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Rachmadi AT, Gyawali P, Summers G, Jabed A, Fletcher GC, Hewitt J. PMAxx-RT-qPCR to Determine Human Norovirus Inactivation Following High-Pressure Processing of Oysters. FOOD AND ENVIRONMENTAL VIROLOGY 2024:10.1007/s12560-024-09585-4. [PMID: 38457095 DOI: 10.1007/s12560-024-09585-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/31/2023] [Accepted: 01/24/2024] [Indexed: 03/09/2024]
Abstract
Norovirus is the leading cause of viral gastroenteritis globally. While person-to-person transmission is most commonly reported route of infection, human norovirus is frequently associated with foodborne transmission, including through consumption of contaminated bivalve molluscan shellfish. Reverse transcription (RT)-qPCR is most commonly used method for detecting human norovirus detection in foods, but does not inform on its infectivity, posing challenges for assessing intervention strategies aimed at risk elimination. In this study, RT-qPCR was used in conjunction with a derivative of the photoreactive DNA binding dye propidium monoazide (PMAxx™) (PMAxx-RT-qPCR) to evaluate the viral capsid integrity of norovirus genogroup I and II (GI and GII) in shellfish following high pressure processing (HPP). Norovirus GI.3 and GII.4 bioaccumulated oysters were subjected to HPP at pressures of 300 and 450 MPa at 15 °C, and 300, 450 and 600 MPa at 20 °C. Samples were analysed using both RT-qPCR and PMAxx-RT-qPCR. For each sample, norovirus concentration (genome copies/g digestive tissue) determined by RT-qPCR was divided by the PMAxx-RT-qPCR concentration, giving the relative non-intact (RNI) ratio. The RNI ratio values relate to the amount of non-intact (non-infectious) viruses compared to fully intact (possible infectious) viruses. Our findings revealed an increasing RNI ratio value, indicating decreasing virus integrity, with increasing pressure and decreasing pressure. At 300 MPa, for norovirus GI, the median [95% confidence interval, CI] RNI ratio values were 2.6 [1.9, 3.0] at 15 °C compared to 1.1 [0.9, 1.8] at 20 °C. At 450 MPa, the RNI ratio values were 5.5 [2.9, 7.0] at 15 °C compared to 1.3 [1.0, 1.6] at 20 °C. At 600 MPa, the RNI ratio value was 5.1 [2.9, 13.4] at 20 °C. For norovirus GII, RT-qPCR and PMAxx-RT-qPCR detections were significantly reduced at 450 and 600 MPa at both 15 °C and 20 °C, with the median [95% CI] RNI ratio value at 300 MPa being 1.1 [0.8, 1.6]. Following HPP treatment, the use of PMAxx-RT-qPCR enables the selective detection of intact and potential infectious norovirus, enhancing our understanding of the inactivation profiles and supporting the development of more effective risk assessment strategies.
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Affiliation(s)
- Andri Taruna Rachmadi
- Institute of Environmental Science and Research Ltd (ESR), Kenepuru Science Centre, PO Box 50348, Porirua, 5240, New Zealand
| | - Pradip Gyawali
- Institute of Environmental Science and Research Ltd (ESR), Kenepuru Science Centre, PO Box 50348, Porirua, 5240, New Zealand
| | - Graeme Summers
- The New Zealand Institute for Plant and Food Research Ltd (PFR), Private Bag 92169, Auckland, 1142, New Zealand
| | - Anower Jabed
- Institute of Environmental Science and Research Ltd (ESR), Kenepuru Science Centre, PO Box 50348, Porirua, 5240, New Zealand
| | - Graham C Fletcher
- The New Zealand Institute for Plant and Food Research Ltd (PFR), Private Bag 92169, Auckland, 1142, New Zealand
| | - Joanne Hewitt
- Institute of Environmental Science and Research Ltd (ESR), Kenepuru Science Centre, PO Box 50348, Porirua, 5240, New Zealand.
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Balestreri C, Schroeder DC, Sampedro F, Marqués G, Palowski A, Urriola PE, van de Ligt JLG, Yancy HF, Shurson GC. Unexpected thermal stability of two enveloped megaviruses, Emiliania huxleyi virus and African swine fever virus, as measured by viability PCR. Virol J 2024; 21:1. [PMID: 38172919 PMCID: PMC10765680 DOI: 10.1186/s12985-023-02272-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2023] [Accepted: 12/18/2023] [Indexed: 01/05/2024] Open
Abstract
BACKGROUND The particle structure of Emiliania huxleyi virus (EhV), an algal infecting member of nucleocytoplasmic large DNA viruses (NCLDVs), contains an outer lipid membrane envelope similar to that found in animal viruses such as African swine fever virus (ASFV). Despite both being enveloped NCLDVs, EhV and ASFV are known for their stability outside their host environment. METHOD Here we report for the first time, the application of a viability qPCR (V-qPCR) method to describe the unprecedented and similar virion thermal stability of both EhV and ASFV. This result contradicts the cell culture-based assay method that suggests that virus "infectivity" is lost in a matter of seconds (for EhV) and minutes (for ASFV) at temperature greater than 50 °C. Confocal microscopy and analytical flow cytometry methods was used to validate the V-qPCR data for EhV. RESULTS We observed that both EhV and ASFV particles has unprecedented thermal tolerances. These two NCLDVs are exceptions to the rule that having an enveloped virion anatomy is a predicted weakness, as is often observed in enveloped RNA viruses (i.e., the viruses causing Porcine Reproductive and Respiratory Syndrome (PRRS), COVID-19, Ebola, or seasonal influenza). Using the V-qPCR method, we confirm that no PRRSV particles were detectable after 20 min of exposure to temperatures up to 100 °C. We also show that the EhV particles that remain after 50 °C 20 min exposure was in fact still infectious only after the three blind passages in bioassay experiments. CONCLUSIONS This study raises the possibility that ASFV is not always eliminated or contained after applying time and temperature inactivation treatments in current decontamination or biosecurity protocols. This observation has practical implications for industries involved in animal health and food security. Finally, we propose that EhV could be used as a surrogate for ASFV under certain circumstances.
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Affiliation(s)
- Cecilia Balestreri
- Department of Veterinary Population Medicine, University of Minnesota, St. Paul, MN, 55108, USA
| | - Declan C Schroeder
- Department of Veterinary Population Medicine, University of Minnesota, St. Paul, MN, 55108, USA.
| | - Fernando Sampedro
- Environmental Health Sciences Division, University of Minnesota, St. Paul, MN, 55455, USA
| | - Guillermo Marqués
- Department of Neuroscience, University Imaging Centers, University of Minnesota, Minneapolis, MN, 55455, USA
| | - Amanda Palowski
- Department of Veterinary Population Medicine, University of Minnesota, St. Paul, MN, 55108, USA
| | - Pedro E Urriola
- Department of Veterinary Population Medicine, University of Minnesota, St. Paul, MN, 55108, USA
- Department of Animal Science, University of Minnesota, St. Paul, MN, 55108, USA
| | | | - Haile F Yancy
- U.S. Food and Drug Administration, Center for Veterinary Medicine, Laurel, MD, 20708, USA
| | - Gerald C Shurson
- Department of Animal Science, University of Minnesota, St. Paul, MN, 55108, USA.
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Lamas A, Santos SB, Prado M, Garrido-Maestu A. Phage amplification coupled with loop-mediated isothermal amplification (PA-LAMP) for same-day detection of viable Salmonella Enteritidis in raw poultry meat. Food Microbiol 2023; 115:104341. [PMID: 37567642 DOI: 10.1016/j.fm.2023.104341] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2023] [Revised: 07/10/2023] [Accepted: 07/10/2023] [Indexed: 08/13/2023]
Abstract
Salmonella Enteritidis is the main serotype responsible for human salmonellosis in the European Union. One of the main sources of Salmonella spp. in the food chain are poultry products, such as eggs or chicken meat. In recent years, molecular methods have become an alternative to culture dependent methods for the rapid screening of Salmonella spp. In this work, the strain S. Enteritidis S1400, and previously isolated and characterized bacteriophage PVP-SE2, were used to develop and evaluate a same-day detection method combining Phage Amplification and Loop-mediated isothermal amplification (PA-LAMP) to specifically detect viable S. Enteritidis in chicken breast. This method is based on the detection of the phage DNA rather than bacterial DNA. The virus is added to the sample during pre-enrichment in buffered peptone water, where it replicates in the presence of viable S. Enteritidis. The detection of phage DNA allows, on the one hand to detect viable bacteria, since viruses only replicate in them, and on the other hand to increase the sensitivity of the method since for each infected S. Enteritidis cell, hundreds of new viruses are produced. Two different PA-LAMP detection strategies were evaluated, a real time fluorescence and a naked-eye detection. The present method could down to 0.2 fg/μL of pure phage DNA and a concentration of viral particles of 2.2 log PFU/mL. After a short Salmonella recovery step of 3 h and a co-culture of 4 h of the samples with phage particles, both real-time fluorescence and naked-eye method showed a LoD95 of 6.6 CFU/25 g and a LoD50 of 1.5/25 g in spiked chicken breast samples. The entire detection process, including DNA extraction and LAMP analysis, can be completed in around 8 h. In the current proof-of-concept, the novel PA-LAMP obtained comparable results to those of the reference method ISO 6579, to detect Salmonella Enteritidis in poultry meat.
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Affiliation(s)
- Alexandre Lamas
- Food Hygiene, Inspection and Control Laboratory, Department of Analytical Chemistry, Nutrition and Bromatology, University of Santiago de Compostela, Spain
| | - Sílvio B Santos
- Centre of Biological Engineering, University of Minho, 4710-057, Braga, Portugal; LABBELS - Associate Laboratory, 4800-122, Braga, Guimarães, Portugal
| | - Marta Prado
- International Iberian Nanotechnology Laboratory, Av. Mestre José Veiga s/n, 4715-330, Braga, Portugal
| | - Alejandro Garrido-Maestu
- International Iberian Nanotechnology Laboratory, Av. Mestre José Veiga s/n, 4715-330, Braga, Portugal.
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DeJaco RF, Roberts MJ, Romsos EL, Vallone PM, Kearsley AJ. Reducing Bias and Quantifying Uncertainty in Fluorescence Produced by PCR. Bull Math Biol 2023; 85:83. [PMID: 37574503 PMCID: PMC10423706 DOI: 10.1007/s11538-023-01182-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2022] [Accepted: 06/20/2023] [Indexed: 08/15/2023]
Abstract
We present a new approach for relating nucleic-acid content to fluorescence in a real-time Polymerase Chain Reaction (PCR) assay. By coupling a two-type branching process for PCR with a fluorescence analog of Beer's Law, the approach reduces bias and quantifies uncertainty in fluorescence. As the two-type branching process distinguishes between complementary strands of DNA, it allows for a stoichiometric description of reactions between fluorescent probes and DNA and can capture the initial conditions encountered in assays targeting RNA. Analysis of the expected copy-number identifies additional dynamics that occur at short times (or, equivalently, low cycle numbers), while investigation of the variance reveals the contributions from liquid volume transfer, imperfect amplification, and strand-specific amplification (i.e., if one strand is synthesized more efficiently than its complement). Linking the branching process to fluorescence by the Beer's Law analog allows for an a priori description of background fluorescence. It also enables uncertainty quantification (UQ) in fluorescence which, in turn, leads to analytical relationships between amplification efficiency (probability) and limit of detection. This work sets the stage for UQ-PCR, where both the input copy-number and its uncertainty are quantified from fluorescence kinetics.
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Affiliation(s)
- Robert F. DeJaco
- Applied and Computational Mathematics Division, National Institute of Standards and Technology, 100 Bureau Dr., MS 8910, Gaithersburg, MD 20899-8910 USA
- Department of Chemistry and Biochemistry, University of Maryland, 8051 Regents Dr., College Park, MD 20742-4454 USA
| | - Matthew J. Roberts
- Applied and Computational Mathematics Division, National Institute of Standards and Technology, 100 Bureau Dr., MS 8910, Gaithersburg, MD 20899-8910 USA
- Cost Analysis and Research Division, Institute for Defense Analyses, 730 E. Glebe Rd., Alexandria, VA 22305-3086 USA
| | - Erica L. Romsos
- Biomolecular Measurement Division, National Institute of Standards and Technology, 100 Bureau Dr., MS 8314, Gaithersburg, MD 20899-8314 USA
| | - Peter M. Vallone
- Biomolecular Measurement Division, National Institute of Standards and Technology, 100 Bureau Dr., MS 8314, Gaithersburg, MD 20899-8314 USA
| | - Anthony J. Kearsley
- Applied and Computational Mathematics Division, National Institute of Standards and Technology, 100 Bureau Dr., MS 8910, Gaithersburg, MD 20899-8910 USA
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Atoui A, Cordevant C, Chesnot T, Gassilloud B. SARS-CoV-2 in the environment: Contamination routes, detection methods, persistence and removal in wastewater treatment plants. THE SCIENCE OF THE TOTAL ENVIRONMENT 2023; 881:163453. [PMID: 37059142 PMCID: PMC10091716 DOI: 10.1016/j.scitotenv.2023.163453] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 12/30/2022] [Revised: 04/07/2023] [Accepted: 04/07/2023] [Indexed: 06/01/2023]
Abstract
The present study reviewed the occurrence of SARS-CoV-2 RNA and the evaluation of virus infectivity in feces and environmental matrices. The detection of SARS-CoV-2 RNA in feces and wastewater samples, reported in several studies, has generated interest and concern regarding the possible fecal-oral route of SARS-CoV-2 transmission. To date, the presence of viable SARS-CoV-2 in feces of COVID-19 infected people is not clearly confirmed although its isolation from feces of six different patients. Further, there is no documented evidence on the infectivity of SARS-CoV-2 in wastewater, sludge and environmental water samples, although the viral genome has been detected in these matrices. Decay data revealed that SARS-CoV-2 RNA persisted longer than infectious particle in all aquatic environment, indicating that genome quantification of SARS-CoV-2 does not imply the presence of infective viral particles. In addition, this review also outlined the fate of SARS-CoV-2 RNA during the different steps in the wastewater treatment plant and focusing on the virus elimination along the sludge treatment line. Studies showed complete removal of SARS-CoV-2 during the tertiary treatment. Moreover, thermophilic sludge treatments present high efficiency in SARS-CoV-2 inactivation. Further studies are required to provide more evidence with respect to the inactivation behavior of infectious SARS-CoV-2 in different environmental matrices and to examine factors affecting SARS-CoV-2 persistence.
