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  1. Article ; Online: Flow Virometry: A Fluorescence-Based Approach to Enumerate Bacteriophages in Liquid Samples.

    Dlusskaya, Elena A / Dey, Rafik

    Methods in molecular biology (Clifton, N.J.)

    2023  Volume 2738, Page(s) 175–184

    Abstract: Correctly designed flow cytometry (virometry) assays allow accurate detection and enumeration of viruses in water. However, rigorous controls and calibrators are needed to obtain quality data. In the absence of proper controls, the use of fluorescent ... ...

    Abstract Correctly designed flow cytometry (virometry) assays allow accurate detection and enumeration of viruses in water. However, rigorous controls and calibrators are needed to obtain quality data. In the absence of proper controls, the use of fluorescent dyes for virus enumeration can produce false positive signals and lead to the wrong estimation of total virus counts by misreporting colloid particles as virions. Here we describe a protocol that addresses the problems that might potentially confound virometry data accuracy.
    MeSH term(s) Bacteriophages ; Biological Assay ; Data Accuracy ; Flow Cytometry ; Fluorescent Dyes
    Chemical Substances Fluorescent Dyes
    Language English
    Publishing date 2023-11-15
    Publishing country United States
    Document type Journal Article
    ISSN 1940-6029
    ISSN (online) 1940-6029
    DOI 10.1007/978-1-0716-3549-0_11
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  2. Article: First evidence of free-living Naegleria species in recreational lakes of Alberta, Canada.

    Dey, Rafik / Dlusskaya, Elena / Oloroso, Mariem / Ashbolt, Nicholas J

    Journal of water and health

    2023  Volume 21, Issue 3, Page(s) 439–442

    Abstract: Rising temperatures are increasing environmental habitats for thermotolerant pathogens, such as the so-called 'brain-eating amoeba', Naegleria fowleri. To the best of our knowledge, however, Naegleria species have not been reported in environmental water ...

    Abstract Rising temperatures are increasing environmental habitats for thermotolerant pathogens, such as the so-called 'brain-eating amoeba', Naegleria fowleri. To the best of our knowledge, however, Naegleria species have not been reported in environmental water sources in Canada. We surveyed popular recreational lakes in Alberta, Canada during the summer bathing period to determine the presence or absence of Naegleria species. While N. fowleri was not isolated in this study, we identified other thermotolerant species, including Naegleria pagei, Naegleria gruberi, Naegleria jejuensis and Naegleria fultoni using culture-based methods, hence indicating the potential conditions to support N. fowleri. Ongoing monitoring and examination of water for pathogenic amoebae is recommended in order to assist in the public health management of water sources.
    MeSH term(s) Naegleria ; Lakes ; Alberta ; Naegleria fowleri ; Water
    Chemical Substances Water (059QF0KO0R)
    Language English
    Publishing date 2023-06-13
    Publishing country England
    Document type Journal Article
    ZDB-ID 2123845-5
    ISSN 1996-7829 ; 1477-8920
    ISSN (online) 1996-7829
    ISSN 1477-8920
    DOI 10.2166/wh.2023.325
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  3. Article: SARS-CoV-2 surrogate (Phi6) environmental persistence within free-living amoebae.

    Dey, Rafik / Dlusskaya, Elena / Ashbolt, Nicholas J

    Journal of water and health

    2022  Volume 20, Issue 1, Page(s) 83–91

    Abstract: The reported persistence of SARS-CoV-2 virions in aquatic environments highlights the need to better understand potential mechanisms that may prolong its dissemination. We evaluated the possibility that amoebae might serve as transport hosts by studying ... ...

