Expression of EBNA-3 family in fresh B lymphocytes infected with Epstein-Barr virus

Four transcripts belonging to the EBNA-3 family were detected during immortalization of human tonsillar lymphocytes with the Epstein-Barr virus. These four transcripts were also detected in immortalized B-lymphoblastoid cells (LCL) and the Burkitt's lymphoma cell line, Namalwa. A 5.0-kb transcript hybridized with the EBNA-3A probe; a 8.5-kb transcript hybridized with the EBNA-3B and -3C probes; and a 5.6- and a 3.6-kb transcript hybridized with the EBNA-3C probe. Sequencing and cDNA analysis showed that the EBNA-3C transcripts contained exons of the most rightward BamHI-E open reading frames, BERF-3 and BERF-4. Moreover, sequencing of cDNA clones revealed exons in the 5' portion homologous to regions in EBV BamHI-C, -W, and -U. Hybridization experiments with EBV BamHI-W and -U probes identified the 8.5- and 5.6-kb transcripts but not the 3.6-kb transcript in LCL. Organization of these transcripts from the EBNA-3 family is discussed.