Figure 7

Polymerase proteins cooperatively increase H7N9 polymerase activity in mammalian cells. Plasmids encoding the PB2, PB1, PA, and NP proteins derived from JTC4 with the indicated segment substitutions were transfected into HEK293T cells at the indicated temperatures, together with the firefly luciferase reporter plasmid and internal control plasmid. At 24 h post-transfection, luciferase activities were measured.