Table 1.
Replication efficiency of 1918/K173 recombinant viruses in ferrets*
| Virus | Virus titer (mean log10PFU ± SD/g) in: |
||
|---|---|---|---|
| Nasal turbinates | Trachea | Lungs | |
| 1918 WT | 7.43 ± 0.13 | 6.65 ± 0.73 | 6.40 ± 0.40 |
| K173 WT | 5.92 ± 0.67 | —† | — |
| 1918(3P + NP)/K173 | 6.69 ± 0.37 | 5.21 ± 0.62 | 5.98 ± 0.28 |
| K173(3P + NP)/1918 | 6.90 ± 0.38 | 2.72 | — |
| 1918PA/K173 | 4.26 ± 0.11 | — | — |
| 1918PB1/K173 | 5.62 ± 0.32 | 2.84, 1.85 | 4.31, 5.36 |
| 1918PB2/K173 | 5.24 ± 0.28 | — | — |
| 1918NP/K173 | 5.55 ± 0.65 | — | 3.58 |
| 1918HA/K173 | 5.74 ± 0.11 | — | — |
| 1918NA/K173 | 4.44 ± 0.02 | — | — |
| 1918M/K173 | 5.35 ± 1.39 | — | — |
| 1918NS/K173 | 5.55 ± 0.37 | — | 2.36 |
* Ferrets, anesthetized with ketamine and xylazine, were infected intranasally with 105 PFU/500 μl of virus. Three ferrets from each group were euthanized on day 3 p.i. for virus titration. Individual titers were recorded when virus was not recovered from all three ferrets.
† —, Virus not isolated.