Process of immortalization by Epstein-Barr virus and oncogenic conversion of the immortalized cells.

Transcription of Epstein Barr virus (EBV) genome during immortalization of tonsil lymphocytes was studied. Cytoplasmic poly(A) RNA was Northern blot hybridized with 32P-labeled cloned EBV fragments. A 5.1 kb band was detected by hybridization with BamHI-H, -F, -K, -A and het fragments. The implication of this finding is discussed. DNA obtained from cells established from a colony of immortalized tonsil lymphocytes in 0.4% soft agar was found to transform NIH 3T3 cells. The transformed cells were able to induce tumor in nude mice, although the originally established lymphocytes from the colony did not. This may indicate that a certain population of EBV immortalized cells may contain a potentially oncogenic gene which can function as an oncogene in NIH 3T3 cells.