Novel Antiviral Characteristics of Nanosized Copper(I) Iodide Particles Showing Inactivation Activity against 2009 Pandemic H1N1 Influenza Virus

We investigated the antiviral activity of nanosized copper(I) iodide (Cut) particles having an average size of 160 nm. Cut particles showed aqueous stability and generated hydroxyl radicals, which were probably derived from monovalent copper (Cu+). We confirmed that Cut particles showed antiviral activity against an influenza A virus of swine origin (pandemic [H1N1] 2009) by plaque titration assay. The virus titer decreased in a dose-dependent manner upon incubation with Cut particles, with the 50% effective concentration being approximately 17 mu g/ml after exposure for 60 min. SDS-PAGE analysis confirmed the inactivation of the virus due to the degradation of viral proteins such as hemagglutinin and neuraminidase by CuI. Electron spin resonance (ESR) spectroscopy revealed that Cut generates hydroxyl radicals in aqueous solution, and radical production was found to be blocked by the radical scavenger N-acetylcysteine. Taken together, these findings indicate that Cut particles exert antiviral activity by generating hydroxyl radicals. Thus, CuI may be a useful material for protecting against viral attacks and may be suitable for applications such as filters, face masks, protective clothing, and kitchen cloths.