Functional roles of terminal glycomoieties in varicella-zoster virus infection

Terminal glycomoieties of varicella-zoster virus glycoproteins were characterized by their reactivity with lectins and glycosidases, and the functional roles of terminal sugars were analyzed by cell-free virus infectivity. Terminal glycan structures of gpl possessed sialic acid linked alpha (2-3) to galactose of O-linked glycan and galactose-beta (1-4)-N-acetylglucosamine of N-linked glycan. Those of the putative gpIV possessed galactose-beta (1-4)-N-acetylglucosamine of N-linked glycan. Both glycoproteins had mannose alpha (1-3, 6, or 2) linked to mannose in their glycans. Their biological functions on cell-free virus infectivity were assessed by using lectins and exoglycosidases. Sialic acid of glycans on both the viral envelope and the cell surface had a negative effect on infectivity, and the latter had a larger effect on infectivity than the former. Maackia amurensis agglutinin, which recognizes sialic acid, enhanced infectivity more than expected from the simple neutralization of the negative effects of sialic acids between cells and virus. alpha-Mannosidase and alpha-glucosidase treatments of virus significantly reduced infectivity but those of cells did not. Therefore, alpha-mannose and alpha-glucose residues on the viral envelope had functional roles in cell-free virus infection. Inactivation of virus infectivity by concanavalin A was mainly due to the blocking of functional roles of terminal alpha-mannose and alpha-glucose residues of viral glycoproteins.