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Affiliation(s)
- Ali Atoui
- ANSES, Nancy Laboratory for Hydrology, Water Microbiology Unit, 40, rue Lionnois, 54 000 Nancy, France.
| | - Christophe Cordevant
- ANSES, Strategy and Programs Department, Research and Reference Division, Maisons-Alfort F-94 700, France
| | - Thierry Chesnot
- ANSES, Nancy Laboratory for Hydrology, Water Microbiology Unit, 40, rue Lionnois, 54 000 Nancy, France
| | - Benoît Gassilloud
- ANSES, Nancy Laboratory for Hydrology, Water Microbiology Unit, 40, rue Lionnois, 54 000 Nancy, France
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Kim KH, Kang G, Woo WS, Sohn MY, Son HJ, Park CI. Development of a Propidium Monoazide-Based Viability Quantitative PCR Assay for Red Sea Bream Iridovirus Detection. Int J Mol Sci 2023; 24:ijms24043426. [PMID: 36834834 PMCID: PMC9958570 DOI: 10.3390/ijms24043426] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2023] [Revised: 01/30/2023] [Accepted: 02/07/2023] [Indexed: 02/11/2023] Open
Abstract
Red sea bream iridovirus (RSIV) is an important aquatic virus that causes high mortality in marine fish. RSIV infection mainly spreads through horizontal transmission via seawater, and its early detection could help prevent disease outbreaks. Although quantitative PCR (qPCR) is a sensitive and rapid method for detecting RSIV, it cannot differentiate between infectious and inactive viruses. Here, we aimed to develop a viability qPCR assay based on propidium monoazide (PMAxx), which is a photoactive dye that penetrates damaged viral particles and binds to viral DNA to prevent qPCR amplification, to distinguish between infectious and inactive viruses effectively. Our results demonstrated that PMAxx at 75 μM effectively inhibited the amplification of heat-inactivated RSIV in viability qPCR, allowing the discrimination of inactive and infectious RSIV. Furthermore, the PMAxx-based viability qPCR assay selectively detected the infectious RSIV in seawater more efficiently than the conventional qPCR and cell culture methods. The reported viability qPCR method will help prevent the overestimation of red sea bream iridoviral disease caused by RSIV. Furthermore, this non-invasive method will aid in establishing a disease prediction system and in epidemiological analysis using seawater.
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Bromberger B, Mester PJ. Rapid detection of Listeria monocytogenes in dairy products by a novel chemilumonogenic approach. Food Microbiol 2023; 109:104150. [DOI: 10.1016/j.fm.2022.104150] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2022] [Revised: 09/03/2022] [Accepted: 09/16/2022] [Indexed: 11/29/2022]
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8
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Pardo-Freire M, Domingo-Calap P. Phages and Nanotechnology: New Insights against Multidrug-Resistant Bacteria. BIODESIGN RESEARCH 2023; 5:0004. [PMID: 37849463 PMCID: PMC10521656 DOI: 10.34133/bdr.0004] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2022] [Accepted: 12/21/2022] [Indexed: 10/19/2023] Open
Abstract
Bacterial infections are a major threat to the human healthcare system worldwide, as antibiotics are becoming less effective due to the emergence of multidrug-resistant strains. Therefore, there is a need to explore nontraditional antimicrobial alternatives to support rapid interventions and combat the spread of pathogenic bacteria. New nonantibiotic approaches are being developed, many of them at the interface of physics, nanotechnology, and microbiology. While physical factors (e.g., pressure, temperature, and ultraviolet light) are typically used in the sterilization process, nanoparticles and phages (bacterial viruses) are also applied to combat pathogenic bacteria. Particularly, phage-based therapies are rising due to the unparalleled specificity and high bactericidal activity of phages. Despite the success of phages mostly as compassionate use in clinical cases, some drawbacks need to be addressed, mainly related to their stability, bioavailability, and systemic administration. Combining phages with nanoparticles can improve their performance in vivo. Thus, the combination of nanotechnology and phages might provide tools for the rapid and accurate detection of bacteria in biological samples (diagnosis and typing), and the development of antimicrobials that combine the selectivity of phages with the efficacy of targeted therapy, such as photothermal ablation or photodynamic therapies. In this review, we aim to provide an overview of how phage-based nanotechnology represents a step forward in the fight against multidrug-resistant bacteria.
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Affiliation(s)
- Marco Pardo-Freire
- Institute for Integrative Systems Biology, I2SysBio, Universitat de València-CSIC, 46980 Paterna, Spain
| | - Pilar Domingo-Calap
- Institute for Integrative Systems Biology, I2SysBio, Universitat de València-CSIC, 46980 Paterna, Spain
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Ismail AA, Al-Hajji L, Azad I, Al-Yaqoot A, Habibi N, Alseidi M, Ahmed S. Self-cleaning application of mesoporous ZnO, TiO2 and Fe2O3 films with the accommodation of silver nanoparticles for antibacterial activity. J Taiwan Inst Chem Eng 2023. [DOI: 10.1016/j.jtice.2022.104627] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
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10
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Rausch F, Tanneberger F, Abd El Wahed A, Truyen U. Validation of the efficacy of air purifiers using molecular techniques. PLoS One 2023; 18:e0280243. [PMID: 36622844 PMCID: PMC9829175 DOI: 10.1371/journal.pone.0280243] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2022] [Accepted: 12/23/2022] [Indexed: 01/10/2023] Open
Abstract
The importance of air purifiers has increased in recent years, especially with the "coronavirus disease 2019" pandemic. The efficacy of air purifiers is usually determined under laboratory conditions before widespread application. The standard procedure for testing depends on virus cultivation and titration on cell culture. This, however, requires several days to deliver results. The aim of this study was to establish a rapid molecular assay which can differentiate between intact infectious and distorted non-infectious virus particles. Feline Coronavirus was selected as model for screening. First the samples were pretreated with enzymes (universal nuclease and RNase cocktail enzyme mixture) or viability dye (propidium monoazide) to eliminate any free nucleic acids. The ribonucleic acid (RNA) from intact virus was released via magnetic beads-based extraction, then the amount of the RNA was determined using real-time reverse transcription polymerase chain reaction (RT-PCR) or reverse transcription recombinase-aided amplification (RT-RAA). All results were compared to the infectivity assay based on the calculation of the 50% tissue culture infectious dose (TCID50). The nuclease has eliminated 100% of the free Feline Coronavirus RNA, while propidium monoazide underperformed (2.3-fold decrease in free RNA). Both RT-RAA and real-time RT-PCR produced similar results to the infectivity assay on cell culture with limit of detection of 102 TCID50/mL. Two UV-C air purifiers with prosperities of 100% inactivation of the viruses were used to validate the established procedure. Both real-time RT-PCR and RT-RAA were able to differentiate between intact virus particles and free RNA. To conclude, this study revealed a promising rapid method to validate the efficacy of air purifiers by combining enzymatic pretreatment and molecular assays.
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Affiliation(s)
- Finja Rausch
- Faculty of Veterinary Medicine, Institute of Animal Hygiene and Veterinary Public Health, Leipzig University, Leipzig, Germany
| | - Franziska Tanneberger
- Faculty of Veterinary Medicine, Institute of Animal Hygiene and Veterinary Public Health, Leipzig University, Leipzig, Germany
| | - Ahmed Abd El Wahed
- Faculty of Veterinary Medicine, Institute of Animal Hygiene and Veterinary Public Health, Leipzig University, Leipzig, Germany
- * E-mail:
| | - Uwe Truyen
- Faculty of Veterinary Medicine, Institute of Animal Hygiene and Veterinary Public Health, Leipzig University, Leipzig, Germany
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Yang Z, Shen B, Yue L, Miao Y, Hu Y, Ouyang R. Application of Nanomaterials to Enhance Polymerase Chain Reaction. MOLECULES (BASEL, SWITZERLAND) 2022; 27:molecules27248854. [PMID: 36557991 PMCID: PMC9781713 DOI: 10.3390/molecules27248854] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 10/30/2022] [Revised: 11/27/2022] [Accepted: 12/05/2022] [Indexed: 12/15/2022]
Abstract
Polymerase Chain Reaction (PCR) is one of the most common technologies used to produce millions of copies of targeted nucleic acid in vitro and has become an indispensable technique in molecular biology. However, it suffers from low efficiency and specificity problems, false positive results, and so on. Although many conditions can be optimized to increase PCR yield, such as the magnesium ion concentration, the DNA polymerases, the number of cycles, and so on, they are not all-purpose and the optimization can be case dependent. Nano-sized materials offer a possible solution to improve both the quality and productivity of PCR. In the last two decades, nanoparticles (NPs) have attracted significant attention and gradually penetrated the field of life sciences because of their unique chemical and physical properties, such as their large surface area and small size effect, which have greatly promoted developments in life science and technology. Additionally, PCR technology assisted by NPs (NanoPCR) such as gold NPs (Au NPs), quantum dots (QDs), and carbon nanotubes (CNTs), etc., have been developed to significantly improve the specificity, efficiency, and sensitivity of PCR and to accelerate the PCR reaction process. This review discusses the roles of different types of NPs used to enhance PCR and summarizes their possible mechanisms.
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Affiliation(s)
- Zhu Yang
- Institute of Bismuth and Rhenium Science, School Materials and Chemistry, University of Shanghai for Science and Technology, Shanghai 200093, China
- Institut Pasteur of Shanghai, Chinese Academy of Sciences, University of Chinese Academy of Sciences, Shanghai 200031, China
| | - Bei Shen
- CAS Key Laboratory of Molecular Virology & Immunology, Institutional Center for Shared Technologies and Facilities, Pathogen Discovery and Big Data Platform, Institute Pasteur of Shanghai, Chinese Academy of Sciences, Shanghai 200031, China
| | - Lihuan Yue
- CAS Key Laboratory of Molecular Virology & Immunology, Institutional Center for Shared Technologies and Facilities, Pathogen Discovery and Big Data Platform, Institute Pasteur of Shanghai, Chinese Academy of Sciences, Shanghai 200031, China
- School of Life Sciences and Biotechnology, Shanghai Jiao Tong University, Shanghai 200240, China
| | - Yuqing Miao
- Institute of Bismuth and Rhenium Science, School Materials and Chemistry, University of Shanghai for Science and Technology, Shanghai 200093, China
- Correspondence: (Y.M.); (Y.H.); (R.O.)
| | - Yihong Hu
- CAS Key Laboratory of Molecular Virology & Immunology, Institutional Center for Shared Technologies and Facilities, Pathogen Discovery and Big Data Platform, Institute Pasteur of Shanghai, Chinese Academy of Sciences, Shanghai 200031, China
- Correspondence: (Y.M.); (Y.H.); (R.O.)
| | - Ruizhuo Ouyang
- Institute of Bismuth and Rhenium Science, School Materials and Chemistry, University of Shanghai for Science and Technology, Shanghai 200093, China
- Correspondence: (Y.M.); (Y.H.); (R.O.)
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12
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Palowski A, Balestreri C, Urriola PE, van de Ligt JLG, Sampedro F, Dee S, Shah A, Yancy HF, Shurson GC, Schroeder DC. Survival of a surrogate African swine fever virus-like algal virus in feed matrices using a 23-day commercial United States truck transport model. Front Microbiol 2022; 13:1059118. [PMID: 36569067 PMCID: PMC9782974 DOI: 10.3389/fmicb.2022.1059118] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2022] [Accepted: 11/11/2022] [Indexed: 12/13/2022] Open
Abstract
African swine fever virus (ASFV) is a member of the nucleocytoplasmic large DNA viruses (NCLDVs) and is stable in a variety of environments, including animal feed ingredients as shown in previous laboratory experiments and simulations. Emiliania huxleyi virus (EhV) is another member of the NCLDVs, which has a restricted host range limited to a species of marine algae called Emiliania huxleyi. This algal NCLDV has many similar morphological and physical characteristics to ASFV thereby making it a safe surrogate, with results that are applicable to ASFV and suitable for use in real-world experiments. Here we inoculated conventional soybean meal (SBMC), organic soybean meal (SBMO), and swine complete feed (CF) matrices with EhV strain 86 (EhV-86) at a concentration of 6.6 × 107 virus g-1, and then transported these samples in the trailer of a commercial transport vehicle for 23 days across 10,183 km covering 29 states in various regions of the United States. Upon return, samples were evaluated for virus presence and viability using a previously validated viability qPCR (V-qPCR) method. Results showed that EhV-86 was detected in all matrices and no degradation in EhV-86 viability was observed after the 23-day transportation event. Additionally, sampling sensitivity (we recorded unexpected increases, as high as 49% in one matrix, when virus was recovered at the end of the sampling period) rather than virus degradation best explains the variation of virus quantity observed after the 23-day transport simulation. These results demonstrate for the first time that ASFV-like NCLDVs can retain viability in swine feed matrices during long-term transport across the continental United States.
