Table 1

Optimization of the M2-VLP assay for HTSa

MetricValue for VLP:
HK/156/1997HK/1073/1999Udorn/307/1972Udorn/307/1972 (S31N)PR/8/1934VN/1194/2004B/Lee/40Null-VLPs + FCCP
Adamantane sensitivitySensitiveSensitiveSensitiveResistantResistantResistantResistantNA
SerotypeH5N1H9N2H3N2H3N2H1N1H5N1Influenza BNA
Positive signal CV (%)2.44.39.114.76.37.96.34.0
Signal-to-noise ratio3830262623543465
Signal-to-background ratio52431218241629
Z′ factor0.740.770.650.520.710.700.710.83
  • a Screening metrics for the M2-VLP assay using seven different variants of M2 and FCCP-VLPs. Each VLP variant was screened in at least two separate experiments against a small-scale library of 71 known ion channel inhibitors (BioMol ion channel library), along with 6 positive (uninhibited) controls and 4 negative controls. Average screening metrics for each strain are shown, including % coefficient of variation (CV) of the positive controls, signal-to-noise ratio [(mean signal − mean background)/(standard deviation of background)], signal-to-background ratio (mean signal/mean background), and the estimated Z′ factor. The Z′ factor was calculated using 100 μM amantadine controls for adamantane-sensitive strains and Null-VLP controls for adamantane-resistant strains and FCCP-VLPs. NA, not applicable.