Identification of a new carbohydrate-binding site of influenza virus

It has recently been shown that the influenza virus can specifically bind the residue of a nonsialylated sulfated oligosaccharide Gal(6SO 3 H)β1-4GlcNAcβ (6’ S LacNAc). To identify by photoaffinity labeling the virion component that binds 6’ S LacNAc, we synthesized a carbohydrate probe containing a 125 I labeled diazocyclopentadien-2-yl carbonyl group as an aglycone. According to the electrophoretic data, the labeled areas corresponded to a large hemagglutinin subunit, a nucleocapsid protein, and neuraminidase (NA). Probing in the presence of an excess of 6’ S LacNAcβ-OCH 2 CH 2 NHAc glycoside resulted in redistribution of the labeling intensity, with the maximum inhibition being observed for NA. The data obtained indicate that NA is a viral 6’ S LacNAc-binding protein.