Blocking the Hemagglutinin of Influenza A Virus by Multivalent Inhibitors

Abstract

The aim of this thesis is to develop multivalent carbohydrate-based ligands as inhibitors of the adhesion of the Influenza A virus (IAV). The adhesion protein hemagglutinin (HA) plays a central role in the infection process, and has potential as a drug target besides the neuraminidase. HA is a challenging target, since it binds only weakly to its target ligands: sialylated LacNAc derivatives, relying on multivalency for strong viral adhesion. The inhibitor design consisted of three different parts: a ligand that contains an α-2,6-sialylated glycan (3 copies), a propeller shaped scaffold, and a short rigid spacer that links the ligands to the scaffold. The synthetic strategy to combine these three parts is based on the efficient copper catalyzed azide-alkyne cycloaddition (CuAAC, ‘click’) reaction under microwave assistance. Another strategy is based on divalent ligands presenting galactose residues with variations in the length of the spacer to fit a divalent binding mode. By linking sialylated LacNAc units to di- and trivalent scaffolds, inhibitors were obtained with a potent inhibition effect in several assays. A 428-fold enhancement was achieved with the long-armed inhibitors containing either two or three sialyl-LacNAc-Lac units in a bio-layer interferometry (BLI) assay. Results were also confirmed by hemagglutination inhibition assay and by inhibition of an IAV infection of a human lung cell line.