Assay Method Information

Assay Name:  Measuring Compound Inhibitory Potency
Description:  Measurement of inhibition by compounds was performed using the HCV replicon system. Several different replicons encoding different HCV genotypes or mutations were used. In addition, potency measurements were made using different formats of the replicon assay, including different ways of measurements and different plating formats. See Jan M. Vrolijk et al., A replicons-based bioassay for the measurement of interferons in patients with chronic hepatitis C, 110 J. VIROLOGICAL METHODS 201 (2003); Steven S. Carroll et al., Inhibition of Hepatitis C Virus RNA Replication by 2′-Modified Nucleoside Analogs, 278(14) J. BIOLOGICAL CHEMISTRY 11979 (2003). However, the underlying principles are common to all of these determinations, and are outlined below.Stable neomycin phosphotransferase encoding replicon-harboring cell lines were used, so all cell lines were maintained under G418 selection prior to the assay. In some cases, the cell lines encoded a luciferase:Neor fusion and could be assayed either directly by determination of RNA copy number, or indirectly through measurement of the luciferase activity.To initiate an assay, replicon cells were plated in the presence of a dilution series of test compound in the absence of G418. Typically, the assays were performed in a 96-well plate format for manual operation, or a 384-well plate in an automated assay. Replicon cells and compound were incubated for 24 to 72 hours. At the end of the assay, cells are washed free of media and compound and then lysed. Luciferase activity was measured using a conventional luciferase assay. EC50 determinations were calculated as a percent of a DMSO control by fitting the data to a four parameter fit function.
Affinity data for this assay

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