    Abstract The reported persistence of SARS-CoV-2 virions in aquatic environments highlights the need to better understand potential mechanisms that may prolong its dissemination. We evaluated the possibility that amoebae might serve as transport hosts by studying the interaction of the enveloped bacteriophage Phi6, as a potential surrogated along with one of the most common amoebae in engineered aquatic environments, Vermamoeba vermiformis. Using microscopy, imaging flow cytometry and bacteriophage cell culture, our results imply that the SARS-CoV-2 surrogate triggers amoebic mitochondria and induced apoptosis to promote viral persistence in trophozoites. Furthermore, virus-infected amoebae were still infectious after 2 months within FLA cysts. These results suggest that amoebae could contribute to the environmental persistence of SARS-CoV-2, including disinfection processes. In addition, amoebae could be a successful model system for understanding respiratory virus-eukaryotic biology at the cellular and molecular levels.
    MeSH term(s) Amoeba ; Bacteriophages ; COVID-19 ; Humans ; SARS-CoV-2 ; Viruses
    Language English
    Publishing date 2022-01-31
    Publishing country England
    Document type Journal Article
    ZDB-ID 2123845-5
    ISSN 1996-7829 ; 1477-8920
    ISSN (online) 1996-7829
    ISSN 1477-8920
    DOI 10.2166/wh.2021.167
    Database MEDical Literature Analysis and Retrieval System OnLINE

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    Z 7513: Show issues

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  4. Article ; Online: Legionella

    Dey, Rafik / Ashbolt, Nicholas J

    ACS ES&T water

    2020  Volume 1, Issue 1, Page(s) 13–14

    Language English
    Publishing date 2020-09-23
    Publishing country United States
    Document type Journal Article
    ISSN 2690-0637
    ISSN (online) 2690-0637
    DOI 10.1021/acsestwater.0c00151
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  5. Article ; Online: Extracellular amoebal-vesicles: potential transmission vehicles for respiratory viruses.

    Dey, Rafik / Folkins, Melanie A / Ashbolt, Nicholas J

    NPJ biofilms and microbiomes

    2021  Volume 7, Issue 1, Page(s) 25

    Abstract: Human respiratory syncytial virus (RSV) is a major cause of acute respiratory tract infections in children and immunocompromised adults worldwide. Here we report that amoebae-release respirable-sized vesicles containing high concentrations of infectious ... ...

    Abstract Human respiratory syncytial virus (RSV) is a major cause of acute respiratory tract infections in children and immunocompromised adults worldwide. Here we report that amoebae-release respirable-sized vesicles containing high concentrations of infectious RSV that persisted for the duration of the experiment. Given the ubiquity of amoebae in moist environments, our results suggest that extracellular amoebal-vesicles could contribute to the environmental persistence of respiratory viruses, including potential resistance to disinfection processes and thereby offering novel pathways for viral dissemination and transmission.
    MeSH term(s) Adult ; Amoeba/growth & development ; Amoeba/virology ; Child ; Extracellular Vesicles/virology ; HeLa Cells ; Humans ; Immunocompromised Host ; Models, Biological ; Respiratory Syncytial Virus Infections/transmission ; Respiratory Syncytial Virus, Human/pathogenicity ; Virus Replication
    Language English
    Publishing date 2021-03-17
    Publishing country United States
    Document type Journal Article ; Research Support, Non-U.S. Gov't
    ZDB-ID 2817021-0
    ISSN 2055-5008 ; 2055-5008
    ISSN (online) 2055-5008
    ISSN 2055-5008
    DOI 10.1038/s41522-021-00201-y
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  6. Article ; Online: Interactions between Human Reovirus and Free-Living Amoebae: Implications for Enteric Virus Disinfection and Aquatic Persistence.

    Folkins, Melanie A / Dey, Rafik / Ashbolt, Nicholas J

    Environmental science & technology

    2020  Volume 54, Issue 16, Page(s) 10201–10206

    Abstract: Free-living amoebae (FLA) are ubiquitous protozoa in aquatic/soil habitats and known to resist various disinfection methods commonly used in drinking and wastewater treatment plants. Reoviruses are emerging as useful infectious enteric virus indicators ... ...

