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. 1999 Apr 27;96(9):5188–5193. doi: 10.1073/pnas.96.9.5188

Figure 5.

Figure 5

Southern blot analysis of immortalized B cell lines that were established with virus stocks derived from the TR−2/293 packaging cell line after transfection with mini-EBV plasmid DNA p1495.4 (24). Total DNA from the immortalized B cell lines was digested with BamHI, separated by electrophoresis, blotted, and hybridized with a probe specific for the pMBO131 plasmid (6). DNAs extracted from the wild-type B95.8 cell line served as a negative control. The positive control consisted of 10 μg of a 293 cell clone that stably carries the B95.8/F factor plasmid (11). The number of copies of this plasmid was estimated to lie between one and two copies per cell. All tested immortalized B cell lines were found to carry the intact mini-EBV F-factor DNA and no helper virus DNA.