Reaerosolization of MS2 Bacteriophage from an N95 Filtering Facepiece Respirator by Simulated Coughing

Abstract The supply of N95 filtering facepiece respirators (FFRs) may not be adequate to match demand during a pandemic outbreak. One possible strategy to maintain supplies in healthcare settings is to extend FFR use for multiple patient encounters; however, contaminated FFRs may serve as a source for the airborne transmission of virus particles. In this study, reaerosolization of virus particles from contaminated FFRs was examined using bacteriophage MS2 as a surrogate for airborne pathogenic viruses. MS2 was applied to FFRs as droplets or droplet nuclei. A simulated cough (370 l min−1 peak flow) provided reverse airflow through the contaminated FFR. The number and size of the reaerosolized particles were measured using gelatin filters and an Andersen Cascade Impactor (ACI). Two droplet nuclei challenges produced higher percentages of reaerosolized particles (0.21 and 0.08%) than a droplet challenge (<0.0001%). Overall, the ACI-determined size distribution of the reaerosolized particles was larger than the characterized loading virus aerosol. This study demonstrates that only a small percentage of viable MS2 viruses was reaerosolized from FFRs by reverse airflow under the conditions evaluated, suggesting that the risks of exposure due to reaerosolization associated with extended use can be considered negligible for most respiratory viruses. However, risk assessments should be updated as new viruses emerge and better workplace exposure data becomes available.

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Targeting Viral Surface Proteins through Structure-Based Design

Viruses ◽

10.3390/v13071320 ◽

2021 ◽

Vol 13 (7) ◽

pp. 1320

Author(s):

Yogesh B Narkhede ◽

Karen J Gonzalez ◽

Eva-Maria Strauch

Keyword(s):

Public Health ◽

Viral Infections ◽

Respiratory Viruses ◽

Surface Proteins ◽

Host Cells ◽

Viral Fusion ◽

Health It ◽

Viral Particles ◽

Pathogenic Viruses ◽

Viral Surface

The emergence of novel viral infections of zoonotic origin and mutations of existing human pathogenic viruses represent a serious concern for public health. It warrants the establishment of better interventions and protective therapies to combat the virus and prevent its spread. Surface glycoproteins catalyzing the fusion of viral particles and host cells have proven to be an excellent target for antivirals as well as vaccines. This review focuses on recent advances for computational structure-based design of antivirals and vaccines targeting viral fusion machinery to control seasonal and emerging respiratory viruses.

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Transkingdom interactions important for the pathogenesis of human viruses

The Journal of Infectious Diseases ◽

10.1093/infdis/jiaa735 ◽

2020 ◽

Author(s):

Andrew Nishimoto ◽

Nicholas Wohlgemuth ◽

Jason Rosch ◽

Stacey Schultz-Cherry ◽

Valerie Cortez ◽

...

Keyword(s):

Tissue Remodeling ◽

Respiratory Viruses ◽

Viral Pathogenesis ◽

Indirect Interactions ◽

Mammalian Host ◽

Murine Models ◽

Pathogenic Viruses ◽

Health And Disease ◽

Human Viruses

Abstract The bacterial, fungal and helminthic species that comprise the microbiome of the mammalian host have profound effects on health and disease. Pathogenic viruses must contend with the microbiome during infection, and likely have evolved to exploit or evade the microbiome. Both direct interactions between the virions and the microbiota and immunomodulation and tissue remodeling caused by the microbiome alter viral pathogenesis in either host- or virus-beneficial ways. Recent insights from in vitro and murine models of viral pathogenesis have highlighted synergistic and antagonistic, direct and indirect interactions between the microbiome and pathogenic viruses. This review will focus on the transkingdom interactions between human gastrointestinal and respiratory viruses and the constituent microbiome of those tissues.