    Abstract Free-living amoebae (FLA) are ubiquitous protozoa in aquatic/soil habitats and known to resist various disinfection methods commonly used in drinking and wastewater treatment plants. Reoviruses are emerging as useful infectious enteric virus indicators of wastewater treatment efficacy. The possible enhanced protection FLA may provide reoviruses, however, has not been previously described. Using an infectious clinical reovirus isolate in coculture with three FLA, namely,
    MeSH term(s) Acanthamoeba ; Amoeba ; Disinfection ; Enterovirus ; Humans ; Water Microbiology
    Language English
    Publishing date 2020-07-27
    Publishing country United States
    Document type Journal Article ; Research Support, Non-U.S. Gov't
    ISSN 1520-5851
    ISSN (online) 1520-5851
    DOI 10.1021/acs.est.0c02896
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  7. Article: Interactions between Human Reovirus and Free-Living Amoebae: Implications for Enteric Virus Disinfection and Aquatic Persistence

    Folkins, Melanie A / Dey, Rafik / Ashbolt, Nicholas J

    Environmental science & technology. 2020 July 09, v. 54, no. 16

    2020  

    Abstract: Free-living amoebae (FLA) are ubiquitous protozoa in aquatic/soil habitats and known to resist various disinfection methods commonly used in drinking and wastewater treatment plants. Reoviruses are emerging as useful infectious enteric virus indicators ... ...

    Abstract Free-living amoebae (FLA) are ubiquitous protozoa in aquatic/soil habitats and known to resist various disinfection methods commonly used in drinking and wastewater treatment plants. Reoviruses are emerging as useful infectious enteric virus indicators of wastewater treatment efficacy. The possible enhanced protection FLA may provide reoviruses, however, has not been previously described. Using an infectious clinical reovirus isolate in coculture with three FLA, namely, Vermamoeba vermiformis, Acanthamoeba polyphaga, and Willaertia magna, we followed reovirus persistence (by quantitative reverse transcription polymerase chain reaction (RT-qPCR)) and infectivity (TCID₅₀). Virions present in samples persisted over the experimental time period, with most virions remaining infectious. Surprisingly, electron microscopy revealed virions accumulated within the nucleus of amoebae. The current work appears to be the first report of reovirus being internalized within FLA and remaining infectious, providing a previously unreported environmental reservoir and potential mode of dissemination. FLA also appeared to be providing some logs in protection to internalized viruses during UV irradiation, which if not accounted for when determining UV dosage needed for sufficient disinfection may result in unintentional release of pathogens into surrounding water systems.
    Keywords Acanthamoeba ; Reoviridae ; coculture ; disinfection ; electron microscopy ; humans ; pathogenicity ; reverse transcriptase polymerase chain reaction ; soil ; ultraviolet radiation ; virion ; viruses ; wastewater treatment
    Language English
    Dates of publication 2020-0709
    Size p. 10201-10206.
    Publishing place American Chemical Society
    Document type Article
    Note NAL-AP-2-clean
    ISSN 1520-5851
    DOI 10.1021/acs.est.0c02896
    Database NAL-Catalogue (AGRICOLA)

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  8. Article ; Online: Legionella Infection during and after the COVID-19 Pandemic

    Dey, Rafik / Ashbolt, Nicholas J.

    ACS ES&T Water ; ISSN 2690-0637

    2020  

    Keywords covid19
    Language English
    Publisher American Chemical Society (ACS)
    Publishing country us
    Document type Article ; Online
    DOI 10.1021/acsestwater.0c00151
    Database BASE - Bielefeld Academic Search Engine (life sciences selection)

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  9. Article ; Online: Role of amoebae for survival and recovery of 'non-culturable' Helicobacter pylori cells in aquatic environments.

    Dey, Rafik / Rieger, Aja / Banting, Graham / Ashbolt, Nicholas J

    FEMS microbiology ecology

    2020  Volume 96, Issue 10

    Abstract: Helicobacter pylori is a fastidious Gram-negative bacterium that infects over half of the world's population, causing chronic gastritis and is a risk factor for stomach cancer. In developing and rural regions where prevalence rate exceeds 60%, ... ...

