Virucidal Efficacy of Blue LED and Far-UVC Light Disinfection against Feline Infectious Peritonitis Virus as a Model for SARS-CoV-2

Abstract

Transmission of the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) occurs through respiratory droplets passed directly from person to person or indirectly through fomites, such as common use surfaces or objects. The aim of this study was to determine the virucidal efficacy of blue LED (405 nm) and far-UVC (222 nm) light in comparison to standard UVC (254 nm) irradiation for the inactivation of feline infectious peritonitis virus (FIPV) on different matrices as a model for SARS-CoV-2. Wet or dried FIPV on stainless steel, plastic, or paper discs, in the presence or absence of artificial saliva, were exposed to various wavelengths of light for different time periods (1-90 min). Dual activity of blue LED and far-UVC lights were virucidal for most wet and dried FIPV within 4 to 16 min on all matrices. Individual action of blue LED and far-UVC lights were virucidal for wet FIPV but required longer irradiation times (8-90 min) to reach a 4-log reduction. In comparison, LED (265 nm) and germicidal UVC (254 nm) were virucidal on almost all matrices for both wet and dried FIPV within 1 min exposure. UVC was more effective for the disinfection of surfaces as compared to blue LED and far-UVC individually or together. However, dual action of blue LED and far-UVC was virucidal. This combination of lights could be used as a safer alternative to traditional UVC.

Keywords: 405 nm blue light; coronavirus; far-UVC; feline infectious peritonitis virus; light disinfection; pandemic; ultraviolet light; viral inactivation.

Figure 1

Inactivation of feline infectious peritonitis virus (FIPV) in growth media by blue LED 405 nm, far-UV 222 nm and dual 405 nm + 222 nm lights. All exposures were done at 25 cm distance. Error bars represent standard deviation.

Figure 2

Log reduction of feline infectious peritonitis virus (FIPV) spotted on contaminated surfaces and exposed to blue LED (405 nm), far-UVC (222 nm) and dual (405 nm + 222 nm) lights. FIPV was either dried onto plastic (A), paper (B), or metal (C) discs in the presence or absence of saliva or left wet prior to being exposed to light for 30 min (plastic and paper) or 8 min (metal). All exposures were done at 25 cm distance. Data is displayed as mean log reduction in titre ± SD. Statistically significant differences are indicated by different letters (a to f), (p < 0.05). * No CPE observed after large volume culture. TCID₅₀ = tissue culture infectious dose, 50%.