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  1. Article ; Online: Toward Standardized Aerovirology: A Critical Review of Existing Results and Methodologies.

    Groth, Robert / Niazi, Sadegh / Oswin, Henry P / Haddrell, Allen E / Spann, Kirsten / Morawska, Lidia / Ristovski, Zoran

    Environmental science & technology

    2024  Volume 58, Issue 8, Page(s) 3595–3608

    Abstract: Understanding the airborne survival of viruses is important for public health and epidemiological modeling and potentially to develop mitigation strategies to minimize the transmission of airborne pathogens. Laboratory experiments typically involve ... ...

    Abstract Understanding the airborne survival of viruses is important for public health and epidemiological modeling and potentially to develop mitigation strategies to minimize the transmission of airborne pathogens. Laboratory experiments typically involve investigating the effects of environmental parameters on the viability or infectivity of a target airborne virus. However, conflicting results among studies are common. Herein, the results of 34 aerovirology studies were compared to identify links between environmental and compositional effects on the viability of airborne viruses. While the specific experimental apparatus was not a factor in variability between reported results, it was determined that the experimental procedure was a major factor that contributed to discrepancies in results. The most significant contributor to variability between studies was poorly defined initial viable virus concentration in the aerosol phase, causing many studies to not measure the rapid inactivation, which occurs quickly after particle generation, leading to conflicting results. Consistently, studies that measured their reference airborne viability minutes after aerosolization reported higher viability at subsequent times, which indicates that there is an initial loss of viability which is not captured in these studies. The composition of the particles which carry the viruses was also found to be important in the viability of airborne viruses; however, the mechanisms for this effect are unknown. Temperature was found to be important for aerosol-phase viability, but there is a lack of experiments that directly compare the effects of temperature in the aerosol phase and the bulk phase. There is a need for repeated measurements between different research groups under identical conditions both to assess the degree of variability between studies and also to attempt to better understand already published data. Lack of experimental standardization has hindered the ability to quantify the differences between studies, for which we provide recommendations for future studies. These recommendations are as follows: measuring the reference airborne viability using the "direct method"; use equipment which maximizes time resolution; quantify all losses appropriately; perform, at least, a 5- and 10-min sample, if possible; report clearly the composition of the virus suspension; measure the composition of the gas throughout the experiment. Implementing these recommendations will address the most significant oversights in the existing literature and produce data which can more easily be quantitatively compared.
    MeSH term(s) Viruses ; Aerosols
    Chemical Substances Aerosols
    Language English
    Publishing date 2024-02-14
    Publishing country United States
    Document type Journal Article ; Review
    ISSN 1520-5851
    ISSN (online) 1520-5851
    DOI 10.1021/acs.est.3c07275
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  2. Article ; Online: An assessment of the airborne longevity of group A Streptococcus.

    Oswin, Henry P / Blake, Evie / Haddrell, Allen E / Finn, Adam / Sriskandan, Shiranee / Reid, Jonathan P / Halliday, Alice / Goenka, Anu

    Microbiology (Reading, England)

    2024  Volume 170, Issue 1

    Abstract: Group A streptococcus (GAS) infections result in more than 500 000 deaths annually. Despite mounting evidence for airborne transmission of GAS, little is known about its stability in aerosol. Measurements of GAS airborne stability were carried out using ... ...

    Abstract Group A streptococcus (GAS) infections result in more than 500 000 deaths annually. Despite mounting evidence for airborne transmission of GAS, little is known about its stability in aerosol. Measurements of GAS airborne stability were carried out using the Controlled Electrodynamic Levitation and Extraction of Bioaerosols onto a Substrate (CELEBS) instrument. CELEBS measurements with two different isolates of GAS suggest that it is aerostable, with approximately 70 % of bacteria remaining viable after 20 min of levitation at 50 % relative humidity (RH), with lower survival as RH was reduced. GAS airborne viability loss was driven primarily by desiccation and efflorescence (i.e. salt crystallization), with high pH also potentially playing a role, given reduced survival in bicarbonate containing droplet compositions. At low enough RH for efflorescence to occur, a greater proportion of organic components in the droplet appeared to protect the bacteria from efflorescence. These first insights into the aerosol stability of GAS indicate that airborne transmission of these respiratory tract bacteria may occur, and that both the composition of the droplet containing the bacteria, and the RH of the air affect the duration of bacterial survival in this environment. Future studies will explore a broader range of droplet and air compositions and include a larger selection of GAS strains.
    MeSH term(s) Streptococcus pyogenes ; Sodium Chloride ; Aerosols
    Chemical Substances Sodium Chloride (451W47IQ8X) ; Aerosols
    Language English
    Publishing date 2024-01-05
    Publishing country England
    Document type Journal Article ; Research Support, Non-U.S. Gov't
    ZDB-ID 1180712-x
    ISSN 1465-2080 ; 1350-0872
    ISSN (online) 1465-2080
    ISSN 1350-0872
    DOI 10.1099/mic.0.001421
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  3. Article ; Online: Oxidative Stress Contributes to Bacterial Airborne Loss of Viability.

