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SARS-CoV, influenza A and syncitial respiratory virus resistance against common disinfectants and ultraviolet irradiation



To evaluate the virucidal efficacy of six commonly used chemical disinfectants, and ultraviolet radiation (U.V.) against SARS-CoV and compare it to the resistance of other airborne viruses, such as Influenza and Respiratory Sincytial Virus, a salt solution containing a standard concentration of cell-grown viruses, was mixed with a larger volume of different disinfectants at their use dilution and the mixtures were held for a defined contact time. The virucidal efficacy of disinfectants and U.V. was evaluated by infectivity, detected by inoculation of samples in suitable cell culture and genome integrity, detected by nested RT-PCR. SARS-CoV as well as RSV seem to be sensible to the different disinfectants tested in our study and U.V. radiation, while influenza virus appear to be more resistant in particular to the action of chlorhexidine digluconate and benzalkonium-chloride. In consideration of the possible infectious role of SARS-CoV RNA, sodium hypochlorite 0.1% appear to be the more efficacious disinfectant for surfaces and hands potentially contaminated with respiratory viruses and SARS-CoV.
In late 2002 a new acute and often severe respiratory
illness (SARS) emerged in Southern China and spread
to distant areas within a very short period of time 1. The
aetiological agent for SARS is a novel Coronavirus
called SARS-CoV, that H has never been described
both in human and animals previously 2-4. CDC in ac-
cording to WHO, reports that a total of 8,098 people in
32 countries became sick with this new illness during
2003 outbreak. Of these 774 died, with a case-fatality
rate of about 10% that reach 50% in > 64 year age
group 5. On 5 July 2003 WHO announced that SARS
epidemic was over. During outbreak the major percent-
age of cases was among health-care workers because
the main way of transmission seems to be by close per-
son to person contact during the peak of viral shedding
that occurs about ten days after onset of symptoms.
Since epidemic was over there have been a number of
laboratory confirmed SARS-CoV infections resulting
from laboratory accidents and from exposure to animal
sources or environmental contamination 6.
In consideration of the high efficiency in nosocomial
transmission and the occurrence of infection in laborato-
ry, to know the resistance of this new virus in environ-
ment and towards common disinfectants appear to be a
fundamental tool to choose the correct control measures.
The aim of this work is to evaluate the virucidal effica-
cy of chemical disinfectants, used to clean surfaces,
and ultraviolet radiation (U.V.) against SARS-CoV and
compare it to the resistance of other airborne enveloped
viruses, such as Influenza and Respiratory Sincytial
Virus (RSV).
Materials and methods
A known quantity (1ml) of salt solution containing a
standard concentration of cell-grown virus, was mixed
with a larger volume (2 ml) of different disinfectants
under evaluation at their use dilution. The mixtures
were held for a defined contact time (30 seconds, 1
minute, 2 min, 5 min, 15 min, 30 min) at controlled tem-
perature (18°C) and humidity (40%). The virucidal ac-
tivity of the test products was arrested immediately by
adding a neutralizer (Sodium thiosulphate for sodium
hypoclorite; sodium hydroxide for acid peracetic) or di-
luting the germicide-mixture. For evaluate the physical
effects of U.V. irradiation (40mW/cm2), the salt solu-
tions containing viruses, were distributed on a plate of
20 cm2 and exposed to U.V. irradiation for above-men-
tioned contact time. A positive control containing a
standard concentration of cell-grown virus without dis-
infectant was used in every run. Preliminary tests were
made to evaluate the sensibility of cells against disin-
fectants and neutralizer/disinfectant solution for select-
ing the right dilution that did not damage the cells.
