Many viruses recognize specific sugar residues, particularly sulfated, sialylated glycans or its modified forms as the infection receptors.  Influenza is an infectious disease caused by the influenza virus that mainly infects birds and mammals. The influenza virus has two important surface glycoproteins, hemagglutinin (HA) and neuraminidase (NA), which play important roles in cellular entry to cause first stage of infection by forming complexes with sialic acid residues and release of new virus particles to infect new cells respectively. [2,3] Avian influenza and human influenza viruses use different sugar residues as their receptors, resulting in different host range of infections. Although the mechanism of influenza virus infection and replication has thoroughly investigated but their molecular recognition towards many sialylated glycans is poorly understood. Sialic acids (SAs) are a group of α-keto acids with a nine-carbon backbone diversely found in nature at non-reducing end of glycans implicated in the pathogenies. It is known that sialic acid-α(2→6) galactose epitope is a receptor for human influenza virus, whereas avian influenza virus recognize α(2→3) galactose on cell surface glycoconjugates. This study investigates the synthesis of sialylated N-glycans with N-acetylneuraminic acid (Neu5Ac) α(2→6) and α(2→3)-linked to galactose (Gal) glycoconjuagets made use of N-phthaloyl-protected sialyl imidate as donor and suitably protected lactosamine building block as an acceptor. In the synthesis of sialylated glycans, lactosamine building block was prepared and used as repeating unit for chain elongation and branching point to append sialic acid residue in its specified position for the viral recognition. The resulting Neu5Ac-capped glycans were purified, characterized by NMR, mass spectrometry and currently biological assays were underway.
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