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Rapid and complete inactivation of SARS-CoV-2 by ultraviolet-C irradiation

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The severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) pandemic has devastated global public health systems and economies, with over 23 million people infected, millions of jobs and businesses lost, and more than 800 000 deaths recorded to date. Contact with surfaces contaminated with droplets generated by infected persons through exhaling, talking, coughing and sneezing is a major driver of SARS-CoV-2 transmission, with the virus being able to survive on surfaces for extended periods of time. To interrupt these chains of transmission, there is an urgent need for devices that can be deployed to inactivate the virus on both recently and existing contaminated surfaces. Here, we describe the inactivation of SARS-CoV-2 in both wet and dry format using radiation generated by a commercially available Signify ultraviolet (UV)-C light source at 254 nm. We show that for contaminated surfaces, only seconds of exposure is required for complete inactivation, allowing for easy implementation in decontamination workflows.
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Rapid and complete inactivation of SARS-CoV-2 by
ultraviolet-C irradiation
Nadia Storm
Boston University
Lindsay McKay
Boston University
Sierra Downs
Boston University
Rebecca Johnson
Boston University
Dagnachew Birru
Signify Research
Marc de Samber
Signify Research
Walter Willaert
Signify Research
Giovanni Cennini
Signify Research
Anthony Griths ( )
Boston University
Keywords: SARS-CoV-2, radiation, Signify ultraviolet (UV)-C light, decontamination
License: This work is licensed under a Creative Commons Attribution 4.0 International License. 
Read Full License
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The severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) pandemic has devastated global
public health systems and economies, with over 23 million people infected, millions of jobs and
businesses lost, and more than 800 000 deaths recorded to date. Contact with surfaces contaminated
with droplets generated by infected persons through exhaling, talking, coughing and sneezing is a major
driver of SARS-CoV-2 transmission, with the virus being able to survive on surfaces for extended periods
of time. To interrupt these chains of transmission, there is an urgent need for devices that can be
deployed to inactivate the virus on both recently and existing contaminated surfaces. Here, we describe
the inactivation of SARS-CoV-2 in both wet and dry format using radiation generated by a commercially
available Signify ultraviolet (UV)-C light source at 254 nm. We show that for contaminated surfaces, only
seconds of exposure is required for complete inactivation, allowing for easy implementation in
decontamination workows.
Towards the end of 2019, an outbreak of life-threatening pneumonia caused by a novel betacoronavirus
occurred in the Hubei Province of China1. The virus, named severe acute respiratory syndrome
coronavirus 2 (SARS-CoV-2), has since spread across the world at an alarming rate to cause a debilitating
and ongoing pandemic, with only a few islands not reporting any cases to date. While SARS-CoV-2 is
thought to be of zoonotic origin2, intense and extensive human-to-human transmission has mainly been
driven by the inhalation of respiratory droplets and virus-bearing particles spread through the air3, or by
contact with surfaces contaminated with settled droplets4. Although academic institutions and
pharmaceutical organizations worldwide have banded together to develop countermeasures against the
virus, there are still no licensed vaccines or therapeutics available. The disruption of transmission chains
is therefore crucial for managing the outbreak and preventing additional infections.
Ultraviolet (UV) irradiation is an extensively tested, widely used and effective no-contact method for
inactivating viral pathogens5–7. There are three types of UV, including UV-A (315–400nm), UV-B (280–
315nm) and UV-C (100–280nm), of which UV-C is most commonly employed in germicidal applications.
At a wavelength of 254nm, viral inactivation can be attributed to direct UV-C light absorption and
photochemical damage to nucleic acid, leading to the disruption of viral replication8. Despite its wide use,
limited data exists on the effectiveness of UV-C on inactivating wet and dried SARS-CoV-2 on
contaminated surfaces. In particular, the ecacy of UV-C for inactivating SARS-CoV-2 in uids needs to
be determined, as the UV absorbance characteristics of uid constituents may inuence the dose required
to achieve complete viral inactivation.
In this paper, we describe the complete and rapid inactivation of SARS-CoV-2 in both wet and dried
droplets using 254nm UV-C irradiation. Our results suggest that UV-C is an affordable and effective tool
for preventing SARS-CoV-2 contact transmission that can easily be deployed to manage the coronavirus
disease outbreak.
