The Significance of Neuraminic Acid, Serine and Threonine for a Glycoprotein Inhibiting Influenza Virus Haemagglutination

Abstract

Summary.A short review is given of the impact which Sir Macfarlane Burnet's observations, on the influenza virus enzyme and RDE and on the influenza virus haemagglutinin inhibitors, has had on the development of the chemistry of glycoproteins in general and on the elucidation of the molecular structure of neuraminic acid in particular.The structure of the ovine subniaxillary (OSM) glycoprotein, prepared from sheep submaxillary glands, is described and its potency as influenza virus haemagglutinin inhibitor discussed in terms of multiple carbohydrate groups, each terminated by a neuraminic acid residue.Evidence is presented that in OSM (from three-year-old sheep) the predominant linkage of carbohydrate to protein is an O-glycosidic linkage to the hydroxyl group of serine and threonine residues. This linkage is easily split by dilute alkali, most probably by the lnechanisin of ^-elimination.Towards the end of the forties three observations were made at the Walter and Eliza Hall Institute, Melboiime, under the leadership of Sir Macfarlane Burnet, which have done much to renew interest in a nearly forgotten carbohydrate, neuraminic acid, to stimulate research in the long neglected field of mucoproteins and, last, but not least, to elucidaite the basic mechanism by wliich influenza virus particles agglutinate red blood cdls and are adsorbed to host cells. At that time Rurnet and his colleagues were intrigued by Hirst's discovery that the influenza virus particle agglutinates fowl, guinea pig and human eryithrocytes at 4° by being adsorbed to and forming bridges between the red cells. At this temperature, the virus remains attached to the surface of the red cells for more than 15 hours. At 37°, howevei", the virus, once adsorbed at the receptor site of red cells, soon elutes spontaneously leaving behind a red blood cell altered in such a manner so that it can no longer adsorb fresh influenza virus. Hii'St clearly recognized the resemblance of this phenomenon to an enzyme-substrate interaction, the enzyme being possessed by the virus particle and the substrate being embedded in the surface stiucture of the red cell (for review, see Burnet, 1951).

Physicochemical properties of transmissible gastroenteritis virus hemagglutinin

“…Sentsui and his associates reported that neuraminidase rendered horse, cat, and guinea pig erythrocytes more susceptible to agglutination by equine infectious anemia virus [22] and mouse erythrocytes more susceptible to agglutination by bovine leukemia virus [23]. Further orthomyxoviruses are well known to elute from erythrocytes at 37 °C by neuraminidase activity possessed by the virus particle [6,10]. The TGE viius used in this study did not show any cross reaction with the swine influenza virus A (Wisconsin strain), HEV, BCV, and porcine parvovirus by hemagglutination inhibition and neutralization tests in our laboratory (data not shown).…”

Association of Placental Alkaline Phosphatase Activity with Preparations of the Human Placental Inhibitor to Hemagglutination by H-1 Virus

“…The similarities in physical and chemical properties (1, 2, 4-7, 12) between the human placental inhibitor to hemagglutination by H-1 virus and the large molecular-weight variants of placental alkaline phosphatases, raises the question of whether the enzyme and the inhibitor are the same glycoprotein with the enzyme active , site in the polypeptide part of the molecule and the hemagglutination inhibitory site active in the carbohydrate region or, whether, alternatively, the two glycoproteins are differ-ent. This concept would explain the finding that ovine submaxillary glycoprotein (OSM) with a molecular weight of 1 X loG has an inhibitory titer against inactive influenza viruses of 2.25 X 10G/mg substance, whereas OSM treated with a very small dose of trypsin under controlled conditions to produce glycopeptides with a molecular weight of approximately 50,000, has a titer of only 100 (18). I t is apparently also necessary that the protein part of the molecule be intact in order that HA-I occur, since treatment with proteolytic enzymes such as trypsin, chymotrypsin, papain, and pepsin either destroyed or drastically reduced the HA-I activity (2).…”