Fig 5.

Polymerase activity of ribonucleoprotein complexes of wild-type A/Hong Kong/213/03 (H5N1) (A) and A/Turkey/65–1242/06 (H5N1) (B) viruses and their variants with single point mutations. Amino acid mutations are indicated by shading of a residue below each plot. The polymerase activities were determined by dual-luciferase reporter assay in three independent experiments. The 293T cells were transfected in triplicate with luciferase and Renilla reporter plasmids, with plasmids expressing PB2, PB1, PA, and NP from HK/213, TK/65, or mutated viruses. Cells were incubated at 33°C, 37°C, or 39°C for 24 h, and cell lysates were analyzed to measure firefly luciferase and Renilla activities. The latter was used to normalize transfection efficiency. Values shown represent the means ± standard deviations of activities of each RNP complex relative to that of the respective wild-type virus. *, P < 0.05; °, P < 0.01 (compared with the value for respective wild-type virus by one-way ANOVA).