Immunization with Components of the Viral Fusion Apparatus Elicits Antibodies That Neutralize Epstein-Barr Virus in B Cells and Epithelial Cells
Authors: Bu, Wei; Joyce, M. Gordon; Hanh Nguyen; Banh, Dalton V.; Aguilar, Fiona; Tariq, Zeshan; Yap, Moh Lan; Tsujimura, Yusuke; Gillespie, Rebecca A.; Tsybovsky, Yaroslav; Andrews, Sarah F.; Narpala, Sandeep R.; McDermott, Adrian B.; Rossmann, Michael G.; Yasutomi, Yasuhiro; Nabel, Gary J.; Kanekiyo, Masaru; Cohen, Jeffrey I.
Epstein-Barr virus (EBV) causes infectious mononucleosis and is associated with epithelial-cell cancers and B cell lymphomas. An effective EBV vaccine is not available. We found that antibodies to the EBV glycoprotein gH/gL complex were the principal components in human plasma that neutralized infection of epithelial cells and that antibodies to gH/gL and gp42 contributed to B cell neutralization. Immunization of mice and nonhuman primates with nanoparticle vaccines that displayed components of the viral-fusion machinery EBV gH/gL or gH/gL/gp42 elicited antibodies that potently neutralized both epithelial-cell and B cell infection. Immune serum from nonhuman primates inhibited EBV-glycoprotein-mediated fusion of epithelial cells and B cells and targeted an epitope critical for virus-cell fusion. Therefore, unlike the leading EBV gp350 vaccine candidate, which only protects B cells from infection, these EBV nanoparticle vaccines elicit antibodies that inhibit the virus-fusion apparatus and provide cell-type-independent protection from virus infection.
Characterization of EBV gB indicates properties of both class I and class II viral fusion proteins
Authors: Backovic, Marija; Leser, George P.; Lamb, Robert A.; Longnecker, Richard; Jardetzky, Theodore S.
To gain insight into Epstein-Barr virus (EBV) glycoprotein B (gB), recombinant, secreted variants were generated. The role of putative transmembrane regions, the proteolytic processing and the oligomerization state of the gB variants were investigated. Constructs containing 2 of 3 C-terminal hydrophobic regions were secreted, indicating that these do not act as transmembrane anchors. The efficiency of cleavage of the gB furin site was found to depend on the nature of C-terminus. All of the gB constructs formed rosette structures reminiscent of the postfusion aggregates formed by other viral fusion proteins. However, substitution of putative fusion loop residues, WY112-113 and WLIY193-196, with less hydrophobic amino acids from HSV-1 gB, produced trimeric protein and abrogated the ability of the EBV gB ectodomains to form rosettes. These data demonstrate biochemical features of EBV gB that are characteristic of other class I and class 11 viral fusion proteins, but not of HSV-1 gB. (C) 2007 Elsevier Inc. All rights reserved.