Solar simulated ultraviolet radiation inactivates HCoV-NL63 and SARS-CoV-2 coronaviruses at environmentally relevant doses

• Main Authors: Jandova, J. (Author), Schenten, D. (Author), Williams, S.J (Author), Wondrak, G.T (Author)
• Format: Article
• Language: English
• Published: Elsevier B.V. 2021
• Subjects: animal; animal cell; Animals; Article; cell line; Cell Line; Chlorocebus aethiops; controlled study; Coronavirus; Coronavirus infection; Coronavirus Infections; Coronavirus NL63, Human; Epithelial Cells; epithelium cell; gene expression; gene expression profiling; genetic analysis; Genome, Viral; HCoV-NL63; human; human cell; Human coronavirus NL63; Humans; nonhuman; oxidation reduction reaction; physiological stress; physiology; plaque assay; radiation dose; radiation response; respiratory tract infection; Respiratory Tract Infections; reverse transcription polymerase chain reaction; SARS-CoV-2; sensitivity analysis; Severe acute respiratory syndrome coronavirus 2; simulation; solar radiation; Solar simulated ultraviolet radiation; sunlight; Sunlight; transcriptome; Transcriptome; ultraviolet radiation; Ultraviolet Rays; Viral inactivation; viral plaque assay; Viral Plaque Assay; virology; virus genome; virus inactivation; Virus Inactivation; virus replication; Virus Replication
• Online Access: View Fulltext in Publisher

 The germicidal properties of short wavelength ultraviolet C (UVC) light are well established and used to inactivate many viruses and other microbes. However, much less is known about germicidal effects of terrestrial solar UV light, confined exclusively to wavelengths in the UVA and UVB regions. Here, we have explored the sensitivity of the human coronaviruses HCoV-NL63 and SARS-CoV-2 to solar-simulated full spectrum ultraviolet light (sUV) delivered at environmentally relevant doses. First, HCoV-NL63 coronavirus inactivation by sUV-exposure was confirmed employing (i) viral plaque assays, (ii) RT-qPCR detection of viral genome replication, and (iii) infection-induced stress response gene expression array analysis. Next, a detailed dose-response relationship of SARS-CoV-2 coronavirus inactivation by sUV was elucidated, suggesting a half maximal suppression of viral infectivity at low sUV doses. Likewise, extended sUV exposure of SARS-CoV-2 blocked cellular infection as revealed by plaque assay and stress response gene expression array analysis. Moreover, comparative (HCoV-NL63 versus SARS-CoV-2) single gene expression analysis by RT-qPCR confirmed that sUV exposure blocks coronavirus-induced redox, inflammatory, and proteotoxic stress responses. Based on our findings, we estimate that solar ground level full spectrum UV light impairs coronavirus infectivity at environmentally relevant doses. Given the urgency and global scale of the unfolding SARS-CoV-2 pandemic, these prototype data suggest feasibility of solar UV-induced viral inactivation, an observation deserving further molecular exploration in more relevant exposure models. © 2021 Elsevier B.V.