Ultraviolet A light effectively reduces bacteria and viruses including coronavirus

Area of Science:

• Microbiology
• Photomedicine
• Infectious Diseases

Background:

• Emerging antimicrobial-resistant and novel pathogens necessitate new therapeutic strategies.
• Ultraviolet-A (UVA) phototherapy is FDA-approved for dermatological conditions but not internal applications.
• The potential of UVA for treating internal infections remains unexplored.

Purpose of the Study:

• To investigate the effects of Ultraviolet-A (UVA) on human cells and mouse colonic tissue.
• To assess the efficacy of UVA against a range of bacteria, yeast, and viruses in vitro.
• To evaluate the safety of internal UVA exposure in a preclinical in vivo model.

Main Methods:

• Human cell lines (HeLa, alveolar, tracheal epithelial) and mouse colonic tissue were exposed to specific UVA regimens.
• Pathogen reduction was assessed for Pseudomonas aeruginosa, Klebsiella pneumoniae, Escherichia coli, Enterococcus faecalis, Clostridioides difficile, Streptococcus pyogenes, Staphylococcus epidermidis, Proteus mirabilis, and Candida albicans.
• Cell viability, oxidative DNA damage (8-Oxo-2'-deoxyguanosine), and viral protein expression were measured.
• In vivo safety was evaluated in wild-type mice using intracolonic UVA exposure, assessing endoscopic and histologic changes.

Main Results:

• Controlled UVA exposure significantly reduced all tested bacterial and yeast pathogens.
• UVA treatment of coxsackievirus-transfected HeLa cells increased cell survival.
• UVA treatment of coronavirus-229E-transfected tracheal cells reduced viral spike protein, increased antiviral signaling, and decreased cell death.
• No significant effects on human cell growth or DNA damage were observed.
• In vivo UVA exposure in mice showed no discernible adverse endoscopic, histologic, or dysplastic changes.

Conclusions:

• Specific UVA exposure conditions effectively reduce a variety of pathogens, including coronavirus-229E.
• Internal UVA application appears safe in preclinical models.
• UVA phototherapy presents a potential safe and effective treatment for internal infectious diseases.
• Further clinical studies are warranted to confirm safety and efficacy in humans.