Table 3.
Comparison of pathogenicities of PA mutant viruses lacking N-truncated PAs in mice
| Virus | MLD50 (log10 PFU)a |
|---|---|
| WSN | 3.8 |
| M155L | 5.3 |
| M182L | 4.0 |
| DM | 5.5 |
a
Groups (n = 3 per group) of 6-week-old female BALB/c mice were anesthetized with isoflurane and infected intranasally with 50 μl of serial 10-fold dilutions of viruses, thereby creating doses ranging from 102 to 106 PFU. The mice were monitored daily for clinical signs of infection for 14 days p.i. MLD50 values were calculated by using the method of Reed and Muench (21).