EBV TRANSFORMATION OF B LYMPHOCYTES--EBNA REGULATION

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DESCRIPTION: Epstein-Barr virus is strongly associated with Burkitt lymphoma and nasopharyngeal carcinoma and is responsible for lymphoproliferative disease in immunocompromised individuals. The long-term objectives of the studies proposed are to determine the mechanisms of cellular transformation by EBV. When this virus infects B cells in vitro, the lymphocytes become immortalized. Activation of the EBV W promoter (Wp) is the first viral transcriptional event detected during infection. Wp directs the early expression of Epstein-Barr virus nuclear antigens (EBNA). The EBNA proteins are involved in cellular and viral gene regulation and the maintenance of chronic EBV latency. Later in infection, there is a switch to usage of the other EBNA promoters, Cp, then Qp. While Cp and Qp have been studied extensively, almost no information exists regarding the specific cis and trans constituents of Wp regulation. Our preliminary studies have demonstrated the presence of at least three cis elements within the W promoter, so these elements have been selected for detailed study in this proposal. In the first specific aim, the particular cellular transcription factors which interact with critical cis elements in Wp will be characterized. Extensive promoter mutagenesis, gel shift assays, promoter footprinting and southwestern gels of bound factors will be employed. The second specific aim will explore the functional importance of Wp cis elements. This will be accomplished with transfection studies using expression vectors for pertinent transactivators and using various Wp deletional and mutational constructs. In the third aim, in vivo footprinting of Wp, and the use of whole EBV mutants with disruption of key cis elements will be used to demonstrate the in vivo significance of Wp domains. Finally, these studies will ascertain the in vivo role of factors acting upon Wp in trans during the time course of EBNA promoter switching. Knowledge gained from these studies might ultimately produce means of exploiting the control of EBV gene expression to augment immune destruction of EBV-infected malignant cells in such catastrophic diseases as Burkitt lymphoma or Hodgkin's disease.