In this study SARS-CoV, Influenza virus and RSV
were tested with six common disinfectants at the fol-
lowing dilutions:
Sodium Hypochlorite 0.01% 0.05% 0.1%;
Ethanol 70%;
Benzalkonium-chloride 1%;
Chlorhexidine digluconate 1%;
SARS-CoV, influenza A and syncitial respiratory virus
resistance against common disinfectants and
ultraviolet irradiation
Department of Health Sciences, University of Genoa
Key words
SARS-CoV Disinfectants Virucidal efficacy
To evaluate the virucidal efficacy of six commonly used chem-
ical disinfectants, and ultraviolet radiation (U.V.) against SARS-
CoV and compare it to the resistance of other airborne viruses,
such as Influenza and Respiratory Sincytial Virus, a salt solu-
tion containing a standard concentration of cell-grown viruses,
was mixed with a larger volume of different disinfectants at their
use dilution and the mixtures were held for a defined contact
time. The virucidal efficacy of disinfectants and U.V. was eval-
uated by infectivity, detected by inoculation of samples in suit-
able cell culture and genome integrity, detected by nested RT-
PCR. SARS-CoV as well as RSV seem to be sensible to the dif-
ferent disinfectants tested in our study and U.V. radiation, while
influenza virus appear to be more resistant in particular to the
action of chlorhexidine digluconate and benzalkonium-chloride.
In consideration of the possible infectious role of SARS-CoV
RNA, sodium hypochlorite 0.1% appear to be the more effica-
cious disinfectant for surfaces and hands potentially contami-
nated with respiratory viruses and SARS-CoV.
2-benzil-chlorophenol 2%;
Peracetic acid 0.035%.
To evaluate the virucidal efficacy of disinfectants and
U.V. we considered two parameters: (i) infectivity, de-
tected by inoculation of samples in suitable cell culture,
i.e. Vero E6 for SARS-CoV, MDCK for influenza virus,
HEp2c for RSV 7; (ii) genome integrity, detected by
nested RT-PCR for SARS-CoV and multiplex nested
All practice of experiment with SARS-CoV were made
in laboratory BSL3 as recommended by WHO 6.
Conventional viral culture was performed by inoculat-
ing 0.3 ml of each specimen (virus-disinfectant mix-
ture) into Vero E6, MDCK and HEp-2 cells for SARS-
CoV, influenza and RSV isolation, respectively 7. Virus
detection was performed by PCR indirect immuno flu-
orescence and hemagglutination test for SARS-CoV
RSV, and influenza, respectively 8.
RNA was extracted using QIA techniques, following
the manufacturers instructions (Rneasy Minikit, Qia-
gen, Valencia, CA). Amplification of specific RSV and
Influenza virus sequence was performed by multiplex
RT-nested PCR (Influenza/RSV multiplex, Amplimed-
ical S.p.A., BIOLINE, Italy). SARS-CoV was detected
by a commercial RT-PCR kit (SARS-CoV RNA poly-
merase, Amplimedical S.p.A., BIOLINE, Italy).
The results of preliminary test of citotoxicy showed that
0.2 ml ethanol 70%, benzalkonium-chloride 1%,
chlorhexidine digluconate 1% in 2 ml cell culture medi-
um did not significantly damage the cell monolayer.
Sodium hypochlorite 10% and peracetic acid 0.035% de-
termined a strong cytotoxic effect on cells, that disap-
peared when disinfectant-neutralizer mixture was used.
Also 2-benzil-chlorophenol 2% showed a strong cyto-
toxic effect on cells that declined and disappeared when
a 1:3 and 1:10 dilution was inoculated, respectively. For
this reason after the end of contact time the mixture
virus-disinfectant was diluted 1:10 before inoculation.
In Table I last virus-disinfectant contact times resulting
positive by cell culture and PCR are reported. Peracetic
acid 0.035%, ethanol 70% and sodium hypochlorite
0.05% showed to inhibit viral replication in cell culture
after < 2contact time, while viral genome seems to be
intact after prolonged exposition (30).
Sodium hypochlorite 0.1%, 2-benzil-chlorophenol 2%
and U.V. have a stronger virucidal effect: they inhibit
completely viral replication and damage viral genome
after < 2 minutes of exposition. In particular, sodium
hypochlorite 0.1% showed the more rapid action: after
1of contact, influenza virus, RSV and SARS-CoV
were not able to replicate and their genome integrity
was lost. This data is confirmed by electronic mi-
croscopy: the viral structures appear completely de-
stroyed with lost of spikes and envelope integrity after
1of exposition (data not shown).
Chlorhexidine digluconate 1% and benzalkonium-chlo-
ride 1% showed a similar pattern of virucidal efficacy:
they inhibited RSV replication after 1of contact, while
prolonged exposition (30) did not affect infectivity of
influenza virus. SARS-CoV replication was inhibited
by 5exposition to benzalkonium-chloride 1%, while
all experimental samples collected at different time re-
sulted culture negative after contact with chlorhexidine
digluconate 1%. Influenza virus, RSV and SARS-CoV
RNA is still detectable after 30 minutes of contact time
Tab. I. Last contact time resulting positive by cell culture and PCR.
