FIG. 2.

In vitro transgene expression is upregulated by the HSV1 TK gene sequence carried in HCAd (right) but not in Ad (left), while WPRE increased expression in Ad (left), but not in HCAd (right). Rat (CNS-1), mouse (GL26), and dog (J3T) glioma cells, monkey kidney cells (Cos7), and human glioma cells (IN859 and U251) were infected at an MOI of 300 vgs/cell. Cells were incubated for 72 h, and transgene expression was determined by β-Gal activity assay of cell lysates. Experiments were performed in triplicate. Numbers of vgs were determined for all the viral preparations using quantitative PCR. Bars represent the means ± standard errors of the means of β-Gal activity, calculated as o-nitrophenol produced (pmol)/(sample protein content [mg/ml] × incubation time (min), per inoculated vg. Data were analyzed by one-way ANOVA followed by the Tukey-Kramer multiple comparison test. *, P < 0.05 versus control group (cells infected with the corresponding vector bearing the mCMV-β-Gal cassette).