Amide-sialoside protein conjugates as neomucin bioshields prevent influenza virus infection

We report the preparation of multivalent amide-sialoside-decorated human serum albumin (HSA) and bovine serum albumin (BSA) as mimics of natural mucin and bioshields against influenza virus infection. Free sialic acid with an amine on C-2 was covalently attached to the protein scaffolds using di-(N-succinimidyl) adipate. Dynamic light scattering (DLS) showed that the synthetic neomucins were able to act as bioshields and aggregate the influenza virion particles. The dissociation constants (K_D) of the interactions between the prepared glycoconjugates and three different viral strains were measured by isothermal titration calorimetry (ITC) indicating the multivalent presentation of sialyl ligands on the HSA and BSA backbones can dramatically enhance the adsorbent capability compared to the corresponding monomeric sialoside. Hemagglutinin inhibition (HAI) and neuraminidase inhibition (NAI) assays showed that the glycoconjugates acted as moderate HA and NA inhibitors, thus impeding viral infection. Moreover, the different binding affinities of the glycoproteins to HA and NA proteins from different influenza viruses demonstrated the importance of HA/NA balance in viral replication and evolution. These findings provide a foundation for the development of antiviral drugs and viral adsorbent materials based on mimicking the structure of mucin.