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 a2,6- and a2,3-sialyllactoses were conjugated to an artificial carrier, named sequential oligopeptide carrier (SOC4), to formulate human and avian receptor mimics, respectively. SOC4, formed by the tripeptide unit Lys-Aib-Gly, adopts a rigid helicoids-type conformation, which enables the conjugation of biomolecules to the Lys-NeH2 groups. By doing so, it preserves their initial conformations and functionalities of the epitopes. We report that SOC4-glyco-conjugate bearing two copies of the a2,6-sialyllactose is specifically recognized by the biotinylated Sambucus nigra (elderberry) bark lectin, which binds preferentially to sialic acid in an a2,6-linkage. SOC4-glyco-conjugate bearing two copies of the a2,3-sialyllactose was not recognized by the biotinylated Maackia amurensis lectin, despite its well-known a2,3-sialyl bond specificity. However, preliminary immune blot assays showed that H1N1 virus binds to both the SOC4-glyco-conjugates immobilized onto nitrocellulose membrane. It is concluded that Ac-SOC4[(Ac)2,(3'SL-Aoa)2]-NH2 5 and Ac-SOC4[(Ac)2,(6'SL-Aoa)2]-NH2 6 mimic the HA receptors. These findings could be useful for easy screening of binding and inhibition assays of virusreceptor interactions. Copyright (C) 2011 European Peptide Society and John Wiley & Sons, Ltd.