FIG. 8.

Infectivity of Ad vectors on 293 cells after their recovery at different time points from infected HeLa cells by freeze-thawing. HeLa cells were infected on ice with Ad5 or Ad5/35L vectors expressing β-galactosidase (A) or GFP (B) under conditions that provide equivalent Ad attachment. Unattached virus particles were then removed and cells were transferred to 37°C for different times and were subjected to four freeze-thaw cycles to release cell-associated virus particles. In the control settings (0 min) cells with attached viruses were lysed without incubation at 37°C. HeLa cell lysates were obtained and applied on 293 cells, and the β-galactosidase activity or the percentage of GFP-expressing cells was analyzed 24 h later. All infections were performed in triplicate. The capsids of Ad5-β-gal and Ad5/35L-β-gal were identical to those of Ad5-GFP and Ad/35L-GFP, respectively. RLU, relative light units.