Only EBV-infected B lymphocytes which express the B cell
activation marker CD23 are capable of establishing immortalised cell lines. Epstein-Barr virus determined nuclear antigen 2 (EBNA-2) is essential for EBV-induced growth transformation (Cohen, et al, 1989) and can specifically upregulate CD23 gene expression (Wang, et al, 1987). The regulation of CD23 gene expression is likely to be an important factor in EBV-induced B cell growth transformation. The cellular CD23 promoter and EBV TP-1 promoter have previously been shown to be transactivated by EBNA-2 (Wang, et al, 1991, Le Roux, et al, 1993). Studies have also shown that while EBNA-3A itself has no effect on the TP-1 promoter, it can repress EBNA-2-mediated transactivation in a B cell background (Le Roux, et al, 1994). Homologies have been shown between sequences present in the EBV TP-1 EBNA-2 responsive element and other functionally similar sequences which are found in the CD23 promoter region. The purpose of this study was ...