Table 1.
Virus recovery by use of reverse geneticsa
| Virus | Supernatant of plasmid-transfected cells collected at: |
Virus recovery | |||
|---|---|---|---|---|---|
| 48 hpt and CPE in MDCK cells observed at: |
72 hpt and CPE in MDCK cells observed at: |
||||
| 24 hpi | 48 hpi | 24 hpi | 48 hpi | ||
| Wild-type WSN | ++ | ++++ | +++ | ++++ | Yes |
| WSN-M1R76A | + | ++ | ++ | +++ | Yes |
| WSN-M1R77A | – | ++ | – | ++ | Yes |
| WSN-M1R78A | – | – | – | + | Yes |
| WSN-M1R76D | – | – | – | – | No |
| WSN-M1R77D | – | – | – | – | No |
| WSN-M1R78D | – | – | – | – | No |
| WSN-M1R76K | ++ | ++++ | +++ | ++++ | Yes |
| WSN-M1R77K | ++ | ++++ | +++ | ++++ | Yes |
| WSN-M1R78K | ++ | ++++ | +++ | ++++ | Yes |
| WSN-M1R76/77A | – | – | – | – | No |
| WSN-M1R76/78A | – | – | – | – | No |
| WSN-M1R77/78A | – | – | – | – | No |
| WSN-M1R76/77K | ++ | ++++ | +++ | ++++ | Yes |
| WSN-M1R76/78K | ++ | ++++ | +++ | ++++ | Yes |
| WSN-M1R77/78K | ++ | ++++ | +++ | ++++ | Yes |
| WSN-M1R76/77/78K | ++ | ++++ | +++ | ++++ | Yes |
a
293T cells were transfected with a vRNA expression plasmid for either the wild-type or mutated M1 vRNA segment along with the vRNA expression plasmids for the remaining seven vRNA segments and four protein expression plasmids for PB2, PB1, PA, and NP. Culture supernatants were harvested at 48 and 72 h post transfection and inoculated into MDCK cells. The cytopathic effect (CPE) was monitored for 48 to 72 h. +, Only a few cells showed a CPE; ++, ca. 50% of the cells showed a CPE; +++, 75% of the cells showed a CPE; ++++, 100% of the cells showed a CPE. hpt, hours post transfection;hpi, hours postinfection.