Fig 1.

Cell surface activity of recombinant A/Québec/144147/09 neuraminidase (NA) proteins. Recombinant WT and mutant (E119G and Q136K) NA proteins were expressed in 293T cells. The empty pLLBA and pLLBA-HA plasmids were used as mock and negative controls, respectively. Twenty-four h posttransfection, the cells were briefly treated and resuspended in a nonlysing buffer to be used in an NA assay with MUNANA as the substrate. Final values were normalized by the fluorescence of cells transfected with the empty pLLBA plasmid. The mean values for three experiments ± standard deviations are shown (**, P < 0.01).