FIG. 4.

Replication-deficient plasmids exhibit moderate retention in the presence of LANA. (A) BJAB (dashed lines) or LANA-positive BJAB/TetOn/ORF73 (+Dox) cells (solid lines) were transfected with equimolar amounts of plasmid DNA corresponding to 5,000 copies per cell, subjected to FACS at 20 h posttransfection, and monitored by flow cytometry. Transfections were done in duplicate. (B) Replication-deficient plasmids are retained as episomes in LANA-expressing cells. DNA extracted by the Hirt method at 4 days posttransfection was analyzed by Southern blotting. Undigested episomal DNA was detected using pGFP as a probe. (C) Loss rates for each plasmid were calculated between 1 and 4 days post-FACS. According to Student's t test, P values were <0.01 for LANA-positive versus BJAB cells and <0.01 for p1TR compared to pRELBS1/2 and p3XLBS1/2.