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Affiliation(s)
- Amanda Palowski
- Department of Veterinary Population Medicine, College of Veterinary Medicine, University of Minnesota, St. Paul, MN, United States
| | - Cecilia Balestreri
- Department of Veterinary Population Medicine, College of Veterinary Medicine, University of Minnesota, St. Paul, MN, United States
| | - Pedro E. Urriola
- Department of Animal Science, College of Food Agricultural and Natural Resource Sciences, University of Minnesota, St. Paul, MN, United States
| | - Jennifer L. G. van de Ligt
- Department of Veterinary Population Medicine, College of Veterinary Medicine, University of Minnesota, St. Paul, MN, United States
| | - Fernando Sampedro
- Environmental Health Sciences Division, School of Public Health, University of Minnesota, Minneapolis, MN, United States
| | - Scott Dee
- Pipestone Applied Research, Pipestone Veterinary Services, Pipestone, MN, United States
| | | | - Haile F. Yancy
- U.S. Food and Drug Administration, Center for Veterinary Medicine, Office of Research, Laurel, MD, United States
| | - Gerald C. Shurson
- Department of Animal Science, College of Food Agricultural and Natural Resource Sciences, University of Minnesota, St. Paul, MN, United States,*Correspondence: Gerald C. Shurson,
| | - Declan C. Schroeder
- Department of Veterinary Population Medicine, College of Veterinary Medicine, University of Minnesota, St. Paul, MN, United States,School of Biological Sciences, University of Reading, Reading, United Kingdom,Declan C. Schroeder,
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Liu H, Meng F, Nyaruaba R, He P, Hong W, Jiang M, Liu D, Zhou W, Bai D, Yu J, Wei H. A triton X-100 assisted PMAxx-qPCR assay for rapid assessment of infectious African swine fever virus. Front Microbiol 2022; 13:1062544. [PMID: 36545208 PMCID: PMC9760672 DOI: 10.3389/fmicb.2022.1062544] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2022] [Accepted: 11/09/2022] [Indexed: 12/07/2022] Open
Abstract
Introduction African Swine Fever (ASF) is a highly infectious disease of pigs, caused by African swine fever virus (ASFV). The lack of vaccines and drugs makes strict disinfection practices to be one of the main measurements to curb the transmission of ASF. Therefore, it is important to assess if all viruses are inactivated after disinfection or after long time exposure in their natural conditions. Currently, the infectivity of ASFV is determined by virus isolation and culture in a biosafety level 3 (BSL-3) laboratory. However, BSL-3 laboratories are not readily available, need skilled expertise and may be time consuming. Methods In this study, a Triton X-100 assisted PMAxx-qPCR method was developed for rapid assessment of infectious ASFV in samples. PMAxx, an improved version of propidium monoazide (PMA), can covalently cross-link with naked ASFV-DNA or DNA inside inactivated ASFV virions under assistance of 0.1% (v/v) TritonX-100, but not with ASFV-DNA inside live virions. Formation of PMAxx-DNA conjugates prevents PCR amplification, leaving only infectious virions to be detected. Under optimum conditions, the limit of detection of the PMAxx-qPCR assay was 2.32log10HAD50/mL of infectious ASFV. Testing different samples showed that the PMAxx-qPCR assay was effective to evaluate intact ASFV virions after treatment by heat or chemical disinfectants and in simulated samples such as swine tissue homogenate, swine saliva swabs, and environmental swabs. However, whole-blood and saliva need to be diluted before testing because they may inhibit the PCR reaction or the cross-linking of PMAxx with DNA. Conclusion The Triton X-100 assisted PMAxx-qPCR assay took less than 3 h from sample to result, offering an easier and faster way for assessing infectious ASFV in samples from places like pig farms and pork markets.
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Affiliation(s)
- Huan Liu
- CAS Key Laboratory of Special Pathogens and Biosafety, Center for Biosafety Mega-Science, Wuhan Institute of Virology, Chinese Academy of Sciences, Wuhan, China,College of Life Sciences, University of Chinese Academy of Sciences, Beijing, China
| | - Fei Meng
- CAS Key Laboratory of Special Pathogens and Biosafety, Center for Biosafety Mega-Science, Wuhan Institute of Virology, Chinese Academy of Sciences, Wuhan, China,African Swine Fever Regional Laboratory of China (Wuhan), Wuhan, China
| | - Raphael Nyaruaba
- CAS Key Laboratory of Special Pathogens and Biosafety, Center for Biosafety Mega-Science, Wuhan Institute of Virology, Chinese Academy of Sciences, Wuhan, China,College of Life Sciences, University of Chinese Academy of Sciences, Beijing, China
| | - Ping He
- CAS Key Laboratory of Special Pathogens and Biosafety, Center for Biosafety Mega-Science, Wuhan Institute of Virology, Chinese Academy of Sciences, Wuhan, China,College of Life Sciences, University of Chinese Academy of Sciences, Beijing, China
| | - Wei Hong
- CAS Key Laboratory of Special Pathogens and Biosafety, Center for Biosafety Mega-Science, Wuhan Institute of Virology, Chinese Academy of Sciences, Wuhan, China,College of Life Sciences, University of Chinese Academy of Sciences, Beijing, China
| | - Mengwei Jiang
- CAS Key Laboratory of Special Pathogens and Biosafety, Center for Biosafety Mega-Science, Wuhan Institute of Virology, Chinese Academy of Sciences, Wuhan, China,African Swine Fever Regional Laboratory of China (Wuhan), Wuhan, China
| | - Dongqing Liu
- Comprehensive Agricultural Law Enforcement Bureau, Wuhan, China
| | - Wenhao Zhou
- CAS Key Laboratory of Special Pathogens and Biosafety, Center for Biosafety Mega-Science, Wuhan Institute of Virology, Chinese Academy of Sciences, Wuhan, China,College of Life Sciences, University of Chinese Academy of Sciences, Beijing, China
| | - Dan Bai
- CAS Key Laboratory of Special Pathogens and Biosafety, Center for Biosafety Mega-Science, Wuhan Institute of Virology, Chinese Academy of Sciences, Wuhan, China,College of Life Sciences, University of Chinese Academy of Sciences, Beijing, China
| | - Junping Yu
- CAS Key Laboratory of Special Pathogens and Biosafety, Center for Biosafety Mega-Science, Wuhan Institute of Virology, Chinese Academy of Sciences, Wuhan, China,College of Life Sciences, University of Chinese Academy of Sciences, Beijing, China,African Swine Fever Regional Laboratory of China (Wuhan), Wuhan, China,*Correspondence: Junping Yu,
| | - Hongping Wei
- CAS Key Laboratory of Special Pathogens and Biosafety, Center for Biosafety Mega-Science, Wuhan Institute of Virology, Chinese Academy of Sciences, Wuhan, China,College of Life Sciences, University of Chinese Academy of Sciences, Beijing, China,African Swine Fever Regional Laboratory of China (Wuhan), Wuhan, China,Hongping Wei,
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Shen J, McFarland AG, Blaustein RA, Rose LJ, Perry-Dow KA, Moghadam AA, Hayden MK, Young VB, Hartmann EM. An improved workflow for accurate and robust healthcare environmental surveillance using metagenomics. MICROBIOME 2022; 10:206. [PMID: 36457108 PMCID: PMC9716758 DOI: 10.1186/s40168-022-01412-x] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 02/15/2022] [Accepted: 11/04/2022] [Indexed: 06/17/2023]
Abstract
BACKGROUND Effective surveillance of microbial communities in the healthcare environment is increasingly important in infection prevention. Metagenomics-based techniques are promising due to their untargeted nature but are currently challenged by several limitations: (1) they are not powerful enough to extract valid signals out of the background noise for low-biomass samples, (2) they do not distinguish between viable and nonviable organisms, and (3) they do not reveal the microbial load quantitatively. An additional practical challenge towards a robust pipeline is the inability to efficiently allocate sequencing resources a priori. Assessment of sequencing depth is generally practiced post hoc, if at all, for most microbiome studies, regardless of the sample type. This practice is inefficient at best, and at worst, poor sequencing depth jeopardizes the interpretation of study results. To address these challenges, we present a workflow for metagenomics-based environmental surveillance that is appropriate for low-biomass samples, distinguishes viability, is quantitative, and estimates sequencing resources. RESULTS The workflow was developed using a representative microbiome sample, which was created by aggregating 120 surface swabs collected from a medical intensive care unit. Upon evaluating and optimizing techniques as well as developing new modules, we recommend best practices and introduce a well-structured workflow. We recommend adopting liquid-liquid extraction to improve DNA yield and only incorporating whole-cell filtration when the nonbacterial proportion is large. We suggest including propidium monoazide treatment coupled with internal standards and absolute abundance profiling for viability assessment and involving cultivation when demanding comprehensive profiling. We further recommend integrating internal standards for quantification and additionally qPCR when we expect poor taxonomic classification. We also introduce a machine learning-based model to predict required sequencing effort from accessible sample features. The model helps make full use of sequencing resources and achieve desired outcomes. Video Abstract CONCLUSIONS: This workflow will contribute to more accurate and robust environmental surveillance and infection prevention. Lessons gained from this study will also benefit the continuing development of methods in relevant fields.
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Affiliation(s)
- Jiaxian Shen
- Department of Civil and Environmental Engineering, Northwestern University, Evanston, IL, 60208-3109, USA.
| | - Alexander G McFarland
- Department of Civil and Environmental Engineering, Northwestern University, Evanston, IL, 60208-3109, USA
| | - Ryan A Blaustein
- Department of Nutrition and Food Science, University of Maryland, College Park, USA
| | - Laura J Rose
- Centers for Disease Control and Prevention, Atlanta, USA
| | | | - Anahid A Moghadam
- Department of Civil and Environmental Engineering, Northwestern University, Evanston, IL, 60208-3109, USA
| | - Mary K Hayden
- Division of Infectious Diseases, Department of Internal Medicine, Rush Medical College, Chicago, USA
| | - Vincent B Young
- Department of Internal Medicine/Division of Infectious Diseases, The University of Michigan Medical School, Ann Arbor, USA
| | - Erica M Hartmann
- Department of Civil and Environmental Engineering, Northwestern University, Evanston, IL, 60208-3109, USA
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Chin NA, Salihah NT, Shivanand P, Ahmed MU. Recent trends and developments of PCR-based methods for the detection of food-borne Salmonella bacteria and Norovirus. JOURNAL OF FOOD SCIENCE AND TECHNOLOGY 2022; 59:4570-4582. [PMID: 36276542 PMCID: PMC9579247 DOI: 10.1007/s13197-021-05280-5] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Revised: 09/13/2021] [Accepted: 09/15/2021] [Indexed: 05/17/2023]
Abstract
In recent years, rapid detection methods such as polymerase chain reaction (PCR) and quantitative real-time PCR (qPCR) have been continuously developed to improve the detection of food-borne pathogens in food samples. The recent developments of PCR and qPCR in the detection and identification of these food-borne pathogens are described and elaborated throughout this review. Specifically, further developments and improvements of qPCR are discussed in detecting Salmonella and norovirus. Promising advances in these molecular detection methods have been widely used to prevent human food-borne illnesses and death caused by the food-borne pathogens. In addition, this review presents the limitations and challenges of the detection methods which include conventional culture method and conventional PCR method in detecting Salmonella and norovirus. Furthermore, several advances of qPCR such as viability PCR (vPCR) and digital PCR (dPCR) have been discussed in the detection of Salmonella and norovirus. Good practice of analysis of the food-borne pathogens and other contaminants in the food industry as well as the advancement of molecular detection methods will help improve and ensure food safety and food quality.
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Affiliation(s)
- Nur Areena Chin
- Biosensors and Nanobiotechnology Laboratory, Integrated Science Building, Faculty of Science, Universiti Brunei Darussalam, Jalan Tungku Link, Gadong, BE1410 Brunei Darussalam
| | - Nur Thaqifah Salihah
- Universiti Islam Sultan Sharif Ali, Jalan Pasar Baharu, Gadong, BE1310 Brunei Darussalam
| | - Pooja Shivanand
- Environmental and Life Sciences Programme, Faculty of Science, Universiti Brunei Darussalam, Jalan Tungku Link, Gadong, BE1410 Brunei Darussalam
| | - Minhaz Uddin Ahmed
- Biosensors and Nanobiotechnology Laboratory, Integrated Science Building, Faculty of Science, Universiti Brunei Darussalam, Jalan Tungku Link, Gadong, BE1410 Brunei Darussalam
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Rapid Quantification of Infectious Cucumber green mottle mosaic virus in Watermelon Tissues by PMA Coupled with RT-qPCR. Viruses 2022; 14:v14092046. [PMID: 36146852 PMCID: PMC9506375 DOI: 10.3390/v14092046] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2022] [Accepted: 09/09/2022] [Indexed: 11/24/2022] Open
Abstract
Cucumber green mottle mosaic virus (CGMMV) belongs to the Tobamovirus genus and is an important quarantine virus of cucurbit crops. Seedborne transmission is one of the principal modes for CGMMV spread, and effective early detection is helpful to prevent the occurrence of the disease. Quantitative real-time reverse-transcription PCR (RT-qPCR) is a sensitive and rapid method for detecting CGMMV nucleic acids, but it cannot distinguish between infectious and noninfectious viruses. In the present work, a propidium monoazide (PMA) assisted RT-qPCR method (PMA-RT-qPCR) was developed to rapidly distinguish infectious and inactive CGMMV. PMA is a photoactive dye that can selectively react with viral RNA released or inside inactive CGMMV virions but not viral RNA inside active virions. The formation of PMA-RNA conjugates prevents PCR amplification, leaving only infectious virions to be amplified. The primer pair cp3-1F/cp3-1R was designed based on the coat protein (cp) gene for specific amplification of CGMMV RNA by RT-qPCR. The detection limit of the RT-qPCR assay was 1.57 × 102 copies·μL−1. PMA at 120 μmol·L−1 was suitable for the selective quantification of infectious CGMMV virions. Under optimal conditions, RT-qPCR detection of heat-inactivated CGMMV resulted in Ct value differences larger than 16 between PMA-treated and non-PMA-treated groups, while Ct differences less than 0.23 were observed in the detection of infectious CGMMV. For naturally contaminated watermelon leaf, fruit and seedlot samples, infectious CGMMV were quantified in 13 out of the 22 samples, with infestation levels of 102~105 copies·g−1. Application of this assay enabled the selective detection of infectious CGMMV and facilitated the monitoring of the viral pathogen in watermelon seeds and tissues, which could be useful for avoiding the potential risks of primary inoculum sources.
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Dubovitskaya O, Seinige D, Valero A, Reich F, Kehrenberg C. Quantitative assessment of Campylobacter spp. levels with real-time PCR methods at different stages of the broiler food chain. Food Microbiol 2022; 110:104152. [DOI: 10.1016/j.fm.2022.104152] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2022] [Revised: 09/08/2022] [Accepted: 09/20/2022] [Indexed: 11/26/2022]
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Hu L, Fu Y, Zhang S, Pan Z, Xia J, Zhu P, Guo J. An Assay Combining Droplet Digital PCR With Propidium Monoazide Treatment for the Accurate Detection of Live Cells of Vibrio vulnificus in Plasma Samples. Front Microbiol 2022; 13:927285. [PMID: 35910629 PMCID: PMC9335127 DOI: 10.3389/fmicb.2022.927285] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2022] [Accepted: 06/24/2022] [Indexed: 11/17/2022] Open
Abstract
Vibrio vulnificus (V. vulnificus) is one of the most common pathogenic Vibrio species to humans; therefore, the establishment of timely and credible detection methods has become an urgent requirement for V. vulnificus illness surveillance. In this study, an assay combining droplet digital PCR (ddPCR) with propidium monoazide (PMA) treatment was developed for detecting V. vulnificus. The primers/probes targeting the V. vulnificus hemolysin A (vvhA) gene, amplification procedures, and PMA processing conditions involved in the assay were optimized. Then, we analyzed the specificity, sensitivity, and ability to detect live cell DNA while testing the performance of PMA-ddPCR in clinical samples. The optimal concentrations of primers and probes were 1.0 and 0.3 μM, respectively. The annealing temperature achieving the highest accuracy in ddPCR assay was 60°C. With an initial V. vulnificus cell concentration of 108 CFU/mL (colony-forming units per milliliter), the optimal strategy to distinguish live cells from dead cells was to treat samples with 100 μM PMA for 15 min in the dark and expose them to LED light with an output wavelength of 465 nm for 10 min. The specificity of the PMA-ddPCR assay was tested on 27 strains, including seven V. vulnificus strains and 20 other bacterial strains. Only the seven V. vulnificus strains were observed with positive signals in specificity analysis. Comparative experiments on the detection ability of PMA-ddPCR and PMA-qPCR in pure cultures and plasma samples were performed. The limit of detection (LOD) and the limit of quantitation (LOQ) in pure culture solutions of V. vulnificus were 29.33 and 53.64 CFU/mL in PMA-ddPCR, respectively. For artificially clinical sample tests in PMA-ddPCR, V. vulnificus could be detected at concentrations as low as 65.20 CFU/mL. The sensitivity of the PMA-ddPCR assay was 15- to 40-fold more sensitive than the PMA-qPCR in this study. The PMA-ddPCR assay we developed provides a new insight to accurately detect live cells of V. vulnificus in clinical samples, which is of great significance to enhance public health safety and security capability and improve the emergency response level for V. vulnificus infection.
