Table 2. Virus titers in the nasal turbinates and lungs of mice challenged with PR8 virusa.
| Immunogen (PFU) | Day after challenge | Virus Titer (mean log10PFU ± SD/g) in: | ||
|---|---|---|---|---|
| Nasal turbinates | Lungs | |||
| PB2-RSVF virus | 104 | 3 | 6.4±0.5 | 8.4±0.1 |
| 6 | 7.6±0.9 | 8.2±0.7 | ||
| 105 | 3 | 6.2* | 7.6±0.3 | |
| 6 | 5.8 | 7.9, 7.2 | ||
| 106 | 3 | 7.0* | 7.2*,** | |
| 6 | 5.0 | 4.3 | ||
| FI-PR8 virus | 106 | 3 | 6.5, 6.9 | 8±0.3 |
| 6 | 6.2, 7.6 | 5.8,7.8 | ||
| PBS | 3 | 7.3±0.6 | 8.5±0.2 | |
| 6 | 8.9, 7.8,b | 7.1,6.6,b | ||
a
Mice immunized with the indicated agents (104, 105, or 106 PFU of the PB2-RSVF virus or controls [formalin-inactivated PR8 (FI-PR8) virus and PBS) were challenged with 10 MLD50 of PR8 virus two weeks after the boost immunization. Three mice per group were euthanized on days 3 and 6 post-challenge for virus titration in the nasal turbinates and lungs. When virus was not detected (detection limit, 5 PFU/g organ) in all mice, individual titers were recorded.
b
One mouse died before this sampling time point; therefore, data could not be recorded for that mouse.
Statistically significant differences (P ≤ 0.05) compared with the PBS (*) and FI-PR8 (**) control groups are indicated by asterisks.