FIG. 3.
Most infected BJAB cells harbor viral DNA months following initial infection. BJAB cells were infected with Ad2 or Ad5dl309 for 40 days or 76 days, respectively. The infected cells were used for limiting dilution analysis to estimate the frequency of virus-bearing cells. A master lysate plate was prepared by diluting infected BJAB cells at 1,000, 100, 10, 1.0, and 0.1 cells per well with uninfected cells so that the total equaled 1 × 105 cells/well. Twelve wells for each dilution were tested. The total sample in each well was digested with proteinase K at 55°C for 9 h, followed by inactivation at 95°C for 15 min. Nested PCR for the hexon gene was performed, and the PCR products were visualized on a 1% agarose gel. The percentage of hexon-positive wells was plotted with a best-fit three-parameter logistic fit constrained between 0% and 100%. Dashed lines indicate the number of cells added per well that yield 63% positive wells, which corresponds to one adenovirus DNA-positive cell per well.