A high-throughput screening strategy to overcome virus instability

Respiratory syncytial virus (RSV) is a widely distributed pathogen that causes severe disease in children, the elderly, and immunocompromised individuals. Both vaccine development and drug discovery have been hampered by the inherent instability of the virus itself. Drug discovery efforts have had limited success due, at least in part, to the lack of an antiviral assay robust enough for high-throughput screening. Instability of the purified virus has long been recognized as a problem in RSV research and has been a major hurdle to producing a virus-based screening assay. Using frozen RSV-infected cells as the source of infectious material, we have overcome the problem of virus instability and validated a cell-based high-throughput screening assay to screen for inhibitors of RSV-induced cytopathic effect. The assay was validated with 1,280 compounds identified as potentially active against RSV (Long strain) in a virus-based screen. To date over 300,000 compounds have been screened over several months with minimal variability in cell or virus controls. Long-term assay stability studies are still in progress.