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1.
Sci Rep ; 12(1): 5869, 2022 Apr 07.
Article in English | MEDLINE | ID: covidwho-1778639

ABSTRACT

The ongoing COVID-19 global pandemic has necessitated evaluating various disinfection technologies for reducing viral transmission in public settings. Ultraviolet (UV) radiation can inactivate pathogens and viruses but more insight is needed into the performance of different UV wavelengths and their applications. We observed greater than a 3-log reduction of SARS-CoV-2 infectivity with a dose of 12.5 mJ/cm2 of 254 nm UV light when the viruses were suspended in PBS, while a dose of 25 mJ/cm2 was necessary to achieve a similar reduction when they were in an EMEM culture medium containing 2%(v/v) FBS, highlighting the critical effect of media in which the virus is suspended, given that SARS-CoV-2 is always aerosolized when airborne or deposited on a surface. It was found that SARS-CoV-2 susceptibility (a measure of the effectiveness of the UV light) in a buffer such as PBS was 4.4-fold greater than that in a cell culture medium. Furthermore, we discovered the attenuation of UVC disinfection by amino acids, vitamins, and niacinamide, highlighting the importance of determining UVC dosages under a condition close to aerosols that wrap the viruses. We developed a disinfection model to determine the effect of the environment on UVC effectiveness with three different wavelengths, 222 nm, 254 nm, and 265 nm. An inverse correlation between the liquid absorbance and the viral susceptibility was observed. We found that 222 nm light was most effective at reducing viral infectivity in low absorbing liquids such as PBS, whereas 265 nm light was most effective in high absorbing liquids such as cell culture medium. Viral susceptibility was further decreased in N95 masks with 222 nm light being the most effective. The safety of 222 nm was also studied. We detected changes to the mechanical properties of the stratum corneum of human skins when the 222 nm accumulative exposure exceeded 50 J/cm2.The findings highlight the need to evaluate each UV for a given application, as well as limiting the dose to the lowest dose necessary to avoid unnecessary exposure to the public.


Subject(s)
COVID-19 , Viruses , COVID-19/prevention & control , Disinfection , Humans , SARS-CoV-2 , Ultraviolet Rays , Virus Inactivation/radiation effects
2.
J Microbiol Immunol Infect ; 55(1): 166-169, 2022 Feb.
Article in English | MEDLINE | ID: covidwho-1700704

ABSTRACT

This was a preliminary study on ultraviolet C (UVC) irradiation for SARS-CoV-2-contaminated hospital environments. Forty-eight locations were tested for SARS-CoV-2 using RT-PCR (33.3% contamination rate). After series dosages of 222-nm UVC irradiation, samples from the surfaces were negative at 15 s irradiation at 2 cm length (fluence: 81 mJ/cm2).


Subject(s)
COVID-19 , SARS-CoV-2 , Disinfection , Humans , Ultraviolet Rays , Virus Inactivation/radiation effects
3.
Virol J ; 19(1): 29, 2022 02 10.
Article in English | MEDLINE | ID: covidwho-1690906

ABSTRACT

Ultraviolet (UV) light has previously been established as useful method of disinfection, with demonstrated efficacy to inactivate a broad range of microorganisms. The advent of ultraviolet light-emitting diodes provides advantages in ease of disinfection, in that there can be delivery of germicidal UV with the same light unit that delivers standard white light to illuminate a room. Herein we demonstrate the efficacy and feasibility of ultraviolet light-emitting diodes as a means of decontamination by inactivating two distinct virus models, human coronavirus 229E and human immunodeficiency virus. Importantly, the same dose of ultraviolet light that inactivated human viruses also elicited complete inactivation of ultraviolet-resistant bacterial spores (Bacillus pumilus), a gold standard for demonstrating ultraviolet-mediated disinfection. This work demonstrates that seconds of ultraviolet light-emitting diodes (UV-LED) exposure can inactivate viruses and bacteria, highlighting that UV-LED could be a useful and practical tool for broad sanitization of public spaces.


