Chemical and antigenic characterization of the carbohydrate side chains of an Asian (N2) influenza virus neuraminidase.

The Pronase-released neuraminidase heads from the Asian influenza virus A/Tokyo/3/67 contain four oligosaccharide units attached at asparagine residues 86, 146, 200, and 234. Chemical analysis of the isolated tryptic, chymotryptic, or thermolytic glycopeptides shows that the oligosaccharide side chains attached at residues 86 and 200 are essentially of the oligomannoside (simple or Type II) variety containing two residues of N-acetylglucosamine, five residues of mannose, and less than molar ratios of galactose and fucose. The carbohydrate side chains attached at residues 146 and 234 are of the N-acetyllactosamine (complex or Type I) type and contain N-acetylglucosamine, mannose, galactose, and fucose. The complex oligosaccharide unit at residue 146 is unusual in that it also contains N-acetylgalactosamine, a sugar residue rarely found in N-glycosidically linked carbohydrates. Antigenic analysis of these four isolated glycopeptides showed that only the N-acetyllactosamine oligosaccharide unit at asparagine residue 146 was capable of binding to antibodies raised against uninfected chick chorioallantoic membranes and is hence antigenically related to chick embryo host antigen.