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Results And Discussion
Estimation of viral decay time
To examine the inactivation ecacy of UV-C on SARS-CoV-2, virus was applied to 60 mm plastic dishes
and exposed to UV radiation as either wet or dried droplets for varying amounts of time ranging from 0.8
to 120 seconds. Under a UV-C irradiance of 0.849 mW/cm2, partial inactivation occurred from 0.8
seconds of exposure, while SARS-CoV-2 virus infectivity was reduced to below detectable levels in as few
as 9 seconds for dried virus (Figure 1A) and 4 seconds for wet virus (Figure 1B). Virus inactivation by UV
light is expected to be an exponential process9. Therefore, to estimate the decay time, we used linear
regression methods with single and double exponential decay functions (Figure 1). The single
exponential decay function has the form , while the double exponential function has the
form are the decay times of the linear regressions. In
case of double exponential decay,
is the fraction of the viruses that survive the rst decay. For the
analysis, data points were normalized so that the initial condition
= 0 corresponds to 100% infectivity
with no irradiance.
In the linear regression of dried droplets, the reduced χ2 for double exponential decay (0.36) was lower
than the one corresponding to single exponential decay (0.52). The R2 for double exponential was higher
than the R2 of the single exponential. Hence, we used the double exponential decay to estimate the decay
times, obtaining In case of wet
droplets, we observed the opposite: the χ2 for the double exponential (1.0) was higher than the one
corresponding to the single exponential (0.8). The R2 for the double exponential and the single
exponential was the same (0.9). We therefore used the single exponential decay as a best t of the data
to estimate the decay time, translating into an average decay time of Within
one standard deviation, the decay times of wet and dried droplets are congruent. This is most likely due
to the limited resolution of the measurements. In addition, this indicates that given the observation limits,
UV-C absorption by media constituents did not signicantly affect virus inactivation at a wavelength of
254 nm.
It should be noted that the experiments for this study were performed under specic and controlled
conditions. Factors such as humidity, textured surfaces and the presence of dust and other particles may
reduce the effectiveness of UV-C and inuence the dose required to achieve complete viral inactivation6. It
is also important to consider the composition of respiratory droplets when evaluating the effectiveness of
254 nm UV-C irradiation. Droplets are likely to be in solvent with a variety of other biological uids such
as respiratory mucus (phlegm) which may include viral glycoproteins, and UV-C absorption of these uids
and particles may result in a reduction in viral inactivation eciencies. The results obtained in this study
should therefore be interpreted as the minimum dose of radiation required to achieve viral inactivation.
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Although beyond the scope of this study, future studies should address the effects of humidity, surface
conformation and the natural matrices in which the virus may exist on the required UV-C inactivation
Direct exposure of the skin and eyes to 254 nm UV-C light presents a serious health hazard10 and as
such, 254 nm UV-C light should only be used with proper training or where people are not at risk of being
exposed. Forthcoming studies will explore the viral inactivation effectiveness of far UV-C wavelengths
(207-222 nm) that have been proposed to be a safer alternative to 254 nm UV-C light7.
Although several techniques exist for inactivating SARS-CoV-2, the lack of proven effective tools and
interventions have allowed for the unmanageable spread of the virus in the human population. Our
results show that UV-C is a powerful tool that can be applied extensively in a wide range of public
institutions including hospitals, nursing homes, workplaces, schools, airports and shopping centers to
disinfect contaminated equipment and surfaces to prevent and reduce SARS-CoV-2 contact transmission.
UV-C device
A test apparatus was designed, optimized, fabricated and calibrated to enable accurate and controlled
UV-C treatment of test samples. A collimated beam setup was fabricated based on a dual chamber
construction. The top chamber contains the UV-C light source, the electronic driver, and a shutter system
to control the exposure times of the samples while keeping the lamp output stable. Samples were treated
in the bottom chamber using deep UV-C light generated with a classical Mercury type TUV PLL 35W light
source, generating a peak wavelength at 254 nm. Multiple sensor-based safety measures were applied to
protect the user against incidental exposure to the UV-C radiation. The irradiance level for three different
lamps inside the treatment chamber was measured using a calibrated UV-C sensor system
(Spectroradiometer GL Optic Spectis 5.0 Touch with detector GL Opti Probe 5.1.50), which provided
irradiance patterns and levels from which optimal treatment locations could be deduced.
