FIG 1.

Inhibition of host gene expression by A/Viet Nam/1203/2004 PA-X. Human HEK293T or avian DF-1 cells (96-well plate format, 10⁴ cells/well, triplicates) were cotransfected with 0, 1, 10, or 100 ng of pCAGGS expression plasmids encoding A/Viet Nam/1203/2004 H5N1 PA-X fused to an HA epitope tag, together with 250 ng of pCAGGS plasmids encoding Gluc or GFP under the control of the human polymerase II promoter. Empty plasmid was included as a control. At 24 hpt, GFP was observed under a fluorescence microscope (A), and Gluc activity was quantified using a luciferase plate reader (B). Scale bars, 300 μm. The activity of Gluc was normalized to cells transfected with the empty plasmid control (100%). Results represent means and SD of triplicates. The data are representative of three independent experiments. ****, P < 0.0001 (0 ng of PA-X WT plasmid versus other concentrations), determined using one-way ANOVA. (C) PA-X and GFP expression levels by Western blotting from total cell lysates were detected using specific PAbs against the HA epitope tag (PA-X) or GFP, respectively. A MAb against β-actin was included as a loading control. Sizes of molecular markers (kDa) are noted on the left.