A Structural Investigation of the Epstein--Barr (EB) Virus Membrane Antigen Glycoprotein, gp340

Abstract

SUMMARYEpstein-Barr (EB) virus membrane antigen (MA) glycoprotein (gp340) purified by a molecular weight-based technique has been subjected to biochemical analysis. Following treatment with glycosidases or tunicamycin during synthesis, the carbohydrate moiety was found to be made up of both O-linked and N-linked types and to constitute about 50~o of the molecular mass. Digestion studies with neuraminidase and oligosaccharidase have indicated that the molecule is heavily sialated with most of the sialic acid located on the O-linked sugars. The high carbohydrate content of gp340 appears to confer resistance to proteolysis, thus, V8 protease was only effective at concentrations above 1 mg/ml when three large fragments of mol. wt. 330K, 190K and 160K were generated. Removal of sialic acid before V8 protease digestion did not alter this pattern nor affect the antigenicity of the digestion fragments. Antigenicity of the intact molecule was likewise unaffected by removal of sialic acid nor were the O-linked and N-linked carbohydrate moieties essential for this property. The binding of virusneutralizing human sera and monoclonal antibody by gp340 from which either Olinked or N-linked sugars had been removed seems to indicate that the sites on the molecule that generate the neutralizing antibodies are present in the protein component. The significance of these results is discussed in relation to the development of a subunit vaccine against EB virus.

Characterization of the Human Cytomegalovirus Envelope Glycoproteins

“…This protein together with gp95 and gp 130 produces characteristic diffuse bands on polyacrylamide gels which may indicate microheterogeneity within the polysaccharide moieties. A similar high molecular weight glycoprotein, which contains a high proportion of carbohydrate and which plays a major role in the host response to virus infection, has been isolated and characterized from cells transformed with Epstein-Barr virus (Morgan et al, 1984). Our results regarding gp52, gp67, gp95 and gp130 agree well with the data of Nowak et al (1984) who used radiolabelled concanavalin A to detect glycoproteins with mol.…”

Distribution of epitopes within the amino acid sequence of the Epstein--Barr virus major envelope glycoprotein, gp340, recognized by hyperimmune rabbit sera

“…The concentration of continuous B cell epitopes in this amino-terminal domain may imply that this region is not concealed in the native gp340 molecule either as a result of protein folding or glycosylation (Morgan et al, 1984). The majority of epitopes defined above do not appear to be important in virus neutralization but could have some role in controlling the outcome of EBV infection by acting as targets in the membrane of lytically infected cells for ADCC or complement fixation (Beisel et al, 1985;Jondal, 1976;Qualti6re et al, 1982;Khyatti et al, 1991 ;Sairenji et al, 1991).…”

Comparative immunogenicity studies on epstein‐barr virus membrane antigen (MA) gp340 with novel adjuvants in mice, rabbits, and cotton‐top tamarins

“…The efficacy of subunit antiviral vaccines has been demonstrated in both human and veterinary diseases [Szmuness et al, 1981;Bittle et al, 19821; structural studies on the gp340 component of MA have indicated that immunogenicity resides in the polypeptide moiety of the molecule [Morgan et al, 1983b;Epstein and Morgan, 19831, and the development of an EB virus vaccine can now proceed in the same direction.…”