INTEGRATION OF AN EPSTEIN-BARR-VIRUS EPISOME-3' INTO THE GENE ENCODING IMMUNOGLOBULIN HEAVY-CHAIN ALPHA-1 IN A LYMPHOBLASTOID CELL-LINE

For the first time we have characterized an unoccupied site of Epstein -Barr (EBV) virus integration in a lymphoblastoid cell line, RGN1. The site of integration is about 1.5 kb downstream from the gene encoding the heavy chain constant alpha 1, specifying immunoglobulin A (IgA). Sequence and Southern analysis allowed us to hypothesize that integrat ion occurred via a double exchange involving the viral latent origin o f DNA replication (oriP) and the human DNA. The region involved in the integration is transcribed into poly(A)(+)RNA in all the tested lymph oid lines, but not in the RGN1 line. We suggest a mechanism of integra tion primed by interactions between oriP and cell ori and its potentia l role in the establishment and/or evolution of EBV-carrying lines.