Glycopeptide components of influenza viral glycoproteins

Abstract

The oligosaccharide moieties of the WSN strain of influenza virus were analyzed by Pronase digestion of viral glycoproteins followed by gel filtration. Oligosaccharides of influenza virions grown in MDBK cells consist of at least two size classes. The larger one contains glucosamine, mannose, galactose, and fucose and is designated type I. In addition, smaller oligosaccharides (type II) contain a high amount of mannose in addition to glucosamine but probably lack galactose and fucose. Type I glycopeptides were found both in HA 1 and HA 2 (two cleavage products of hemagglutinin), whereas type II was found in HA 1 only. The oligosaccharides of virions grown in MDCK and BHK21-F cells also consisted of two size classes. The presence of both types of glycopeptides in HA 1 and the absence of type II in HA 2 were also observed with virions grown in MDCK cells. The presence of sulfated glycopeptides was demonstrated with virions grown in all of these cell types, and most of the 35SO 4 2− label appears to be linked to type I glycopeptides. However, the elution profile of sulfated glycopeptides was slightly different from that of type I glycopeptides, suggesting that type I glycopeptides may be heterogeneous with respect to the extent of sulfation. The molecular weights of type I and type II glycopeptides of virions grown in MDBK cells were estimated to be about 2900 and 1650 to 2200, respectively. However, the sizes of the oligosaccharide components varied with the host cell type. These values, together with previous estimates of the carbohydrate content of the HA glycoprotein, suggest that in the case of virions grown in MDBK cells HA 2 contains a single type I oligosaccharide group, whereas HA, contains two type I oligosaccharides plus one or two type II oligosaccharides.