Glycoproteins in the virion envelope play an important role in the adsorption and penetration of enveloped viruses into eukaryotic cells. Studies proposed in this application will focus on the glycoproteins specified by human cytomegalovirus (CMV) and the cell surface proteins to which they bind. The three major objectives of the study are as follows. First, we will identify all of the antigenically distinct CMV glycoproteins, their precursors and fully glycosylated products. We already have available, for this purpose, monoclonal antibodies reactive with different antigenic domains on CMV glycoproteins; these have been selected by neutralization and surface immunofluorescence tests. Immune precipitation experiments will be done with CMV infected cell polypeptides, radiolabeled under various conditions to identify antigenically related glycoproteins. Second, the cell surface proteins which bind specifically to each CMV glycoprotein will be identified. To accomplish this objective, an affinity system of glycoproteins, immobilized on monoclonal antibody columns will be constructed. Monoclonal antibodies reactive with hydrophilic and hydrophobic antigenic domains will orient the glycoproteins in different conformations. To identify the cell membrane proteins which bind specifically to immobilized glycoproteins, extracts from surface iodinated cells will be adsorbed to the affinity columns. Specificity of cell reactive proteins for viral glycoproteins will be determined by the extent to which the binding is dependent on the source of cell membrane proteins, the type of viral glycoprotein, and orientation of the glycoprotein in the affinity columns. The third objective is to differentiate between specific cell surface receptors for CMV and cell reactive proteins which may bind to viral glycoproteins. Membrane proteins which function as receptors for CMV should bind to virions and interfere with adsorption to the cell surface membrane. In addition, monoclonal antibody produced against receptor proteins, should bind to the cell surface, interfere with adsorption of virions to the cell membrane, and confirm the role of the protein as the surface receptor for CMV.
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