FIG. 1.

Schematic of the Epstein-Barr Virus (EBV) genome and the sequence of EBNA-LP. The EBV genome is shown in linear form with relevant structural motifs and location of exons (black boxes) encoding latency proteins, which are labeled above. The internal repeat region (IR1) is also shown by the gray box. The viral transcript encoding EBNA-LP is shown below and is derived from the latency W promoter (Wp). The first exon transcribed from Wp is W0 and is noncoding. Alternative splicing from W0 to W1 can result in formation of an initiation codon (W1′) or no initiation codon (W1). Splicing that generates W1′ gives rise to transcripts encoding EBNA-LP. EBNA-LP is thus composed of repeated W1 and W2 exons as well as two unique exons known as Y1 and Y2. The transcript is bi-cistronic as it also contains the EBNA2 ORF at the 3′ end. The dashed line from the EBNA2 protein indicates promoters that are activated by EBNA2. The viral bidirectional promoter, which controls expression of LMP-1 and LMP2B, is indicated by asterisks. Transcripts encoding LMP-1 are shown below. A sequence comparison between EBV EBNA-LP and other nonhuman primate lymphocryptoviruses is shown below indicating presence of conserved regions (CR). Location of nuclear localization signals (NLS) and regions required for EBNA2 coactivation are indicated. Inverted triangles above the sequence indicate conserved serine residues.