The full length PB1-F2 protein is necessary to inhibit NF-κB signaling.

<p>Vero cells were co-transfected with the NF-κB reporter, the different N-terminal (A) or C-terminal (B) PB1-F2 constructs or empty pcDNA4, the β-galactosidase control plasmid and 100 ng of pcDNA3-IKKβ. Cells transfected with the full length (FL) PB1-F2 Q/HK97 expression vector were used as a positive control for inhibition of NF-κB signalling. Forty eight hours post-transfection, the cells were lysed and the luciferase and galactosidase activities were measured. Data are representative of at least 3 independent experiments. Bars represent average values and standard deviations of firefly luciferase activities from triplicate samples normalized to the expression of galactosidase. Asterisks indicate results significantly different from control empty vector (one-way ANOVA followed by Dunnett's test; *, P≤0.05; ****, P≤0.0001).