Ultraviolet A light effectively reduces bacteria and viruses including coronavirus

Abstract

Antimicrobial-resistant and novel pathogens continue to emerge, outpacing efforts to contain and treat them. Therefore, there is a crucial need for safe and effective therapies. Ultraviolet-A (UVA) phototherapy is FDA-approved for several dermatological diseases but not for internal applications. We investigated UVA effects on human cells in vitro, mouse colonic tissue in vivo, and UVA efficacy against bacteria, yeast, coxsackievirus group B and coronavirus-229E. Several pathogens and virally transfected human cells were exposed to a series of specific UVA exposure regimens. HeLa, alveolar and primary human tracheal epithelial cell viability was assessed after UVA exposure, and 8-Oxo-2'-deoxyguanosine was measured as an oxidative DNA damage marker. Furthermore, wild-type mice were exposed to intracolonic UVA as an in vivo model to assess safety of internal UVA exposure. Controlled UVA exposure yielded significant reductions in Pseudomonas aeruginosa, Klebsiella pneumoniae, Escherichia coli, Enterococcus faecalis, Clostridioides difficile, Streptococcus pyogenes, Staphylococcus epidermidis, Proteus mirabilis and Candida albicans. UVA-treated coxsackievirus-transfected HeLa cells exhibited significantly increased cell survival compared to controls. UVA-treated coronavirus-229E-transfected tracheal cells exhibited significant coronavirus spike protein reduction, increased mitochondrial antiviral-signaling protein and decreased coronavirus-229E-induced cell death. Specific controlled UVA exposure had no significant effect on growth or 8-Oxo-2'-deoxyguanosine levels in three types of human cells. Single or repeated in vivo intraluminal UVA exposure produced no discernible endoscopic, histologic or dysplastic changes in mice. These findings suggest that, under specific conditions, UVA reduces various pathogens including coronavirus-229E, and may provide a safe and effective treatment for infectious diseases of internal viscera. Clinical studies are warranted to further elucidate the safety and efficacy of UVA in humans.

Environmental effects of stratospheric ozone depletion, UV radiation, and interactions with climate change: UNEP Environmental Effects Assessment Panel, Update 2020

“…This assumption is consistent with the work by Darnell et al . [ 527 ] who demonstrated that UV-A radiation does not damage SARS-CoV-1 (a virus similar to SARS-CoV-2), but contradicts more recent work [ 511 ], suggesting that UV-A does contribute to the inactivation of SARS-CoV-2. It has also been shown that the viruses can be damaged by peroxides and other reactive oxygen species, which are created by UV-A radiation [ 528 ].…”

“…As we show below, these long lifetimes of SARS-CoV-2 particles decrease greatly upon exposure to UV-C and UV-B radiation. Also some deactivation by UV-A radiation currently cannot be ruled out [ 511 ]. Research on lifetimes focuses on indoor surfaces and mainly in health-care facilities [ 512 – 514 ] where no solar UV-B radiation is present and rigorous biocidal disinfection routines are followed.…”

Endotracheal application of ultraviolet A light in critically ill severe acute respiratory syndrome coronavirus-2 patients: A first-in-human study

“…specific intensity, peak wavelength, exposure time and distance to target tissue), reduces bacteria, fungi, and viruses including coronavirus-229E but does not harm human ( in vitro) or murine ( in vivo) columnar epithelial cells. [6] Moreover, UVA exposure of coronavirus-229E transfected human primary tracheal cells led to activation of the MAVS protein, reduction in spike protein, and resumption of cell proliferation similar to uninfected cells, suggesting that UVA may induce a beneficial antiviral state in infected human cells. [6]…”

Beware of UVC sanitizers: not all are good

“…Reference [10] indicates that with a dose close to 3800 mJ/cm 2 of UVA is possible to achieve a reduction of 90% of Sars-CoV-2. Reference [11] analyzes other microorganisms, showing for example that a dose of 3600 mJ/cm 2 in the UVA range is needed for inactivating Escherichia Coli. Besides the work of R. Tomb et.al.…”

“…Concerning other microorganisms Rezaie et.al. [11] analyses the response to UVA. As an example, they show that for inactivating Escherichia Coli a dose of 3600 mJ/cm 2 is needed.…”