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Binding sites for rubella virus on erythrocyte membrane
P Mastromarino1, S Rieti, L Cioè
1Institute of Microbiology, School of Medicine, University of Rome, La Sapienza, Italy.
Abstract:
To identify molecule(s) with the properties of rubella virus (RV) receptor, goose erythrocyte membranes were isolated and tested for their ability to complete with whole cells for viral binding and fusion. Solubilized membranes showed a dose-dependent inhibiting activity on either rubella virus attachment or its fusion with erythrocytes at acidic pH. The inhibitory activity was enhanced by trypsin and neuraminidase, and inactivated by phospholipase A2 digestion, pointing towards the involvement of lipid structures as receptor sites for RV. After isolation of the different membrane components, only the lipid moiety, specifically phospholipids and glycolipids, was found to inhibit viral biological activities. When the major membrane lipids were examined separately, phosphatidylserine and cerebroside sulfate showed a strong inhibiting activity on viral hemagglutination and subsequent hemolysis. The capacity of several pure phospholipids (phosphatidylinositol, phosphatidylcholine and sphingomyelin) to inhibit the hemolysis but not the binding of the virus to the erythrocytes indicated that different membrane lipid components are involved in the attachment and the fusion step. Enzymatic and chemical modifications of whole erythrocytes confirmed the role of membrane lipid molecules in the cell surface receptor for RV.
Insights
Goose erythrocyte membranes contain lipid molecules, specifically phospholipids and glycolipids, that act as rubella virus (RV) receptors. These lipids are crucial for both viral attachment and fusion with host cells.
Area of Science:
- Virology
- Cell Biology
- Biochemistry
Background:
- Rubella virus (RV) requires specific cell surface receptors for entry.
- Identifying these receptors is key to understanding viral infection mechanisms.
Purpose of the Study:
- To identify the molecular components of goose erythrocyte membranes that function as rubella virus receptors.
- To elucidate the role of specific lipids in rubella virus attachment and fusion.
Main Methods:
- Isolation and solubilization of goose erythrocyte membranes.
- Assays for viral binding, fusion, hemagglutination, and hemolysis.
- Enzymatic (trypsin, neuraminidase, phospholipase A2) and chemical modifications of membrane components.
- Examination of purified lipid fractions and individual lipids.
Main Results:
- Solubilized membranes inhibited rubella virus attachment and fusion in a dose-dependent manner.
- Inhibitory activity was enhanced by trypsin/neuraminidase and abolished by phospholipase A2, suggesting lipid involvement.
- Lipid moieties, including phospholipids and glycolipids, were identified as inhibitors.
- Phosphatidylserine and cerebroside sulfate strongly inhibited hemagglutination and hemolysis.
- Specific phospholipids inhibited hemolysis but not binding, indicating distinct roles in fusion.
Conclusions:
- Cell surface receptors for rubella virus are primarily composed of membrane lipid molecules.
- Phospholipids and glycolipids, particularly phosphatidylserine and cerebroside sulfate, play critical roles in rubella virus-erythrocyte interactions.
- Different membrane lipids mediate distinct steps in the viral infection process, including attachment and fusion.