Disinfectant Virus
Influenza virus RSV SARS-CoV
Culture PCR Culture PCR Culture PCR
Peracetic acid 0.035% 30’ 30’ 30’
Ethanol 70% 2’ 30’ 30’ 30’
Sodium Hypochlorite 0.01% 30’ 30’ 30’ 30’ 30’ 30’
Sodium Hypochlorite 0.05% 30’ 30’ 1’ 2’ 1’ 30’
Sodium Hypochlorite 0.1% 30î 1’ 1’ 30î
Chlorhexidine digluconate 1% 30’ 30’ 1’ 30’ 30’
2-benzil-chlorophenol 2% 2’ 2’
Benzalkonium– chloride 1% 30’ 30’ 1’ 30’ 5’ 30’
UV irradiation 1’ 1’ 1’ 1’ 2’ 2’
Legend: – negative after 30’ contact time.
with chlorhexidine digluconate 1% and benzalkonium-
chloride 1%.
Since when SARS epidemic appeared, SARS-CoV has
shown high efficiency in nosocomial transmission and
high risk of virus spread in laboratory setting. The new
outbreak and the emergence of new respiratory viruses
such as avian influenza virus and human metapneu-
movirus, underline the needs to improve the knowledge
about the resistance of these microorganisms in envi-
ronment and towards common disinfectants for choos-
ing the correct control measures.
Studies on SARS-CoV demonstrated that the virus is
more stable at room temperature than the previously
known human Coronavirus 9 10. Preliminary study of
WHO laboratory network showed that the virus survive
for up to 48 hours on plastic surfaces and up to 4 days in
diarrhoea. Nevertheless, the virus loses infectivity after
exposure to different commonly used disinfectants and
fixatives 9 10. Our study confirmed that SARS-CoV is
quite sensible to common disinfectants. In fact, SARS-
CoV appears to be completely inactivated by disinfec-
tants such as acid peracetic, ethanol 70%, sodium
hypochlorite 0.05% and 0.1%, chlorhexidine digluconate
1% and 2-benzil-chlorophenol 2% after < 1exposition,
while a longer contact time with benzalkonium-chloride
1% is necessary to inhibit the replication in culture. PCR
findings are of interest, not only to demonstrate the com-
plete destruction of viral structure, but also as RNAs of
some Coronaviruses are infectious 11 12 . As regards as hu-
man infecting SARS-CoV, this biological property has
not been demonstrated yet. Only sodium hypochlorite
0.1% and 2-benzil-chlorophenol 2% are rapidly effica-
cious in destruction of viral RNA at an undetectable lev-
el after < 2contact time, while prolonged exposition
with other disinfectants seems not alter RNA integrity.
RSV showed a resistance pattern rather similar to
SARS-CoV and appears to be completely inactivated
by disinfectants such as acid peracetic, ethanol 70%,
sodium hypochlorite 0.05% and 0.1%, chlorhexidine
digluconate 1% and 2-benzil-chlorophenol 2% and
benzalkonium-chloride 1% after < 1exposition. The
RSV weakness was confirmed by on-field studies on
disinfection and survival studies 13 14.
Influenza can not replicate after short exposure to acid
peracetic, ethanol 70%, sodium hypochlorite 0.05%
and 0.1%, and 2-benzil-chlorophenol 2%, while it
showed high stability after contact with chlorhexidine
digluconate 1% and benzalkonium-chloride 1%. The
complete inefficacy of benzalkonium-chloride 1% is
not completely unexpected as quaternary ammonium
were shown to be very effective against herpes virus
but totally ineffective against non-enveloped virus and
influenza virus, as demonstrated also Moldenhauer 15.
On the other hand, chlorhexidine showed to be totally
ineffective against rotavirus, enveloped virus such as
influenza virus 16.
U.V. radiation, instead, damage nucleic acid because
RNA adsorb UV radiation of germicidal wavelengths
and is the major targets of the powerful antimicrobal
effects of these type of electromagnetic radiation. In
according to this, irradiation of UV for few minutes
(1-2) on the virus in culture medium resulted in the
destruction of viral infectivity.
