Epstein-Barr virus (EBV) is a human lymphotropic herpesvirus which is the etiologic agent of infectious mononucleosis, a self-limiting lymphoproliferative disorder. In addition, EBV is closely associated with two human cancers, African Burkitt's lymphoma (BL) and nasopharyngeal carcinoma (NPC), and also appears to be associated with a significant percentage of Hodgkin's lymphoma (HD) as well as the non-Hodgkin's lymphoms that arise in immunosuppressed patients. The role of EBV in lymphomagenesis has remained enigmatic. While viral gene expression in the EBV-associated non-Hodgkin's large cell lymphomas that arise in immunosupppressed individuals mirrors that observed in B lymphocytes immortalized by EBV in tissue culture, the recently characterized restricted pattern of viral gene expression in African Burkitt's lymphoma (BL) raises important questions about the role of EBV in the etiology of these tumors. Addressing these questions will require a thoroug understanding of how restricted EBV latency is regulated. It is critical to determine whether restricted latency is a normal viral program, or whether it is brought about by selection during lymphomagenesis. One of the important long range goals of this research is to determine whether this form of restricted viral latency occurs in normal seropositive individuals. We propose to focus on regulation of viral gene expression in group 1 Burkitt's lymphoma cell lines, and to assess whether infection of some population of normal peripheral B lymphocytes results in restricted latency, as follows: 1. characterize the roles of Fp and the newly identified Qp in driving transcription of the EBNA 1 gene in group 1 BL cell lines; 2. characterize the viral genomes present in group 1 BL cell lines and clone the critical control regions of the EBNA 1 gene promoter from a representative group 1 BL cell line; 3. assay EBV infection time courses of peripheral blood B lymphocytes for presence of the restricted EBNA 1 transcription pattern; 4. investigate alternative splicing from the U exon to the EBNA 3a, EBNA 3c and EBNA 1 coding exons; and 5. generate a recombinant EBV harboring mutations in the low ffinity EBNA 1 binding sites in the viral BamHI Q fragment, and assess the impact of these mutations on EBNA 1 gene transcription in primary B cells.
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