FIG 4 .
Functional evaluation of the involvement of the UPS PB2 partners in the multiplication of H3N2 and H1N1pdm09. A549 cells transfected with nontargeting (NT) or UPS-targeting siRNA for 48 h were infected with H1N1pdm09 or H3N2 at an MOI of 0.001 PFU/cell. The titers of the viruses produced were determined in the supernatants collected at 24 h postinfection by plaque-forming assay and expressed as ratios relative to the titers obtained with nontargeting siRNA. UPS factors with statistically significant effects are red (H3N2) or pink (H1N1pdm09); hatched bars indicate that a PPI with the corresponding PB2 protein has been detected, taking into account positive scoring at least two times in the NRL retesting experiments; and plain bars indicate that no interaction was detected (validated fewer than two times in NLR retesting). Data represent the mean ± the standard error of the mean of three independent experiments, and P values were calculated with a two-tailed nonparametric Student t test. *, P <0.05; **, P <0.01; ***, P <0.001.