In conclusion, SARS-CoV as well as RSV seem to be
sensible to the different disinfectants tested in our
study and U.V. radiation, while influenza virus appear
to be more resistant in particular to the action of
chlorhexidine digluconate and benzalkonium-chloride.
In consideration of the possible infectious role of
SARS-CoV RNA, sodium hypochlorite 0.1% appear
to be the more efficacious disinfectant for surfaces and
hands potentially contaminated with respiratory virus-
es and SARS-CoV.
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Correspondence: Filippo Ansaldi, Department of Health Scien-
ces, University of Genoa, Via Pastore 1, 16132 Genoa, Italy. Tel.
+39 010 3533002. E-mail:
... Among the 38 studies, 37 studies were in vitro and 01 study was an in vitro plus in vivo study [15]. Regarding the data we have found a total of 18 studies about light irradiation of cell or tissue cultures/plate solutions [15][16][17][18][19][20][21][22][23][24][25][26][27][28][29][30][31][32], 10 experimental studies about the irradiation of blood/plasma product [33][34][35][36][37][38][39][40][41][42], 03 studies about N95 face masks decontamination [43][44][45], 03 studies about inanimate surface decontamination (glass coverslips, plastic, and stainless steel) [46][47][48], 03 studies about UV irradiation of viral aerosols [49][50][51] and 01 study about the irradiation of areas from hospital rooms environment [52]. Thirty-five of them are about Ultraviolet irradiation (UV), UVA, or UVC, 02 studies evaluated Photodynamic Therapy (PDT) decontamination technique [36,37] and one study evaluated the use of Blue LED Light [31]. ...
... About viral etiology we found 17 studies including SARS-CoV-2 [23][24][25][26][27][28][29][30][31][32]34,40,44,45,47,48,52], 08 studies including SARS-CoV-1 [17][18][19][20]33,36,41,49], 06 studies including MERS-CoV [35,[37][38][39]42,46], 02 studies including porcine respiratory coronavirus (PRCV) [43,51], 02 studies including Canine coronavirus (CCoV) [16,21], 01 study including airborne human coronaviruses alpha HCoV-229E and beta HCoV-OC43 [50], 01 study including HCoV-OC43 Virus [22], 01 study including coronavirus-229E [15]. ...
... Twenty-four studies had a control group without irradiation or submitted to standard treatment [15][16][17]19,21,[24][25][26][27][28][30][31][32][36][37][38][39]41,[43][44][45][46][47]49] among which one study was in mice [15] and 23 experimental were in vitro studies. Even if a study published by Rezaie et. ...
COVID‐19 appeared in December 2019, needing efforts of science. Besides, a range of light therapies (PDT, Ultraviolet UV, Laser) has shown scientific alternatives to conventional decontamination therapies. METHODS: Investigating the efficacy of light‐based therapies for environment decontamination against SARS‐CoV2, a PRISMA systematic review of Phototherapies against SARS‐CoV or MERS‐CoV species discussing changes in viral RT‐PCR was done. After searching MEDLINE/PubMed, EMBASE, and LILACS we have found studies about cell cultures irradiation (18), blood components irradiation (10), N95 masks decontamination (03), inanimate surface decontamination (03), aerosols decontamination (03), hospital rooms irradiation (01) with PDT, LED, and UV therapy. The best quality results showed an effective low time and dose UV irradiation for environments and inanimate surfaces without human persons as long as the devices have safety elements dependent on the surfaces, viral charge, humidity, radiant exposure. To interpersonal contamination in humans, PDT or LED therapy seems very promising and are encouraged.
... Also, the genome integrity of virus is lost. 35 • Alginate: Povidone-iodine rapidly inactivates the SARS-CoV and the MERS-CoV. 29 As a precautionary measure, povidoneiodine disinfectant solution can also be used for disinfecting the alginate impressions. ...
... 37 Sodium hypochlorite 0.525% could disinfect alginate most effectively at pH 10 or lower. 38 • Elastomeric impression: Immersion of silicone impression in 0.5% sodium hypochlorite for 5 to 10 minutes is enough to be viricidal 35 and to inhibit bacterial growth without losing the dimensional stability. 39 A 3% hydrogen peroxide without significant changes in three-dimensional silicone dental impressions showed high antimicrobial efficiency. ...
