ABSTRACT

Coronaviruses such as SARS-CoV1, MERS-CoV, and SARS-CoV2 (the virus responsible for COVID-19), have caused several global pandemics of respiratory diseases over the last two decades. A primary exposure pathway for coronavirus infections is through skin contact with contaminated surfaces followed by touching of facial areas. Effective and safe methods for surface disinfection against coronaviruses is urgently needed. This is particularly true in healthcare settings where reusable personal protective equipment (PPE), medical instruments, and surfaces in operating rooms need repeated disinfection. Beyond clinical settings, high-touch areas such as public transportation and commercial shops have an urgent need to stay virus-free as intervention efforts to control the pandemic are eased. Current surface disinfection methods using chemicals like bleach and alcohol can result in material corrosion and chemical residuals. A potential solution for surface disinfection is the use of ultraviolet light (UV) devices. UV light has been proven to be effective against other viruses but must be optimized to treat SARS-CoV2 and other coronaviruses because of their unique molecular structure. The study aims to understand how UV light from different sources (including newly available UVLEDs) damage the nucleic acid and proteins in SARS-CoV2 coatings. The findings will provide guidance for UV device design and operation for disinfecting contaminated surfaces, which will help in the fight against the COVID-19 global pandemic and future coronavirus-caused respiratory outbreaks.

Ultraviolet light (UV) devices emitting UVC irradiation (200-280 nm) have proven to be effective for virus disinfection by damaging nucleic acids and proteins. UV exposure to non-enveloped viruses revealed that DNA/RNA damage is the primary cause for virus inactivation, with a peak efficacy around 265nm, whereas protein damage is important at wavelengths at the high (~280 nm) and low (<240 nm) ends of the UV spectrum. Coronavirus, which is an enveloped, non-segmented positive-sense RNA virus, may respond to UVC irradiation differently due to its unique molecular structure. The goal of this project is to investigate inactivation kinetics and RNA and structural protein damage of coronavirus under UVC irradiation across wavelengths from 220 to 280 nm. Murine coronavirus and murine hepatitis virus (MHV) will be used as a representative coronavirus and a surrogate of human coronavirus in this project. The UVC inactivation efficiencies and kinetics of coronavirus will be determined by exposing MHV contaminated surface samples and water samples under UVC irradiation in a bench-scale collimated beam apparatus with three different UV sources: a UVLED system (emitting at 255, 265, and/or 285 nm), a KrCl excimer lamp (222 nm), and a low pressure UV lamp (254 nm). The RNA damage of MHV under UVC irradiation across wavelengths will be investigated using long range reverse transcript quantitative polymerase chain reaction and the protein damage will be assessed using peptide liquid chromatography tandem mass spectrometry. The fundamental scientific relationship between virus molecular structure and UV inactivation efficiency and mechanisms will be evaluated by comparing the UV action of coronavirus to those of nonenveloped viruses used in previous studies. These findings will lead to generation of definitive UV-disinfection kinetics of coronavirus on surfaces to inform proper operation and use of UV devices and support the engineering of new disinfection devices that will serve as urgent and effective interventions during relevant public health emergencies.

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