scholarly journals Adherence of SARS-CoV-2 delta variant to surgical mask and N95 respirators

2022 ◽  
Author(s):  
Ana C Lorenzo-Leal ◽  
Selvarani Vimalanathan ◽  
Horacio Bach
Keyword(s):  
Plaque Assay ◽  
Vero Cells ◽  
Log Reduction ◽  
N95 Respirators

The use of facial protection, including masks and respirators, has been adopted globally due to the COVID-19 pandemic. These products have been demonstrated to be effective in reducing the transmission of the virus. To determine whether or not the virus adheres to masks and respirators, we dissected four respirators and one surgical mask into layers. These individual layers were contaminated with the SARS-CoV-2 delta variant, and its release by vortexing was performed. Samples were used to infect Vero cells, and a plaque assay was used to determine to evaluate the adherence of the virus. Results showed that a cumulative log reduction of the layers reduced the load of the virus six-folds. Our study confirms the effectiveness of facial protection in reducing the transmission and or infection of the virus.

scholarly journals Volume and surface changes in vero cell and its nucleus after infection with measles virus: a stereological study

2011 ◽  
Vol 2 (1) ◽  
pp. 18
Author(s):  
Ali Noorafshan ◽  
Mohammad Motamedifar ◽  
Saied Karbalay-Doust
Keyword(s):  
Vero Cell ◽  
Post Infection ◽  
Measles Virus ◽  
Plaque Assay ◽  
Vero Cells ◽  
Uninfected Control ◽  
Mean Cell Volume ◽  
Significant Difference ◽  
Infected Cells ◽  
The Mean

Measles virus has no or indistinctive cytopathic effects (CPE) in cell couture system. Employment of some detecting methods like plaque assay or stereologic experiments, as a method of detecting of viral infection in the cells would be applicable. The aim of this study was investigating the early changes in quantitative parameters of measles virus infected Vero cells. Stereological methods using invariator, were applied for the first time to estimate cell and nucleus volume and cell surface of the infected Vero cell line with the measles virus.This method can be applied on other cultured cells.Vero cells grown in tissue culture plates for 48 hours at 36˚C were infected with 100TCID50 of AiK strain of measles virus. Volume and surface of the infected Vero cells were studied at 4, 9 and 25 hours post infection along with uninfected control cells. The mean cell volume and surface of the cells infected with measles virus, increased ~87% and ~50%, respectively, 4 hours post-infection, as compared with the uninfected control. The nuclei did not show any differences. The mean parameters of infected cells in other time intervals showed no significant difference comparing with the control cells. Although there are other specific methods, stereology may be used as an integrated protocol to detect cytophatic changes of the measles virus infected cells early in the permissive cell culture system.

scholarly journals Silicon Nitride Inactivates SARS-CoV-2 in vitro

2020 ◽  
Author(s):  
Caitlin W. Lehman ◽  
Rafaela Flur ◽  
Kylene Kehn-Hall ◽  
Bryan J. McEntire ◽  
B. Sonny Bal ◽  
...  
Keyword(s):  
Silicon Nitride ◽  
Mammalian Cells ◽  
Aqueous Suspension ◽  
Bacterial Species ◽  
Plaque Assay ◽  
Treatment Strategies ◽  
Vero Cells ◽  
Growth Media ◽  
Minimal Impact

ABSTRACTIntroductionSevere acute respiratory syndrome coronavirus 2 (SARS-CoV-2), which is responsible for the COVID-19 pandemic, remains viable and therefore potentially infectious on several materials. One strategy to discourage the fomite-mediated spread of COVID-19 is the development of materials whose surface chemistry can spontaneously inactivate SARS-CoV-2. Silicon nitride (Si3N4), a material used in spine fusion surgery, is one such candidate because it has been shown to inactivate several bacterial species and viral strains. This study hypothesized that contact with Si3N4 would inactivate SARS-CoV-2, while mammalian cells would remain unaffected.MaterialsSARS-CoV-2 virions (2×104 PFU/mL diluted in growth media) were exposed to 5, 10, 15, and 20% (w/v) of an aqueous suspension of sintered Si3N4 particles for durations of 1, 5, and 10 minutes, respectively. Before exposure to the virus, cytotoxicity testing of Si3N4 alone was assessed in Vero cells at 24 and 48 hour post-exposure times. Following each exposure to Si3N4, the remaining infectious virus was quantitated by plaque assay.ResultsVero cell viability increased at 5% and 10% (w/v) concentrations of Si3N4 at exposure times up to 10 minutes, and there was only minimal impact on cell health and viability up to 20% (w/v). However, the SARS-CoV-2 titers were markedly reduced when exposed to all concentrations of Si3N4; the reduction in viral titers was between 85% - 99.6%, depending on the dose and duration of exposure.ConclusionsSi3N4 was non-toxic to the Vero cells while showing strong antiviral activity against SARS-CoV-2. The viricidal effect increased with increasing concentrations of Si3N4 and longer duration of exposure. Surface treatment strategies based on Si3N4 may offer novel methods to discourage SARS-CoV-2 persistence and infectivity on surfaces and discourage the spread of COVID-19.

