Growth kinetics of Ad vectors were obtained essentially as described previously [26] . HEK293 cells were plated in 6-well plates at the density of 3610 5 cells per well 24 h before infection. The cells were infected with Ads at 5 VPs/cell in 500 ml growth medium containing 2% FBS. 1.5 ml more growth medium containing 10% FBS was then added into each well after 2 h incubation at 37uC in 5% CO 2 humidified incubator. The infected cells were monitored and harvested with medium at various time points post-infection until complete CPE was formed. The collected cells together with the medium were lysed by four freeze-thaw cycles, and subjected to centrifugation at 3000 6g for 30 min at 4uC for cell debris removal. The total viruses in each well were determined by multiplying TCID 50 titer with the total volume of the supernatant, and plotted as growth curves.