Sialic acid and sialyl-lactose glyco-conjugates: Design, synthesis and binding assays to lectins and swine influenza H1N1 virus

The terminal parts of the influenza hemagglutinin (HA) receptors α2,6- and α2,3-sialyllactoses were conjugated to an artificial carrier, named sequential oligopeptide carrier (SOC 4), to formulate human and avian receptor mimics, respectively. SOC 4, formed by the tripeptide unit Lys-Aib-Gly, adopts a rigid helicoids-type conformation, which enables the conjugation of biomolecules to the Lys-N εH 2 groups. By doing so, it preserves their initial conformations and functionalities of the epitopes. We report that SOC 4-glyco-conjugate bearing two copies of the α2,6-sialyllactose is specifically recognized by the biotinylated Sambucus nigra (elderberry) bark lectin, which binds preferentially to sialic acid in an α2,6-linkage. SOC 4-glyco-conjugate bearing two copies of the α2,3-sialyllactose was not recognized by the biotinylated Maackia amurensis lectin, despite its well-known α2,3-sialyl bond specificity. However, preliminary immune blot assays showed that H1N1 virus binds to both the SOC 4-glyco-conjugates immobilized onto nitrocellulose membrane. It is concluded that Ac-SOC 4[(Ac) 2,(3'SL-Aoa) 2]-NH 2 5 and Ac-SOC 4[(Ac) 2,(6'SL-Aoa) 2]-NH 2 6 mimic the HA receptors. These findings could be useful for easy screening of binding and inhibition assays of virus-receptor interactions. © 2011 European Peptide Society and John Wiley & Sons, Ltd.