    Oswin, Henry P / Haddrell, Allen E / Hughes, Cordelia / Otero-Fernandez, Mara / Thomas, Richard J / Reid, Jonathan P

    Microbiology spectrum

    2023  , Page(s) e0334722

    Abstract: While the airborne decay of bacterial viability has been observed for decades, an understanding of the mechanisms driving the decay has remained elusive. The airborne transport of bacteria is often a key step in their life cycle and as such, ... ...

    Abstract While the airborne decay of bacterial viability has been observed for decades, an understanding of the mechanisms driving the decay has remained elusive. The airborne transport of bacteria is often a key step in their life cycle and as such, characterizing the mechanisms driving the airborne decay of bacteria is an essential step toward a more complete understanding of microbial ecology. Using the Controlled Electrodynamic Levitation and Extraction of Bioaerosols onto a Substrate (CELEBS), it was possible to systematically evaluate the impact of different physicochemical and environmental parameters on the survival of Escherichia coli in airborne droplets of Luria Bertani broth. Rather than osmotic stress driving the viability loss, as was initially considered, oxidative stress was found to play a key role. As the droplets evaporate and equilibrate with the surrounding environment, the surface-to-volume ratio increases, which in turn increased the formation of reactive oxygen species in the droplet. These reactive oxygen species appear to play a key role in driving the airborne loss of viability of E. coli.
    Language English
    Publishing date 2023-03-13
    Publishing country United States
    Document type Journal Article
    ZDB-ID 2807133-5
    ISSN 2165-0497 ; 2165-0497
    ISSN (online) 2165-0497
    ISSN 2165-0497
    DOI 10.1128/spectrum.03347-22
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  4. Article ; Online: Aerobiology: Experimental Considerations, Observations, and Future Tools.

    Haddrell, Allen E / Thomas, Richard J

    Applied and environmental microbiology

    2017  Volume 83, Issue 17

    Abstract: Understanding airborne survival and decay of microorganisms is important for a range of public health and biodefense applications, including epidemiological and risk analysis modeling. Techniques for experimental aerosol generation, retention in the ... ...

    Abstract Understanding airborne survival and decay of microorganisms is important for a range of public health and biodefense applications, including epidemiological and risk analysis modeling. Techniques for experimental aerosol generation, retention in the aerosol phase, and sampling require careful consideration and understanding so that they are representative of the conditions the bioaerosol would experience in the environment. This review explores the current understanding of atmospheric transport in relation to advances and limitations of aerosol generation, maintenance in the aerosol phase, and sampling techniques. Potential tools for the future are examined at the interface between atmospheric chemistry, aerosol physics, and molecular microbiology where the heterogeneity and variability of aerosols can be explored at the single-droplet and single-microorganism levels within a bioaerosol. The review highlights the importance of method comparison and validation in bioaerosol research and the benefits that the application of novel techniques could bring to increasing the understanding of aerobiological phenomena in diverse research fields, particularly during the progression of atmospheric transport, where complex interdependent physicochemical and biological processes occur within bioaerosol particles.
    MeSH term(s) Aerosols/analysis ; Air Microbiology ; Bacteria/classification ; Bacteria/genetics ; Bacteria/isolation & purification ; Microbiological Techniques/instrumentation ; Microbiological Techniques/methods ; Microbiological Techniques/trends ; Particle Size
    Chemical Substances Aerosols
    Language English
    Publishing date 2017-08-17
    Publishing country United States
    Document type Journal Article ; Review ; Research Support, Non-U.S. Gov't
    ZDB-ID 223011-2
    ISSN 1098-5336 ; 0099-2240
    ISSN (online) 1098-5336
    ISSN 0099-2240
    DOI 10.1128/AEM.00809-17
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  5. Article: Water Uptake by Evaporating pMDI Aerosol Prior to Inhalation Affects Both Regional and Total Deposition in the Respiratory System.