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Which healthcare workers work with acute respiratory illness? Evidence from Canadian acute-care hospitals during 4 influenza seasons: 2010–2011 to 2013–2014

Infection Control and Hospital Epidemiology ◽

10.1017/ice.2019.141 ◽

2019 ◽

Vol 40 (8) ◽

pp. 889-896 ◽

Cited By ~ 9

Author(s):

Lili Jiang ◽

Allison McGeer ◽

Shelly McNeil ◽

Kevin Katz ◽

Mark Loeb ◽

...

Keyword(s):

Healthcare Workers ◽

Multivariable Analysis ◽

Respiratory Illness ◽

Respiratory Viruses ◽

Onset Date ◽

Adjusted Relative Risk ◽

Acute Respiratory Illness ◽

Illness Onset ◽

Factors Associated ◽

Healthcare Settings

AbstractBackground:Healthcare workers (HCWs) are at risk of acquiring and transmitting respiratory viruses while working in healthcare settings.Objectives:To investigate the incidence of and factors associated with HCWs working during an acute respiratory illness (ARI).Methods:HCWs from 9 Canadian hospitals were prospectively enrolled in active surveillance for ARI during the 2010–2011 to 2013–2014 influenza seasons. Daily illness diaries during ARI episodes collected information on symptoms and work attendance.Results:At least 1 ARI episode was reported by 50.4% of participants each study season. Overall, 94.6% of ill individuals reported working at least 1 day while symptomatic, resulting in an estimated 1.9 days of working while symptomatic and 0.5 days of absence during an ARI per participant season. In multivariable analysis, the adjusted relative risk of working while symptomatic was higher for physicians and lower for nurses relative to other HCWs. Participants were more likely to work if symptoms were less severe and on the illness onset date compared to subsequent days. The most cited reason for working while symptomatic was that symptoms were mild and the HCW felt well enough to work (67%). Participants were more likely to state that they could not afford to stay home if they did not have paid sick leave and were younger.Conclusions:HCWs worked during most episodes of ARI, most often because their symptoms were mild. Further data are needed to understand how best to balance the costs and risks of absenteeism versus those associated with working while ill.

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Separation and Disinfection of Contagious Aerosols from the Perspective of SARS-CoV-2

Separations ◽

10.3390/separations8100190 ◽

2021 ◽

Vol 8 (10) ◽

pp. 190

Author(s):

J. J. H. Brouwers

Keyword(s):

Indoor Air ◽

Service Time ◽

Particle Number ◽

Random Distribution ◽

Particle Removal ◽

Virus Particles ◽

Number Distribution ◽

Clean Air ◽

Particle Separator ◽

Droplet Nuclei

An assessment was performed on methods of separating and disinfecting airborne droplet nuclei containing viruses, such as SARS-CoV-2. The droplet nuclei originate from evaporating aerosols emitted by the coughing, singing, sneezing, etc. of infected humans. Based on empirical data and theoretical analysis, we successively determined: (i) the particle number distribution of nuclei versus the nucleus diameter, (ii) the statistical distribution of the viral content in the droplet nuclei starting from a uniform random distribution of viruses in the mucus, (iii) the particle number distribution of droplet nuclei containing at least one virus particle, and (iv) the effectiveness of methods for removing and disinfecting nuclei containing one or more virus particles from indoor air; viz., ventilation with fresh air, filtering with porous media, such as HEPA, and centrifugal separation and simultaneous disinfection, particularly with a rotational particle separator (RPS). Indoor aerosol removal with RPS supplemented with HEPA to arrest tiny volumes of very small particles was found to be the most effective. It is as good as particle removal through ventilation with clean air over long periods of time. An RPS facilitates direct elimination of viruses in the collected nuclei by flushing with a disinfection liquid. The components of an RPS are recyclable. Combining HEPA with an RPS extends the service time of HEPA by almost two orders of magnitude compared to the relatively short service time of stand-alone HEPA filters.