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Affiliation(s)
- Ling Hu
- Hangzhou Medical College, Hangzhou, China
- Ningbo Stomatology Hospital, Ningbo, China
| | - Yidong Fu
- Hwa Mei Hospital, University of Chinese Academy of Sciences, Ningbo, China
- Ningbo Institute of Life and Health Industry, University of Chinese Academy of Sciences, Ningbo, China
- Key Laboratory of Diagnosis and Treatment of Digestive System Tumors of Zhejiang Province, Ningbo, China
| | - Shun Zhang
- Hwa Mei Hospital, University of Chinese Academy of Sciences, Ningbo, China
- Ningbo Institute of Life and Health Industry, University of Chinese Academy of Sciences, Ningbo, China
- Key Laboratory of Diagnosis and Treatment of Digestive System Tumors of Zhejiang Province, Ningbo, China
| | - Zhilei Pan
- Hwa Mei Hospital, University of Chinese Academy of Sciences, Ningbo, China
| | - Jiang Xia
- Pilot Gene Technologies (Hangzhou) Co., Ltd., Hangzhou, China
| | - Peng Zhu
- Hwa Mei Hospital, University of Chinese Academy of Sciences, Ningbo, China
- Ningbo Institute of Life and Health Industry, University of Chinese Academy of Sciences, Ningbo, China
- Key Laboratory of Diagnosis and Treatment of Digestive System Tumors of Zhejiang Province, Ningbo, China
- *Correspondence: Peng Zhu,
| | - Jing Guo
- Hangzhou Medical College, Hangzhou, China
- Ningbo Stomatology Hospital, Ningbo, China
- Jing Guo,
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Rocha-Melogno L, Crank KC, Ginn O, Bergin MH, Brown J, Gray GC, Hamilton KA, Bibby K, Deshusses MA. Quantitative microbial risk assessment of outdoor aerosolized pathogens in cities with poor sanitation. THE SCIENCE OF THE TOTAL ENVIRONMENT 2022; 827:154233. [PMID: 35245543 DOI: 10.1016/j.scitotenv.2022.154233] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/16/2021] [Revised: 02/08/2022] [Accepted: 02/25/2022] [Indexed: 06/14/2023]
Abstract
The aeromicrobiological transmission pathway of enteric pathogens in places with unsafe sanitation services is poorly understood. In an attempt to partly fill this knowledge gap, we assessed the potential public health impact of bioaerosols near open waste canals (OWCs) using Quantitative Microbial Risk Assessment (QMRA). We used data acquired in La Paz, Bolivia to characterize the risk of disease that aerosolized enteric pathogens may pose through food, fomites and inhalation (all followed by ingestion). Three reference pathogens were selected to conduct the assessment: enterotoxigenic Escherichia coli (ETEC), Shigella flexneri, and Campylobacter jejuni. Inhalation followed by ingestion had the highest median infection risk per event i.e. 3 × 10-5 (3 infections for every 100,000 exposures), compared to contaminated food e.g. 5 × 10-6 and fomites e.g. 2 × 10-7, all for C. jejuni infections. Our sensitivity analysis showed that bacterial fluxes from the air were the most influential factor on risk. Our results suggest that fecal bacterial aerosols from OWCs present non-negligible risks of infection in La Paz, with median annual infection risks by C. jejuni being 18 (food), and 100 (inhalation) times greater than the EPA's standard for drinking water (1 × 10-4). We included two of the QMRA models presented here in a novel web application we developed for user-specified application in different contexts.
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Affiliation(s)
- Lucas Rocha-Melogno
- Department of Civil and Environmental Engineering, Duke University, Durham, NC 27708, United States; Duke Global Health Institute, Duke University, Durham, NC 27710, United States; ICF, 2635 Meridian Parkway Suite 200, Durham, NC 27713, United States
| | - Katherine C Crank
- Department of Civil and Environmental Engineering and Earth Sciences, University of Notre Dame, IN 46556, United States
| | - Olivia Ginn
- School of Civil and Environmental Engineering, Georgia Institute of Technology, Atlanta, GA 30332, United States
| | - Michael H Bergin
- Department of Civil and Environmental Engineering, Duke University, Durham, NC 27708, United States
| | - Joe Brown
- Department of Environmental Sciences and Engineering, Gillings School of Global Public Health, University of North Carolina, Chapel Hill, NC 27599, United States
| | - Gregory C Gray
- Duke Global Health Institute, Duke University, Durham, NC 27710, United States; Division of Infectious Diseases, Duke University School of Medicine, Durham, NC 27710, United States; Global Health Research Center, Duke-Kunshan University, Kunshan, China; Emerging Infectious Diseases Program, Duke-NUS Medical School, Singapore, Singapore; Division of Infectious Diseases, University of Texas Medical Branch (UTMB), Galveston, TX 77555, United States
| | - Kerry A Hamilton
- School of Sustainable Engineering and the Built Environment, Arizona State University, 770 S College Ave, Tempe, AZ 85281, United States; The Biodesign Institute Center for Environmental Health Engineering, Arizona State University, 1001 S McAllister Ave, Tempe, AZ 85281, United States
| | - Kyle Bibby
- Department of Civil and Environmental Engineering and Earth Sciences, University of Notre Dame, IN 46556, United States
| | - Marc A Deshusses
- Department of Civil and Environmental Engineering, Duke University, Durham, NC 27708, United States; Duke Global Health Institute, Duke University, Durham, NC 27710, United States.
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Canh VD, Liu M, Sangsanont J, Katayama H. Capsid integrity detection of pathogenic viruses in waters: Recent progress and potential future applications. THE SCIENCE OF THE TOTAL ENVIRONMENT 2022; 827:154258. [PMID: 35248642 DOI: 10.1016/j.scitotenv.2022.154258] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/06/2022] [Revised: 02/26/2022] [Accepted: 02/27/2022] [Indexed: 06/14/2023]
Abstract
Waterborne diseases caused by pathogenic human viruses are a major public health concern. To control the potential risk of viral infection through contaminated waters, a rapid, reliable tool to assess the infectivity of pathogenic viruses is required. Recently, an advanced approach (i.e., capsid integrity (RT-)qPCR) was developed to discriminate intact viruses (potentially infectious) from inactivated viruses. In this approach, samples were pretreated with capsid integrity reagents (e.g., monoazide dyes or metal compounds) before (RT -)qPCR. These reagents can only penetrate inactivated viruses with compromised capsids to bind to viral genomes and prevent their amplification, but they cannot enter viruses with intact capsids. Therefore, only viral genomes of intact viruses were amplified or detected by (RT-)qPCR after capsid integrity treatment. In this study, we reviewed recent progress in the development and application of capsid integrity (RT-)qPCR to assess the potential infectivity of viruses (including non-enveloped and enveloped viruses with different genome structures [RNA and DNA]) in water. The efficiency of capsid integrity (RT-)qPCR has been shown to depend on various factors, such as conditions of integrity reagent treatment, types of viruses, environmental matrices, and the capsid structure of viruses after disinfection treatments (e.g., UV, heat, and chlorine). For the application of capsid integrity (RT-)qPCR in real-world samples, the use of suitable virus concentration methods and process controls is important to control the efficiency of capsid integrity (RT-)qPCR. In addition, potential future applications of capsid integrity (RT-)qPCR for determining the mechanism of disinfection treatment on viral structure (e.g., capsid or genome) and a combination of capsid integrity treatment and next-generation sequencing (NGS) (capsid integrity NGS) for monitoring the community of intact pathogenic viruses in water are also discussed. This review provides essential information on the application of capsid integrity (RT-)qPCR as an efficient tool for monitoring the presence of pathogenic viruses with intact capsids in water.
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Affiliation(s)
- Vu Duc Canh
- Graduate School of Engineering, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656, Japan.
| | - Miaomiao Liu
- Graduate School of Engineering, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656, Japan
| | - Jatuwat Sangsanont
- Department of Environmental Science, Faculty of Science, Chulalongkorn University, Bangkok 10330, Thailand; Water Science and Technology for Sustainable Environmental Research Group, Chulalongkorn University, Bangkok 10330, Thailand
| | - Hiroyuki Katayama
- Graduate School of Engineering, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656, Japan.
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Chen L, Li L, Xie X, Chai A, Shi Y, Fan T, Xie J, Li B. An Improved Method for Quantification of Viable Fusarium Cells in Infected Soil Products by Propidium Monoazide Coupled with Real-Time PCR. Microorganisms 2022; 10:microorganisms10051037. [PMID: 35630479 PMCID: PMC9143521 DOI: 10.3390/microorganisms10051037] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2022] [Revised: 05/07/2022] [Accepted: 05/08/2022] [Indexed: 11/30/2022] Open
Abstract
Fusarium is a soil-borne pathogen that causes root rot disease in cucumber. To date, quantitative real-time PCR (qPCR) is a common tool to detect the content of Fusarium in soil. However, qPCR cannot distinguish between viable and nonviable cells. The aim of this study was to develop a detection technique to pretreat tissue fluid with propidium monoazide (PMA) followed by extract DNA, and then to quantify viable Fusarium cells in contaminated soil. In this work, the specific primer pair F8-1/F8-2 was designed based on the translation elongation factor (EF) gene and a PMA-qPCR assay was established to amplify and quantify soils of viable Fusarium cells. The PMA pretreatment test was optimized, which indicated that the optimal PMA concentration and light exposure time were 50 mmol L−1 and 15 min, respectively. The lowest limit of viable cells in suspension detected and soil by PMA-qPCR were 82 spore mL−1 and 91.24 spore g−1, respectively. For naturally contaminated soil, viable Fusarium cells were detected in eight of the 18 samples, and the Fusarium amount ranged from 104 to 106 spore g−1. In conclusion, the PMA-qPCR method has the characteristics of high sensitivity, efficiency, and time saving, which could support nursery plants to avoid Fusarium infection and agro-industry losses.
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Affiliation(s)
- Lida Chen
- College of Horticulture, Gansu Agricultural University, Lanzhou 730070, China;
- Institute of Vegetables and Flowers, Chinese Academy of Agricultural Sciences, Beijing 100081, China; (L.L.); (X.X.); (A.C.); (Y.S.); (T.F.)
| | - Lei Li
- Institute of Vegetables and Flowers, Chinese Academy of Agricultural Sciences, Beijing 100081, China; (L.L.); (X.X.); (A.C.); (Y.S.); (T.F.)
| | - Xuewen Xie
- Institute of Vegetables and Flowers, Chinese Academy of Agricultural Sciences, Beijing 100081, China; (L.L.); (X.X.); (A.C.); (Y.S.); (T.F.)
- Shouguang R&D Center of Vegetables, Chinese Academy of Agricultural Sciences, Weifang 262700, China
| | - Ali Chai
- Institute of Vegetables and Flowers, Chinese Academy of Agricultural Sciences, Beijing 100081, China; (L.L.); (X.X.); (A.C.); (Y.S.); (T.F.)
| | - Yanxia Shi
- Institute of Vegetables and Flowers, Chinese Academy of Agricultural Sciences, Beijing 100081, China; (L.L.); (X.X.); (A.C.); (Y.S.); (T.F.)
| | - Tengfei Fan
- Institute of Vegetables and Flowers, Chinese Academy of Agricultural Sciences, Beijing 100081, China; (L.L.); (X.X.); (A.C.); (Y.S.); (T.F.)
| | - Jianming Xie
- College of Horticulture, Gansu Agricultural University, Lanzhou 730070, China;
- Correspondence: (J.X.); (B.L.)
| | - Baoju Li
- Institute of Vegetables and Flowers, Chinese Academy of Agricultural Sciences, Beijing 100081, China; (L.L.); (X.X.); (A.C.); (Y.S.); (T.F.)
- Correspondence: (J.X.); (B.L.)
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22
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Zhou Y, Ren M, Zhang P, Jiang D, Yao X, Luo Y, Yang Z, Wang Y. Application of Nanopore Sequencing in the Detection of Foodborne Microorganisms. NANOMATERIALS 2022; 12:nano12091534. [PMID: 35564242 PMCID: PMC9100974 DOI: 10.3390/nano12091534] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/17/2022] [Revised: 04/28/2022] [Accepted: 04/29/2022] [Indexed: 12/21/2022]
Abstract
Foodborne pathogens have become the subject of intense interest because of their high incidence and mortality worldwide. In the past few decades, people have developed many methods to solve this challenge. At present, methods such as traditional microbial culture methods, nucleic acid or protein-based pathogen detection methods, and whole-genome analysis are widely used in the detection of pathogenic microorganisms in food. However, these methods are limited by time-consuming, cumbersome operations or high costs. The development of nanopore sequencing technology offers the possibility to address these shortcomings. Nanopore sequencing, a third-generation technology, has the advantages of simple operation, high sensitivity, real-time sequencing, and low turnaround time. It can be widely used in the rapid detection and serotyping of foodborne pathogens. This review article discusses foodborne diseases, the principle of nanopore sequencing technology, the application of nanopore sequencing technology in foodborne pathogens detection, as well as its development prospects.
