between BHA rosettes and the fetuin-derivitized sensor surface.