Subject(s)
Coronavirus 229E, Human , Disinfection , HIV-1 , Ultraviolet Rays , Virus Inactivation/radiation effects , Coronavirus 229E, Human/radiation effects , Disinfection/methods , HIV-1/radiation effects , Humans
4.
J Hazard Mater ; 405: 124043, 2021 03 05.
Article in English | MEDLINE | ID: covidwho-1635125

ABSTRACT

In this review, we present the environmental perspectives of the viruses and antiviral drugs related to SARS-CoV-2. The present review paper discusses occurrence, fate, transport, susceptibility, and inactivation mechanisms of viruses in the environment as well as environmental occurrence and fate of antiviral drugs, and prospects (prevalence and occurrence) of antiviral drug resistance (both antiviral drug resistant viruses and antiviral resistance in the human). During winter, the number of viral disease cases and environmental occurrence of antiviral drug surge due to various biotic and abiotic factors such as transmission pathways, human behaviour, susceptibility, and immunity as well as cold climatic conditions. Adsorption and persistence critically determine the fate and transport of viruses in the environment. Inactivation and disinfection of virus include UV, alcohol, and other chemical-base methods but the susceptibility of virus against these methods varies. Wastewater treatment plants (WWTPs) are major reserviors of antiviral drugs and their metabolites and transformation products. Ecotoxicity of antiviral drug residues against aquatic organisms have been reported, however more threatening is the development of antiviral resistance, both in humans and in wild animal reservoirs. In particular, emergence of antiviral drug-resistant viruses via exposure of wild animals to high loads of antiviral residues during the current pandemic needs further evaluation.


Subject(s)
Antiviral Agents , Drug Resistance, Viral/drug effects , Environmental Microbiology , Environmental Pollutants , SARS-CoV-2 , Virus Inactivation , Adsorption , Animals , Antiviral Agents/chemistry , Antiviral Agents/therapeutic use , Antiviral Agents/toxicity , Aquatic Organisms/drug effects , COVID-19/drug therapy , COVID-19/epidemiology , COVID-19/etiology , Ecotoxicology , Environmental Pollutants/chemistry , Environmental Pollutants/therapeutic use , Environmental Pollutants/toxicity , Humans , SARS-CoV-2/drug effects , SARS-CoV-2/pathogenicity , Seasons , Virus Inactivation/drug effects , Virus Inactivation/radiation effects , Water Purification
5.
ACS Appl Mater Interfaces ; 14(4): 4892-4898, 2022 Feb 02.
Article in English | MEDLINE | ID: covidwho-1633913

ABSTRACT

This paper presents results of a study of a new cationic oligomer that contains end groups and a chromophore affording inactivation of SARS-CoV-2 by visible light irradiation in solution or as a solid coating on paper wipes and glass fiber filtration substrates. A key finding of this study is that the cationic oligomer with a central thiophene ring and imidazolium charged groups gives outstanding performance in both the killing of E. coli bacterial cells and inactivation of the virus at very short times. Our introduction of cationic N-methyl imidazolium groups enhances the light activation process for both E. coli and SARS-CoV-2 but dampens the killing of the bacteria and eliminates the inactivation of the virus in the dark. For the studies with this oligomer in solution at a concentration of 1 µg/mL and E. coli, we obtain 3 log killing of the bacteria with 10 min of irradiation with LuzChem cool white lights (mimicking indoor illumination). With the oligomer in solution at a concentration of 10 µg/mL, we observe 4 log inactivation (99.99%) in 5 min of irradiation and total inactivation after 10 min. The oligomer is quite active against E. coli on oligomer-coated paper wipes and glass fiber filter supports. The SARS-CoV-2 is also inactivated by oligomer-coated glass fiber filter papers. This study indicates that these oligomer-coated materials may be very useful as wipes and filtration materials.


