Table 1.

Growth of T1L × D-EA1 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-EA1EEEEEEEEEE2.70 × 107 9.91 × 107 0.273
Reassortant
 1-31LLLLLLELEE4.80 × 106 1.20 × 107 0.4001
 1-6EELLELLELE1.05 × 106 8.28 × 106 0.1272
 35EEEELELEEE2.55 × 106 2.20 × 107 0.1163
 1-57LLLLELLEEE1.35 × 106 1.21 × 107 0.1124
 1-29EEEEEELEEE1.17 × 106 1.40 × 107 0.08365
 33EEELEELEEE2.40 × 105 2.90 × 106 0.08286
 1-25EEELEELEEE1.32 × 106 1.90 × 107 0.06927
 1-28EELEEEEELE3.35 × 106 5.30 × 107 0.06328
 29EEEEEELEEE6.85 × 105 1.19 × 107 0.05769
 1-1EEEEEELELE7.75 × 105 2.30 × 107 0.033710
 1-11EEELELLEEL4.53 × 105 1.75 × 107 0.025911
 1-9EEELELLEEL4.08 × 105 1.63 × 107 0.025112
 1-56EEEELLLEEL2.25 × 104 1.05 × 106 0.021413
 1-10LLLLLELLEL2.95 × 105 2.20 × 107 0.013414
 47EEELEELEEL3.15 × 104 2.85 × 106 0.011115
 1-27EEEEEELEEL9.25 × 104 1.03 × 107 0.0090216
 1-30EELEEEELEL4.00 × 105 5.40 × 107 0.0074117
 22LELEEELEEL8.05 × 104 1.33 × 107 0.0060818
 1-44EELEEELEEL3.80 × 104 1.23 × 107 0.0030919
 37EEELEEEEEL4.95 × 104 2.15 × 107 0.0023020
  • a Parental origin of each gene segment: L, gene segment derived from T1L; E, gene segment derived from D-EA1.

  • 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.