Transcriptional analysis of the Epstein-Barr virus interleukin-10 homologue during the lytic cycle.

The Epstein-Barr virus (EBV) open reading frame (ORF) BCRF1, expressed in the late phase of the viral cycle, encodes a homologue of human interleukin-10 (hIL-10). Unspliced, 3' co-terminal transcripts of 0.8 and 1.6 kb from O-tetradecanoylphorbol 13-acetate (TPA)-treated B95-8 cells have been described but other results indicated the existence of uncharacterized transcript(s) initiated upstream of the 1.6 kb BCRF1 mRNA. Here we describe two additional large transcripts of the BCRF1 ORF, a possibly spliced product of 3.5 kb and an unspliced product of 4.5 kb. The time course of the expression of BCRF1 transcripts and of the secreted protein from Akata cells were also determined.