Carbohydrate microarray-based analysis of specific interactions between saccharides from algin and influenza A viral hemagglutinin

The specific interaction of carbohydrates and hemagglutinin (HA) on influenza A virus (IAV) is of great interest for carbohydrate-based anti-IAV drug discovery. Herein, a carbohydrate microarray-based method was developed for the determination of the specific interaction between carbohydrates and HA. Four marine acidic saccharides from algin (L-guluronic acid, GulA; L-diguluronic acid, GulA2; L-triguluronic acid, GulA3; and L-tetraguluronic acid, GulA4) were immobilized on poly(2-hydroxyethyl methacrylate)-cyanuric chloride-modified substrates, recently reported by us, to form a microarray. GulA, GulA2, GulA3, and GulA4 all showed specific binding with HA from influenza A H1N1 subtype and exhibited increased binding affinity. Molecular docking was adopted to simulate the complexes formed by investigated saccharides and HA to gain better insight into their binding behaviors. The reliability of the carbohydrate microarray-based assay was also verified by cytopathic effect inhibition assay and surface plasmon resonance analysis. By adopting this microarray-based method, the consumption of saccharides could be reduced to the pmol level and the limit of detection of HA could be reduced to 8.4 nM without any further signal amplification. This carbohydrate microarray-based assay is thus an ideal tool for studying specific interactions of carbohydrates and HA or other proteins, and will provide a promising platform for carbohydrate-based drug discovery and development.