TABLE 1.
Mutant WSN virus replication in cell culture and their pathogenicity in mice
| Virus | Amino acid residue at position 453 (codon) | Titer of stock virus grown in MDCK cells (log10 PFU/ml) | MLD50a (log10 PFU) | Viral replication in respiratory organs (mean log10 PFU/g ± SD)b
|
|
|---|---|---|---|---|---|
| Nasal turbinate | Lung | ||||
| Wild-type WSN | Lys (AAG) | 7.6 | 3.4 | 3.0 ± 0.8 | 6.1 ± 0.2 |
| WSN-NA453R | Arg (CGC) | 8.0 | 6.3 | 3.8 ± 0.9 | 5.3 ± 0.2 |
| WSN-NA453L | Leu (CTA) | 7.7 | 7.7 | 2.8c | 4.4 ± 0.2 |
a
BALB/c mice were infected intranasally with 100 μl of virus and observed for 2 weeks.
b
Five BALB/c mice were infected intranasally with 50 μl (2.1 × 106 PFU) of virus. Organs were harvested on day 4 postinfection, and virus was titrated on MDCK cells in the presence of 0.5 μg of trypsin/ml.
c
Virus was isolated from one of five mice.