Epstein–Barr virus (EBV) is a potent mitogenic and anti-apoptotic agent for B lymphocytes and is associated with several different types of human tumour. The abundantly expressed small viral RNA, EBER-1, binds to the growth inhibitory and pro-apoptotic protein kinase R (PKR) and blocks activation of the latter by double-stranded RNA. Recent evidence has suggested that expression of EBER-1 alone in EBV-negative B cells promotes a tumorigenic phe-notype and that this may be related to inhibition of the pro-apoptotic effects of PKR
