Detection of EBV DNA in EBV-transformed T cells. (A) EBV DNA was detected by PCR analysis on DNA extracted from seven different EBV-transformed T-cell lines (EBV 41, T1B5, TFS, 2C8, 2G4, 2G8, NC5, respectively, lanes 1 to 7), a T-cell lymphoma Jurkat (lane 8), or two EBV-LCLs (lanes 9 and 10), or a control without DNA (lane 11) using primer pairs specific for LMP-1 amplifying a 562-bp fragment. (B) The presence of EBV DNA in EBV-transformed T cells (NC5 and TC) was confirmed by Southern blot hybridization on 10 μg of EcoRI digested genomic DNA (lanes 1 to 4) or on BamHI digested Hirt extract from 2 × 10⁶ cells (lanes 6 to 9) with a LMP-1 specific probe. Lanes 4 and 9, EBV LCL; lanes 3 and 8, Jurkat cells; lanes 2 and 7, NC5 cells; lanes 1 and 6, TC cells; lanes 5 and 10, molecular weight markers II (Boehringer Mannheim, France).