    Legh-Land, Victoria / Haddrell, Allen E / Lewis, David / Murnane, Darragh / Reid, Jonathan P

    Pharmaceutics

    2021  Volume 13, Issue 7

    Abstract: As pulmonary drug deposition is a function of aerosol particle size distribution, it is critical that the dynamics of particle formation and maturation in pMDI sprays in the interim between generation and inhalation are fully understood. This paper ... ...

    Abstract As pulmonary drug deposition is a function of aerosol particle size distribution, it is critical that the dynamics of particle formation and maturation in pMDI sprays in the interim between generation and inhalation are fully understood. This paper presents an approach to measure the evaporative and condensational fluxes of volatile components and water from and to solution pMDI droplets following generation using a novel technique referred to as the Single Particle Electrodynamic Lung (SPEL). In doing so, evaporating aerosol droplets are shown capable of acting as condensation nuclei for water. Indeed, we show that the rapid vaporisation of volatile components from a volatile droplet is directly correlated to the volume of water taken up by condensation. Furthermore, a significant volume of water is shown to condense on droplets of a model pMDI formulation (hydrofluoroalkane (HFA), ethanol and glycerol) during evaporative droplet ageing, displaying a dramatic shift from a core composition of a volatile species to that of predominantly water (non-volatile glycerol remained in this case). This yields a droplet with a water activity of 0.98 at the instance of inhalation. The implications of these results on regional and total pulmonary drug deposition are explored using the International Commission of Radiological Protection (ICRP) deposition model, with an integrated semi-analytical treatment of hygroscopic growth. Through this, droplets with water activity of 0.98 upon inhalation are shown to produce markedly different dose deposition profiles to those with lower water activities at the point of inspiration.
    Language English
    Publishing date 2021-06-24
    Publishing country Switzerland
    Document type Journal Article
    ZDB-ID 2527217-2
    ISSN 1999-4923
    ISSN 1999-4923
    DOI 10.3390/pharmaceutics13070941
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  6. Article ; Online: Transformative Approach To Investigate the Microphysical Factors Influencing Airborne Transmission of Pathogens.

    Otero Fernandez, Mara / Thomas, Richard J / Oswin, Henry / Haddrell, Allen E / Reid, Jonathan P

    Applied and environmental microbiology

    2020  Volume 86, Issue 23

    Abstract: Emerging outbreaks of airborne pathogenic infections worldwide, such as the current severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) pandemic, have raised the need to understand parameters affecting the airborne survival of microbes in order ... ...

    Abstract Emerging outbreaks of airborne pathogenic infections worldwide, such as the current severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) pandemic, have raised the need to understand parameters affecting the airborne survival of microbes in order to develop measures for effective infection control. We report a novel experimental strategy, TAMBAS (tandem approach for microphysical and biological assessment of airborne microorganism survival), to explore the synergistic interactions between the physicochemical and biological processes that impact airborne microbe survival in aerosol droplets. This innovative approach provides a unique and detailed understanding of the processes taking place from aerosol droplet generation through to equilibration and viability decay in the local environment, elucidating decay mechanisms not previously described. The impact of evaporation kinetics, solute hygroscopicity and concentration, particle morphology, and equilibrium particle size on airborne survival are reported, using
    MeSH term(s) Aerosols ; Air Microbiology ; Betacoronavirus/physiology ; COVID-19 ; Coronavirus Infections/transmission ; Cough/microbiology ; Crystallization ; Escherichia coli/physiology ; Escherichia coli Infections/transmission ; Humans ; Infection Control/methods ; Microbial Viability ; Pandemics ; Particle Size ; Pneumonia, Viral/transmission ; SARS-CoV-2 ; Sneezing/physiology
    Chemical Substances Aerosols
    Keywords covid19
    Language English
    Publishing date 2020-11-10
    Publishing country United States
    Document type Journal Article ; Research Support, Non-U.S. Gov't
    ZDB-ID 223011-2
    ISSN 1098-5336 ; 0099-2240
    ISSN (online) 1098-5336
    ISSN 0099-2240
    DOI 10.1128/AEM.01543-20
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  7. Article: Mucin Transiently Sustains Coronavirus Infectivity through Heterogenous Changes in Phase Morphology of Evaporating Aerosol

    Alexander, Robert W. / Tian, Jianghan / Haddrell, Allen E. / Oswin, Henry P. / Neal, Edward / Hardy, Daniel A. / Otero-Fernandez, Mara / Mann, Jamie F. S. / Cogan, Tristan A. / Finn, Adam / Davidson, Andrew D. / Hill, Darryl J. / Reid, Jonathan P.