scholarly journals Scalable, effective, and rapid decontamination of SARS-CoV-2 contaminated N95 respirators using germicidal ultra-violet C (UVC) irradiation device

2020 ◽  
Author(s):  
Raveen Rathnasinghe ◽  
Robert F. Karlicek ◽  
Michael Schotsaert ◽  
Mattheos Koffas ◽  
Brigitte Arduini ◽  
...  
Keyword(s):  
Ultra Violet ◽  
Front Line ◽  
Log Reduction ◽  
Healthcare Settings ◽  
Front Line Workers ◽  
N95 Respirators ◽  
Primary Measure ◽  
Level 2 ◽  
Irradiation Device ◽  
Biosafety Level

AbstractImportanceParticulate respirators such as N95 masks are an essential component of personal protective equipment (PPE) for front-line workers. This study describes a rapid and effective UVC irradiation system that would facilitate the safe re-use of N95 respirators and provides supporting information for deploying UVC for decontamination of SARS-CoV-2 during the COVID19 pandemic.ObjectiveTo assess the inactivation potential of the proposed UVC germicidal device as a function of time by using 3M® 8211 - N95 particulate respirators inoculated with SARS-CoV-2.DesignA germicidal UVC device to deliver tailored UVC dose was developed and snippets (2.5cm2) of the 3M-N95 respirator were inoculated with 106 plaque-forming units (PFU) of SARS-CoV-2 and were UV irradiated. Different exposure times were tested (0-164 seconds) by fixing the distance between the lamp (10 cm) and the mask while providing an exposure of at least 5.43 mWcm-2.SettingThe current work is broadly applicable for healthcare-settings, particularly during a pandemic such as COVID-19.ParticipantsNot applicable.Main Outcome(s) and Measure(s)Primary measure of outcome was titration of infectious virus recovered from virus-inoculated respirator pieces after UVC exposure. Other measures included the method validation of the irradiation protocol, using lentiviruses (biosafety level-2 agent) and establishment of the germicidal UVC exposure protocol.ResultsAn average of 4.38×103 PFUml-1(SD 772.68) was recovered from untreated masks while 4.44×102 PFUml-1(SD 203.67), 4.00×102 PFUml-1(SD 115.47), 1.56×102 PFUml-1(SD 76.98) and 4.44×101 PFUml-1(SD 76.98) was recovered in exposures 2s,6s,18s and 54 seconds per side respectively. The germicidal device output and positioning was monitored and a minimum output of 5.43 mWcm-2 was maintained. Infectious SARS-CoV-2 was not detected by plaque assays (minimal level of detection is 67 PFUml-1) on N95 respirator snippets when irradiated for 120s per side or longer suggesting 3.5 log reduction in 240 seconds of irradiation.Conclusions and RelevanceA scalable germicidal UVC device to deliver tailored UVC dose for rapid decontamination of SARS-CoV-2 was developed. UVC germicidal irradiation of N95 snippets inoculated with SARS-CoV-2 for 120s per side resulted in 100% (3.5 log in total) reduction of virus. These data support the reuse of N95 particle-filtrate apparatus upon irradiation with UVC and supports use of UVC-based decontamination of SARS-CoV-2 virus during the COVID19 pandemic.

