Epstein-Barr virus (EBV) is a member of the herpes virus family, causing infectious mononucleosis and establishing life-long latency in infected individuals. EBV is also associated with cancers of both B cells and epithelial cells, the two cell types that it infects in vivo. EBV entry into B cells and epithelial cells requires the coordinated action of four (gH, gL, gB and gp42) and three (gH, gL and gB) viral glycoproteins, respectively. The process by which receptor recognition triggers membrane fusion and virus entry is not well understood. The gH, gL and gB proteins form the core fusion machinery for all herpesviruses and it is thought that gB acts as the primary fusogen in this process. The gH/gL heterodimer is thought to act as the regulator for gB activation, triggering conformational changes in gB after receptor binding. We recently determined the low- resolution electron microscopy structure of the EBV B cell entry triggering complex composed of gH/gL, gp42 and host receptor HLA, clarifying how this complex bridges the viral and cellular membranes, bringing them into closer proximity prior to gB activation. Here, we (the Jardetzky, Longnecker and Zhou research groups) propose to study complexes of wild type and mutant gH/gL with integrins that act as the entry receptor for EBV infection of epithelial cells by a combination of virology, mutagenesis and biophysics means. We will first characterize molecular interactions between the wt (wild type) or mutant gH/gL proteins and integrin receptors and determine how initial complexes between gH/gL and integrins may convert to an activated state to trigger gB- mediated fusion. We will then compare the architectures of the B cell and epithelial cell triggering complexes by cryo electron microscopy. The anticipated results would establish the molecular interactions of the two EBV entry complexes and reveal the structural commonalities between them. Such structural information is key to understanding the subsequent steps of gB activation and EBV entry and, by extension, the general mechanism of cell entry by human herpesviruses.
Epstein-Barr virus (EBV) causes infectious mononucleosis and is associated with cancers of B cell and epithelial cell origins. The specificity of cell entry leading to EBV infection is governed by two entry 'triggering' complexes involving cell receptors and viral glycoproteins, gH, gL, gB and gp42. The proposed studies will determine the architecture and mechanism of EBV epithelial cell triggering complexes, to gain greater insight into herpesvirus entry into cells. The results will reveal general features of herpesvirus-mediated membrane fusion and open new possibilities for antiviral or vaccine development.
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| Sathiyamoorthy, Karthik; Jiang, Jiansen; Möhl, Britta S et al. (2017) Inhibition of EBV-mediated membrane fusion by anti-gHgL antibodies. Proc Natl Acad Sci U S A 114:E8703-E8710 |
| Möhl, Britta S; Chen, Jia; Sathiyamoorthy, Karthik et al. (2016) Structural and Mechanistic Insights into the Tropism of Epstein-Barr Virus. Mol Cells 39:286-91 |
| Sathiyamoorthy, Karthik; Hu, Yao Xiong; Möhl, Britta S et al. (2016) Structural basis for Epstein-Barr virus host cell tropism mediated by gp42 and gHgL entry glycoproteins. Nat Commun 7:13557 |
| Chen, Jia; Jardetzky, Theodore S; Longnecker, Richard (2016) The Cytoplasmic Tail Domain of Epstein-Barr Virus gH Regulates Membrane Fusion Activity through Altering gH Binding to gp42 and Epithelial Cell Attachment. MBio 7: |
