| To test this we cloned 12 colonies from cells that had been passaged on agar plates for 8 days. |
| These cells had been passaged through 14 passages and were grown to confluence in 35 mm culture dishes. |
| The MA lines and the marker strain were passaged together for 69 passages and then checked for contamination. |
| Deletions of gene 1.3 were introduced into the preadapted virus, and the recombinant virus was then passaged to allow fitness recovery. |
| In addition, influenza viruses are usually passaged in embryonated chicken eggs before isolation. |
| Two days after transfection had been initiated, cells were passaged onto coverslips. |
