Molecular Design of Spacer-N-Linked Sialoglycopolypeptide as Polymeric Inhibitors Against Influenza Virus Infection

A series of spacer-N-linked glycopolymers carrying long/short alpha 2,3/6 sialylated glycan were designed as polymeric inhibitors of influenza virus. Lactose (Lac) and N-acetyllactosamine (LN: Gal beta 1,4GlcNAc) were first converted to spacer-N-linked disaccharide glycosides, followed by consecutive enzymatic addition of GlcNAc and Gal residues to the glycosides. The resulting spacer-N-linked glycosides with di-, tetra-, and hexasaccharides carrying a Lac, LN, lacto-N-neotetraose (LNnT: Gal beta 1,4GlcNAc beta 1,3Gal beta 1,4Glc), and LN beta 1,3LNnT were coupled to the carboxy group of gamma-polyglutamic acid (gamma-PGA) and enzymatically converted to glycopolypeptides carrying alpha 2,3/6 sialylated glycans. The interactions of a series of sialoglycopolypeptides with avian and human influenza virus strains were investigated using a hemagglutination inhibition assay. The avian virus A/Duck/HongKong/313/4/78 (H5N3) bound specifically, regardless of the structure of the asialo portion. In contrast, human virus A/Aichi/2/68 (H3N2) bound preferentially to long alpha 2,6sialylated glycans with penta- or heptasaccharides in a glycan length-dependent manner. Furthermore, the Sambucus sieboldiana (SNA) lectin was also useful as a model of human virus hemagglutinin (HA) for understanding the carbohydrate binding properties, because the recognition motifs of the inner sugar in the receptor were very similar.