Table 2.
Biological properties of mutant VD5 viruses with human-like amino acids in their PB2, PA or NP genes.
| Virus | Mutations |
Titers of stock virus grown in eggs (PFU/ml)* | MLD50(PFU)† | ||
|---|---|---|---|---|---|
| PB2 | PA | NP | |||
| VD5 | 2.6 × 107 | > 106 | |||
| VD5-PB2-9N | D9N | 1.8 × 108 | 8.9 × 105 | ||
| VD5-PB2-199S | A199S | 6.6 × 107 | 3.3 × 105 | ||
| VD5-PB2-368K | R368K | 1.9 × 108 | > 106 | ||
| VD5K | E627K | 2.6 × 108 | 41 | ||
| VD5-PA-142N | K142N | 1.6 × 108 | 2.5 × 105 | ||
| VD5-PA-142E | K142E | 3.3 × 108 | > 106 | ||
| VD5-PA-421I | S421I | 4.9 × 107 | 5.7 × 105 | ||
| VD5-NP-33I | V33I | 9.1 × 107 | > 106 | ||
| VD5-NP-100V | R100V | - | ND | ||
| VD5-NP-100I | R100I | - | ND | ||
| VD5-NP-283P | L283P | - | ND | ||
| VD5-NP-357K | Q357K | 3.0 × 108 | > 106 | ||
| VD5K-PB2-9N | E627K/D9N | 3.9 × 108 | 11 | ||
| VD5K-PB2-199S | E627K/A199S | 4.3 × 108 | 6.8 | ||
| VD5K-PB2-368K | E627K/R368K | 3.7 × 108 | 1.0 | ||
| VD5K-PA-142N | E627K | K142N | 6.0 × 108 | 1.7 | |
| VD5K-PA-142E | E627K | K142E | 3.4 × 108 | 5.4 | |
| VD5K-PA-421I | E627K | S421I | 2.6 × 108 | 7.3 | |
| VD5K-NP-33I | E627K | V33I | 2.5 × 108 | 41 | |
| VD5K-NP-100V | E627K | R100V | 5.8 × 108 | > 106 | |
| VD5K-NP-100I | E627K | R100I | 4.1 × 108 | > 106 | |
| VD5K-NP-283P | E627K | L283P | 5.0 × 108 | 4.5 × 103 | |
| VD5K-NP-357K | E627K | Q357K | 2.8 × 108 | 0.8 | |
*
Mutant viruses possessing human-like amino acids in the genetic background of VD5 generated by reverse genetics as described previously (Neumann et al., 1999). Rescued viruses were amplified in eggs and their virus titers were determined by plaque assays in MDCK cells. -, virus was not rescued.
†
To determine the dose lethal to 50% of mice (MLD50), we infected 6-week-old female Balb/c mice intranasally with 50μl of serial 10-fold dilutions of virus and observed them for 2 weeks. ND, not determined.