Evaluation of Copper Alloy Surfaces for Inactivation of Tulane Virus and Human Noroviruses

2020 ◽  
Vol 83 (10) ◽  
pp. 1782-1788
Author(s):  
JORDAN D. RECKER ◽  
XINHUI LI
Keyword(s):  
Copper Alloy ◽  
Copper Alloys ◽  
Plaque Assay ◽  
Copper Surface ◽  
Surface Treatments ◽  
Qpcr Assay ◽  
Alloy Surface ◽  
Log Reduction ◽  
Porcine Gastric Mucin ◽  
Tulane Virus

ABSTRACT This study evaluated the efficacy of copper alloy surfaces for inactivation of Tulane virus (TV), assessed by plaque assay and porcine gastric mucin–conjugated magnetic bead (PGM-MB) binding assay, followed by quantitative reverse transcription PCR (PGM-MB–RT-qPCR assay). In addition, the efficacy of a copper surface for inactivation of human norovirus (HuNoV) GII.4 Sydney and GI.3B Potsdam strains was evaluated by PGM-MB–RT-qPCR assay. Results of time-dependent inactivation of viruses on copper, bronze, and brass coupons revealed that 15 min of surface treatments of each of the copper and copper alloys achieved >4-log reduction of purified TV, as assessed by plaque assay, while up to 20 min of copper alloy surface treatments only achieved ∼2-log reduction, as assessed by PGM-MB–RT-qPCR assay. As assessed by PGM-MB–RT-qPCR assay, 10 min of copper surface treatments achieved reductions of 3 and 4 log units for HuNoVs GII.4 Sydney and GI.3B Potsdam, respectively. Results from this study suggest that even though PGM-MB–RT-qPCR assay underestimated the efficacy of copper alloy surface inactivation of TV, copper alloy surfaces were able to effectively inactivate TV and HuNoVs. Therefore, copper alloys can be used as a preventive measure to prevent HuNoV infection and are an effective surface treatment for HuNoVs. HIGHLIGHTS

scholarly journals Chloroquine Inhibits Dengue Virus Type 2 Replication in Vero Cells but Not in C6/36 Cells

2013 ◽  
Vol 2013 ◽  
pp. 1-5 ◽  
Author(s):  
Kleber Juvenal Silva Farias ◽  
Paula Renata Lima Machado ◽  
Benedito Antônio Lopes da Fonseca
Keyword(s):  
Dengue Virus ◽  
Virus Type ◽  
Mammalian Cells ◽  
Plaque Assay ◽  
Antiviral Drug ◽  
Vero Cells ◽  
Significant Difference ◽  
Dengue Virus Type 2

Dengue viruses are the most important arthropod-borne viruses in terms of morbidity and mortality in the world. Since there is no dengue vaccine available for human use, we have set out to investigate the use of chloroquine as an antiviral drug against dengue. Chloroquine, an amine acidotropic drug known to affect intracellular exocytic pathways by increasing endosomal pH, was used in the in vitro treatment of Vero and C6/36 cells infected with dengue virus type 2 (DENV-2). Real-time RT-PCR and plaque assays were used to quantify the DENV-2 load in infected Vero and C6/36 cells after chloroquine treatment. Our results showed that a dose of 50 μg/ml of chloroquine was not toxic to the cells and induced a statistically significant inhibition of virus production in infected Vero cells when compared to untreated cells. In C6/36 cells, chloroquine does not induce a statistically significant difference in viral replication when compared to untreated cells, showing that this virus uses an unlikely pathway of penetration in these cells, and results were also confirmed by the plaque assay (PFU). These data suggest that the inhibition of virus infection induced by chloroquine is due to interference with acidic vesicles in mammalian cells.

Inactivation of Norovirus Surrogates on Surfaces and Raspberries by Steam-Ultrasound Treatment

2012 ◽  
Vol 75 (2) ◽  
pp. 376-381 ◽  
Author(s):  
ANNA CHARLOTTE SCHULTZ ◽  
KATRINE UHRBRAND ◽  
BIRGIT NØRRUNG ◽  
ANDERS DALSGAARD
Keyword(s):  
Treatment Time ◽  
Plaque Assay ◽  
Disease Outbreaks ◽  
Ultrasound Treatment ◽  
Murine Norovirus ◽  
Power Ultrasound ◽  
Real Time Quantitative Pcr ◽  
Log Reduction ◽  
High Power Ultrasound ◽  
Plastic Surfaces

