Table 2.

Growth of T1L × D-EA3 reassortant viruses in the presence and absence of E64

Virus strain Origin of gene segmenta: Viral titer inb: L+E64/L ratiocRankd
L1L2L3M1M2M3S1S2S3S4E64-treated cellsUntreated cells
Parental
 T1L L L L LL L L L L L 4.18 × 105 2.20 × 107 0.0190
 D-EA3EEEEEEEEEE1.25 × 107 6.93 × 107 0.181
Reassortant
 3-45EELEEELEEE1.08 × 105 6.50 × 105 0.1651
 3-40EEEEEELELE7.80 × 105 4.75 × 106 0.1642
 3-35EELLELLEEE1.20 × 106 7.70 × 106 0.1563
 3-28ELEEEEEEEE1.63 × 106 1.73 × 107 0.09464
 3-25EEEEEELEEE3.60 × 106 4.55 × 107 0.07905
 3-2LELEEELEEE3.20 × 106 5.05 × 107 0.06346
 3-32EELEEELEEE1.25 × 106 3.30 × 107 0.03797
 3-46EELEELLLLE1.34 × 105 6.88 × 106 0.01948
 3-37LELLELLEEL2.22 × 106 1.31 × 108 0.01699
 3-9LELELLLEEL2.30 × 105 1.95 × 107 0.011810
 3-7EEEEEEEEEL2.25 × 105 4.50 × 107 0.0050011
  • a Parental origin of each gene segment: L, gene segment derived from T1L; E, gene segment derived from D-EA3.

  • b L cells (4 × 105) were infected with virus strains at an MOI of 2 PFU per cell. After a 1-h adsorption period, the inoculum was removed, fresh medium with or without 100 μM E64 was added, and cells were incubated at 37°C for 24 h. Cells were frozen and thawed twice, and viral titers in cell lysates were determined by plaque assay. The results are presented as mean viral titer at 24 h for two to four independent experiments for the reassortant viruses and six independent experiments for the parental viruses.

  • c The mean viral titer at 24 h in E64-treated cells was divided by that in untreated cells to calculate an L+E64/L ratio for each virus strain.

  • d Reassortant viruses are ranked from highest to lowest based on their L+E64/L ratios.