TABLE 2.
Efficiency of pPolIC250 (PR8/VN1194) 6:2 reassortant virus generation in MDCK cells
| Expt | Infectivity titer (PFU/ml)a
|
|
|---|---|---|
| Trypsin−b | Trypsin+c | |
| 1 | 1.3 × 102 | 3.2 × 106 |
| 2 | 1.1 × 102 | 1.2 × 106 |
| 3 | 1.3 × 102 | 3.6 × 106 |
a
At 48 h after transfection, virus titers in the supernatant were determined by plaque assays of MDCK cells. The results are from three independent experiments (experiments 1 to 3). pPolIC250 (PR8/VN1194) indicates transfection of cells with pPolIC250-PB2, -PB1, -PA, -NP, -M, -NS, -1194HA, and −1194NA and pCAGGS-PB2, -PB1, -PA, and -NP.
b
Trypsin−, cells were cultured with trypsin-free Opti-Mem.
c
Trypsin+, cells were cultured with Opti-Mem containing trypsin.