FIG 5.

Additional mutations that stabilizes the Venus gene inserted into the NS segment. (A) Identified amino acid mutations were mapped onto the influenza polymerase complex (PDB ID 4WSB). (B) Polymerase internal tunnels (shown as yellow tubes). The vRNA promoter binds to the polymerase, and the template vRNA enters the polymerase complex. The template vRNA passes through the active site, where RNA synthesis occurs, and then leaves via the template exit. The RNA products synthesized at the active site, leave via the product exit. (C) Each mutant Venus-PR8 virus was passaged four times in MDCK cells, and the proportion of Venus-expressing plaques after passaging was determined in MDCK cells by using fluorescence microscopy. (D) Percentages of influenza A virus strains containing mutations that stabilize the Venus gene in Venus-PR8 (i.e., the number of strains containing the indicated amino acid/total number of strains available in the Influenza Research Database).