Irradiation by a Combination of Different Peak-Wavelength Ultraviolet-Light Emitting Diodes Enhances the Inactivation of Influenza A Viruses

Influenza A viruses (IAVs) pose a serious global threat to humans and their livestock. This study aimed to determine the ideal irradiation by ultraviolet-light emitting diodes (UV-LEDs) for IAV disinfection. We irradiated the IAV H1N1 subtype with 4.8 mJ/cm(2) UV using eight UV-LEDs [peak wavelengths (WL) = 365, 310, 300, 290, 280, 270, and 260 nm)] or a mercury low pressure (LP)-UV lamp (Peak WL = 254 nm). Inactivation was evaluated by the infection ratio of Madin–Darby canine kidney (MDCK) cells or chicken embryonated eggs. Irradiation by the 260 nm UV-LED showed the highest inactivation among all treatments. Because the irradiation-induced inactivation effects strongly correlated with damage to viral RNA, we calculated the correlation coefficient (R(AE)) between the irradiant spectrum and absorption of viral RNA. The R(AE) scores strongly correlated with the inactivation by the UV-LEDs and LP-UV lamp. To increase the R(AE) score, we combined three different peak WL UV-LEDs (hybrid UV-LED). The hybrid UV-LED (R(AE) = 86.3) significantly inactivated both H1N1 and H6N2 subtypes to a greater extent than 260 nm (R(AE) = 68.6) or 270 nm (R(AE) = 42.2) UV-LEDs. The R(AE) score is an important factor for increasing the virucidal effects of UV-LED irradiation.