Subject(s)
Antiviral Agents/pharmacology , COVID-19/therapy , SARS-CoV-2/radiation effects , COVID-19/genetics , COVID-19/virology , Cations/pharmacology , Escherichia coli/drug effects , Escherichia coli/radiation effects , Humans , Light , Phototherapy , SARS-CoV-2/pathogenicity , Ultraviolet Rays , Virus Inactivation/drug effects , Virus Inactivation/radiation effects
6.
J Infect Dis ; 225(4): 587-592, 2022 02 15.
Article in English | MEDLINE | ID: covidwho-1569705

ABSTRACT

The spread of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) since 2019 has made mask-wearing, physical distancing, hygiene, and disinfection complementary measures to control virus transmission. Especially for health facilities, we evaluated the efficacy of an UV-C autonomous robot to inactivate SARS-CoV-2 desiccated on potentially contaminated surfaces. ASSUM (autonomous sanitary sterilization ultraviolet machine) robot was used in an experimental box simulating a hospital intensive care unit room. Desiccated SARS-CoV-2 samples were exposed to UV-C in 2 independent runs of 5, 12, and 20 minutes. Residual virus was eluted from surfaces and viral titration was carried out in Vero E6 cells. ASSUM inactivated SARS-CoV-2 by ≥ 99.91% to ≥ 99.99% titer reduction with 12 minutes or longer of UV-C exposure and onwards and a minimum distance of 100cm between the device and the SARS-CoV-2 desiccated samples. This study demonstrates that ASSUM UV-C device is able to inactivate SARS-CoV-2 within a few minutes.


Subject(s)
COVID-19 , Robotics , SARS-CoV-2/radiation effects , Sterilization/methods , Ultraviolet Rays , Virus Inactivation/radiation effects , COVID-19/prevention & control , Hospitals , Humans
7.
Sci Rep ; 11(1): 22612, 2021 11 19.
Article in English | MEDLINE | ID: covidwho-1526106

ABSTRACT

This paper proposes an investigating SARS-CoV-2 inactivation on surfaces with UV-C LED irradiation using our in-house-developed ray-tracing simulator. The results are benchmarked with experiments and Zemax OpticStudio commercial software simulation to demonstrate our simulator's easy accessibility and high reliability. The tool can input the radiant profile of the flexible LED source and accurately yield the irradiance distribution emitted from an LED-based system in 3D environments. The UV-C operating space can be divided into the safe, buffer, and germicidal zones for setting up a UV-C LED system. Based on the published measurement data, the level of SARS-CoV-2 inactivation has been defined as a function of UV-C irradiation. A realistic case of public space, i.e., a food court in Singapore, has been numerically investigated to demonstrate the relative impact of environmental UV-C attenuation on the SARS-CoV-2 inactivation. We optimise a specific UV-C LED germicidal system and its corresponding exposure time according to the simulation results. These ray-tracing-based simulations provide a useful guideline for safe deployment and efficient design for germicidal UV-C LED technology.


Subject(s)
SARS-CoV-2/radiation effects , Ultraviolet Rays , Virus Inactivation/radiation effects , Computer Simulation , Disinfection/instrumentation , Imaging, Three-Dimensional , Singapore , Sterilization/instrumentation
8.
Appl Environ Microbiol ; 87(22): e0153221, 2021 10 28.
Article in English | MEDLINE | ID: covidwho-1494943

