Epstein-Barr virus (EBV) is a herpesvirus that has been implicated in the development of Burkitt's lymphoma, lymphomas in immunocompromised individuals, and nasopharyngeal carcinomas. EBV infects human B lymphocytes and induces their proliferation and differentiation into permanently growing, immortalized cell lines. Within B cells, EBV usually does not replicate itself, and a limited repertoire of viral genes is expressed. This limited repertoire is presumed to play a key role in host cell transformation and maintenance of viral latency. One of these genes EBNA-2, appears to be critical for EBV-induced growth transformation. Recent experiments involving transfection of each EBV latent gene individually into EBV negative Burkitt lymphoma B cells have revealed that EBNA-2 is able to confer a phenotypic change in growth characteristic of EBV and may function by inducing expression of both a cellular gene, CD23, important in B cell growth and a viral gene, LMP, which has direct growth transforming activity. This EBNA-2 transactivation occurs at the level of transcription. This project will examine both the molecular mechanisms and biological significance of these EBNA-2 effects. Specifically, the long range plan is to i) confirm the transactivation of LMP by EBNA-2, ii) determine whether the increased levels of CD23 and LMP RNA induced by EBNA-2 are due to increased rates of transcription versus effects on post-transcriptional processing, iii) identify the target of EBNA-2 transactivation (presumably enhancer-like regions in each gene), iv) determine whether EBNA- 2 acts directly or indirectly and if these effects are tissue or species specific, v) determine what EBNA-2 domains are important for transactivation, vi) determine the biologic relationship between transactivation by EBNA-2 and growth transformation, vii) evaluate the role of CD23 in B cell activation by overexpress or inhibition of CD23, and viii) define other EBNA- 2 induced genes by cDNA cloning and subtractive hybridization. Knowledge of the detailed functions of these viral genes will likely reveal important aspects of the molecular basis for EBV induced cell proliferation, of normal B cell growth regulation, and of mechanisms important in herpesvirus latency. Such knowledge will contribute to the understanding of EBV related diseases.