Disinfection of influenza a viruses by Hypocrellin a-mediated photodynamic inactivation

Background: Influenza A viruses can be transmitted indirectly by surviving on the surface of an object. Photo-dynamic inactivation (PDI) is a promising approach for disinfection of pathogens.Methods: PDI was generated using Hypocrellin A (HA) and red light emitting diode (625-635 nm, 280 W/m(2)). Effects of the HA-mediated PDI on influenza viruses H1N1 and H3N2 were evaluated by the reduction of viral titers compared to virus control. After selection of the HA concentrations and illumination times, the applica-bility of PDI was assessed on surgical masks. Reactive oxygen species (ROS) were determined using a 2 '-7 '- dichlorodihydrofluorescein diacetate fluorescence probe.Results: In solution, 10 mu M HA inactivated up to 5.11 +/- 0.19 log(10) TCID50 of H1N1 and 4.89 +/- 0.38 log(10) TCID(50 )of H3N2 by illumination for 5 and 30 min, respectively. When surgical masks were contaminated by virus before HA addition, PDI inactivated 99.99% (4.33 +/- 0.34 log reduction) of H1N1 and 99.40% (2.22 +/- 0.39 log reduction) of H3N2 under the selected condition. When the masks were pretreated with HA before virus addition, PDI decontaminated 99.92% (3.11 +/- 0.19 log reduction) of H1N1 and 98.71% (1.89 +/- 0.20 log reduction) of H3N2 virus. The fluorescence intensity of 2 ',7 '-dichlorofluorescein in photoactivated HA was significantly higher than the cell control (P > 0.05), indicating that HA efficiently generated ROS.Conclusions: HA-mediated PDI is effective for the disinfection of influenza viruses H1N1 and H3N2. The approach could be an alternative to decontaminating influenza A viruses on the surfaces of objects.