New strategy for high throughput screening of anti-influenza virus M2 ion channel inhibitors.

Since the recent emergence of swine and avian flu, there has been a sense of urgency to discover new anti-influenza drugs. In this study, a stable cell line with M2 ion channel/enhanced Green fluorescent protein (EGFP) co-expression was established in order to develop an EGFP-based high-throughput assay for screening M2 ion channel inhibitors. This assay directly monitors the proton conductivity of the M2 ion channel by measuring the fluorescence intensity of EGFP, which is dependent on and sensitive to pH. The ability of amantadine to inhibit the M2 ion channel was detected by this novel EGFP-based assay and then confirmed by a patch clamp recording assay. With this assay, (1S,2S,3S,5R)-(+)-3-Isopinocampheylamine and (1R,2R,3R,5S)-(-)-3-Isopinocampheylamine were identified to inhibit M2 ion channel with an antiviral profile similar to that of amantadine. This new technique will facilitate the discovery of pharmaceutical candidates and will aid in the development of new, potent, and safe anti-influenza agents.