ABSTRACT

Effective disinfection technology to combat severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) can help reduce viral transmission during the ongoing COVID-19 global pandemic and in the future. UV devices emitting UVC irradiation (200 to 280 nm) have proven to be effective for virus disinfection, but limited information is available for SARS-CoV-2 due to the safety requirements of testing, which is limited to biosafety level 3 (BSL3) laboratories. In this study, inactivation of SARS-CoV-2 in thin-film buffered aqueous solution (pH 7.4) was determined across UVC irradiation wavelengths of 222 to 282 nm from krypton chloride (KrCl*) excimers, a low-pressure mercury-vapor lamp, and two UVC light-emitting diodes. Our results show that all tested UVC devices can effectively inactivate SARS-CoV-2, among which the KrCl* excimer had the best disinfection performance (i.e., highest inactivation rate). The inactivation rate constants of SARS-CoV-2 across wavelengths are similar to those for murine hepatitis virus (MHV) from our previous investigation, suggesting that MHV can serve as a reliable surrogate of SARS-CoV-2 with a lower BSL requirement (BSL2) during UV disinfection tests. This study provides fundamental information on UVC's action on SARS-CoV-2 and guidance for achieving reliable disinfection performance with UVC devices. IMPORTANCE UV light is an effective tool to help stem the spread of respiratory viruses and protect public health in commercial, public, transportation, and health care settings. For effective use of UV, there is a need to determine the efficiency of different UV wavelengths in killing pathogens, specifically SARS-CoV-2, to support efforts to control the ongoing COVID-19 global pandemic and future coronavirus-caused respiratory virus pandemics. We found that SARS-CoV-2 can be inactivated effectively using a broad range of UVC wavelengths, and 222 nm provided the best disinfection performance. Interestingly, 222-nm irradiation has been found to be safe for human exposure up to thresholds that are beyond those effective for inactivating viruses. Therefore, applying UV light from KrCl* excimers in public spaces can effectively help reduce viral aerosol or surface-based transmissions.


Subject(s)
Disinfection/methods , SARS-CoV-2/radiation effects , Virus Inactivation/radiation effects , Animals , Bacteriophage phi 6/radiation effects , COVID-19/prevention & control , COVID-19/transmission , Coronavirus 229E, Human/radiation effects , Disinfection/instrumentation , Humans , Mice , Murine hepatitis virus/radiation effects , Ultraviolet Rays
9.
Sci Rep ; 11(1): 19930, 2021 10 07.
Article in English | MEDLINE | ID: covidwho-1462026

ABSTRACT

Transmission of SARS-CoV-2 by aerosols has played a significant role in the rapid spread of COVID-19 across the globe. Indoor environments with inadequate ventilation pose a serious infection risk. Whilst vaccines suppress transmission, they are not 100% effective and the risk from variants and new viruses always remains. Consequently, many efforts have focused on ways to disinfect air. One such method involves use of minimally hazardous 222 nm far-UVC light. Whilst a small number of controlled experimental studies have been conducted, determining the efficacy of this approach is difficult because chamber or room geometry, and the air flow within them, influences both far-UVC illumination and aerosol dwell times. Fortunately, computational multiphysics modelling allows the inadequacy of dose-averaged assessment of viral inactivation to be overcome in these complex situations. This article presents the first validation of the WYVERN radiation-CFD code for far-UVC air-disinfection against survival fraction measurements, and the first measurement-informed modelling approach to estimating far-UVC susceptibility of viruses in air. As well as demonstrating the reliability of the code, at circa 70% higher, our findings indicate that aerosolized human coronaviruses are significantly more susceptible to far-UVC than previously thought.


Subject(s)
Coronavirus 229E, Human/radiation effects , Coronavirus Infections/prevention & control , Coronavirus OC43, Human/radiation effects , Disinfection/methods , Ultraviolet Rays , Virus Inactivation/radiation effects , Aerosols/isolation & purification , Air Microbiology , COVID-19/prevention & control , Computer Simulation , Coronavirus 229E, Human/isolation & purification , Coronavirus 229E, Human/physiology , Coronavirus OC43, Human/isolation & purification , Coronavirus OC43, Human/physiology , Disinfection/instrumentation , Equipment Design , Humans , Models, Biological
10.
Sci Rep ; 11(1): 19470, 2021 09 30.
Article in English | MEDLINE | ID: covidwho-1447318

