In order to study the interactions between the EBV genome and cell genome and the association of specific EBV products with specific regions of the virus genome, we will implement a marker rescue system recently developed by us. We will use a variety of epithelial hybrid cell lines prepared by the fusion of human epithelial cells to different EBV genome positive lyphoblastoid cells (LCL). The choice of LCLs used to prepare these hybrids will depend on the type of EBV genome in the cell, so that a range of different types of EBV genome positive hybrid cells will be available to perform marker rescue studies. We will also study the degree of methylation of EBV DNA to determine whether histones are present or missing from actively transcribing regions of EBV DNA. These data will be related to gene expression in those regions.