Carbohydrates of influenza virus. V. Oligosaccharides attached to individual glycosylation sites of the hemagglutinin of fowl plague virus.

The carbohydrate side chains of the hemagglutinin of fowl plague virus (A/FPV/Rostock/34 (H7N1] have been localized by a procedure involving fragmentation of the polypeptide with cyanogen bromide and various proteases. The positions of the fragments were determined by radioactive labeling of the sugars and of specific amino acids. Side chains of the complex type I are attached to asparagine residues 12, 28, 123, 149, and 478. A mannose-rich (type II) side chain is linked to asparagine 406. Asparagine 231 is not glycosylated. The side chains attached to asparagine residues 12, 123, 149, and 478 contain sulfate. Glycopeptides derived by Pronase digestion from the individual attachment sites have been analyzed by their affinity to concanavalin A and Lens culinaris agglutinin. The results indicate that each glycosylation site has a typical set of heterogeneous oligosaccharides. Comparison of the glycosylation patterns of the hemagglutinins of FPV and other influenza A viruses reveals that the glycosylation sites at asparagine residues 12, 28, and 478, which are located at the base of the spike, are highly conserved. Mannose-rich side chains appear to be located preferentially at interfaces between the three monomers of a spike or between the globular and fibrous domains of a monomer.