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23
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Hrdy J, Vasickova P. Virus detection methods for different kinds of food and water samples – The importance of molecular techniques. Food Control 2022. [DOI: 10.1016/j.foodcont.2021.108764] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
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Lewis CL, Senecal AG, Wiederoder MS, Lewis BM. Differentiating Live Versus Dead Gram-Positive and Gram-Negative Bacteria With and Without Oxidative Stress Using Buoyant Mass Measurements. Curr Microbiol 2022; 79:74. [DOI: 10.1007/s00284-022-02764-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2021] [Accepted: 01/10/2022] [Indexed: 11/24/2022]
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25
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Cuevas-Ferrando E, Girón-Guzmán I, Falcó I, Pérez-Cataluña A, Díaz-Reolid A, Aznar R, Randazzo W, Sánchez G. Discrimination of non-infectious SARS-CoV-2 particles from fomites by viability RT-qPCR. ENVIRONMENTAL RESEARCH 2022; 203:111831. [PMID: 34352235 PMCID: PMC8327643 DOI: 10.1016/j.envres.2021.111831] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/25/2021] [Revised: 07/01/2021] [Accepted: 08/01/2021] [Indexed: 05/05/2023]
Abstract
The ongoing coronavirus 2019 (COVID-19) pandemic constitutes a concerning global threat to public health and economy. In the midst of this pandemic scenario, the role of environment-to-human COVID-19 spread is still a matter of debate because mixed results have been reported concerning SARS-CoV-2 stability on high-touch surfaces in real-life scenarios. Up to now, no alternative and accessible procedures for cell culture have been applied to evaluate SARS-CoV-2 infectivity on fomites. Several strategies based on viral capsid integrity have latterly been developed using viability markers to selectively remove false-positive qPCR signals resulting from free nucleic acids and damaged viruses. These have finally allowed an estimation of viral infectivity. The present study aims to provide a rapid molecular-based protocol for detection and quantification of viable SARS-CoV-2 from fomites based on the discrimination of non-infectious SARS-CoV-2 particles by platinum chloride (IV) (PtCl4) viability RT-qPCR. An initial assessment compared two different swabbing procedures to recover inactivated SARS-CoV-2 particles from fomites coupled with two RNA extraction methods. Procedures were validated with human (E229) and porcine (PEDV) coronavirus surrogates, and compared with inactivated SARS-CoV-2 suspensions on glass, steel and plastic surfaces. The viability RT-qPCR efficiently removed the PCR amplification signals from heat and gamma-irradiated inactivated SARS-CoV-2 suspensions that had been collected from specified surfaces. This study proposes a rapid viability RT-qPCR that discriminates non-infectious SARS-CoV-2 particles on surfaces thus helping researchers to better understand the risk of contracting COVID-19 through contact with fomites and to develop more efficient epidemiological measures.
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Affiliation(s)
- Enric Cuevas-Ferrando
- Department of Preservation and Food Safety Technologies, Institute of Agrochemistry and Food Technology, IATA-CSIC, Av. Agustín Escardino 7, Paterna, 46980, Valencia, Spain
| | - Inés Girón-Guzmán
- Department of Preservation and Food Safety Technologies, Institute of Agrochemistry and Food Technology, IATA-CSIC, Av. Agustín Escardino 7, Paterna, 46980, Valencia, Spain; Department of Microbiology and Ecology, University of Valencia, Valencia, Spain
| | - Irene Falcó
- Department of Preservation and Food Safety Technologies, Institute of Agrochemistry and Food Technology, IATA-CSIC, Av. Agustín Escardino 7, Paterna, 46980, Valencia, Spain
| | - Alba Pérez-Cataluña
- Department of Preservation and Food Safety Technologies, Institute of Agrochemistry and Food Technology, IATA-CSIC, Av. Agustín Escardino 7, Paterna, 46980, Valencia, Spain
| | - Azahara Díaz-Reolid
- Department of Preservation and Food Safety Technologies, Institute of Agrochemistry and Food Technology, IATA-CSIC, Av. Agustín Escardino 7, Paterna, 46980, Valencia, Spain
| | - Rosa Aznar
- Department of Preservation and Food Safety Technologies, Institute of Agrochemistry and Food Technology, IATA-CSIC, Av. Agustín Escardino 7, Paterna, 46980, Valencia, Spain; Department of Microbiology and Ecology, University of Valencia, Valencia, Spain
| | - Walter Randazzo
- Department of Preservation and Food Safety Technologies, Institute of Agrochemistry and Food Technology, IATA-CSIC, Av. Agustín Escardino 7, Paterna, 46980, Valencia, Spain
| | - Gloria Sánchez
- Department of Preservation and Food Safety Technologies, Institute of Agrochemistry and Food Technology, IATA-CSIC, Av. Agustín Escardino 7, Paterna, 46980, Valencia, Spain.
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Fan X, Li X, Zhang T, Xu J, Shi Z, Wu Z, Wu J, Pan D, Du L. A Novel qPCR Method for the Detection of Lactic Acid Bacteria in Fermented Milk. Foods 2021; 10:3066. [PMID: 34945617 PMCID: PMC8700909 DOI: 10.3390/foods10123066] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2021] [Revised: 12/05/2021] [Accepted: 12/07/2021] [Indexed: 12/04/2022] Open
Abstract
The number of live lactic acid bacteria (LAB) is an important quality indicator for yogurt, the quantitative testing of LAB has become an important task in the evaluation of product quality and function. By analyzing and comparing the performance of 16S rRNA gene and tuf gene used in absolute quantification, the tuf gene with copy number 1 was selected as the target gene of six LAB. By drawing a standard curve to achieve qualitative and quantitative detection of six strains of LAB, the detection range was found to be 1 × 103-1 × 108 copies/µL. The traditional plate colony count and Flow Cytometry (FCM) were compared with the method of qPCR, which was used in this experiment. Meanwhile, the confocal laser microscope combined with STYO 9 and propidium iodide dyes was used to determine that the content of viable bacteria in the yogurt was more than 90%, which proved that the detection result using qPCR method was closer to the true level of LAB in yogurt. Compared with the existing methods, the method in this study allowed the qualitative and quantitative detection of the six kinds of LAB in yogurt, and the distribution of live and dead bacteria in yogurt could be calculated.
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Affiliation(s)
- Xiankang Fan
- State Key Laboratory for Managing Biotic and Chemical Threats to the Quality and Safety of Agro-Products, Ningbo University, Ningbo 315211, China; (X.F.); (X.L.); (T.Z.); (J.X.); (Z.S.); (Z.W.); (L.D.)
- Key Laboratory of Animal Protein Food Processing Technology of Zhejiang Province, College of Food and Pharmaceutical Sciences, Ningbo University, Ningbo 315832, China
| | - Xiefei Li
- State Key Laboratory for Managing Biotic and Chemical Threats to the Quality and Safety of Agro-Products, Ningbo University, Ningbo 315211, China; (X.F.); (X.L.); (T.Z.); (J.X.); (Z.S.); (Z.W.); (L.D.)
- Key Laboratory of Animal Protein Food Processing Technology of Zhejiang Province, College of Food and Pharmaceutical Sciences, Ningbo University, Ningbo 315832, China
| | - Tao Zhang
- State Key Laboratory for Managing Biotic and Chemical Threats to the Quality and Safety of Agro-Products, Ningbo University, Ningbo 315211, China; (X.F.); (X.L.); (T.Z.); (J.X.); (Z.S.); (Z.W.); (L.D.)
- Key Laboratory of Animal Protein Food Processing Technology of Zhejiang Province, College of Food and Pharmaceutical Sciences, Ningbo University, Ningbo 315832, China
| | - Jue Xu
- State Key Laboratory for Managing Biotic and Chemical Threats to the Quality and Safety of Agro-Products, Ningbo University, Ningbo 315211, China; (X.F.); (X.L.); (T.Z.); (J.X.); (Z.S.); (Z.W.); (L.D.)
- Key Laboratory of Animal Protein Food Processing Technology of Zhejiang Province, College of Food and Pharmaceutical Sciences, Ningbo University, Ningbo 315832, China
| | - Zihang Shi
- State Key Laboratory for Managing Biotic and Chemical Threats to the Quality and Safety of Agro-Products, Ningbo University, Ningbo 315211, China; (X.F.); (X.L.); (T.Z.); (J.X.); (Z.S.); (Z.W.); (L.D.)
- Key Laboratory of Animal Protein Food Processing Technology of Zhejiang Province, College of Food and Pharmaceutical Sciences, Ningbo University, Ningbo 315832, China
| | - Zhen Wu
- State Key Laboratory for Managing Biotic and Chemical Threats to the Quality and Safety of Agro-Products, Ningbo University, Ningbo 315211, China; (X.F.); (X.L.); (T.Z.); (J.X.); (Z.S.); (Z.W.); (L.D.)
- Key Laboratory of Animal Protein Food Processing Technology of Zhejiang Province, College of Food and Pharmaceutical Sciences, Ningbo University, Ningbo 315832, China
| | - Jihuan Wu
- Ningbo Yifule Biotechnology Co., Ltd., Ningbo 315500, China;
| | - Daodong Pan
- State Key Laboratory for Managing Biotic and Chemical Threats to the Quality and Safety of Agro-Products, Ningbo University, Ningbo 315211, China; (X.F.); (X.L.); (T.Z.); (J.X.); (Z.S.); (Z.W.); (L.D.)
- Key Laboratory of Animal Protein Food Processing Technology of Zhejiang Province, College of Food and Pharmaceutical Sciences, Ningbo University, Ningbo 315832, China
| | - Lihui Du
- State Key Laboratory for Managing Biotic and Chemical Threats to the Quality and Safety of Agro-Products, Ningbo University, Ningbo 315211, China; (X.F.); (X.L.); (T.Z.); (J.X.); (Z.S.); (Z.W.); (L.D.)
- Key Laboratory of Animal Protein Food Processing Technology of Zhejiang Province, College of Food and Pharmaceutical Sciences, Ningbo University, Ningbo 315832, China
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Ulmann V, Modrá H, Babak V, Weston RT, Pavlik I. Recovery of Mycobacteria from Heavily Contaminated Environmental Matrices. Microorganisms 2021; 9:microorganisms9102178. [PMID: 34683499 PMCID: PMC8538195 DOI: 10.3390/microorganisms9102178] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2021] [Revised: 10/13/2021] [Accepted: 10/14/2021] [Indexed: 11/22/2022] Open
Abstract
For epidemiology studies, a decontamination method using a solution containing 4.0% NaOH and 0.5% tetradecyltrimethylammonium bromide (TDAB) represents a relatively simple and universal procedure for processing heavily microbially contaminated matrices together with increase of mycobacteria yield and elimination of gross contamination. A contamination rate only averaging 7.3% (2.4% in Cluster S; 6.9% in Cluster R and 12.6% in Cluster E) was found in 787 examined environmental samples. Mycobacteria were cultured from 28.5% of 274 soil and water sediments samples (Cluster S), 60.2% of 251 samples of raw and processed peat and other horticultural substrates (Cluster R), and 29.4% of 262 faecal samples along with other samples of animal origin (Cluster E). A total of 38 species of slow and rapidly growing mycobacteria were isolated. M. avium ssp. hominissuis, M. fortuitum and M. malmoense were the species most often isolated. The parameters for the quantitative detection of mycobacteria by PCR can be significantly refined by treating the sample suspension before DNA isolation with PMA (propidium monoazide) solution. This effectively eliminates DNA residue from both dead mycobacterial cells and potentially interfering DNA segments present from other microbial flora. In terms of human exposure risk assessment, the potential exposure to live non-tuberculous mycobacteria can be more accurately determined.
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Affiliation(s)
- Vit Ulmann
- Public Health Institute in Ostrava, Partyzanske Nam. 7, 702 00 Ostrava, Czech Republic;
| | - Helena Modrá
- Faculty of Regional Development and International Studies, Mendel University in Brno, Tr. Generala Piky 7, 613 00 Brno, Czech Republic;
| | - Vladimir Babak
- Veterinary Research Institute, v.v.i., Hudcova 70, 621 00 Brno, Czech Republic;
| | - Ross Tim Weston
- Department of Biochemistry and Genetics, La Trobe Institute for Molecular Science, La Trobe University, Bundoora, Melbourne, VIC 3086, Australia;
| | - Ivo Pavlik
- Faculty of Regional Development and International Studies, Mendel University in Brno, Tr. Generala Piky 7, 613 00 Brno, Czech Republic;
- Correspondence: ; Tel.: +420-773-491-836
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28
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Chiang ELC, Lee S, Medriano CA, Li L, Bae S. Assessment of physiological responses of bacteria to chlorine and UV disinfection using a plate count method, flow cytometry and viability PCR. J Appl Microbiol 2021; 132:1788-1801. [PMID: 34637587 DOI: 10.1111/jam.15325] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2021] [Revised: 10/03/2021] [Accepted: 10/05/2021] [Indexed: 11/28/2022]
Abstract
AIMS This study aimed to investigate the physiological responses of two gram-negative bacteria (Escherichia coli and Pseudomonas aeruginosa) and two gram-positive bacteria (Enterococcus faecalis and Bacillus sphaericus) to ultraviolet (UV) and chlorine disinfection. METHODS AND RESULTS Bacterial inactivation by UV and chlorine disinfection were evaluated with a plate count method for culturability, FCM and PMA-qPCR for membrane integrity and DyeTox13-qPCR for enzymatic activity, respectively. Both UV and chorine disinfection caused complete loss of culturability while membrane integrity remained intact after UV disinfection. Both DyeTox13-qPCR and PMA-qPCR showed high ΔCt values up to 8.9 after chlorine disinfection, indicating that both methods were able to distinguish non-treated from chlorine-treated cells. Although PMA-qPCR could not differentiate membrane integrity of cells on UV exposure, DyeTox13-qPCR showed significant differences in ΔCt values of 5.05 and 10.4 for gram-negative (E. coli) and gram-positive (Enterococcus) bacteria, respectively. However, DyeTox13-qPCR for gram-negative bacteria displayed relatively small differences in ΔCt values compared with gram-positive bacteria. CONCLUSION UV and chlorine disinfection led to changes in physiological state of gram-negative and gram-positive bacteria. Particularly, UV disinfection could induce active but non-culturable (ABNC) for gram-negative bacteria and dormant cell for gram-positive bacteria where intact cells no longer showed the enzymatic activity. SIGNIFICANCE AND IMPACT OF THE STUDY UV and chlorine are commonly used to disinfect water, food and fomites to inactivate pathogenic bacteria. However, a viable but non-culturable (VBNC) state of bacteria induced by disinfection may underestimate the health risks because of the potential resuscitation of VBNC cells. This study highlighted that bacteria could undergo different physiological (ABNC or dormant) states during UV and chlorine disinfection. In addition, viability PCR techniques could provide insight into the changes in physiological states during disinfection processes.
