Detection of Epstein-Barr virus BGLF4 protein kinase in virus replication compartments and virus particles

J Gen Virol. 2005 Dec;86(Pt 12):3215-3225. doi: 10.1099/vir.0.81313-0.


BGLF4 is the only serine/threonine protein kinase identified in Epstein-Barr virus (EBV); it is known to phosphorylate viral DNA polymerase processivity factor, EA-D (BMRF1), EBNA-LP, EBNA-2, cellular EF-1delta and nucleoside analogue ganciclovir. However, the expression and biological functions of BGLF4 have not yet been clearly demonstrated in EBV-infected cells. To reveal authentic functions of BGLF4 protein within viral-replicating cells, a panel of specific monoclonal antibodies was generated and characterized. The major immunogenic regions of BGLF4 were mapped to aa 27-70 and 327-429. Using these antibodies, the expression kinetics and localization of BGLF4 were analysed in reactivated EBV-positive lymphoid and epithelial cells. BGLF4 was expressed as a phosphoprotein at the early lytic stage and was detected predominantly in the nucleus of EBV-positive cells, but small amounts of BGLF4 were observed in cytosolic and heavy membrane fractions at the late phase of virus replication. Additionally, it was demonstrated that BGLF4 co-localizes with viral DNA polymerase processivity factor, EA-D (BMRF1), in the virus replication compartment and that it is a virion component. Finally, possible functional domains at the N terminus of BGLF4 were analysed and it was found that aa 1-26 of BGLF4 are dispensable for EA-D phosphorylation, whereas deletion of aa 27-70 reduced kinase activity.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Antibodies, Monoclonal
  • Antibodies, Viral
  • Antigens, Viral / analysis
  • Antigens, Viral / metabolism
  • Cell Membrane / chemistry
  • Cell Nucleus / chemistry
  • Cytoplasm / chemistry
  • Epithelial Cells / chemistry
  • Epithelial Cells / virology
  • Gene Expression
  • Herpesvirus 4, Human / chemistry*
  • Lymphocytes / chemistry
  • Lymphocytes / virology
  • Mice
  • Phosphorylation
  • Phosphotransferases / analysis
  • Phosphotransferases / genetics
  • Phosphotransferases / metabolism
  • Protein Serine-Threonine Kinases / analysis*
  • Protein Serine-Threonine Kinases / genetics
  • Protein Serine-Threonine Kinases / metabolism
  • Protein Structure, Tertiary / genetics
  • Protein Structure, Tertiary / physiology
  • Sequence Deletion
  • Staining and Labeling
  • Time Factors
  • Viral Proteins / analysis*
  • Viral Proteins / genetics
  • Viral Proteins / metabolism
  • Virion / chemistry*


  • Antibodies, Monoclonal
  • Antibodies, Viral
  • Antigens, Viral
  • Epstein-Barr virus early antigen diffuse component
  • Viral Proteins
  • Phosphotransferases
  • BGLF4 protein, Epstein-Barr virus
  • Protein Serine-Threonine Kinases