Virus inactivation procedures
All experiments were performed in the biosafety level 4 laboratory of the National Emerging Infectious
Diseases Laboratories of Boston University. A volume of 100 µl SARS-CoV-2 (7.33 x 103 PFU/ml)
(USA/WA1-2020)11 was plated onto the surface of 60 mm plastic tissue culture dishes (TPP) in 5 µl
aliquots. The virus was allowed to dry for approximately 2 hours on a subset of the dishes while the rest
were processed immediately in the prototype UV-C device. Briey, a pair of dishes (one to be treated and
one control wrapped tightly in aluminum foil) were placed in the center of the device at an irradiance level
of 0.849 mW/cm2, and towards the side of the UV-C device, respectively. The dishes were UV-C-treated for
either 0.8, 2, 3, 4, 5, 6, 9, 15, 30 or 120 seconds, with each treatment time tested in triplicate. Dishes
containing dried virus were treated in the same manner. Following treatment, the wet and dried virus were
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resuspended in 1.9 ml or 2 ml, respectively, of high glucose Dulbecco's Modied Eagle Medium (DMEM)
(Gibco) containing 0.04 mM phenol red, 1 x antibiotic-antimycotic (Gibco), 1 x non-essential amino acids
(Gibco), 1 x GlutaMAX-I (Gibco), 1 mM sodium pyruvate (Gibco) and 2% fetal bovine serum (FBS)(Gibco).
The resuspended virus was then serially diluted from 1 x 100 to 1 x 10-2.5 using half-logarithmic dilutions
for the crystal violet plaque assay, or from 1 x 100 to 1 x 10-5 using 10-fold dilutions for the anti-SARS-
CoV-2 antibody plaque assay. A back-titration of the virus was included for each experiment.
Conrmation of virus inactivation by plaque assay
a) Plaque identication using crystal violet
Vero E6 cells maintained in high glucose DMEM (Gibco) supplemented with 1 x GlutaMAX-I, 1 mM
sodium pyruvate, 10% FBS (Gibco) and 1 x non-essential amino acids (Gibco) were seeded into 6-well
CellBIND plates (Corning) at a density of 8.0 x 105 cells per well. The cells were incubated at 37°C and 5%
CO2 overnight. The media was removed from each well and 200 µl of each dilution prepared from
resuspended virus was added to the respective wells of a 6-well plate. One well containing only DMEM
with 2% FBS was included as a control on each plate. A back-titer of the virus used to prepare the 60 mm
dishes was performed in triplicate by inoculating each well of a 6-well plate with 1 x 10-2 to 1 x 10-6
dilutions of the virus, respectively. Plates were incubated at 37°C and 5% CO2 for 1 hour with intermittent
rocking. Cells were then overlaid with 2 ml of a 1:1 solution of 2.5% Avicel RC-591 (DuPont Nutrition and
Health) and 2 x Temin's Modied Eagle Medium (Gibco) without phenol red, supplemented with 10% FBS
(Gibco), 2 x antibiotic-antimycotic (Gibco) and 2 x GlutaMAX-I (Gibco). The cells were incubated at 37°C
and 5% CO2 for 2 days. Plates were xed in 10% neutral buffered formalin (ThermoFisher Scientic),
followed by staining with 0.2% Gentian Violet (Ricca Chemical) in 10% neutral buffered formalin. The
number of plaques per virus dilution were determined by eye and used to calculate the titer of the virus
using the following formula:
Virus titer in PFU/ml = Number of plaques / (virus dilution in well x volume plated in ml)
Statistical analysis
The statistical package Microcal Origin® was used to analyze the data. A detailed explanation of the
statistical methods used is provided with the results.
Data availability
Additional data supporting the ndings of this study are available from the corresponding author upon
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The authors acknowledge Lauren E. Malsick for technical assistance. This work was supported by
Signify Research.
Author Contributions
AG, SND, NS and LGAM conceptualized the study design. SND, NS, LGAM and RIJ performed the
experiments. NS, SND, LGAM, GC and AG analyzed the data and wrote the rst draft of the paper with
input from DB, MdS and WW. All authors read, revised and approved the nal paper.
Competing interests
AG, NS, LGAM, SND, and RIJ have no competing interests to declare. MdS, GC, DB, and WW are
employees of Signify Research.
Materials and correspondence
Correspondence and materials requests should be addressed to AG.
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Figure 1
Reduction in infectivity of SARS-CoV-2 after exposure to UV-C irradiation. The virus was exposed to UV-C
as dried droplets (A) or wet droplets (B). Each set of data (dry samples and wet samples) shows a
decrease of the remaining infectivity as a function of time, normalized to 1. Blue lines indicate single
exponential decay functions while red lines indicate double exponential decay functions.