ABSTRACT

The germicidal potential of specific wavelengths within the electromagnetic spectrum is an area of growing interest. While ultra-violet (UV) based technologies have shown satisfactory virucidal potential, the photo-toxicity in humans coupled with UV associated polymer degradation limit their use in occupied spaces. Alternatively, longer wavelengths with less irradiation energy such as visible light (405 nm) have largely been explored in the context of bactericidal and fungicidal applications. Such studies indicated that 405 nm mediated inactivation is caused by the absorbance of porphyrins within the organism creating reactive oxygen species which result in free radical damage to its DNA and disruption of cellular functions. The virucidal potential of visible-light based technologies has been largely unexplored and speculated to be ineffective given the lack of porphyrins in viruses. The current study demonstrated increased susceptibility of lipid-enveloped respiratory pathogens of importance such as SARS-CoV-2 (causative agent of COVID-19) and influenza A virus to 405 nm, visible light in the absence of exogenous photosensitizers thereby indicating a potential alternative porphyrin-independent mechanism of visible light mediated viral inactivation. These results were obtained using less than expected irradiance levels which are considered safe for humans and commercially achievable. Our results support further exploration of the use of visible light technology for the application of continuous decontamination in occupied areas within hospitals and/or infectious disease laboratories, specifically for the inactivation of respiratory pathogens such as SARS-CoV-2 and Influenza A.


Subject(s)
Disinfection/methods , Influenza A Virus, H1N1 Subtype/radiation effects , SARS-CoV-2/radiation effects , Disinfection/instrumentation , Dose-Response Relationship, Radiation , Encephalomyocarditis virus/radiation effects , Light , Time Factors , Virus Inactivation/radiation effects
11.
Photochem Photobiol ; 98(2): 471-483, 2022 03.
Article in English | MEDLINE | ID: covidwho-1441853

ABSTRACT

It has been demonstrated in laboratory environments that ultraviolet-C (UVC) light is effective at inactivating airborne viruses. However, due to multiple parameters, it cannot be assumed that the air inside a room will be efficiently disinfected by commercial germicidal ultraviolet (GUV) systems. This research utilizes numerical simulations of airflow, viral spread, inactivation by UVC and removal by mechanical ventilation in a typical classroom. The viral load in the classroom is compared for conventional upper-room GUV and the emerging "Far-UVC." In our simulated environment, GUV is shown to be effective in both well and poorly ventilated rooms, with greatest benefit in the latter. At current exposure limits, 18 commercial Far-UVC systems were as effective at reducing viral load as a single upper-room GUV. Improvements in Far-UVC irradiation distribution and recently proposed increases to exposure limits would dramatically increase the efficacy of Far-UVC devices. Modifications to current Far-UVC devices, which would improve their real-world efficacy, could be implemented now without requiring legislative change. The prospect of increased safety limits coupled with our suggested technological modifications could usher in a new era of safe and rapid whole room air disinfection in occupied indoor spaces.


Subject(s)
COVID-19 , COVID-19/prevention & control , Disinfection/methods , Humans , SARS-CoV-2 , Ultraviolet Rays , Virus Inactivation/radiation effects
12.
J Photochem Photobiol B ; 224: 112319, 2021 Nov.
Article in English | MEDLINE | ID: covidwho-1433572

ABSTRACT

The germicidal properties of short wavelength ultraviolet C (UVC) light are well established and used to inactivate many viruses and other microbes. However, much less is known about germicidal effects of terrestrial solar UV light, confined exclusively to wavelengths in the UVA and UVB regions. Here, we have explored the sensitivity of the human coronaviruses HCoV-NL63 and SARS-CoV-2 to solar-simulated full spectrum ultraviolet light (sUV) delivered at environmentally relevant doses. First, HCoV-NL63 coronavirus inactivation by sUV-exposure was confirmed employing (i) viral plaque assays, (ii) RT-qPCR detection of viral genome replication, and (iii) infection-induced stress response gene expression array analysis. Next, a detailed dose-response relationship of SARS-CoV-2 coronavirus inactivation by sUV was elucidated, suggesting a half maximal suppression of viral infectivity at low sUV doses. Likewise, extended sUV exposure of SARS-CoV-2 blocked cellular infection as revealed by plaque assay and stress response gene expression array analysis. Moreover, comparative (HCoV-NL63 versus SARS-CoV-2) single gene expression analysis by RT-qPCR confirmed that sUV exposure blocks coronavirus-induced redox, inflammatory, and proteotoxic stress responses. Based on our findings, we estimate that solar ground level full spectrum UV light impairs coronavirus infectivity at environmentally relevant doses. Given the urgency and global scale of the unfolding SARS-CoV-2 pandemic, these prototype data suggest feasibility of solar UV-induced viral inactivation, an observation deserving further molecular exploration in more relevant exposure models.


