FIG. 4.

Ability of segment 2 polypeptides to support IAV gene expression. 293T cells were transfected with plasmids encoding PB2, PA, NP, and a synthetic vRNA analogue containing a luciferase gene along with the indicated combinations of plasmids (WT [WT PB1]) and, 48 h later, the luciferase activity quantified. The data in panel A are the means ± the SEM of three independent experiments plotted relative to the activity seen in the absence of a PB1 gene, whereas the data in panel B are the means ± the SEM of a minimum of six independent experiments plotted as the percent activity seen with WT PB1 for each experiment. **, P < 0.01.