... UVGI applications use low-pressure mercury discharge lamps that emit shortwave ultraviolet-C (UV-C) radiation. UV-C radiation inactivates viral pathogens by damaging their deoxyribonucleic acid (DNA) [129,130,131]. ...
Climate change is causing alterations to the geophysical system; rising global temperatures are causing extreme heat events, wildfires, and changes in infectious agents; sea-level rise and extreme precipitation events are increasing the frequency and intensity of flood events. These climate change impacts have a negative effect on human health, specifically on the most vulnerable populations. Vulnerability is the idea of susceptibility to damage or harm; with respect to climate change, it is a function of exposure, sensitivity, and adaptive capacity. This case study explores the exposure and sensitivity of long-term care facility occupants in British Columbia (B.C.), Canada, because of the high proportion of long-term care residents that are sensitive to climate change. The climate change impacts under review were identified as those with the greatest risk to B.C., the potential to result in significant consequences, as well as current events and prevalence in the region over the past decade. The health effects of these primary climate change impacts were identified through a literature review. Both age and health condition are factors of sensitivity; in B.C., 97% of long-term care facility occupants have chronic diseases (including cardiovascular, endocrine, musculoskeletal, neurological, pulmonary, psychiatric, respiratory, and sensory diseases), and 95% are over the age of 65. A number of chronic diseases (e.g. hypertension and dementia) have been identified that are likely to be exacerbated because of climate change, specifically the four most significant and relevant climate change impacts in B.C.: extreme heat, flooding, changes in infectious agents, and wildfires. In this paper, the proportions of long-term care facility occupants in B.C. with these chronic diseases have been quantified, highlighting the importance of building the adaptive capacity of these populations to decrease their vulnerability. Various building design solutions were explored, confirming the relationship identified in past studies between the built environment, climate change, and occupant health.
The COVID19 pandemic that terrorizes the world with terrible aggression calls for the urgent finding of tools that would quickly inactivate viruses in the environment to reduce the chance of aerosol infection and contact transmission. For the inactivation of SARS – CoV – 2 viruses we used LEDs with maximum emission on the wavelength 255 ± 5 nm. All sources of UVC bactericidal radiation have emission peaks close to the center of the DNA and RNA absorption spectrum and may underlie devices and therapies to disrupt the spread of infection.
Background The concern with environmental security to avoid contamination of people was intensified with the crisis established by SARS-CoV-2. The COVID-19 pandemic has shown the necessity to create systems and devices capable of clearing the air of an environment from microorganisms more efficiently. The development of systems that allow removing micro-droplets mainly originated from breathing or talking from the air was the motivation of this study. Aim: This article describes a portable and easy-to-operate system that helps to eliminate the droplets or aerosols present in the environment by circulating air through a UV-C reactor. Methods: We described the development of an air circulation device, and we performed a proof-of-principle study using the device against bacteria in simulated and natural environments. The microbiological analysis was carried out by the simple sedimentation technique. For comparing the experimental results and the expected results for other microorganisms, the reduction rate values for bacteria and viruses were calculated and compared to the experimental results based on technical parameters (CADR and ACH). Findings: Results showed the microorganisms were eliminated with high efficiency by the air circulation decontamination device, with reductions of 99.9% in the proof-of-principle study, and 84% to 97% at hospital environments study, contributing to reduce people contamination in environments considered to offer risk. Conclusion: This study resulted in a low-cost and relatively simple device, which showed to be effective and safe. It can be replicated, especially in low-income countries, respecting the standards for air disinfection using UV-C technologies.
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A direct approach to limit airborne viral transmissions is to inactivate them within a short time of their production. Germicidal ultraviolet light, typically at 254 nm, is effective in this context but, used directly, can be a health hazard to skin and eyes. By contrast, far-UVC light (207–222 nm) efficiently kills pathogens potentially without harm to exposed human tissues. We previously demonstrated that 222-nm far-UVC light efficiently kills airborne influenza virus and we extend those studies to explore far-UVC efficacy against airborne human coronaviruses alpha HCoV-229E and beta HCoV-OC43. Low doses of 1.7 and 1.2 mJ/cm2 inactivated 99.9% of aerosolized coronavirus 229E and OC43, respectively. As all human coronaviruses have similar genomic sizes, far-UVC light would be expected to show similar inactivation efficiency against other human coronaviruses including SARS-CoV-2. Based on the beta-HCoV-OC43 results, continuous far-UVC exposure in occupied public locations at the current regulatory exposure limit (~3 mJ/cm2/hour) would result in ~90% viral inactivation in ~8 minutes, 95% in ~11 minutes, 99% in ~16 minutes and 99.9% inactivation in ~25 minutes. Thus while staying within current regulatory dose limits, low-dose-rate far-UVC exposure can potentially safely provide a major reduction in the ambient level of airborne coronaviruses in occupied public locations.
