Fig. 3

Variations on NP-31 and NP-450 residues affected polymerase activity. The mini-genome assay was carried out to analyze the polymerase activity with various point substitutions on NP at (a) 33 °C and (b) 37 °C. Polymerase activity with alanine point substitutions was also analyzed both at (c) 33 °C and (d) 37 °C. The X-axis showed the NP origins and the Y-axis showed the relative polymerase activity where firefly luciferase was normalized with renilla luciferase, internal control. The t-test value was calculated; *p < 0.05, **p < 0.01. (The black stars in (a) and (b) indicated comparison with NP₃₁K-NP₃₇₇S-NP₄₅₀G, and in (c) and (d) indicated comparison with A/Taiwan/3446/02. Blue colored stars indicated a comparison between groups labeled with a line)