    Viruses. 2022 Aug. 24, v. 14, no. 9

    2022  

    Abstract: Respiratory pathogens can be spread though the transmission of aerosolised expiratory secretions in the form of droplets or particulates. Understanding the fundamental aerosol parameters that govern how such pathogens survive whilst airborne is essential ...

    Abstract Respiratory pathogens can be spread though the transmission of aerosolised expiratory secretions in the form of droplets or particulates. Understanding the fundamental aerosol parameters that govern how such pathogens survive whilst airborne is essential to understanding and developing methods of restricting their dissemination. Pathogen viability measurements made using Controlled Electrodynamic Levitation and Extraction of Bioaerosol onto Substrate (CELEBS) in tandem with a comparative kinetics electrodynamic balance (CKEDB) measurements allow for a direct comparison between viral viability and evaporation kinetics of the aerosol with a time resolution of seconds. Here, we report the airborne survival of mouse hepatitis virus (MHV) and determine a comparable loss of infectivity in the aerosol phase to our previous observations of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Through the addition of clinically relevant concentrations of mucin to the bioaerosol, there is a transient mitigation of the loss of viral infectivity at 40% RH. Increased concentrations of mucin promoted heterogenous phase change during aerosol evaporation, characterised as the formation of inclusions within the host droplet. This research demonstrates the role of mucus in the aerosol phase and its influence on short-term airborne viral stability.
    Keywords Murine hepatitis virus ; Severe acute respiratory syndrome coronavirus 2 ; bioaerosols ; droplets ; evaporation ; mucins ; mucus ; particulates ; pathogenicity ; pathogens ; viability
    Language English
    Dates of publication 2022-0824
    Publishing place Multidisciplinary Digital Publishing Institute
    Document type Article
    ZDB-ID 2516098-9
    ISSN 1999-4915
    ISSN 1999-4915
    DOI 10.3390/v14091856
    Database NAL-Catalogue (AGRICOLA)

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  8. Article ; Online: Mucin Transiently Sustains Coronavirus Infectivity through Heterogenous Changes in Phase Morphology of Evaporating Aerosol.

    Alexander, Robert W / Tian, Jianghan / Haddrell, Allen E / Oswin, Henry P / Neal, Edward / Hardy, Daniel A / Otero-Fernandez, Mara / Mann, Jamie F S / Cogan, Tristan A / Finn, Adam / Davidson, Andrew D / Hill, Darryl J / Reid, Jonathan P

    Viruses

    2022  Volume 14, Issue 9

    Abstract: Respiratory pathogens can be spread though the transmission of aerosolised expiratory secretions in the form of droplets or particulates. Understanding the fundamental aerosol parameters that govern how such pathogens survive whilst airborne is essential ...

    Abstract Respiratory pathogens can be spread though the transmission of aerosolised expiratory secretions in the form of droplets or particulates. Understanding the fundamental aerosol parameters that govern how such pathogens survive whilst airborne is essential to understanding and developing methods of restricting their dissemination. Pathogen viability measurements made using Controlled Electrodynamic Levitation and Extraction of Bioaerosol onto Substrate (CELEBS) in tandem with a comparative kinetics electrodynamic balance (CKEDB) measurements allow for a direct comparison between viral viability and evaporation kinetics of the aerosol with a time resolution of seconds. Here, we report the airborne survival of mouse hepatitis virus (MHV) and determine a comparable loss of infectivity in the aerosol phase to our previous observations of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Through the addition of clinically relevant concentrations of mucin to the bioaerosol, there is a transient mitigation of the loss of viral infectivity at 40% RH. Increased concentrations of mucin promoted heterogenous phase change during aerosol evaporation, characterised as the formation of inclusions within the host droplet. This research demonstrates the role of mucus in the aerosol phase and its influence on short-term airborne viral stability.
    MeSH term(s) Animals ; COVID-19 ; Mice ; Microbial Viability ; Mucins ; Respiratory Aerosols and Droplets ; SARS-CoV-2
    Chemical Substances Mucins
    Language English
    Publishing date 2022-08-24
    Publishing country Switzerland
    Document type Journal Article ; Research Support, Non-U.S. Gov't
    ZDB-ID 2516098-9
    ISSN 1999-4915 ; 1999-4915
    ISSN (online) 1999-4915
    ISSN 1999-4915
    DOI 10.3390/v14091856
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  9. Article ; Online: The dynamics of SARS-CoV-2 infectivity with changes in aerosol microenvironment.