Full-text available
Various mitigation measures have been implemented to fight the coronavirus disease 2019 (COVID-19) pandemic, including widely adopted social distancing and mandated face covering. However, assessing the effectiveness of those intervention practices hinges on the understanding of virus transmission, which remains uncertain. Here we show that airborne transmission is highly virulent and represents the dominant route to spread the disease. By analyzing the trend and mitigation measures in Wuhan, China, Italy, and New York City, from January 23 to May 9, 2020, we illustrate that the impacts of mitigation measures are discernable from the trends of the pandemic. Our analysis reveals that the difference with and without mandated face covering represents the determinant in shaping the pandemic trends in the three epicenters. This protective measure alone significantly reduced the number of infections, that is, by over 78,000 in Italy from April 6 to May 9 and over 66,000 in New York City from April 17 to May 9. Other mitigation measures, such as social distancing implemented in the United States, are insufficient by themselves in protecting the public. We conclude that wearing of face masks in public corresponds to the most effective means to prevent interhuman transmission, and this inexpensive practice, in conjunction with simultaneous social distancing, quarantine, and contact tracing, represents the most likely fighting opportunity to stop the COVID-19 pandemic. Our work also highlights the fact that sound science is essential in decision-making for the current and future public health pandemics.
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Understanding the particle size distribution in the air and patterns of environmental contamination of SARS-CoV-2 is essential for infection prevention policies. Here we screen surface and air samples from hospital rooms of COVID-19 patients for SARS-CoV-2 RNA. Environmental sampling is conducted in three airborne infection isolation rooms (AIIRs) in the ICU and 27 AIIRs in the general ward. 245 surface samples are collected. 56.7% of rooms have at least one environmental surface contaminated. High touch surface contamination is shown in ten (66.7%) out of 15 patients in the first week of illness, and three (20%) beyond the first week of illness (p = 0.01, χ2 test). Air sampling is performed in three of the 27 AIIRs in the general ward, and detects SARS-CoV-2 PCR-positive particles of sizes >4 µm and 1–4 µm in two rooms, despite these rooms having 12 air changes per hour. This warrants further study of the airborne transmission potential of SARS-CoV-2. Here, the authors sample air and surfaces in hospital rooms of COVID-19 patients, detect SARS-CoV-2 RNA in air samples of two of three tested airborne infection isolation rooms, and find surface contamination in 66.7% of tested rooms during the first week of illness and 20% beyond the first week of illness.
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Since the SARS outbreak 18 years ago, a large number of severe acute respiratory syndrome-related coronaviruses (SARSr-CoV) have been discovered in their natural reservoir host, bats1–4. Previous studies indicated that some of those bat SARSr-CoVs have the potential to infect humans5–7. Here we report the identification and characterization of a novel coronavirus (2019-nCoV) which caused an epidemic of acute respiratory syndrome in humans in Wuhan, China. The epidemic, which started from 12 December 2019, has caused 2,050 laboratory-confirmed infections with 56 fatal cases by 26 January 2020. Full-length genome sequences were obtained from five patients at the early stage of the outbreak. They are almost identical to each other and share 79.5% sequence identify to SARS-CoV. Furthermore, it was found that 2019-nCoV is 96% identical at the whole-genome level to a bat coronavirus. The pairwise protein sequence analysis of seven conserved non-structural proteins show that this virus belongs to the species of SARSr-CoV. The 2019-nCoV virus was then isolated from the bronchoalveolar lavage fluid of a critically ill patient, which can be neutralized by sera from several patients. Importantly, we have confirmed that this novel CoV uses the same cell entry receptor, ACE2, as SARS-CoV.
