Irradiation by ultraviolet light-emitting diodes inactivates influenza a viruses by inhibiting replication and transcription of viral RNA in host cells.

Influenza A viruses (IAVs) pose a serious global threat to humans and their livestock, especially poultry and pigs. This study aimed to investigate how to inactivate IAVs by using different ultraviolet-light-emitting diodes (UV-LEDs). We developed sterilization equipment with light-emitting diodes (LEDs) those peak wavelengths were 365 nm (UVA-LED), 310 nm (UVB-LED), and 280 nm (UVC-LED). These UV-LED irradiations decreased dose fluence-dependent plaque-forming units of IAV H1N1 subtype (A/Puerto Rico/8/1934) infected Madin-Darby canine kidney (MDCK) cells, but the inactivation efficiency of UVA-LED was significantly lower than UVB- and UVC-LED. UV-LED irradiations did not alter hemagglutination titer, but decreased accumulation of intracellular total viral RNA in infected MDCK cells was observed. Additionally, UV-LED irradiations suppressed the accumulation of intracellular mRNA (messenger RNA), vRNA (viral RNA), and cRNA (complementary RNA), as measured by strand-specific RT-PCR. These results suggest that UV-LEDs inhibit host cell replication and transcription of viral RNA. Both UVB- and UVC-LED irradiation decreased focus-forming unit (FFU) of H5N1 subtype (A/Crow/Kyoto/53/2004), a highly pathogenic avian IAV (HPAI), in infected MDCK cells, and the amount of FFU were lower than the H1N1 subtype. From these results, it appears that IAVs may have different sensitivity among the subtypes, and UVB- and UVC-LED may be suitable for HPAI virus inactivation.