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Variability of Virus Attachment Patterns to Butterhead Lettuce

Journal of Food Protection ◽

10.4315/0362-028x-68.10.2112 ◽

2005 ◽

Vol 68 (10) ◽

pp. 2112-2117 ◽

Cited By ~ 45

Author(s):

EVERARDO VEGA ◽

JEANON SMITH ◽

JAY GARLAND ◽

ANABELLE MATOS ◽

SURESH D. PILLAI

Keyword(s):

Current Model ◽

The United States ◽

Virus Attachment ◽

Virus Particles ◽

Bacteriophage Ms2 ◽

Virus Adsorption ◽

Strong Adsorption ◽

Complex Adsorption ◽

Current Sample ◽

Butterhead Lettuce

Enteric viruses account for most foodborne illness in the United States. The objective of this study was to determine whether the isoelectric point (pI) of viruses such as feline calicivirus (FCV), echovirus 11, and bacteriophages φX174 and MS2 had any effect on their attachment to butterhead lettuce. The adsorption of virus particles to the lettuce was variable. Bacteriophage MS2 was the only virus that fit the current Derjaguin-Landau-Verway-Overbeek model of virus attachment. Echovirus 11 had the highest affinity to lettuce surface. Echovirus 11 appeared to exhibit reversible attachment above its pI, whereas below its pI strong adsorption was observed. Adsorption of FCV was at its maximum above its pI. Bacteriophage φX174 exhibited the most complex adsorption pattern, with attachment occurring only at the pH extremes (pH 3.0 and 8.0). These results suggest the current model for virus adsorption to sediment does not adequately explain the attachment of virus to lettuce. Importantly, the results indirectly suggest that current sample processing methods to recover viruses from lettuce may differentially select for the recovery of only certain virus types.

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Assessing the Power and Quality of Epidemiologic Studies of Asbestos-Exposed Populations

Toxicology and Industrial Health ◽

10.1177/074823378500100407 ◽

1985 ◽

Vol 1 (4) ◽

pp. 93-110 ◽

Cited By ~ 3

Author(s):

Devra Lee Davis ◽

Barbara Mandula ◽

John Van Ryzin

Keyword(s):

Statistical Power ◽

National Research Council ◽

Epidemiologic Studies ◽

Risk Assessments ◽

Royal Commission ◽

Paper Briefly ◽

Exposure Data ◽

Exposed Workers ◽

Commission Report

This paper briefly discusses criteria for evaluating epidemiologic studies for risk assessment purposes, using asbestos as an example. Asbestos is one of the few carcinogens for which substantial data exist on exposures to humans. However, there are major difficulties in using these data for conducting risk assessments. In particular, exposure data are often incomplete, and risk assessments usually involve extrapolating from the higher exposures of the occupational environments to the lower levels typically encountered in the nonoccupational environment. The term "asbestos" refers to the fibrous form of several minerals, and levels of exposures to these fibers are not easily assessed. Criteria for evaluating epidemiologic studies used in an Ontario Royal Commission report on asbestos are discussed. The importance of considering the statistical power of studies to detect an excess risk is examined using as examples major cohort studies of asbestos-exposed workers, as summarized in a report by the U. S. National Research Council.

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Plant-Derived Food Grade Substances (PDFGS) Active Against Respiratory Viruses: A Systematic Review of Non-clinical Studies

Frontiers in Nutrition ◽

10.3389/fnut.2021.606782 ◽

2021 ◽

Vol 8 ◽

Author(s):

Francis U. Umeoguaju ◽

Benson C. Ephraim-Emmanuel ◽

Kingsley C. Patrick-Iwuanyanwu ◽

Judith T. Zelikoff ◽

Orish Ebere Orisakwe

Keyword(s):

