Photoinactivation of the Coronavirus Surrogate phi6 by Visible Light

Abstract

To stop the coronavirus spread, new inactivation approaches are being sought that can also be applied in the presence of humans or even on humans. Here, we investigate the effect of visible violet light with a wavelength of 405 nm on the coronavirus surrogate phi6 in two aqueous solutions that are free of photosensitizers. A dose of 1300 J cm−2 of 405 nm irradiation reduces the phi6 plaque‐forming unit concentration by three log‐levels. The next step should be similar visible light photoinactivation investigations on coronaviruses, which cannot be performed in our lab.

Blue light inactivation of the enveloped RNA virus Phi6

“…The emission spectrum of the employed 455 nm LEDs is given in Fig. 2 , together with the emission spectrum of the 405 nm LED employed by Vatter et al in a former study [ 27 ] and the absorption of known bacterial photosensitizers. This illustrates that at least for bacteria 405 nm and blue 455 nm irradiation involve different photosensitizers.…”

“…1 Scheme of the illumination setup

Fig. 2 455 nm LED emission spectrum, with additional spectrum of the 405 nm LED of [ 27 ] and typical bacterial (!) photosensitizer absorption spectra [ 34 ] for comparison

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“…However, existing phi6 can infect and lyse bacteria. This creates holes/plaques in the agar turbidity from which the concentration of replicable phi6 in the samples and thus the disinfection effect of the 455 nm radiation can be calculated [ 27 , 35 ].…”

“…Initial studies reveal that violet light with a wavelength of 405 nm has an inactivating effect on viruses [ 24 – 26 ]. This is even true for the bacteriophage phi6, which, like the SARS-CoV-2 virus, is an enveloped RNA virus [ 27 ]. Therefore, it is hoped that SARS-CoV-2 is also sensitive to violet light.…”

“…Unfortunately, we are not allowed to work with coronaviruses in our laboratory. Therefore, in the study presented here, experiments on the inactivation of phi6—as a non-pathogenic coronavirus surrogate—are performed with 455 nm blue light and compared to the results of a previous 405 nm investigation [ 27 ].…”