Carbohydrate Components of Influenza C Virions

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Abstract
The carbohydrate components of influenza C virions grown in chicken kidney (CK) cells were analyzed by gel filtration following exhaustive digestion with Pronase. The [ 3 H]glucosamine-labeled glycopeptides were larger and more heterogeneous than those of influenza A/WSN virions; three major size classes (G 1 , G 2 , and G 3 ) were resolved. Treatment with Vibrio cholerae neuraminidase caused a decrease in size of G 1 and G 2 , along with release of about 16% of the 3 H label. The released sugar components were identified as N -acetylneuraminic acid by thin-layer chromatography. Peak G 3 was highly labeled with [ 3 H]mannose, whereas G 1 and G 2 contained lower levels of mannose. The three major viral glycoproteins gp88, gp65, and gp30 were isolated from sodium dodecyl sulfate-polyacrylamide gels, and their glycopeptide components were analyzed after Pronase digestion. The three size classes of glycopeptides were obtained from any of the three glycoproteins; however, the relative amounts of the three components varied among the glycoproteins. Host cell-derived components, which appear to be mucopolysaccharides and glycoproteins, were found associated with influenza C virions grown in CK cells. These components contained glycopeptides that were mainly of sizes similar to peak G 2 from influenza C virions. Previous studies have shown that influenza A/WSN virus grown in several cell types contained only two size classes of glycopeptides. Two size classes comparable to peaks G 2 and G 3 from influenza C virions were also observed in influenza A/WSN grown in CK cells. Thus the large G 1 glycopeptides appear to be characteristic of influenza C virions.