TABLE 2.
Summary of phenotypic properties of the wild type (wt) and virus with a history of persistent replication in LL-5 cells
| Passage | Fitness in cells of line:
|
Virus productiona (PFU/ml) in cells of line:
|
Virulenceb in cells of line:
|
|||
|---|---|---|---|---|---|---|
| LL-5 | BHK-21 | LL5 | BHK-21 | LL-5 | BHK-21 | |
| 0 (wt) | 1 | 1 | >106 | 1010 | − | ++++ |
| 5 | 2,000 | 0.06 | 105 | ND | − | ++ |
| 25 | 6,200 | 0.15 | <104 | ND | − | + |
a
ND, not determined.
b
Minus signs indicate no cell damage; different numbers of plus signs correspond to different levels of virulence, with + being the lowest.