Human disease outbreaks caused by norovirus (NoV) following consumption of contaminated raspberries are an increasing problem. An efficient method to decontaminate the fragile raspberries and the equipment used for processing would be an important step in ensuring food safety. A potential surface treatment that combines pressurized steam and high-power ultrasound (steam-ultrasound) was assessed for its efficacy to inactivate human NoV surrogates: coliphage (MS2), feline calicivirus (FCV), and murine norovirus (MNV) inoculated on plastic surfaces and MS2 inoculated on fresh raspberries. The amounts of infectious virus and viral genomes were determined by plaque assay and reverse transcription–real time quantitative PCR (RT-qPCR), respectively. On plastic surfaces, an inactivation of >99.99% was obtained for both MS2 and FCV, corresponding to a 9.1-log and >4.8-log reduction after 1 or 3 s of treatment, respectively; while a 3.7-log (99.97%) reduction of MNV was reached after 3 s of treatment. However, on fresh raspberries only a 1-log reduction (~89%) of MS2 could be achieved after 1 s of treatment, at which point damage to the texture of the fresh raspberries was evident. Increasing treatment time (0 to 3 s) resulted in negligible reductions of viral genome titers of MS2, FCV, and MNV on plastic surfaces as well as of MS2 inoculated on raspberries. Steam-ultrasound treatment in its current format does not appear to be an appropriate method to achieve sufficient decontamination of NoV-contaminated raspberries. However, steam-ultrasound may be used to decontaminate smooth surface areas and utensils in food production and processing environments.

Development of a real-time RT-PCR assay combined with ethidium monoazide treatment for RNA viruses and its application to detect viral RNA after heat exposure

2011 ◽  
Vol 63 (3) ◽  
pp. 502-507 ◽  
Author(s):  
K. Kim ◽  
H. Katayama ◽  
M. Kitajima ◽  
Y. Tohya ◽  
S. Ohgaki
Keyword(s):  
Rna Viruses ◽  
Heat Exposure ◽  
Plaque Assay ◽  
Gel Filtration ◽  
Viral Rna ◽  
Rt Pcr ◽  
Ethidium Monoazide ◽  
Log Reduction ◽  
Spin Column ◽  
Pcr Method

A method was developed for discriminating damaged viruses or naked viral RNA from intact viruses by ethidium monoazide (EMA) treatment before RT-PCR. The applied EMA treatment consisted of three steps: (1) EMA dose, (2) exposure to light, and (3) additional purification by spin-column gel filtration. Approximately 4-log reduction in viral RNA concentration was observed by adding a dose of 10 μg/mL-EMA with 300 s of light irradiation. Although residual EMA can be an inhibitor of RT-PCR, its effect was reduced by spin-column gel filtration or a QIAamp® Viral RNA Mini Kit. EMA-RT-PCR was applied to the thermally treated PV1. Results of EMA-RT-PCR were similar to the plaque assay when PV1 was thermally inactivated. Although this is a preliminary study investigating applicability of the EMA-RT-PCR method for RNA viruses, the results suggest that the method is potentially applicable for the selective detection of epidemiologically important enteric viruses in water such as enteroviruses and noroviruses.

scholarly journals Survival and Inactivation by Advanced Oxidative Process of Foodborne Viruses in Model Low-Moisture Foods

2021 ◽  
Vol 13 (1) ◽  
pp. 107-116
Author(s):  
Neda Nasheri ◽  
Jennifer Harlow ◽  
Angela Chen ◽  
Nathalie Corneau ◽  
Sabah Bidawid
Keyword(s):  
Ambient Temperature ◽  
Hepatitis A Virus ◽  
Plaque Assay ◽  
Oxidative Process ◽  
Limited Information ◽  
Foodborne Viruses ◽  
Log Reduction ◽  
Viral Survival ◽  
Low Moisture Foods ◽  
Advanced Oxidative Process

AbstractEnteric viruses, such as human norovirus (NoV) and hepatitis A virus (HAV), are the major causes of foodborne illnesses worldwide. These viruses have low infectious dose, and may remain infectious for weeks in the environment and food. Limited information is available regarding viral survival and transmission in low-moisture foods (LMF). LMFs are generally considered as ready-to-eat products, which undergo no or minimal pathogen reduction steps. However, numerous foodborne viral outbreaks associated with LMFs have been reported in recent years. The objective of this study was to examine the survival of foodborne viruses in LMFs during 4-week storage at ambient temperature and to evaluate the efficacy of advanced oxidative process (AOP) treatment in the inactivation of these viruses. For this purpose, select LMFs such as pistachios, chocolate, and cereal were inoculated with HAV and the norovirus surrogates, murine norovirus (MNV) and feline calicivirus (FCV), then viral survival on these food matrices was measured over a four-week incubation at ambient temperature, by both plaque assay and droplet-digital RT-PCR (ddRT-PCR) using the modified ISO-15216 method as well as the magnetic bead assay for viral recovery. We observed an approximately 0.5 log reduction in viral genome copies, and 1 log reduction in viral infectivity for all three tested viruses following storage of select inoculated LMFs for 4 weeks. Therefore, the present study shows that the examined foodborne viruses can persist for a long time in LMFs. Next, we examined the inactivation efficacy of AOP treatment, which combines UV-C, ozone, and hydrogen peroxide vapor, and observed that while approximately 100% (4 log) inactivation can be achieved for FCV, and MNV in chocolate, the inactivation efficiency diminishes to approximately 90% (1 log) in pistachios and 70% (< 1 log) in cereal. AOP treatment could therefore be a good candidate for risk reduction of foodborne viruses from certain LMFs depending on the food matrix and surface of treatment.