Respiratory Tract ◽

Respiratory Viruses ◽

Host Cells ◽

Food Plants ◽

Influenza B Virus ◽

Influenza B ◽

Human Populations ◽

Human Respiratory Tract ◽

Food Grade ◽

Pathogenic Viruses

Human diet comprises several classes of phytochemicals some of which are potentially active against human pathogenic viruses. This study examined available evidence that identifies existing food plants or constituents of edible foods that have been reported to inhibit viral pathogenesis of the human respiratory tract. SCOPUS and PUBMED databases were searched with keywords designed to retrieve articles that investigated the effect of plant-derived food grade substances (PDFGS) on the activities of human pathogenic viruses. Eligible studies for this review were those done on viruses that infect the human respiratory tract. Forty six (46) studies met the specified inclusion criteria from the initial 5,734 hits. The selected studies investigated the effects of different PDFGS on the infectivity, proliferation and cytotoxicity of different respiratory viruses including influenza A virus (IAV), influenza B virus (IBV), Respiratory syncytial virus (RSV), human parainfluenza virus (hPIV), Human coronavirus NL63 (HCoV-NL63), and rhinovirus (RV) in cell lines and mouse models. This review reveals that PDFGS inhibits different stages of the pathological pathways of respiratory viruses including cell entry, replication, viral release and viral-induced dysregulation of cellular homeostasis and functions. These alterations eventually lead to the reduction of virus titer, viral-induced cellular damages and improved survival of host cells. Major food constituents active against respiratory viruses include flavonoids, phenolic acids, tannins, lectins, vitamin D, curcumin, and plant glycosides such as glycyrrhizin, acteoside, geniposide, and iridoid glycosides. Herbal teas such as guava tea, green and black tea, adlay tea, cistanche tea, kuding tea, licorice extracts, and edible bird nest extracts were also effective against respiratory viruses in vitro. The authors of this review recommend an increased consumption of foods rich in these PDFGS including legumes, fruits (e.g berries, citrus), tea, fatty fish and curcumin amongst human populations with high prevalence of respiratory viral infections in order to prevent, manage and/or reduce the severity of respiratory virus infections.

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N6-Methyladenosine Modification and Its Regulation of Respiratory Viruses

Frontiers in Cell and Developmental Biology ◽

10.3389/fcell.2021.699997 ◽

2021 ◽

Vol 9 ◽

Author(s):

Qianyu Feng ◽

Hongwei Zhao ◽

Lili Xu ◽

Zhengde Xie

Keyword(s):

Life Cycle ◽

Disease Burden ◽

Respiratory Virus ◽

Respiratory Viruses ◽

Host Immunity ◽

Rna Modification ◽

Host Interactions ◽

Wide Range ◽

Pathogenic Viruses

N6-methyladenosine (m6A) is a ubiquitous RNA modification in eukaryotes. It plays important roles in the translocation, stabilization and translation of mRNA. Many recent studies have shown that the dysregulation of m6A modification is connected with diseases caused by pathogenic viruses, and studies on the role of m6A in virus-host interactions have shown that m6A plays a wide range of regulatory roles in the life cycle of viruses. Respiratory viruses are common pathogens that can impose a large disease burden on young children and elderly people. Here, we review the effects of m6A modification on respiratory virus replication and life cycle and host immunity against viruses.

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Contamination of air and surfaces in workplaces with SARS-CoV-2 virus: a systematic review

10.1101/2021.01.25.21250233 ◽

2021 ◽

Author(s):

JW Cherrie ◽

MPC Cherrie ◽

A Davis ◽

D Holmes ◽

S Semple ◽

...