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Affiliation(s)
- Elaine L C Chiang
- Department of Civil and Environmental Engineering, National University of Singapore, Singapore, Singapore
| | - Seunguk Lee
- Department of Civil and Environmental Engineering, National University of Singapore, Singapore, Singapore
| | - Carl A Medriano
- Department of Civil and Environmental Engineering, National University of Singapore, Singapore, Singapore
| | - Liyan Li
- Department of Civil and Environmental Engineering, National University of Singapore, Singapore, Singapore
| | - Sungwoo Bae
- Department of Civil and Environmental Engineering, National University of Singapore, Singapore, Singapore
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29
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Lin X, Jin X, Du W, Shan X, Huang Q, Fu R, Lv W, Yang H, Su Y, Huang G. Quantitative and specific detection of viable pathogens on a portable microfluidic chip system by combining improved propidium monoazide (PMAxx) and loop-mediated isothermal amplification (LAMP). ANALYTICAL METHODS : ADVANCING METHODS AND APPLICATIONS 2021; 13:3569-3576. [PMID: 34286728 DOI: 10.1039/d1ay00953b] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
An accurate and specific detection of viable Candida albicans (C. albicans) in vaginal discharge is crucial for the diagnosis of vulvovaginal candidiasis (VVC) and assessment of antifungal effects. In this study, improved propidium monoazide (PMAxx) and loop-mediated isothermal amplification (LAMP) were used for the first time to distinguish between viable and dead C. albicans. A portable microfluidic chip system was developed to detect multiple viable pathogens in parallel. The consumption of samples and reagents in per reaction cell were only 0.94 μL, less than 1/25 of the conventional 25 μL Eppendorf tubular test method, both significantly reducing testing cost and greatly simplifying the detection of multiple viable pathogens. The concentration of PMAxx was optimized against C. albicans at 4.0 log CFU mL-1 to 5.0 log CFU mL-1, and 1 μM PMAxx was proven to be suitable for the detection of C. albicans in clinical samples. When testing mixtures containing different ratios of viable to dead C. albicans, PMAxx-LAMP could circumvent the signal arising from dead cells and, therefore, reflected the abundance of viable cells precisely. Furthermore, the suitability of this technique to evaluate the effects of antifungal agents, including clotrimazole, miconazole, and tioconazole, was assessed. Finally, the viability of Escherichia coli (E. coli) and C. albicans were detected on the portable microfluidic chip system. PMAxx-LAMP based portable microfluidic chip system was determined to be a feasible technique for assessing the viability of multiple pathogens in gynecology and might provide insights into new VVC treatment strategies.
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Affiliation(s)
- Xue Lin
- Department of Biomedical Engineering, The School of Medicine, Tsinghua University, Beijing 100084, P. R. China.
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30
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Bouju-Albert A, Saltaji S, Dousset X, Prévost H, Jaffrès E. Quantification of Viable Brochothrix thermosphacta in Cold-Smoked Salmon Using PMA/PMAxx-qPCR. Front Microbiol 2021; 12:654178. [PMID: 34335490 PMCID: PMC8316974 DOI: 10.3389/fmicb.2021.654178] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2021] [Accepted: 06/17/2021] [Indexed: 11/17/2022] Open
Abstract
The aim of this study was to develop a rapid and accurate PMA-qPCR method to quantify viable Brochothrix thermosphacta in cold-smoked salmon. B. thermosphacta is one of the main food spoilage bacteria. Among seafood products, cold-smoked salmon is particularly impacted by B. thermosphacta spoilage. Specific and sensitive tools that detect and quantify this bacterium in food products are very useful. The culture method commonly used to quantify B. thermosphacta is time-consuming and can underestimate cells in a viable but not immediately culturable state. We designed a new PCR primer set from the single-copy rpoC gene. QPCR efficiency and specificity were compared with two other published primer sets targeting the rpoC and rpoB genes. The viability dyes PMA or PMAxx were combined with qPCR and compared with these primer sets on viable and dead B. thermosphacta cells in BHI broth and smoked salmon tissue homogenate (SSTH). The three primer sets displayed similar specificity and efficiency. The efficiency of new designed rpoC qPCR on viable B. thermosphacta cells in SSTH was 103.50%, with a linear determination coefficient (r2) of 0.998 and a limit of detection of 4.04 log CFU/g. Using the three primer sets on viable cells, no significant difference was observed between cells treated or untreated with PMA or PMAxx. When dead cells were used, both viability dyes suppressed DNA amplification. Nevertheless, our results did not highlight any difference between PMAxx and PMA in their efficiency to discriminate viable from unviable B. thermosphacta cells in cold-smoked salmon. Thus, this study presents a rapid, specific and efficient rpoC-PMA-qPCR method validated in cold-smoked salmon to quantify viable B. thermosphacta in foods.
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31
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Shen J, McFarland AG, Young VB, Hayden MK, Hartmann EM. Toward Accurate and Robust Environmental Surveillance Using Metagenomics. Front Genet 2021; 12:600111. [PMID: 33747038 PMCID: PMC7973286 DOI: 10.3389/fgene.2021.600111] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2020] [Accepted: 01/21/2021] [Indexed: 01/23/2023] Open
Abstract
Environmental surveillance is a critical tool for combatting public health threats represented by the global COVID-19 pandemic and the continuous increase of antibiotic resistance in pathogens. With its power to detect entire microbial communities, metagenomics-based methods stand out in addressing the need. However, several hurdles remain to be overcome in order to generate actionable interpretations from metagenomic sequencing data for infection prevention. Conceptually and technically, we focus on viability assessment, taxonomic resolution, and quantitative metagenomics, and discuss their current advancements, necessary precautions and directions to further development. We highlight the importance of building solid conceptual frameworks and identifying rational limits to facilitate the application of techniques. We also propose the usage of internal standards as a promising approach to overcome analytical bottlenecks introduced by low biomass samples and the inherent lack of quantitation in metagenomics. Taken together, we hope this perspective will contribute to bringing accurate and consistent metagenomics-based environmental surveillance to the ground.
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Affiliation(s)
- Jiaxian Shen
- Department of Civil and Environmental Engineering, Northwestern University, Evanston, IL, United States
| | - Alexander G. McFarland
- Department of Civil and Environmental Engineering, Northwestern University, Evanston, IL, United States
| | - Vincent B. Young
- Division of Infectious Diseases, Department of Internal Medicine, The University of Michigan Medical School, Ann Arbor, MI, United States
| | - Mary K. Hayden
- Division of Infectious Diseases, Department of Internal Medicine, Rush University Medical Center, Chicago, IL, United States
| | - Erica M. Hartmann
- Department of Civil and Environmental Engineering, Northwestern University, Evanston, IL, United States
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32
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Lazou TP, Gelasakis AI, Chaintoutis SC, Iossifidou EG, Dovas CI. Method-Dependent Implications in Foodborne Pathogen Quantification: The Case of Campylobacter coli Survival on Meat as Comparatively Assessed by Colony Count and Viability PCR. Front Microbiol 2021; 12:604933. [PMID: 33732219 PMCID: PMC7956984 DOI: 10.3389/fmicb.2021.604933] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2020] [Accepted: 02/01/2021] [Indexed: 11/28/2022] Open
Abstract
The aim of the present study was to address method-dependent implications during the quantification of viable Campylobacter coli cells on meat over time. Traditional colony counting on selective and non-selective culture media along with an optimized viability real-time PCR utilizing propidium monoazide-quantitative PCR (PMA-qPCR), spheroplast formation and an internal sample process control (ISPC), were comparatively evaluated for monitoring the survival of C. coli on fresh lamb meat during refrigeration storage under normal atmospheric conditions. On day zero of three independent experiments, lamb meat pieces were artificially inoculated with C. coli and then stored under refrigeration for up to 8 days. Three meat samples were tested on different days and the mean counts were determined per quantification method. An overall reduction of the viable C. coli on lamb meat was observed regardless of the applied quantification scheme, but the rate of reduction followed a method-dependent pattern, the highest being observed for colony counting on modified charcoal cefoperazone deoxycholate agar (mCCDA). Univariate ANOVA indicated that the mean counts of viable C. coli using PMA-qPCR were significantly higher compared to Columbia blood agar (CBA) plating (0.32 log10 cell equivalents, p = 0.015) and significantly lower when mCCDA was compared to CBA plating (0.88 log10 CFU, p < 0.001), indicating that selective culture on mCCDA largely underestimated the number of culturable cells during the course of meat storage. PMA-qPCR outperformed the classical colony counting in terms of quantifying both the culturable and viable but non-culturable (VBNC) C. coli cells, which were generated over time on meat and are potentially infectious and equally important from a public health perspective as their culturable counterparts.
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Affiliation(s)
- Thomai P Lazou
- Laboratory of Hygiene of Foods of Animal Origin - Veterinary Public Health, Faculty of Health Sciences, School of Veterinary Medicine, Aristotle University of Thessaloniki, Thessaloniki, Greece
| | - Athanasios I Gelasakis
- Laboratory of Anatomy and Physiology of Farm Animals, Department of Animal Science, School of Animal Biosciences, Agricultural University of Athens, Athens, Greece
| | - Serafeim C Chaintoutis
- Diagnostic Laboratory, Faculty of Health Sciences, School of Veterinary Medicine, Aristotle University of Thessaloniki, Thessaloniki, Greece
| | - Eleni G Iossifidou
- Laboratory of Hygiene of Foods of Animal Origin - Veterinary Public Health, Faculty of Health Sciences, School of Veterinary Medicine, Aristotle University of Thessaloniki, Thessaloniki, Greece
| | - Chrysostomos I Dovas
- Diagnostic Laboratory, Faculty of Health Sciences, School of Veterinary Medicine, Aristotle University of Thessaloniki, Thessaloniki, Greece
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33
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Capone D, Bivins A, Knee J, Cumming O, Nalá R, Brown J. Quantitative Microbial Risk Assessment of Pediatric Infections Attributable to Ingestion of Fecally Contaminated Domestic Soils in Low-Income Urban Maputo, Mozambique. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2021; 55:1941-1952. [PMID: 33472364 PMCID: PMC7860170 DOI: 10.1021/acs.est.0c06972] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/15/2020] [Revised: 01/07/2021] [Accepted: 01/08/2021] [Indexed: 05/03/2023]
Abstract
Rigorous studies of water, sanitation, and hygiene interventions in low- and middle-income countries (LMICs) suggest that children are exposed to enteric pathogens via multiple interacting pathways, including soil ingestion. In 30 compounds (household clusters) in low-income urban Maputo, Mozambique, we cultured Escherichia coli and quantified gene targets from soils (E. coli: ybbW, Shigella/enteroinvasive E. coli (EIEC): ipaH, Giardia duodenalis: β-giardin) using droplet digital PCR at three compound locations (latrine entrance, solid waste area, dishwashing area). We found that 88% of samples were positive for culturable E. coli (mean = 3.2 log10 CFUs per gram of dry soil), 100% for molecular E. coli (mean = 5.9 log10 gene copies per gram of dry soil), 44% for ipaH (mean = 2.5 log10), and 41% for β-giardin (mean = 2.1 log10). Performing stochastic quantitative microbial risk assessment using soil ingestion parameters from an LMIC setting for children 12-23 months old, we estimated that the median annual infection risk by G. duodenalis was 7100-fold (71% annual infection risk) and by Shigella/EIEC was 4000-fold (40% annual infection risk) greater than the EPA's standard for drinking water. Compounds in Maputo, and similar settings, require contact and source control strategies to reduce the ingestion of contaminated soil and achieve acceptable levels of risk.
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Affiliation(s)
- Drew Capone
- Civil
and Environmental Engineering, Georgia Institute
of Technology, Atlanta, Georgia 30332, United States
- Department
of Environmental Sciences and Engineering, Gillings School of Public
Health, University of North Carolina at
Chapel Hill, Chapel Hill, North Carolina 27599, United States
| | - Aaron Bivins
- Department
of Civil and Environmental Engineering and Earth Sciences, University of Notre Dame, Notre Dame, Indiana 46556, United States
| | - Jackie Knee
- Department
of Disease Control, London School of Hygiene
and Tropical Medicine, London WC1E 7HT, U.K.
| | - Oliver Cumming
- Department
of Disease Control, London School of Hygiene
and Tropical Medicine, London WC1E 7HT, U.K.
| | - Rassul Nalá
- Ministério
da Saúde, Instituto Nacional de Saúde Maputo, Maputo 1100, Mozambique
| | - Joe Brown
- Civil
and Environmental Engineering, Georgia Institute
of Technology, Atlanta, Georgia 30332, United States
- Department
of Environmental Sciences and Engineering, Gillings School of Public
Health, University of North Carolina at
Chapel Hill, Chapel Hill, North Carolina 27599, United States
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34
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Di Cola G, Fantilli AC, Pisano MB, Ré VE. Foodborne transmission of hepatitis A and hepatitis E viruses: A literature review. Int J Food Microbiol 2021; 338:108986. [PMID: 33257099 DOI: 10.1016/j.ijfoodmicro.2020.108986] [Citation(s) in RCA: 46] [Impact Index Per Article: 15.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2020] [Revised: 11/04/2020] [Accepted: 11/05/2020] [Indexed: 12/19/2022]
Abstract
Foodborne viruses have been recognized as a growing concern to the food industry and a serious public health problem. Hepatitis A virus (HAV) is responsible for the majority of viral outbreaks of food origin worldwide, while hepatitis E virus (HEV) has also been gaining prominence as a foodborne viral agent in the last years, due to its zoonotic transmission through the consumption of uncooked or undercooked infected meat or derivatives. However, there is a lack of scientific reports that gather all the updated information about HAV and HEV as foodborne viruses. A search of all scientific articles about HAV and HEV in food until March 2020 was carried out, using the keywords "HAV", "HEV", "foodborne", "outbreak" and "detection in food". Foodborne outbreaks due to HAV have been reported since 1956, mainly in the USA, and in Europe in recent years, where the number of outbreaks has been increasing throughout time, and nowadays it has become the continent with the highest foodborne HAV outbreak report. Investigation and detection of HAV in food is more recent, and the first detections were performed in the 1990s decade, most of them carried out on seafood, first, and frozen food, later. On the other hand, HEV has been mainly looked for and detected in food derived from reservoir animals, such as meat, sausages and pate of pigs and wild boars. For this virus, only isolated cases and small outbreaks of foodborne transmission have been recorded, most of them in industrialized countries, due to HEV genotype 3 or 4. Virus detection in food matrices requires special processing of the food matrix, followed by RNA detection by molecular techniques. For HAV, a real-time PCR has been agreed as the standard method for virus detection in food; in the case of HEV, a consensus assay for its detection in food has not been reached yet. Our investigation shows that there is still little data about HAV and HEV prevalence and frequency of contamination in food, prevalent viral strains, and sources of contamination, mainly in developing countries, where there is no research and legislation in this regard. Studies on these issues are needed to get a better understanding of foodborne viruses, their maintenance and their potential to cause diseases.
