TABLE 3.
NA enzyme kinetics of the recombinant H5N1 and H1N1 influenza viruses
| Recombinant virus | Mean Km ± SE (μM)a (95% CI) |
Vmax ratio
|
|
|---|---|---|---|
| Parental NAb | VN1203 NAc | ||
| H5N1 viruses | |||
| VN1203 | 213.7 ± 73.5 (47.48-379.9) | 1.00 | 1.00 |
| VN1203-H274Y | 94.4 ± 32.1 (21.74-167.1) | 0.28 | 0.28 |
| VN1203-N294S | 266.0 ± 58.9 (132.7-399.3) | 0.33 | 0.33 |
| H1N1 viruses | |||
| PR8 | 84.6 ± 16.1 (48.26-121.0) | 1.00 | 0.07 |
| PR8-H274Y | 275.5 ± 28.5 (211.1-339.9) | 0.88 | 0.06 |
| PR8-N294S | 359.2 ± 40.1 (268.6-449.8) | 0.88 | 0.06 |
a
The substrate concentration that resulted in a half-maximal catalytic rate. The enzyme kinetic data were fit to the Michaelis-Menten equation using GraphPad Prism 4. Values are from triplicates of one representative experiment.
b
Ratio of the NA Vmax of the respective recombinant viruses to the Vmax of the parental VN1203 or PR8 NA.
c
Ratio of the NA Vmax of the respective recombinant viruses to the Vmax of VN1203 NA. The recombinant VN1203, VN1203-H274Y, VN1203-N294S, and PR8 viruses were tested in parallel, and the ratios of PR8-H274Y and PR8-N294S to VN1203 were calculated on the basis of parallel tests of PR8, PR8-H274Y, and PR8-N294S viruses.