Keyword(s):

Systematic Review ◽

Health Care ◽

Respiratory Viruses ◽

Work Environments ◽

List Type ◽

Limited Data ◽

Health Care Settings ◽

Healthcare Settings ◽

Virus Rna

ABSTRACTObjectivesThis systematic review aimed to evaluate the evidence for air and surface contamination of workplace environments with SARS-CoV-2 RNA and the quality of the methods used to identify actions necessary to improve the quality of the data.MethodsWe searched Web of Science and Google Scholar until 24th December 2020 for relevant articles and extracted data on methodology and results.ResultsThe vast majority of data come from healthcare settings, with typically around 6 % of samples having detectable concentrations of SARS-CoV-2 RNA and almost none of the samples collected had viable virus. There were a wide variety of methods used to measure airborne virus, although surface sampling was generally undertaken using nylon flocked swabs. Overall, the quality of the measurements was poor. Only a small number of studies reported the airborne concentration of SARS-CoV-2 virus RNA, mostly just reporting the detectable concentration values without reference to the detection limit. Imputing the geometric mean air concentration assuming the limit of detection was the lowest reported value, suggests typical concentrations in health care settings may be around 0.01 SARS-CoV-2 virus RNA copies/m3. Data on surface virus loading per unit area were mostly unavailable.ConclusionThe reliability of the reported data is uncertain. The methods used for measuring SARS-CoV-2 and other respiratory viruses in work environments should be standardised to facilitate more consistent interpretation of contamination and to help reliably estimate worker exposure.Key messagesWhat is already known about this subject?Low level contamination of air and surfaces in hospitals with SARS-CoV-2 RNA have been reported during the Covid-19 pandemic.Limited data have published from non-healthcare settings.What are the new findings?Typically, around 6% of air and surface samples in hospitals were positive for SARS-COV-2 RNA, although there is very limited data for non-healthcare settings.The quality of the available measurement studies is generally poor, with little consistency in the sampling and analytical methods used.Few studies report the concentration of SARS-CoV-2 in air or as surface loading of virus RNA, and very few studies have reported culture of the virus.The best estimate of typical air concentrations in health care settings is around 0.01 SARS-CoV-2 virus RNA copies/m3How might this impact on policy or clinical practice in the foreseeable future?There should be concerted efforts to standardise the methods used for measuring SARS-CoV-2 and other respiratory viruses in work environments.

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Liquid-Immersion Reprocessing Effects on Filtration Efficiency of ‘Single-Use’ Commercial Medical Face Masks

Annals of Work Exposures and Health ◽

10.1093/annweh/wxab079 ◽

2021 ◽

Author(s):

Richard J Everts ◽

Shadha Al Ghusaini ◽

Lucy Telfar-Barnard ◽

Ella Barclay ◽

Shaun Tan ◽

...

Keyword(s):

Water Immersion ◽

Respiratory Viruses ◽

Filtration Efficiency ◽

Hot Water ◽

Pressure Differential ◽

High Quality ◽

Healthcare Settings ◽

Laundry Machine ◽

Single Use ◽

Liquid Immersion

Abstract Purpose Medical masks have inferior filtration efficiency and fit to filtering facepiece respirators (FFRs) but are widely used in healthcare and the community. These masks are intended for disposal after use but in the event of mask shortage re-use after reprocessing may be an option. We investigated eight reprocessing methods that each involved washing or soaking in liquid, are likely to eliminate respiratory viruses, and are safe and available in most community and healthcare settings. Methods Three brands of EN 14683 standards-compliant commercial medical mask were each reprocessed 10 times by one of eight methods. We measured filtration efficiency for poly-dispersed sodium chloride particles and pressure differential. Results Compared with new medical masks, reprocessed masks had significantly reduced filtration efficiency. The reduction was mild-moderate (6.5–25.8%) after warm water wash, hot water soak or boiling water soak; and moderate-large (24.1–51.5%) after detergent, soap or laundry machine wash, or bleach soak. There were mixed and minor changes in pressure differential. Most reprocessed standards-compliant masks had better filtration efficiency than new non-standard commercial masks and then cotton and cotton-polyester mix fabric samples, even triple-layered fabrics. Conclusions High-quality commercial medical masks reprocessed 10 times by water immersion methods had better filtration efficiency than new non-standard masks and washable fabrics. These findings have particular relevance for community and low-resource healthcare settings.

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