TABLE 1.
Virions possessing the PR8 M segment have lower Vmax, but not Km, of NA interaction with MUNANA than virions possessing NL602 M
| Virus and inputa (PFU) | Vmaxb (SE; 95% CI) | Km (SE; 95% CI) |
|---|---|---|
| PR8 | ||
| 1 × 106 | 1,798 (72.1; 1,645–1,950) | 8.1 (1.4; 5.2–11.1) |
| 1,807 (55.7; 1,687–1,926) | 9.9 (1.1; 7.5–12.2) | |
| 1,908 (52.7; 1,794–2,021) | 10.8 (1.1; 8.5–13.1) | |
| PR8/NL M | ||
| 1 × 106 | 2,621 (67.3; 2,476–2,765) | 10.8 (1.0; 8.7–12.9) |
| 2,568 (73.0; 2,411–2,724) | 11.2 (1.1; 8.7–13.5) | |
| 2,749 (73.1; 2,592–2,905) | 11.6 (1.1; 8.9–13.4) | |
| PR8/NL HA+NAc | ||
| 1 × 105 | 1,407 (31.4; 1,304–1,475) | 28.2 (1.8; 24.4–32.0) |
| 1,472 (40.3; 1,386–1,556) | 29.3 (2.2; 24.5–34.0) | |
| 1,618 (22.1; 1,499–1,738) | 22.1 (2.7; 16.3–27.8) | |
| PR8/NL M+NA+HAc | ||
| 1 × 105 | 2,354 (75.5; 2,192–2,516) | 24.7 (2.3; 19.8–29.7) |
| 2,296 (74.4; 2,136–2,455) | 23.3 (2.2; 18.5–28.1) | |
| 2,266 (90.9; 2,073–2,458) | 18.8 (2.8; 13.0–24.7) |
Presence of equal numbers of virions was confirmed by measuring NP RNA copy number using qRT-PCR. No significant difference in copy number was observed between PR8 and PR8/NL M virus preparations or between PR8/NL HA+NA and PR8/NL M+NA+HA virus preparations in independent experiments.
Enzyme kinetics data were fit to the Michaelis-Menten equation by nonlinear regression to determine the Michaelis constant (Km) and maximum velocity (Vmax) of substrate conversion. CI, confidence interval. SE, standard errors. For each virus, data are presented from three independent experiments.
Note that the NA proteins of PR8 NL09 HA+NA and PR8 NL09 HA+NA+M differ from the NA carried by PR8 and PR8 NL09 M; thus, the NL09 NA-containing viruses should only be compared to each other.