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Affiliation(s)
- Guadalupe Di Cola
- Instituto de Virología "Dr. J. M. Vanella", Facultad de Ciencias Médicas, Universidad Nacional de Córdoba, Enfermera Gordillo Gomez s/n, CP: 5016 Córdoba, Argentina; Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Argentina.
| | - Anabella C Fantilli
- Instituto de Virología "Dr. J. M. Vanella", Facultad de Ciencias Médicas, Universidad Nacional de Córdoba, Enfermera Gordillo Gomez s/n, CP: 5016 Córdoba, Argentina; Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Argentina
| | - María Belén Pisano
- Instituto de Virología "Dr. J. M. Vanella", Facultad de Ciencias Médicas, Universidad Nacional de Córdoba, Enfermera Gordillo Gomez s/n, CP: 5016 Córdoba, Argentina; Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Argentina
| | - Viviana E Ré
- Instituto de Virología "Dr. J. M. Vanella", Facultad de Ciencias Médicas, Universidad Nacional de Córdoba, Enfermera Gordillo Gomez s/n, CP: 5016 Córdoba, Argentina; Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Argentina
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Zhang S, Ma Y, Jiang W, Meng L, Cao X, Hu J, Chen J, Li J. Development of a Strain-Specific Quantification Method for Monitoring Bacillus amyloliquefaciens TF28 in the Rhizospheric Soil of Soybean. Mol Biotechnol 2020; 62:521-533. [PMID: 32840729 DOI: 10.1007/s12033-020-00268-6] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 08/14/2020] [Indexed: 10/23/2022]
Abstract
Bacillus amyloliquefaciens TF28 can be used to control soybean root disease. To assess its commercial potential as a biocontrol agent, it is necessary to develop a strain-specific quantification method to monitor its colonization dynamics in the rhizospheric soil of soybean under field conditions. Based on genomic comparison with the same species in NCBI databases, a strain-unique gene ukfpg was used as molecular marker to develop strain-specific PCR assay. Among three primer pairs, only primer pairs (F2/R2) could specifically differentiate TF28 from other strains of B. amyloliquefaciens with the detection limit of 10 fg and 100 CFU/g for DNA extracted from pure culture and dry soil, respectively. Then, a colony count coupled with PCR assay was used to monitor the population of TF28 in the rhizospheric soil of soybean in the field. The results indicated that TF28 successfully colonized in the rhizospheric soil of soybean. The colonization population of TF28 changed dynamically within the 120-day growth period with high population at the branching (V6) and flowering stages (R2). This study provides an efficient method to quantitatively monitor the colonization dynamics of TF28 in the rhizospheric soil of soybean in the field and demonstrates the potential of TF28 as a biocontrol agent for commercial development.
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Affiliation(s)
- Shumei Zhang
- Institute of Microbiology, Heilongjiang Academy of Sciences, 68 Zhaolin Street, Daoli District, Harbin, 150010, Heilongjiang, China
- Institute of Advanced Technology, Heilongjiang Academy of Sciences, Harbin, 150020, China
| | - Yinpeng Ma
- Institute of Advanced Technology, Heilongjiang Academy of Sciences, Harbin, 150020, China
| | - Wei Jiang
- Institute of Microbiology, Heilongjiang Academy of Sciences, 68 Zhaolin Street, Daoli District, Harbin, 150010, Heilongjiang, China
- Institute of Advanced Technology, Heilongjiang Academy of Sciences, Harbin, 150020, China
| | - Liqiang Meng
- Institute of Microbiology, Heilongjiang Academy of Sciences, 68 Zhaolin Street, Daoli District, Harbin, 150010, Heilongjiang, China
- Institute of Advanced Technology, Heilongjiang Academy of Sciences, Harbin, 150020, China
| | - Xu Cao
- Institute of Microbiology, Heilongjiang Academy of Sciences, 68 Zhaolin Street, Daoli District, Harbin, 150010, Heilongjiang, China
- Institute of Advanced Technology, Heilongjiang Academy of Sciences, Harbin, 150020, China
| | - Jihua Hu
- Institute of Advanced Technology, Heilongjiang Academy of Sciences, Harbin, 150020, China
| | - Jingyu Chen
- Institute of Advanced Technology, Heilongjiang Academy of Sciences, Harbin, 150020, China
| | - Jing Li
- Institute of Microbiology, Heilongjiang Academy of Sciences, 68 Zhaolin Street, Daoli District, Harbin, 150010, Heilongjiang, China.
- Institute of Advanced Technology, Heilongjiang Academy of Sciences, Harbin, 150020, China.
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Qin H, Shi X, Yu L, Li K, Wang J, Chen J, Yang F, Xu H, Xu H. Multiplex real-time PCR coupled with sodium dodecyl sulphate and propidium monoazide for the simultaneous detection of viable Listeria monocytogenes, Cronobacter sakazakii, Staphylococcus aureus and Salmonella spp. in milk. Int Dairy J 2020. [DOI: 10.1016/j.idairyj.2020.104739] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
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Haas CN. Quantitative Microbial Risk Assessment and Molecular Biology: Paths to Integration. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2020; 54:8539-8546. [PMID: 32539352 DOI: 10.1021/acs.est.0c00664] [Citation(s) in RCA: 22] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/04/2023]
Abstract
Quantitative microbial risk assessment (QMRA) has now been in use for over 35 years and has formed the basis for developing criteria for ensuring public health related to water, food, and remediation, to name a few areas. The initial data for QMRA (both in exposure assessment and in dose response assessment) came from measurements using assays for viability, such as plate counts, plaque assays, or animal infectivity. With the increasing use of molecular methods for the measurement of microorganisms in the environment, it has become important to assess how to use such data to estimate infectious disease risks. The limitations to the use of such data and needs to resolve the limitations will be addressed.
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Affiliation(s)
- Charles N Haas
- Department of Civil, Architectural & Environmental Engineering, Drexel University, Philadelphia, Pennsylvania 19104, United States
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Sangsanont J, Kurisu F, Furumai H, Katayama H. Ozone disinfection kinetics of poliovirus 1 determined by cell culture assay, RT-qPCR and ethidium monoazide qPCR reduction in a continuous quench-flow reactor. J Appl Microbiol 2020; 129:1530-1540. [PMID: 32681543 DOI: 10.1111/jam.14787] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2018] [Revised: 07/12/2020] [Accepted: 07/13/2020] [Indexed: 11/26/2022]
Abstract
AIMS A continuous quench-flow (CQF) reactor was developed to collect samples at the reaction times of less than one second. The reactor is applied to determine ozone disinfection kinetics of poliovirus and to study whether EMA-qPCR can assess the viral infectivity after ozone disinfection. METHODS Ozone disinfection of poliovirus was conducted in the developed CQF, and the disinfection kinetics were tested in the range of 0·7-5·0 s at ozone concentration of 0·08 and 0·25 mg l-1 . Inactivation, damage on viral genome and damage on capsid integrity were determined by plaque assay, quantitative reverse transcription polymerase chain reaction (RT-qPCR) and ethidium monoazide treatment coupled with RT-qPCR (EMA-qPCR), respectively. RESULTS By using CQF, 2·18 and 2·76 log10 reductions were observed at the reaction time of 0·7 s and ozone concentration of 0·08 and 0·25 mg l-1 , respectively, followed by tailing. Ozone disinfection kinetics of poliovirus 1 were better fit by the efficiency factor Hom model than by the Chick-Watson model, or the modified Chick-Watson model. Kinetics observed were similar between RT-qPCR and EMA-qPCR assays at the reaction times of <2·0 s and ozone concentrations of 0·08 and 0·25 mg l-1 . At reaction times > 5 s, viral concentration evaluated by EMA-qPCR was reduced in comparison to stable RT-qPCR results. Both assays still underestimated the virus inactivation. CONCLUSION The simple developed reactor can be used to investigate viral ozone disinfection kinetics and to elucidate inactivation characteristics or mechanisms at very short exposure times. SIGNIFICANCE AND IMPACT OF THE STUDY The developed CQF reactor is beneficial for better understanding of virus inactivation by ozone, and the reactor can be used to better elucidate disinfection kinetics and mechanisms for future research. This work constitutes an important contribution to the existing knowledge of the application and limitation of the EMA/PMA-qPCR to assess virus infectivity after ozone disinfection.
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Affiliation(s)
- J Sangsanont
- Department of Urban Engineering, The University of Tokyo, Tokyo, Japan.,Department of Environmental Engineering, Faculty of Engineering, Chulalongkorn University, Bangkok, Thailand
| | - F Kurisu
- Research Center for Water Environment Technology, The University of Tokyo, Tokyo, Japan
| | - H Furumai
- Research Center for Water Environment Technology, The University of Tokyo, Tokyo, Japan
| | - H Katayama
- Department of Urban Engineering, The University of Tokyo, Tokyo, Japan
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Rajkovic A, Jovanovic J, Monteiro S, Decleer M, Andjelkovic M, Foubert A, Beloglazova N, Tsilla V, Sas B, Madder A, De Saeger S, Uyttendaele M. Detection of toxins involved in foodborne diseases caused by Gram‐positive bacteria. Compr Rev Food Sci Food Saf 2020; 19:1605-1657. [DOI: 10.1111/1541-4337.12571] [Citation(s) in RCA: 29] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2019] [Revised: 04/10/2020] [Accepted: 04/14/2020] [Indexed: 12/11/2022]
Affiliation(s)
- Andreja Rajkovic
- Laboratory of Food Microbiology and Food Preservation, Department of Food Technology, Safety and Health, Faculty of Bioscience EngineeringGhent University Ghent Belgium
| | - Jelena Jovanovic
- Laboratory of Food Microbiology and Food Preservation, Department of Food Technology, Safety and Health, Faculty of Bioscience EngineeringGhent University Ghent Belgium
| | - Silvia Monteiro
- Laboratorio Analises, Instituto Superior TecnicoUniversidade de Lisboa Lisbon Portugal
| | - Marlies Decleer
- Laboratory of Food Microbiology and Food Preservation, Department of Food Technology, Safety and Health, Faculty of Bioscience EngineeringGhent University Ghent Belgium
- Laboratory of Food Analysis, Department of Bioanalysis, Faculty of Pharmaceutical SciencesGhent University Ghent Belgium
| | - Mirjana Andjelkovic
- Operational Directorate Food, Medicines and Consumer SafetyService for Chemical Residues and Contaminants Brussels Belgium
| | - Astrid Foubert
- Laboratory of Food Analysis, Department of Bioanalysis, Faculty of Pharmaceutical SciencesGhent University Ghent Belgium
| | - Natalia Beloglazova
- Laboratory of Food Analysis, Department of Bioanalysis, Faculty of Pharmaceutical SciencesGhent University Ghent Belgium
- Nanotechnology Education and Research CenterSouth Ural State University Chelyabinsk Russia
| | - Varvara Tsilla
- Laboratory of Food Microbiology and Food Preservation, Department of Food Technology, Safety and Health, Faculty of Bioscience EngineeringGhent University Ghent Belgium
| | - Benedikt Sas
- Laboratory of Food Microbiology and Food Preservation, Department of Food Technology, Safety and Health, Faculty of Bioscience EngineeringGhent University Ghent Belgium
| | - Annemieke Madder
- Laboratorium for Organic and Biomimetic Chemistry, Department of Organic and Macromolecular ChemistryGhent University Ghent Belgium
| | - Sarah De Saeger
- Laboratory of Food Analysis, Department of Bioanalysis, Faculty of Pharmaceutical SciencesGhent University Ghent Belgium
| | - Mieke Uyttendaele
- Laboratory of Food Microbiology and Food Preservation, Department of Food Technology, Safety and Health, Faculty of Bioscience EngineeringGhent University Ghent Belgium
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Chhetri VS, Han Y, Janes ME, Adhikari A. Evaluation of viability of E. coli O157: H7 on chlorine and lactic acid treated spinach leaves using combined propidium monoazide staining and real-time PCR. Lebensm Wiss Technol 2020. [DOI: 10.1016/j.lwt.2020.109259] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
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Dias CO, Scariot MC, de Mello Castanho Amboni RD, Arisi ACM. Application of propidium monoazide coupled with quantitative PCR to evaluate cell viability of Bifidobacterium animalis subsp. lactis in a non-dairy probiotic beverage. ANN MICROBIOL 2020. [DOI: 10.1186/s13213-020-01566-9] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
Abstract
Purpose
In this study, a PMA-qPCR assay was developed for the enumeration of Bifidobacterium animalis subsp. lactis BB-12 viable cells in a non-dairy probiotic beverage.
Methods
Probiotic viability was monitored in three formulations of probiotic passion fruit juice microencapsulated by spray drying, during 30 days of storage at 4 °C. Viable cells were quantified using qPCR and PMA-qPCR assays targeting tuf gene and by plate counting method.
Results
The limit of detection for all samples was 103 genome copies, corresponding to 21.3 pg of DNA. Higher CFU values were obtained for B. lactis BB-12 enumeration by qPCR, when compared to those obtained by PMA-qPCR and plate count, for all probiotic juice microcapsules. Similar quantification values were obtained by PMA-qPCR and plate counting for all samples and remained above 8 log CFU/g during the storage period.
Conclusion
These results demonstrated that the PMA-qPCR technique is a promising approach for B. lactis BB-12 viable cell enumeration in complex matrices such as passion fruit juice microcapsules. This PMA-qPCR assay allowed the achievement of reliable results faster than with the traditional plate counting method.
