Substitutions of amino acids 601 to 607 of the PB2 ‘627’ domain disrupt RNP activity.

<p>Plasmids expressing wild-type or mutant PB2, PA, PB1, NP and a vRNA encoding luciferase were co-transfected along with a plasmid expressing GFP as control. The overall polymerase activity is represented by a ratio of luminescence signal to GFP signal. The activity of polymerase with wild-type PB2 was set to 1. Level of PB2 expression of each mutant was detected by anti-PB2 polyclonal antibodies in Western blotting with karyopherin ß3 as loading control. The bar represents the mean ratio ± standard deviations from three independent experiments. *The p-values are smaller or equal to 0.05 in two-tailed Student’s <i>t</i>-test.