    Abstract Helicobacter pylori is a fastidious Gram-negative bacterium that infects over half of the world's population, causing chronic gastritis and is a risk factor for stomach cancer. In developing and rural regions where prevalence rate exceeds 60%, persistence and waterborne transmission are often linked to poor sanitation conditions. Here we demonstrate that H. pylori not only survives but also replicates within acidified free-living amoebal phagosomes. Bacterial counts of the clinical isolate H. pylori G27 increased over 50-fold after three days in co-culture with amoebae. In contrast, a H. pylori mutant deficient in a cagPAI gene (cagE) showed little growth within amoebae, demonstrating the likely importance of a type IV secretion system in H. pylori for amoebal infection. We also demonstrate that H. pylori can be packaged by amoebae and released in extracellular vesicles. Furthermore, and for the first time, we successfully demonstrate the ability of two free-living amoebae to revert and recover viable but non-cultivable coccoid (VBNC)-H. pylori to a culturable state. Our studies provide evidence to support the hypothesis that amoebae and perhaps other free-living protozoa contribute to the replication and persistence of human-pathogenic H. pylori by providing a protected intracellular microenvironment for this pathogen to persist in natural aquatic environments and engineered water systems, thereby H. pylori potentially uses amoeba as a carrier and a vector of transmission.
    MeSH term(s) Amoeba ; Helicobacter Infections ; Helicobacter pylori/genetics ; Humans
    Language English
    Publishing date 2020-09-08
    Publishing country England
    Document type Journal Article ; Research Support, Non-U.S. Gov't
    ZDB-ID 283722-5
    ISSN 1574-6941 ; 0168-6496
    ISSN (online) 1574-6941
    ISSN 0168-6496
    DOI 10.1093/femsec/fiaa182
    Database MEDical Literature Analysis and Retrieval System OnLINE

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    Zs.A 2967: Show issues Location:
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    bis Jg. 1994: Bestellungen von Artikeln über das Online-Bestellformular
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  10. Article: Searching for Activity Markers that Approximate (VBNC) <i>Legionella pneumophila</i> Infectivity in Amoeba after Ultraviolet (UV) Irradiation

    Grossi, Michael R / Ashbolt, Nicholas J / Dey, Rafik

    Water. 2018 Sept. 10, v. 10, no. 9

    2018  

    Abstract: Legionella pneumophila is an increasingly recognized threat to public health via aerosol exposures; with a variety of control measures including: water temperature/flow management and free chlorine used to reduce the risk of infection within healthcare ... ...

    Abstract Legionella pneumophila is an increasingly recognized threat to public health via aerosol exposures; with a variety of control measures including: water temperature/flow management and free chlorine used to reduce the risk of infection within healthcare centers. Despite these efforts, L. pneumophila often recolonizes plumbing systems after specific treatments, which prompted us to examine ultraviolet (UV) irradiation for a point-of-use, secondary control measure. Currently, there is no data on the efficacy of high (>254 nm) wavelength UV-C (100–280 nm) light inactivation of L. pneumophila with resuscitation of viable but non-culturable (VBNC) cells. We report for the first time L. pneumophila dose-responses for 268.6 nm and 288.6 nm UV-C, as compared to 256 nm, and demonstrate UV induced VBNC L. pneumophila remaining infectious to Acanthamoeba polyphaga during co-culture experiments. Findings were correlated to molecular-based activity assays to identify additional measures of L. pneumophila viability following UV disinfection compared to culture. A collection of viability markers may provide a more representative measure of risk compared to current culture-based detection, since UV-C irradiated L. pneumophila lose culturability, yet retain activity, increased ATP production, and the ability to be resuscitated by amoeba co-culture. This finding is significant as it identifies potential concern from VBNC cells following UV-C disinfection and the need for further research into the efficacy of UV inactivation as a point-of-use application for L. pneumophila control and management.
    Keywords Acanthamoeba ; adenosine triphosphate ; aerosols ; Amoeba ; chlorine ; coculture ; control methods ; disinfection ; dose response ; health services ; irradiation ; Legionella pneumophila ; pathogenicity ; public health ; risk reduction ; ultraviolet radiation ; viability ; water temperature ; wavelengths
    Language English
    Dates of publication 2018-0910
    Publishing place Multidisciplinary Digital Publishing Institute
    Document type Article
    ZDB-ID 2521238-2
    ISSN 2073-4441
    ISSN 2073-4441
    DOI 10.3390/w10091219
    Database NAL-Catalogue (AGRICOLA)

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