Table 3.

Interlaboratory variability in PFA IC50determinations by initial (phase 1) and ACTG consensus (phase 2) plaque reduction assays using plaque-purified viruses

LaboratoryPFA IC50 (μM) for:
AD169aXbaFaC9208bC9209b
Phase 1Phase 2Phase 1Phase 2Phase 1Phase 2Phase 1Phase 2
A112.0686.54
B59.69184.22117.46244.42115.5163.29116.67545.94
C65.6943.90116.49243.09NAc 437.56222.42>1,600
D
E48.1543.5454.9635.2056.5652.53190.69690.59
F50.0970.81219.24140.7319.91336.21
G83.3277.51
H53.79118.8764.0887.0569.13120.44
I50.9976.7498.30139.49229.83210.65274.31445.97
J35.3773.1930.52119.44110.13197.02150.80200.1
K56.5171.2828.9371.49
Total no. of assays1010775677
Mean IC50 61.5784.6672.96134.31146.25183.62191.99562.75
CVd 35.348.352.161.051.476.645.988.4
No. (%) resistant0 (0)0 (0)0 (0)0 (0)0 (0)1 (17)0 (0)4 (57)
  • a Cell-free laboratory strains.

  • b Cell-associated clinical isolates.

  • c NA, IC50 could not be determined due to inconsistent results.

  • d CV determined as (standard deviation/mean) × 100%.