CHEMBL5733646

Measurement of Interferon Production in Human PBMC: Activation of human TLR7 results in robust production of interferon by plasmacytoid dendritic cells present in human blood. The potential of compounds to induce interferon was evaluated by looking at the antiviral activity in the HCV replicon system upon incubation with conditioned media from peripheral blood mononuclear cells (PBMC). The HCV replicon assay is based on a bicistronic expression construct, as described by Lohmann et al. (Science (1999) 285: 110-113; Journal of Virology (2003) 77: 3007-15 3019) with modifications described by Krieger et al. (Journal of Virology (2001) 75: 4614-4624). The assay utilized the stably transfected cell line Huh-7 luc/neo harboring an RNA encoding a bicistronic expression construct comprising the wild type NS3-NS5B regions of HCV type 1b translated from an Internal Ribosome Entry Site (IRES) from encephalomyocarditis virus (EMCV), preceded by a reporter gene (Firefly-luciferase) and a selectable marker gene (neoR, neomycine phosphotransferase). The construct is flanked by 5′ and 3′ NTRs (non-translated regions) from HCV type 1b. Continued culture of the replicon cells in the presence of G418 (neoR) is dependent on the replication of the HCV RNA. The stably transfected replicon cells that replicate HCV RNA autonomously and to high levels, encoding inter alia luciferase, were used for profiling of the conditioned cell culture media. Briefly, PBMCs were prepared from buffy coats of at least two donors using a standard Ficoll centrifugation protocol. Isolated PBMCs were resuspended in RPMI medium supplemented with 10% human AB serum and 2×105 cells/well were dispensed into 384-well plates containing compounds (70 μL total volume). After overnight incubation, μL of supernatant was transferred to 384-well plates containing 2.2×103 replicon cells/well in 30 μL (plated the day before). Following 24 hours of incubation, replication was measured by assaying luciferase activity using 40 μL/well Steady Lite Plus substrate (Perkin Elmer) and measured with ViewLux ultraHTS microplate imager (Perkin Elmer). The inhibitory activity of each compound on the Huh7-luc/neo cells were reported as EC50 values, defined as the compound concentration applied to the PBMCs resulting in a 50% reduction of luciferase activity which in turn indicates the degree of replication of the replicon RNA on transfer of a defined amount of PBMC culture medium. Recombinant interferon α-2a (Roferon-A) was used as a standard control compound.