Role of membrane phospholipids and glycolipids in the Vero cell surface receptor for rubella virus

Membrane receptors for rubella virus (RV) in Vero cells were studied by means of two different approaches: (i) by enzyme treatment of the whole cell membrane and (ii) by testing the ability of isolated plasma membrane molecules to compete with cells for virus binding. The replication of RV was studied with both indirect immunofluorescence assay and molecular hybridization techniques. Phospholipases A2 and C digestion of cells greatly reduced the infectivity by the virus, pointing towards the involvement of lipid structures as receptor sites for RV. Furthermore, susceptibility of Vero cells to virus infection was also reduced after beta-N-acetyl-D-glucosaminidase, alpha-glucosidase and beta-galactosidase treatment, suggesting that carbohydrate residues may participate in a complex cellular receptor structure for RV. When the major membrane lipids were examined separately for their ability to inhibit viral infectivity, several phospholipids (phosphatidylserine, phosphatidylinositol, phosphatidylethanolamine, phosphatidylcholine, sphingomyelin) and glycolipids (gangliosides, lactosylceramide, cerebroside sulphate) showed a strong neutralizing activity, confirming the role of membrane lipid moiety in the cell surface receptor for RV.