FIG. 1.

Schematic illustration of EBNA gene transcription during different EBV latency programs. EBV encodes six EBNAs and two LMPs. In the latency I and II programs, the only EBNA gene expressed is EBNA 1, which is transcribed from the Qp promoter (16). The LMP genes are expressed during the latency II program but are absent from the latency I program. The latency III program, or growth program, involves transcription of all six EBNA genes, driven from either Cp or Wp. A combination of alternative 3′ processing and alternative splicing leads to the production of the mature transcripts encoding each EBNA gene product. In addition to the six EBNA genes, the LMP genes are also expressed during the latency III program. Transcription of the EBNA and LMP genes is autoregulated, as shown here and discussed in the text.