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Hernández I, Sant C, Martínez R, Fernández C. Design of Bacterial Strain-Specific qPCR Assays Using NGS Data and Publicly Available Resources and Its Application to Track Biocontrol Strains. Front Microbiol 2020; 11:208. [PMID: 32210925 PMCID: PMC7077341 DOI: 10.3389/fmicb.2020.00208] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2019] [Accepted: 01/29/2020] [Indexed: 11/29/2022] Open
Abstract
Biological control is emerging as a feasible alternative to chemical pesticides in agriculture. Measuring the microbial biocontrol agent (mBCA) populations in the environment is essential for an accurate environmental and health risk assessment and for optimizing the usage of an mBCA-based plant protection product. We hereby show a workflow to obtain a large number of qPCR markers suitable for robust strain-specific quantification. The workflow starts from whole genome sequencing data and consists of four stages: (i) identifying the strain-specific sequences, (ii) designing specific primer/probe sets for qPCR, and (iii) empirically verifying the performance of the assays. The first two stages involve exclusively computer work, but they are intended for researchers with little or no bioinformatic background: Only a knowledge of the BLAST suite tools and work with spreadsheets are required; a familiarity with the Galaxy environment and next-generation sequencing concepts are strongly advised. All bioinformatic work can be implemented using publicly available resources and a regular desktop computer (no matter the operating system) connected to the Internet. The workflow was tested with five bacterial strains from four different genera under development as mBCAs and yielded thousands of candidate markers and a triplex qPCR assay for each candidate mBCA. The qPCR assays were successfully tested in soils of different natures, water from different sources, and with samples from different plant tissues. The mBCA detection limits and population dynamics in the different matrices are similar to those in qPCR assays designed by other means. In summary, a new accessible, cost-effective, and robust workflow to obtain a large number of strain-specific qPCR markers is presented.
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Affiliation(s)
| | - Clara Sant
- Futureco Bioscience S.A., Barcelona, Spain
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Rahman HU, Yue X, Yu Q, Zhang W, Zhang Q, Li P. Current PCR-based methods for the detection of mycotoxigenic fungi in complex food and feed matrices. WORLD MYCOTOXIN J 2020. [DOI: 10.3920/wmj2019.2455] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
Abstract
Mycotoxins are toxic secondary fungal metabolites produced by certain types of filamentous fungi, such as Aspergillus, Fusarium, and Penicillium spp. Mycotoxigenic fungi and their produced mycotoxins are considered to be an important issue in food and feed safety due to their toxic effects like carcinogenicity, immunosuppression, neurotoxicity, nephrotoxicity, and hepatotoxicity on humans and animals. To boost the safety level of food and feedstuff, detection and identification of toxins are essential at critical control points across food and feed chains. Zero-tolerance policies by the European Union and other organizations about the extreme low level of tolerance of mycotoxins contamination in food and feed matrices have led to an increasing interest to design more sensitive, specific, rapid, cost-effective, and safer to use mycotoxigenic fungi detection technologies. Hence, many mycotoxigenic fungi detection technologies have been applied to measure and control toxins contamination in food and feed substrates. PCR-based mycotoxigenic fungi detection technologies, such as conventional PCR, real-time PCR, nested PCR, reverse transcriptase (RT)-PCR, loop-mediated isothermal amplification (LAMP), in situ PCR, polymerase chain reaction-denaturing gradient gel electrophoresis (PCR DGGE), co-operational PCR, multiplex PCR, DNA arrays, magnetic capture-hybridization (MCH)-PCR and restriction fragment length polymorphism (RFLP), would contribute to our understanding about different mycotoxigenic fungi detection approaches and will enhance our capability about mycotoxigenic fungi identification, isolation and characterization at critical control points across food and feed chains. We have assessed the principles, results, the limit of detection, and application of these PCR-based detection technologies to alleviate mycotoxins contamination problem in complex food and feed substrates. The potential application of these detection technologies can reduce mycotoxins in complex food and feed matrices.
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Affiliation(s)
- H. Ur Rahman
- Oil Crops Research Institute, Chinese Academy of Agricultural Sciences, Wuhan 430062, China P.R
- Key Laboratory of Biology and Genetic Improvement of Oil Crops, Ministry of Agriculture, Wuhan 430062, China P.R
- Key Laboratory of Detection for Mycotoxins, Ministry of Agriculture, Wuhan 430062, China P.R
| | - X. Yue
- Oil Crops Research Institute, Chinese Academy of Agricultural Sciences, Wuhan 430062, China P.R
- Key Laboratory of Biology and Genetic Improvement of Oil Crops, Ministry of Agriculture, Wuhan 430062, China P.R
- Laboratory of Quality & Safety Risk Assessment for Oilseeds Products, Wuhan, Ministry of Agriculture, Wuhan 430062, China P.R
| | - Q. Yu
- Oil Crops Research Institute, Chinese Academy of Agricultural Sciences, Wuhan 430062, China P.R
- Key Laboratory of Biology and Genetic Improvement of Oil Crops, Ministry of Agriculture, Wuhan 430062, China P.R
- Key Laboratory of Detection for Mycotoxins, Ministry of Agriculture, Wuhan 430062, China P.R
- National Reference Laboratory for Agricultural Testing (Biotoxin), Wuhan 430062, China P.R
| | - W. Zhang
- Oil Crops Research Institute, Chinese Academy of Agricultural Sciences, Wuhan 430062, China P.R
- Key Laboratory of Biology and Genetic Improvement of Oil Crops, Ministry of Agriculture, Wuhan 430062, China P.R
- Quality Inspection and Test Center for Oilseeds Products, Ministry of Agriculture, Wuhan 430062, China P.R
| | - Q. Zhang
- Oil Crops Research Institute, Chinese Academy of Agricultural Sciences, Wuhan 430062, China P.R
- Key Laboratory of Biology and Genetic Improvement of Oil Crops, Ministry of Agriculture, Wuhan 430062, China P.R
- Laboratory of Quality & Safety Risk Assessment for Oilseeds Products, Wuhan, Ministry of Agriculture, Wuhan 430062, China P.R
| | - P. Li
- Oil Crops Research Institute, Chinese Academy of Agricultural Sciences, Wuhan 430062, China P.R
- Key Laboratory of Biology and Genetic Improvement of Oil Crops, Ministry of Agriculture, Wuhan 430062, China P.R
- Key Laboratory of Detection for Mycotoxins, Ministry of Agriculture, Wuhan 430062, China P.R
- Laboratory of Quality & Safety Risk Assessment for Oilseeds Products, Wuhan, Ministry of Agriculture, Wuhan 430062, China P.R
- National Reference Laboratory for Agricultural Testing (Biotoxin), Wuhan 430062, China P.R
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Optimization of Preservation Methods Allows Deeper Insights into Changes of Raw Milk Microbiota. Microorganisms 2020; 8:microorganisms8030368. [PMID: 32151050 PMCID: PMC7142718 DOI: 10.3390/microorganisms8030368] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2020] [Revised: 02/29/2020] [Accepted: 03/03/2020] [Indexed: 12/17/2022] Open
Abstract
The temporal instability of raw milk microbiota drastically affects the reliability of microbiome studies. However, little is known about the microbial integrity in preserved samples. Raw cow milk samples were preserved with azidiol or bronopol and stored at 4 °C, or with dimethyl sulfoxide (DMSO) or a mixture of azidiol and DMSO and stored at −20 °C for up to 30 days. Aliquots of 5-, 10-, and 30-day post-storage were treated with propidium monoazide (PMA), then analyzed by sequencing the 16S rRNA gene V3-V4 and V6-V8 regions. The V6-V8 gave a higher richness and lower diversity than the V3-V4 region. After 5-day storage at 4 °C, the microbiota of unpreserved samples was characterized by a drastic decrease in diversity, and a significant shift in community structure. The treatment with azidiol and DMSO conferred the best community stabilization in preserved raw milk. Interestingly, the azidiol treatment performed as well for up to 10 days, thus appearing as a suitable alternative. However, neither azidiol nor bronopol could minimize fungal proliferation as revealed by PMA-qPCR assays. This study demonstrates the preservative ability of a mixture of azidiol and DMSO and provides deeper insights into the microbial changes occurring during the cold storage of preserved raw milk.
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Yadav N, Chhillar AK, Rana JS. Detection of pathogenic bacteria with special emphasis to biosensors integrated with AuNPs. SENSORS INTERNATIONAL 2020. [DOI: 10.1016/j.sintl.2020.100028] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
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Codony F, Dinh-Thanh M, Agustí G. Key Factors for Removing Bias in Viability PCR-Based Methods: A Review. Curr Microbiol 2019; 77:682-687. [DOI: 10.1007/s00284-019-01829-y] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2019] [Accepted: 11/29/2019] [Indexed: 11/24/2022]
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Molecular Evaluation of Vitality and Survival Rate of Dormant Kyoho Grape Seedlings: A Step toward Molecular Farming. PLANTS 2019; 8:plants8120577. [PMID: 31817601 PMCID: PMC6963589 DOI: 10.3390/plants8120577] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/29/2019] [Revised: 11/27/2019] [Accepted: 11/28/2019] [Indexed: 12/18/2022]
Abstract
Vitality and survival rate of grape seedlings are crucial factors affecting quality of vineyards. There is no comprehensive study describing accurate evaluation of dormant grapevine seedlings’ vitality and survival rate. The purpose of this study was to explore the possibility of using molecular information to evaluate viability and survival rate of dormant seedlings before transplanting. After bare roots treatment, 1–5 day expression levels of six HKGs in four buds of tetraploid Kyoho grape (Vitis labruscana: V. labrusca × V. vinifera) seedlings were detected by (Sq.) RT-PCR and qRT-PCR for calibration of the molecular method. The results revealed that HKGs expression indicates vitality and survival of plant, higher expression was strongly linked to higher vitality and survival rate, lower expression was associated with lower vitality, and lowest expression was significantly associated with lowest vitality and survival rate. Moreover, DNA and RNA quality can superficially determine seedling qualities. Finally, the survival rate of the seedlings produced in Juxian-Shandong, Laixi-Shandong, Huailai-Hebei, Suizhong-Liaoning, Changli-Hebei, Guanxian-Shandong, and Zhangjiagang-Jiangsu was 100.00%, 100.00%, 100.00%, 100.00%, 100.00%, 87.77%, and 93.33%, respectively. In conclusion, molecular technique is potential approach for promoting gene information to estimate vitality and survival rate of dormant grape seedlings and might contribute to viticulturists’ efforts.
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MENDONÇA JFMD, VIEIRA FDO, FONSECA I, RIBEIRO JB, ARCURI EF, BORGES MDF, BORGES CAV, SÁ JFOD, MARTINS MF. Detection of Viable Salmonella Typhimurium and Staphylococcus aureus in Coalho Cheese by Real-Time PCR. FOOD SCIENCE AND TECHNOLOGY 2019. [DOI: 10.1590/fst.29318] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
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Lazou TP, Iossifidou EG, Gelasakis AI, Chaintoutis SC, Dovas CI. Viability Quantitative PCR Utilizing Propidium Monoazide, Spheroplast Formation, and Campylobacter coli as a Bacterial Model. Appl Environ Microbiol 2019; 85:e01499-19. [PMID: 31420339 PMCID: PMC6805072 DOI: 10.1128/aem.01499-19] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2019] [Accepted: 08/09/2019] [Indexed: 01/09/2023] Open
Abstract
A viability quantitative PCR (qPCR) utilizing propidium monoazide (PMA) is presented for rapid quantification of viable cells using the foodborne pathogen Campylobacter coli as a bacterial model. It includes optimized spheroplast formation via lysozyme and EDTA, induction of a mild osmotic shock for enhancing the selective penetration of PMA into dead cells, and exploitation of an internal sample process control (ISPC) involving cell inactivation to assess residual false-positive signals within each sample. Spheroplasting of bacteria in exponential phase did not permit PMA entrance into viable cells since a strong linear relationship was detected between simple qPCR and PMA-qPCR quantification, and no differences were observed regardless of whether spheroplasting was utilized. The PMA-qPCR signal suppression of dead cells was elevated using spheroplast formation. With regard to the ISPC, cell inactivation by hydrogen peroxide resulted in higher signal suppression during qPCR than heat inactivation did. Viability quantification of C. coli cells by optimized spheroplasting-PMA-qPCR with ISPC was successfully applied in an aging pure culture under aerobic conditions and artificially inoculated meat. The same method exhibited a high linear range of quantification (1.5 to 8.5 log10 viable cells ml-1), and results were highly correlated with culture-based enumeration. PMA-qPCR quantification of viable cells can be affected by their rigidity, age, culture media, and niches, but spheroplast formation along with osmotic shock and the use of a proper ISPC can address such variations. The developed methodology could detect cells in a viable-but-nonculturable state and might be utilized for the quantification of other Gram-negative bacteria.IMPORTANCE There is need for rapid and accurate methods to detect viable bacterial cells of foodborne pathogens. Conventional culture-based methods are time-consuming and unable to detect bacteria in a viable-but-nonculturable state. The high sensitivity and specificity of the quantitative PCR (qPCR) are negated by its inability to differentiate the DNAs from viable and dead cells. The combination of propidium monoazide (PMA), a DNA-intercalating dye, with qPCR assays is promising for detection of viable cells. Despite encouraging results, these assays still encounter various challenges, such as false-positive signals by dead cells and the lack of an internal control identifying these signals per sample. The significance of our research lies in enhancing the selective entrance of PMA into dead Campylobacter coli cells via spheroplasting and in developing an internal sample process control, thus delivering reliable results in pure cultures and meat samples, approaches that can be applicable to other Gram-negative pathogens.
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Affiliation(s)
- Thomai P Lazou
- Laboratory of Hygiene of Foods of Animal Origin-Veterinary Public Health, School of Veterinary Medicine, Faculty of Health Sciences, Aristotle University of Thessaloniki, Thessaloniki, Greece
| | - Eleni G Iossifidou
- Laboratory of Hygiene of Foods of Animal Origin-Veterinary Public Health, School of Veterinary Medicine, Faculty of Health Sciences, Aristotle University of Thessaloniki, Thessaloniki, Greece
| | - Athanasios I Gelasakis
- Laboratory of Anatomy and Physiology of Farm Animals, Department of Animal Science, School of Animal Biosciences, Agricultural University of Athens, Athens, Greece
| | - Serafeim C Chaintoutis
- Diagnostic Laboratory, School of Veterinary Medicine, Faculty of Health Sciences, Aristotle University of Thessaloniki, Thessaloniki, Greece
| | - Chrysostomos I Dovas
- Diagnostic Laboratory, School of Veterinary Medicine, Faculty of Health Sciences, Aristotle University of Thessaloniki, Thessaloniki, Greece
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