title: C-terminal region of EBNA-2 determines the superior transforming ability of type 1 Epstein-Barr virus by enhanced gene regulation of LMP-1 and CXCR7.
abstract: Type 1 Epstein-Barr virus (EBV) strains immortalize B lymphocytes in vitro much more efficiently than type 2 EBV, a difference previously mapped to the EBNA-2 locus. Here we demonstrate that the greater transforming activity of type 1 EBV correlates with a stronger and more rapid induction of the viral oncogene LMP-1 and the cell gene CXCR7 (which are both required for proliferation of EBV-LCLs) during infection of primary B cells with recombinant viruses. Surprisingly, although the major sequence differences between type 1 and type 2 EBNA-2 lie in N-terminal parts of the protein, the superior ability of type 1 EBNA-2 to induce proliferation of EBV-infected lymphoblasts is mostly determined by the C-terminus of EBNA-2. Substitution of the C-terminus of type 1 EBNA-2 into the type 2 protein is sufficient to confer a type 1 growth phenotype and type 1 expression levels of LMP-1 and CXCR7 in an EREB2.5 cell growth assay. Within this region, the RG, CR7 and TAD domains are the minimum type 1 sequences required. Sequencing the C-terminus of EBNA-2 from additional EBV isolates showed high sequence identity within type 1 isolates or within type 2 isolates, indicating that the functional differences mapped are typical of EBV type sequences. The results indicate that the C-terminus of EBNA-2 accounts for the greater ability of type 1 EBV to promote B cell proliferation, through mechanisms that include higher induction of genes (LMP-1 and CXCR7) required for proliferation and survival of EBV-LCLs.
authors.affiliation: Section of Virology, Faculty of Medicine, Imperial College London, St. Mary's Campus, Norfolk Place, London, UK.
authors.forename: Laila
authors.initials: L
authors.lastname: Cancian
authors.forename: Rachel
authors.initials: R
authors.lastname: Bosshard
authors.forename: Walter
authors.initials: W
authors.lastname: Lucchesi
authors.forename: Claudio Elgueta
authors.initials: CE
authors.lastname: Karstegl
authors.forename: Paul J
authors.initials: PJ
authors.lastname: Farrell
mesh_terms: D001402:B-Lymphocytes / Q000378:metabolism / Q000821:virology; D002460:Cell Line; D049109:Cell Proliferation; D002470:Cell Survival / Q000235:genetics; D002472:Cell Transformation, Viral / Q000502:physiology*; D020031:Epstein-Barr Virus Infections / Q000235:genetics / Q000378:metabolism*; D019309:Epstein-Barr Virus Nuclear Antigens / Q000235:genetics / Q000378:metabolism*; D015967:Gene Expression Regulation, Viral / Q000502:physiology*; D004854:Herpesvirus 4, Human / Q000235:genetics / Q000378:metabolism*; D006801:Humans; D017434:Protein Structure, Tertiary; D054387:Receptors, CXCR / Q000096:biosynthesis* / Q000235:genetics; D014763:Viral Matrix Proteins / Q000096:biosynthesis* / Q000235:genetics; D014764:Viral Proteins / Q000235:genetics / Q000378:metabolism*
chemical_list: C501896:ACKR3 protein, human; C402641:EBNA-2 protein, Human herpesvirus 4; C037662:EBV-associated membrane antigen, Epstein-Barr virus; D019309:Epstein-Barr Virus Nuclear Antigens; D054387:Receptors, CXCR; D014763:Viral Matrix Proteins; D014764:Viral Proteins