Both Epstein‐Barr virus (EBV)‐encoded trans‐acting factors, EB1 and EB2, are required to activate transcription from an EBV early promoter

We have identified two Epstein‐‐Barr virus (EBV) transacting factors which are involved in the transcriptional activation of EBV early promoters in latently infected Raji cells. In Raji cells, expression of the factor EB1 encoded by the open reading frame (ORF) BZLF1 is necessary and sufficient to disrupt latency. However, factor EB2 encoded by the ORF BMLF1‐ BSLF2 does not disrupt latency when expressed alone in Raji cells. Expression of an EBV activatable early promoter depends on the presence of both EB1 and EB2.