scholarly journals Vapor H2O2 sterilization as a decontamination method for the reuse of N95 respirators in the COVID-19 emergency

2020 ◽  
Author(s):  
Ebru Oral ◽  
Keith K. Wannomae ◽  
Rachel Connolly ◽  
Joseph Gardecki ◽  
Hui Min Leung ◽  
...  
Keyword(s):  
Hydrogen Peroxide ◽  
Staphylococcus Aureus ◽  
Medical Devices ◽  
Healthcare Workers ◽  
Hospital Environment ◽  
Bacterial Spores ◽  
Filter Efficiency ◽  
Plasma Generation ◽  
Log Reduction ◽  
N95 Respirators

There are a variety of methods routinely used in the sterilization of medical devices using hydrogen peroxide (H2O2) including vaporization, plasma generation and ionization. Many of these systems are used for sterilization and are validated for bioburden reduction using bacterial spores.Here, we explored the benefits of using vaporized H2O2 (VHP) treatment of N95 respirators for emergency decontamination and reuse to alleviate PPE shortages for healthcare workers in the COVID-19 emergency. The factors that are considered for the effective reuse of these respirators are the fit, the filter efficiency and the decontamination/disinfection level for SARS-CoV-2, which is the causative virus for COVID-19 and other organisms of concern in the hospital environment such as methicillin-resistant Staphylococcus aureus or Clostridium difficile. WE showed that the method did not affect fit or filter efficiency at least for one cycle and resulted in a >6 log reduction in bacterial spores and >3.8 log reduction in the infectious SARS-CoV2 load on N95 respirators.

scholarly journals Rapid Inactivation of Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) by Tungsten Trioxide-Based (WO3) Photocatalysis

2020 ◽  
Author(s):  
Silvia Ghezzi ◽  
Isabel Pagani ◽  
Guido Poli ◽  
Stefano Perboni ◽  
Elisa Vicenzi
Keyword(s):  
Severe Acute Respiratory Syndrome ◽  
Tungsten Trioxide ◽  
Plaque Assay ◽  
Vero Cells ◽  
Viral Rna ◽  
Indoor Environments ◽  
Viral Plaque ◽  
Droplet Nuclei ◽  
Indoor Conditions ◽  
Respiratory Droplets

AbstractSevere acute respiratory syndrome coronavirus-2 (SARS-CoV-2), the etiological agent of coronavirus disease 2019 (COVID-19), is transmitted person-to-person via respiratory droplets and, likely, via smaller droplet nuclei light enough to remain suspended in the air for hours and contaminate surfaces particularly in indoor conditions. Thus, effective measures are needed to prevent SARS-CoV-2 transmission in indoor environments. In this regard, we have investigated whether a system based on a filter combining Tungsten Trioxide-Based (WO3) photocatalysis and an antiviral fabric treated-copper nanocluster could inactivate SARS-CoV-2. To this purpose, an infectious SARS-CoV-2 suspension was introduced in the upper opening of a closed cylinder containing a WO3 filter and a lightbased system that activates WO3 and the antiviral fabric. From the bottom exit, aliquots of fluid were collected every 10 min (up to 60 min) and tested for their infectivity by means of a viral plaque assay in Vero cells whereas, in parallel, the viral RNA content was measured by quantitative PCR (qPCR). As we have previously shown for SARS-CoV, a 1:1,000 ratio of plaque forming units (PFU) vs. viral RNA copies was observed also for SARS-CoV-2. After 10 min, the infectious viral content was already decreased by 98.2% reaching 100% inactivation after 30 min whereas the SARS-CoV-2 RNA load was decreased of 1.5 log10 after 30 min. Thus, in spite of only a partial decrease of viral RNA, SARS-CoV-2 infectivity was completely abolished by the WO3 photocatalysis system by 30 min. These results support the hypothesis that this system could be exploited to achieve SARS-CoV-2 inactivation in indoor environments.

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