Subject(s)
Coronavirus Infections/prevention & control , Coronavirus NL63, Human/radiation effects , Respiratory Tract Infections/prevention & control , SARS-CoV-2/radiation effects , Sunlight , Ultraviolet Rays , Animals , Cell Line , Chlorocebus aethiops , Coronavirus NL63, Human/physiology , Epithelial Cells/virology , Genome, Viral/radiation effects , Humans , SARS-CoV-2/physiology , Transcriptome/radiation effects , Viral Plaque Assay , Virus Inactivation/radiation effects , Virus Replication/radiation effects
13.
Photochem Photobiol ; 97(3): 532-541, 2021 05.
Article in English | MEDLINE | ID: covidwho-1388390

ABSTRACT

During the current SARS-CoV-2 and tuberculosis global pandemics, public health and infection prevention and control professionals wrestle with cost-effective means to control airborne transmission. One technology recommended by Centers for Disease Control and Prevention and the World Health Organization for lowering indoor concentration of these and other microorganisms and viruses is upper-room ultraviolet 254 nm (UVC254 ) systems. Applying both a material balance as well as some nondimensional parameters developed by Rudnick and First, the impact of several critical parameters and their effect on the fraction of microorganisms surviving UVC254 exposure was evaluated. Vertical airspeed showed a large impact at velocities <0.05 m s-1 but a lesser effect at velocities >0.05 m s-1 . In addition, the efficacy of any upper-room UVC system is influenced greatly by the mean room fluence rate as opposed to a simple volume- or area-based dosing criteria. An alternative UVC254 dosing strategy was developed based on the fluence rate as a function of the UVC254 luminaire output (W) and the square root of the product of the room volume and the ceiling height.


Subject(s)
Air Microbiology , Disinfection/instrumentation , Disinfection/methods , Lighting , Ultraviolet Rays , Air Pollution, Indoor/prevention & control , Animals , COVID-19/prevention & control , Environment, Controlled , Infection Control/methods , SARS-CoV-2/radiation effects , Virus Inactivation/radiation effects
14.
Photochem Photobiol ; 97(3): 549-551, 2021 05.
Article in English | MEDLINE | ID: covidwho-1388389

ABSTRACT

Although the environmental control measure of ultraviolet germicidal irradiation (UVGI) for disinfection has not been widely used in the United States and some parts of the world in the past few decades, this technology has been well applied in Russia. UVGI technology has been particularly useful with regard to limiting TB transmission in medical facilities. There is good evidence that UV-C (180-280 nm) air disinfection can be a helpful intervention in reducing transmission of the SARS-CoV-2 virus.


Subject(s)
COVID-19/prevention & control , Disinfection/methods , Hospitals/standards , SARS-CoV-2/radiation effects , Ultraviolet Rays , Virus Inactivation/radiation effects , Air Microbiology , Air Pollution, Indoor/prevention & control , COVID-19/epidemiology , Disinfection/instrumentation , Humans , Infection Control , Russia
15.
Photochem Photobiol ; 97(3): 542-548, 2021 05.
Article in English | MEDLINE | ID: covidwho-1388388

ABSTRACT

Potential for SARS-CoV-2 viral inactivation by solar UV radiation in outdoor spaces in the UK has been assessed. Average erythema effective and UV-A daily radiant exposures per month were higher (statistically significant, P < 0.05) in spring 2020 in comparison with spring 2015-2019 across most of the UK, while irradiance generally appeared to be in the normal expected range of 2015-2019. It was found that these higher radiant exposures may have increased the potential for SARS-CoV-2 viral inactivation outdoors in April and May 2020. Assessment of the 6-year period 2015-2020 in the UK found that for 50-60% of the year, that is most of October to March, solar UV is unlikely to have a significant (at least 90% inactivation) impact on viral inactivation outdoors. Minimum times to reach 90% and 99% inactivation in the UK are of the order of tens of minutes and of the order of hours, respectively. However, these times are best case scenarios and should be treated with caution.


