Research Assistant Professor
Department of Microbiology and Immunology
Lineberger Comprehensive Cancer Center
University of North Carolina at Chapel Hill

Epstein-Barr virus (EBV) is a human pathogen that causes or is associated with a diverse array of diseases, which range from clinically asymptomatic infectious mononucleosis to fatal post-transplantational and AIDS-associated lymphoproliferative disorders. As with all members of Herpesviridae, EBV has a biphasic infection cycle consisting of a latent and a lytic replicative phase. A majority of malignancies associated with the virus are attributed to the activity of EBV latent proteins, whereas involvement of the lytic proteins in viral pathogenesis has been overlooked. My research is focused on defining the role of the EBV-encoded protein kinase in viral infection, and biochemical/structural analyses of this protein.

Our recent data demonstrate that EBV-encoded protein kinase regulates viral nuclear egress, an ordered process that involves both viral and cellular factors. Nuclear egress (also called primary envelopment) is an important component of viral pathogenesis, which is viewed as an attractive target for antiviral therapies. We are currently identifying components of the nuclear egress complex affected by the kinase, and are set to delineate details of this process.

EBV-PK has been shown to phosphorylate a number of viral and cellular targets; however the role for this protein in viral infection remains enigmatic. Recently, by using RNAi approach we have generated and are currently characterizing an EBV-PK knockdown phenotype. The studies include viral RNA and protein expression profiling, infectivity assays, and identification of signaling pathways affected by this knockdown. The results will be further confirmed by using a new EBV-PK knockout virus, which we now have in a collaborative effort with Dr. Henri-Jacques Delecleuse.

Although herpesvirus-encoded protein kinases (HPKs) were first identified by recognition of motifs typical for cellular protein kinases, the homology between these two groups is very low. Since the viral kinases are considered potential targets for antiviral therapy, biochemical characterization and structural analyses are crucial for successful drug studies. We have expressed and purified EBV-PK and are currently studying its enzymology. By a site-directed mutagenesis approach we are identifying the key residues of the kinase responsible for its function and specificity. The long-term goal for this project is to define the 3D-structure of EBV-PK by X-ray crystallography.

1. *Gershburg, E., Raffa, S., Torrisi, M. R. and J. S. Pagano.
   Epstein-Barr virus-encoded protein kinase (BGLF4) is essential for production of infectious virus.
   Journal of Virology. 2007. March 14. Epub ahead of print.
     
2. Seaman, W. T., Gershburg, E., Delecluse, H.-J., Pagano, J. S. and S. C. Kenney
   Effects of the EBV-encoded viral kinase, EBV-PK, on BZLF1 function and SUMO-modification.
   2007. Submitted.
    
3. Seaman, W. T., Holley-Guthrie, E., Gershburg, E., Delecluse, H.-J., Pagano, J. S. and S. C. Kenney
   BMRF1 transcriptional function, but not BMRF1 phosphorylation by the BGLF4-encoded viral kinase, is important for Epstein-Barr virus replication.
   2007. Submitted.
    
4. Gershburg, E. and J. S. Pagano (2005)
   Treatment of Epstein-Barr Virus (EBV) infections.
   J Antimicrob Chemother. 56(2):277-81. Epub 2005 Jul 8.
    
   
5. Yue, W., Gershburg, E., Pagano, J.S.
   Epstein-Barr Virus protein kinase phosphorylates EBNA2 and suppresses EBNA2 transactivation of the LMP1 promoter.
   J. Virol., 2005. 79(9): 5880-5885.
   Abstract|Full Text (HTML)|Reprint (PDF)
    
6. Gershburg, E., Marschall, J., Hong, K. and JS Pagano.
   Expression and localization of the Epstein-Barr virus-encoded protein kinase.
   J.Virol. 2004. 78(22): 12140-12146.
   Abstract|Full Text (HTML)|Reprint (PDF)
    
7. Gershburg E, Hong K, Pagano JS
   Effects of Maribavir and Selective Indolocarbazoles on the Epstein-Barr Virus Protein Kinase BGLF4 and on Viral Lytic Replication
   Antimicrob Agents Chemother. 2004 May; 48(5):1900-3
   Abstract|Full Text (HTML)|Reprint (PDF)
   PMID: 15105156
    
8. Gershburg E, Pagano JS
   Phosphorylation of the Epstein-Barr Virus DNA Polymerase Processivity Factor by the EBV-Encoded Protein Kinase and Effects of the L-Riboside Benzimidazole 1263W94
   J Virol. 2002 Feb:76(3):998-1003
   Abstract|Full Text (HTML)|Reprint (PDF)
   PMID: 11773375
    
9. Zacny VL, Gershburg E, Davis MG, Biron KK, Pagano JS
   Inhibition of Epstein-Barr Virus Replication by a Benzimidazole L-Riboside: Novel Antiviral Mechanism of 5,6-Dichloro-2-(Isopropylamino)-1-beta-L-Ribofuranosyl-1H-Benzimidazole
   J Virol. 1999 Sep;73(9):7271-7
   Abstract|Full Text (HTML)|Reprint (PDF)
   PMID: 10438815
    
10. Gurevitz M, Froy O, Zilberberg N, Turkov M, Strugatsky D, Gershburg E, Lee D, Adams ME, Tugarinov V, Anglister J, Shaanan B, Loret E, Stankiewicz M, Pelhate M, Gordon D, Chejanovsky N
    Sodium Channel Modifiers From Scorpion Venom: Structure-Activity Relationship, Mode of Action, and Application
    Toxicon. 1998 Nov;36(11):1671-82
    PMID: 9792184
     
11. Gershburg E, Stockholm D, Froy O, Rashi S, Gurevitz M, Chejanovsky N
    Baculovirus-mediated Expression of a Scorpion Depressant Toxin Improves the Insecticidal Efficacy Achieved with Excitatory Toxins
    FEBS Lett. 1998 Jan 30;422(2)132-6
    Abstract
    PMID: 9489991
     
12. Gershburg E, Rivkin H, Chejanovsky N
    Expression of the Autographa californica Nuclear Polyhedrosis Virus Apoptotic Suppressor Gene p35 in Nonpermissive Spodoptera littoralis Cells
    J Virol. 1997 Oct;71(10)7593-9
    Abstract|Reprint (PDF)
    PMID: 9311840
     
13. Chejanovsky N, Gershburg E
    The wild-type Autographa californica Nuclear Polyhedrosis Virus Induces Apoptosis of Spodoptera littoralis Cells
    Virology. 1995 Jun 1;209(2):519-25
    Abstract
    PMID: 7778284