Full-text available
In December 2019, a cluster of patients with pneumonia of unknown cause was linked to a seafood wholesale market in Wuhan, China. A previously unknown betacoronavirus was discovered through the use of unbiased sequencing in samples from patients with pneumonia. Human airway epithelial cells were used to isolate a novel coronavirus, named 2019-nCoV, which formed another clade within the subgenus sarbecovirus, Orthocoronavirinae subfamily. Different from both MERS-CoV and SARS-CoV, 2019-nCoV is the seventh member of the family of coronaviruses that infect humans. Enhanced surveillance and further investigation are ongoing. (Funded by the National Key Research and Development Program of China and the National Major Project for Control and Prevention of Infectious Disease in China.).
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The person-to-person transmission of influenza virus, especially in the event of a pandemic caused by a highly virulent strain of influenza, such as H5N1 avian influenza, is of great concern due to widespread mortality and morbidity. The consequences of seasonal influenza are also substantial. Because airborne transmission appears to play a role in the spread of influenza, public health interventions should focus on preventing or interrupting this process. Air disinfection via upper-room 254-nm germicidal UV (UV-C) light in public buildings may be able to reduce influenza transmission via the airborne route. We characterized the susceptibility of influenza A virus (H1N1, PR-8) aerosols to UV-C light using a benchtop chamber equipped with a UVC exposure window. We evaluated virus susceptibility to UV-C doses ranging from 4 to 12 J/m2 at three relative humidity levels (25, 50, and 75%). Our data show that the Z values (susceptibility factors) were higher (more susceptible) to UV-C than what has been reported previously. Furthermore, dose-response plots showed that influenza virus susceptibility increases with decreasing relative humidity. This work provides an essential scientific basis for designing and utilizing effective upper-room UV-C light installations for the prevention of the airborne transmission of influenza by characterizing its susceptibility to UV-C.
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A novel UV-C-light-induced ribozyme activity was discovered within the highly structured 5′-genomic regions of both Hepatitis C Virus (HCV) and the related Classic Swine Fever Virus (CSFV). Cleavage is mediated by exposure to UV-C light but not by exogenous oxygen radicals. It is also very selective, occurring at base positions HCV C79 and CSFV A45 in some molecules and at the immediately adjacent 5′-positions HCV U78 and CSFV U44 in others. Among other reaction products, the majority of biochemically active products detected contained 3′-phosphate and 5′-phosphate-end groups at the newly generated termini, along with a much lower amount of 3′-hydroxyl end group. While preservation of an E-loop RNA structure in the vicinity of the cleavage site was a requisite for HCV RNA self-cleavage, this was not the case for CSFV RNA. The short size of the reactive domains (∼33 nt), which are compatible with primitive RNA motifs, and the lack of sequence homology, indicate that as-yet unidentified UV-activated ribozymes are likely to be found throughout structured RNAs, thereby providing clues to whether early RNA self-cleavage events were mediated by photosensitive RNA structures.
A comprehensive treatment of the mathematical basis for modeling the disinfection process for air using ultraviolet germicidal irradiation (UVGI). A complete mathematical description of the survival curve is developed that incorporates both a two stage inactivation curve and a shoulder. A methodology for the evaluation of the three-dimensional intensity fields around UV lamps and within reflective enclosures is summarized that will enable determination of the UV dose absorbed by aerosolized microbes. The results of past UVGI studies on airborne pathogens are tabulated. The airborne rate constant for Bacillus subtilis is confirmed based on results of an independent test. A re-evaluation of data from several previous studies demonstrates the application of the shoulder and two-stage models. The methods presented here will enable accurate interpretation of experimental results involving aerosolized microorganisms exposed to UVGI and associated relative humidity effects
Ultraviolet radiation is known to cause both benefits and harmful effects on humans. The adverse effects mainly involve two target organs, skin and eye, and can be further divided into short- and long-term effects. The present case report describes an accidental exposure of two health-care workers to ultraviolet radiation produced by a germicidal lamp in a hospital pharmacy. The germicidal lamp presented a spectrum with an intense UV-C component as well as a modest UV-B contribution. Overexposure to UV-C radiation was over 100 times as large as the ICNIRP exposure limits. A few hours after the exposure, the two subjects reported symptoms of acute UV injury and both of them continued having significant clinical signs for over 2 years. In this study, we describe acute and potentially irreversible effects caused by high UV exposure. In addition, we present the results of risk assessment by occupational exposure to germicidal lamps.
Inactivation of the coronavirus that induces severe acute respiratory syndrome, SARS-CoV
  • M E R Darnell
Darnell, M.E.R. et al. Inactivation of the coronavirus that induces severe acute respiratory syndrome, SARS-CoV. J Virol Methods 121, 85-91, (2004).