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Constant risk of contact and proximity to oral cavity and the production of aerosol have increased the risk of coronavirus disease 2019 (COVID-19)among dentists. Transmission of coronavirus (CoV) is through respiratory droplets, close contact, or aerosols. Coronaviruses are lipid bilayer enveloped viruses with the viral structure formed primarily of structural proteins having affinity toward the angiotensin-converting enzyme2 receptors, which are found abundantly on the mucosa of tongue. These facts have led to categorization of dentistry as a very high exposure risk job with high potential for exposure to COVID-19. Due to the absence of vaccine till date, it is crucial to scrutinize and refine preventive maneuver and to implement strict and efficient infection control protocols to prevent cross infection of COVID-19 among dentists, dental team, and patients in the clinical setup. Based on the existing guidelines and the recently initiated guidelines from Centres for Disease Control and Prevention and World Health Organization, this study provides infection control strategies in the field of dentistry in general and in prosthodontics in particular. Keywords: Aerosols, COVID-19, Dentistry, Disinfection, Personal protective equipment, Severe acute respiratory syndrome coronavirus-2 .
... Peroxyacetic acid is considered a more potent biocide than hydrogen peroxide against a broad spectrum of pathogens at lower concentrations (<0.3%) [105]; thus, it is frequently recommended for disinfecting medical devices [17]. However, higher concentrations of peracetic acid (>100 ppm) may be necessary to reduce non-enveloped viruses on surfaces, foods, and fomites [106]. ...
... Ansaldi et al. reported the effectiveness of peroxyacetic acid on coronaviruses: a 0.035% (35 ppm) solution inhibited SARS-CoV replication in a cell culture with a contact time of <2 min, while the same concentration did not affect the viral genome after 30 min of exposure [105]. Another study suggested that SARS-CoV can be inactivated with 500 to 1000 ppm of peroxyacetic acid [108]. ...
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... BZK wipes contain 0.13% benzalkonium chloride, which is an antiseptic and a quaternary ammonium compound; Wet Wipes contain 1% bleach (sodium hypochlorite). Both BZK and sodium hypochlorite are effective at inactivating SARS-CoV-2, as well as other viruses, at relevant concentrations (16)(17)(18)(19), and are feasible to implement in school settings due to their cost and packaging (prepackaged wipes are easy to distribute). RNase Away is a dilution of sodium hydroxide and was included because it is recommended by the FDA to minimize nucleic acid contamination (20,21). ...
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... In this case, the proportion should be set as rectangular with a greater difference between the sides than indicated for the reason of exposing the longer side of the social area and the private area on the facade. The architectural method to maintain hygienic surfaces (as opposed to directly disinfecting them) is to expose them to the sun, which is the most effective means of hyphenizing work surfaces in accordance with the reduced resistance of viruses and bacteria exposed to UV radiation -specifically for coronavirus [33] (also IR radiation -30°C -40°C [18]), influenza virus [30] and other viruses in general [27] [29]. It is recommended that in subsequent surveys, there should be recommendations or minimum standards for sun exposure of the most hidden areas of the dwelling. ...
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... Surrogate coronavirus MHC can get a 3 log reduction in a 30 s contact period using a common disinfectant that contains 0.21% of sodium hypochlorite (Dellanno et al. 2009). The SARS-CoV virus can get completely inactivated in less than 1 min contact time at 0.05% concentrated hypochlorite solution (Ansaldi et al. 2004). Zhang et al. 2020a, b studied RNA removal of SARS-CoV-2 in septic tanks using 800-600 g/m 3 for a contact period of 1.5 h (Zhang et al. 2020a, b). ...
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... The irradiation from different light sources was mapped to develop an irradiance-dosage model for determining inactivation dosages (Fig. S3). The viral suspension formula used by many groups has been employed to experimentally determine the UVC inactivation dosages for many viral pathogens [56][57][58][59][60][61] . We showed that these doses can be overestimated if the properties of the liquid suspensions are not taken into account. ...
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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.
