TABLE 4.
Calculated LD50 and median time to death (TTD) for intranasal mouse challenges.
| Strain | LD50† (95% CL) | P-value compared to WT | Median TTD (days) | P-value compared to WT |
| Fn WT | 0.1 (.,.) | – | 4.0 | – |
| Fn Cip80-1‡ | >23 | <0.0001 | >21 | <0.0001 |
| Fn Cip80-10‡ | >79 | <0.0001 | >21 | <0.0001 |
| Fn Strep512-1 | 1.4 (0.5, 3.6) | 0.0004 | 4.5 | N.S. |
| Fn Strep512-10 | 4.6 (1.7, 12.3) | <0.0001 | 5.0 | N.S. |
| LVS WT | 172 (52, 701) | – | 7.0 | – |
| LVS Cip128-3‡ | >64,000 | <0.0001 | >21 | <0.0001 |
| LVS Cip128-12‡ | >253,000 | <0.0001 | >21 | <0.0001 |
| LVS Strep512-1 | 352 (153, 972) | 0.0002 | 6.0 | N.S. |
| LVS Strep512-4 | 596 (184, 1615) | <0.0001 | 6.0 | N.S. |
| LVS Strep512-5 | 2274 (866, 6313) | <0.0001 | 6.0 | N.S. |
†LD50 values are estimated under a probit model with 95% confidence limits (CL) by Fieller’s method. P-values were obtained from the Wald Chi-Squared test for each LD50 in comparison to the parent strain. Median time to death (TTD) was calculated for the highest dose level tested. ‡Comparisons for these strains, in which all groups of mice survived, were made based on the highest dose levels tested.