Subject(s)
COVID-19/prevention & control , SARS-CoV-2/radiation effects , Ultraviolet Rays , Virus Inactivation/radiation effects , COVID-19/virology , Disinfection/instrumentation , Disinfection/methods , Humans , Radiation Exposure , Sunlight , United Kingdom
16.
Sci Rep ; 11(1): 14295, 2021 07 12.
Article in English | MEDLINE | ID: covidwho-1387482

ABSTRACT

Methylene blue is an FDA (Food and Drug Administration) and EMA (European Medicines Agency) approved drug with an excellent safety profile. It displays broad-spectrum virucidal activity in the presence of UV light and has been shown to be effective in inactivating various viruses in blood products prior to transfusions. In addition, its use has been validated for methemoglobinemia and malaria treatment. In this study, we first evaluated the virucidal activity of methylene blue against influenza virus H1N1 upon different incubation times and in the presence or absence of light activation, and then against SARS-CoV-2. We further assessed the therapeutic activity of methylene blue by administering it to cells previously infected with SARS-CoV-2. Finally, we examined the effect of co-administration of the drug together with immune serum. Our findings reveal that methylene blue displays virucidal preventive or therapeutic activity against influenza virus H1N1 and SARS-CoV-2 at low micromolar concentrations and in the absence of UV-activation. We also confirm that MB antiviral activity is based on several mechanisms of action as the extent of genomic RNA degradation is higher in presence of light and after long exposure. Our work supports the interest of testing methylene blue in clinical studies to confirm a preventive and/or therapeutic efficacy against both influenza virus H1N1 and SARS-CoV-2 infections.


Subject(s)
COVID-19/drug therapy , Influenza, Human/drug therapy , Methylene Blue/pharmacology , Virus Inactivation/drug effects , Animals , COVID-19/genetics , COVID-19/virology , Chlorocebus aethiops , Humans , Influenza, Human/genetics , Influenza, Human/virology , SARS-CoV-2/drug effects , SARS-CoV-2/pathogenicity , Ultraviolet Rays/adverse effects , Vero Cells , Virus Inactivation/radiation effects , Virus Replication/drug effects , Virus Replication/radiation effects
17.
Int J Mol Sci ; 22(16)2021 Aug 17.
Article in English | MEDLINE | ID: covidwho-1360773

ABSTRACT

The current SARS-CoV-2 pandemic causes serious public health, social, and economic issues all over the globe. Surface transmission has been claimed as a possible SARS-CoV-2 infection route, especially in heavy contaminated environmental surfaces, including hospitals and crowded public places. Herein, we studied the deactivation of SARS-CoV-2 on photoactive AgNPs@TiO2 coated on industrial ceramic tiles under dark, UVA, and LED light irradiations. SARS-CoV-2 inactivation is effective under any light/dark conditions. The presence of AgNPs has an important key to limit the survival of SARS-CoV-2 in the dark; moreover, there is a synergistic action when TiO2 is decorated with Ag to enhance the virus photocatalytic inactivation even under LED. The radical oxidation was confirmed as the the central mechanism behind SARS-CoV-2 damage/inactivation by ESR analysis under LED light. Therefore, photoactive AgNPs@TiO2 ceramic tiles could be exploited to fight surface infections, especially during viral severe pandemics.


Subject(s)
Ceramics/chemistry , Metal Nanoparticles/chemistry , SARS-CoV-2/drug effects , SARS-CoV-2/radiation effects , Titanium/chemistry , Antiviral Agents/pharmacology , COVID-19/virology , Humans , Light , Oxidative Stress/drug effects , Oxidative Stress/radiation effects , Pandemics , Particle Size , SARS-CoV-2/metabolism , Surface Properties , Virus Inactivation/drug effects , Virus Inactivation/radiation effects
18.
Sci Rep ; 11(1): 15293, 2021 07 27.
Article in English | MEDLINE | ID: covidwho-1328857