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Peracetic acid (PAA) disinfectants are effective against a wide range of pathogenic microorganisms, including bacteria, fungi, and viruses. Several studies have shown the efficacy of PAA against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2); however, its efficacy in SARS-CoV-2 variants and the molecular mechanism of action of PAA against SARS-CoV-2 have not been investigated. SARS-CoV-2 infection depends on the recognition and binding of the cell receptor angiotensin-converting enzyme 2 (ACE2) via the receptor-binding domain (RBD) of the spike protein. Here, we demonstrated that PAA effectively suppressed pseudotyped virus infection in the Wuhan type and variants, including Delta and Omicron. Similarly, PAA reduced the authentic viral load of SARS-CoV-2. Computational analysis suggested that the hydroxyl radicals produced by PAA cleave the disulfide bridges in the RBD. Additionally, the PAA treatment decreased the abundance of the Wuhan- and variant-type spike proteins. Enzyme-linked immunosorbent assay showed direct inhibition of RBD-ACE2 interactions by PAA. In conclusion, the PAA treatment suppressed SARS-CoV-2 infection, which was dependent on the inhibition of the interaction between the spike RBD and ACE2 by inducing spike protein destabilization. Our findings provide evidence of a potent disinfection strategy against SARS-CoV-2.
Conference Paper
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Since the outbreak of the COVID-19 epidemics, the priority worldwide was to minimize the spread of the virus. Ultraviolet (UV) light has proven a trustworthy solution against various ranges of health disorders and in the inactivation of viruses. Wavelengths between 254 nm and 265 nm from the electromagnetic spectrum are used for the deactivation of viruses, bacteria and fungi. In that sense, UV light can be proven efficient against SARS-CoV-2 transmission due to its germicidal effect. UVC light can damage the virus RNA and hence prevent its replication. Likewise, the development of a disease can be avoided. This study aims an objective assessment of UV light implementation in SARS-CoV-2 disinfection.
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A worldwide outbreak of severe acute respiratory syndrome (SARS) has been associated with exposures originating from a single ill health care worker from Guangdong Province, China. We conducted studies to identify the etiologic agent of this outbreak. We received clinical specimens from patients in seven countries and tested them, using virus-isolation techniques, electron-microscopical and histologic studies, and molecular and serologic assays, in an attempt to identify a wide range of potential pathogens. None of the previously described respiratory pathogens were consistently identified. However, a novel coronavirus was isolated from patients who met the case definition of SARS. Cytopathological features were noted in Vero E6 cells inoculated with a throat-swab specimen. Electron-microscopical examination revealed ultrastructural features characteristic of coronaviruses. Immunohistochemical and immunofluorescence staining revealed reactivity with group I coronavirus polyclonal antibodies. Consensus coronavirus primers designed to amplify a fragment of the polymerase gene by reverse transcription-polymerase chain reaction (RT-PCR) were used to obtain a sequence that clearly identified the isolate as a unique coronavirus only distantly related to previously sequenced coronaviruses. With specific diagnostic RT-PCR primers we identified several identical nucleotide sequences in 12 patients from several locations, a finding consistent with a point-source outbreak. Indirect fluorescence antibody tests and enzyme-linked immunosorbent assays made with the new isolate have been used to demonstrate a virus-specific serologic response. This virus may never before have circulated in the U.S. population. A novel coronavirus is associated with this outbreak, and the evidence indicates that this virus has an etiologic role in SARS. Because of the death of Dr. Carlo Urbani, we propose that our first isolate be named the Urbani strain of SARS-associated coronavirus.
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The severe acute respiratory syndrome (SARS) has recently been identified as a new clinical entity. SARS is thought to be caused by an unknown infectious agent. Clinical specimens from patients with SARS were searched for unknown viruses with the use of cell cultures and molecular techniques. A novel coronavirus was identified in patients with SARS. The virus was isolated in cell culture, and a sequence 300 nucleotides in length was obtained by a polymerase-chain-reaction (PCR)-based random-amplification procedure. Genetic characterization indicated that the virus is only distantly related to known coronaviruses (identical in 50 to 60 percent of the nucleotide sequence). On the basis of the obtained sequence, conventional and real-time PCR assays for specific and sensitive detection of the novel virus were established. Virus was detected in a variety of clinical specimens from patients with SARS but not in controls. High concentrations of viral RNA of up to 100 million molecules per milliliter were found in sputum. Viral RNA was also detected at extremely low concentrations in plasma during the acute phase and in feces during the late convalescent phase. Infected patients showed seroconversion on the Vero cells in which the virus was isolated. The novel coronavirus might have a role in causing SARS.