    Oswin, Henry P / Haddrell, Allen E / Otero-Fernandez, Mara / Mann, Jamie F S / Cogan, Tristan A / Hilditch, Thomas G / Tian, Jianghan / Hardy, Daniel A / Hill, Darryl J / Finn, Adam / Davidson, Andrew D / Reid, Jonathan P

    Proceedings of the National Academy of Sciences of the United States of America

    2022  Volume 119, Issue 27, Page(s) e2200109119

    Abstract: Understanding the factors that influence the airborne survival of viruses such as severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) in aerosols is important for identifying routes of transmission and the value of various mitigation strategies ... ...

    Abstract Understanding the factors that influence the airborne survival of viruses such as severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) in aerosols is important for identifying routes of transmission and the value of various mitigation strategies for preventing transmission. We present measurements of the stability of SARS-CoV-2 in aerosol droplets (∼5 to 10 µm equilibrated radius) over timescales spanning 5 s to 20 min using an instrument to probe survival in a small population of droplets (typically 5 to 10) containing ∼1 virus/droplet. Measurements of airborne infectivity change are coupled with a detailed physicochemical analysis of the airborne droplets containing the virus. A decrease in infectivity to ∼10% of the starting value was observable for SARS-CoV-2 over 20 min, with a large proportion of the loss occurring within the first 5 min after aerosolization. The initial rate of infectivity loss was found to correlate with physical transformation of the equilibrating droplet; salts within the droplets crystallize at relative humidities (RHs) below 50%, leading to a near-instant loss of infectivity in 50 to 60% of the virus. However, at 90% RH, the droplet remains homogenous and aqueous, and the viral stability is sustained for the first 2 min, beyond which it decays to only 10% remaining infectious after 10 min. The loss of infectivity at high RH is consistent with an elevation in the pH of the droplets, caused by volatilization of CO
    MeSH term(s) Aerosolized Particles and Droplets/chemistry ; Aerosolized Particles and Droplets/isolation & purification ; COVID-19/transmission ; Humans ; Humidity ; Hydrogen-Ion Concentration ; SARS-CoV-2/isolation & purification ; SARS-CoV-2/pathogenicity
    Chemical Substances Aerosolized Particles and Droplets
    Language English
    Publishing date 2022-06-28
    Publishing country United States
    Document type Journal Article ; Research Support, Non-U.S. Gov't
    ZDB-ID 209104-5
    ISSN 1091-6490 ; 0027-8424
    ISSN (online) 1091-6490
    ISSN 0027-8424
    DOI 10.1073/pnas.2200109119
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  10. Article ; Online: Reply to Klein et al.: The importance of aerosol pH for airborne respiratory virus transmission.

    Oswin, Henry P / Haddrell, Allen E / Otero-Fernandez, Mara / Mann, Jamie F S / Cogan, Tristan A / Hilditch, Thomas G / Tian, Jianghan / Hardy, Dan / Hill, Darryl J / Finn, Adam / Davidson, Andrew D / Reid, Jonathan P

    Proceedings of the National Academy of Sciences of the United States of America

    2022  Volume 119, Issue 39, Page(s) e2212556119

    MeSH term(s) Air Microbiology ; Cough ; Humans ; Hydrogen-Ion Concentration ; Respiratory Aerosols and Droplets/virology ; Respiratory Tract Infections/transmission ; Respiratory Tract Infections/virology ; Virus Diseases/transmission
    Language English
    Publishing date 2022-08-29
    Publishing country United States
    Document type Letter ; Comment
    ZDB-ID 209104-5
    ISSN 1091-6490 ; 0027-8424
    ISSN (online) 1091-6490
    ISSN 0027-8424
    DOI 10.1073/pnas.2212556119
    Database MEDical Literature Analysis and Retrieval System OnLINE

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