ABSTRACT

The optical absorption coefficient of culture media is critical for the survival analysis of pathogens under optical irradiation. The quality of the results obtained from experiments relies on the optical analysis of the spatial distribution of fluence which also depends on the geometry of the sample. In this contribution, we consider both the geometrical shape and the culture medium's absorption coefficient to evaluate how the spatial distribution of optical radiation affects pathogens/viruses. In this work, we exposed SARS-CoV-2 to UV-C radiation ([Formula: see text] = 254 nm) and we calculated-considering the influence of the optical absorption of the culture medium-a characteristic inactivation fluence of [Formula: see text] = 4.7 J/m2, or an equivalent 10% survival (D90 dose) of 10.8 J/m2. Experimentally, we diluted the virus into sessile drops of Dulbecco's Modified Eagle Medium to evaluate pathogen activity after controlled doses of UV irradiation. To validate the optical absorption mode, we carried out an additional experiment where we varied droplet size. Our model-including optical absorption and geometrical considerations-provides robust results among a variety of experimental situations, and represents our experimental conditions more accurately. These results will help to evaluate the capability of UV disinfecting strategies applied to a variety of everyday situations, including the case of micro-droplets generated by respiratory functions.


Subject(s)
Absorption, Radiation , Culture Media , SARS-CoV-2/physiology , SARS-CoV-2/radiation effects , Ultraviolet Rays , Virus Inactivation/radiation effects , Disinfection
19.
Viruses ; 13(8)2021 07 23.
Article in English | MEDLINE | ID: covidwho-1325790

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.


Subject(s)
COVID-19/virology , Coronavirus, Feline/radiation effects , Disinfection/methods , SARS-CoV-2/radiation effects , Animals , COVID-19/prevention & control , Cats , Coronavirus Infections/virology , Coronavirus, Feline/growth & development , Coronavirus, Feline/physiology , Disinfection/instrumentation , Humans , SARS-CoV-2/growth & development , SARS-CoV-2/physiology , Ultraviolet Rays , Virus Inactivation/radiation effects
20.
Microbiol Spectr ; 9(1): e0033321, 2021 09 03.
Article in English | MEDLINE | ID: covidwho-1319385

ABSTRACT

We studied the stability of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) under different simulated outdoor conditions by changing the temperature (20°C and 35°C), the illuminance (darkness, 10 klx, and 56 klx), and/or the cleanness of the surfaces at 50% relative humidity (RH). In darkness, the loss of viability of the virus on stainless steel is temperature dependent, but this is hidden by the effect of the sunlight from the first minutes of exposure. The virus shows a sensitivity to sunlight proportional to the illuminance intensity of the sunlight. The presence of interfering substances has a moderate effect on virus viability even with an elevated illuminance. Thus, SARS-CoV-2 is rapidly inactivated by simulated sunlight in the presence or absence of high levels of interfering substances at 20°C or 35°C and 50% relative humidity. IMPORTANCE Clinical matrix contains high levels of interfering substances. This study is the first to reveal that the presence of high levels of interfering substances had little impact on the persistence of SARS-CoV-2 on stainless steel following exposure to simulated sunlight. Thus, SARS-CoV-2 should be rapidly inactivated in outdoor environments in the presence or absence of interfering substances. Our results indicate that transmission of SARS-CoV-2 is unlikely to occur through outdoor surfaces, dependent on illuminance intensity. Moreover, most studies are interested in lineage S of SARS-CoV-2. In our experiments, we studied the stability of L-type strains, which comprise the majority of strains isolated from worldwide patients. Nevertheless, the effect of sunlight seems to be similar regardless of the strain studied, suggesting that the greater spread of certain variants is not correlated with better survival in outdoor conditions.


Subject(s)
Microbial Viability/radiation effects , SARS-CoV-2/radiation effects , Sunlight , Virus Inactivation/radiation effects , COVID-19/prevention & control , COVID-19/transmission , Decontamination , Humans , Kinetics , SARS-CoV-2/growth & development , Surface Properties , Temperature
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