Avian infectious bronchitis virus (IBV) was radiolabeled for its nucleic acid component by growth in deembryonated chicken eggs. Purified virions of IBV have a buoyant density in linear sucrose gradients of 1.17-1.18 g/cm3 and contain approximately 4% RNA by weight. The genomic ribonucleic acid of IBV shows the following characteristic: (1) It consists of one size class of single-stranded RNA having a molecular weight of 5.5-5.7 x 108 and a sedimentation coefficient of about 48 S; (2) no evidence for subunit structure is apparent since the RNA resolves as a single species with the same electrophoretic mobility in polyacrylamide gels before and after heat denaturation; (3) at least 20–30% of the RNA molecules extracted from purified virions contain sequences of polyadenylic acid of approximately 4 S size; (4) RNA obtained from detergent-disrupted virus particles by phenol-chloroform extraction is infectious for cultures of chick embryo fibroblasts, giving rise to progeny virus which is lethal for embryonated eggs. These findings, together with the observation that IBV virions do not exhibit detectable transcriptase activity, support the conclusion that the genome of this coronavirus acts directly as a messenger RNA in eukaryotic cells.
RNA with a sedimentation coefficient of 64S was isolated from infectious bronchitis virus, an avian coronavirus. The SNA contained a polyadenylic acid tract and was found to be infectious.
Two of the products commonly used to disinfect the hands of nursing staff are 70% isopropanol and aqueous chlorhexidine-detergent solutions. These have been shown to rapidly destroy respiratory syncytial virus, and are therefore suitable for use where contagious spread of this virus is suspected. The virucidal component of the chlorhexidine-detergent preparation has been shown to be primarily the detergent base and not the chlorhexidine.
Time concentration relations in virus-disinfection by formaldehyde, benzalkonium-chloride, ethanol and isopropanol are evaluated. The exposure time needed to reduce the number of plaque-forming units (PFU) by 10(-3) (99.9%) at a given disinfectant concentration was determined. Influenzavirus, Coxsackie B viruses, Herpesvirus and Mumpsvirus were used in the experiments. Formaldehyde is effective at very low concentrations, provided that sufficient time is allowed for reaction, but has little use in short-term applications. Alcohols act very rapidly at the optimal concentration, but are almost completely ineffective if the reagent is only slightly diluted. Isopropanol does not neutralize entero-viruses to any considerable extent. The effect of the alcohols on viruses is greatly enhanced by the addition of alkali. An 80% (or higher) ethanol solution containing 0.01 n NaOH is very promising as a potent antiviral disinfectant for skin and surface decontamination. Even closely related virus types may differ greatly in their sensitivity to ethanol. The Herpesvirus hominis has a peculiarly high sensitivity to benzalconiumchloride, a sensitivity which is not shared by the Influenzavirus and enteroviruses.
To test whether nosocomial spread of respiratory syncytial virus (RSV) could occur through contact with environmental surfaces contaminated by RSV-infected nasal secretions, survival in the environment of RSV isolated from media, pooled adult secretions, and secretions from hospitalized infants was examined. RSV in freshly obtained infant secretions was recovered from countertops for up to 6 hr, from rubber gloves for up to 1 1/2 hr, from cloth gowns and paper tissue for 30–45 min, and from skin for up to 20 min. RSV in media and pooled secretions survived for slightly longer periods. Further experiments demonstrated that infectious virus could be transferred to hands touching these contaminated surfaces and could be recovered from these hands for up to 25 min. These studies suggest that survival of RSV in the environment of infected infant secretions is sufficient to allow transfer of infectious virus to the hands of hospital personnel. Thus, self-inoculation by contact with contaminated infant secretions may be a potential mode of nosocomial transmission of RSV.
A standardized test procedure is described in which finger tips are inoculated with bovine rotavirus. The level of virus recovered after disinfection of artificially contaminated hands with various disinfectant detergents, alcoholic solutions and alcoholic formulations was determined. The method was found to be easy to perform and reproducible. The most efficient method for removal of virus from fingertips was found to be treatment with alcoholic solutions or products. Soap and water and disinfectant detergents were found to be a much less effective method of removing virus from contaminated hands.