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Turchi B, Campobasso C, Nardinocchi A, Wagemans J, Torracca B, Lood C, Di Giuseppe G, Nieri P, Bertelloni F, Turini L, Ruffo V, Lavigne R, Di Luca M. Isolation and characterization of novel Staphylococcus aureus bacteriophage Hesat from dairy origin. Appl Microbiol Biotechnol 2024; 108:299. [PMID: 38619619 PMCID: PMC11018700 DOI: 10.1007/s00253-024-13129-y] [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: 09/05/2023] [Revised: 03/05/2024] [Accepted: 03/27/2024] [Indexed: 04/16/2024]
Abstract
A novel temperate phage, named Hesat, was isolated by the incubation of a dairy strain of Staphylococcus aureus belonging to spa-type t127 with either bovine or ovine milk. Hesat represents a new species of temperate phage within the Phietavirus genus of the Azeredovirinae subfamily. Its genome has a length of 43,129 bp and a GC content of 35.11% and contains 75 predicted ORFs, some of which linked to virulence. This includes (i) a pathogenicity island (SaPln2), homologous to the type II toxin-antitoxin system PemK/MazF family toxin; (ii) a DUF3113 protein (gp30) that is putatively involved in the derepression of the global repressor Stl; and (iii) a cluster coding for a PVL. Genomic analysis of the host strain indicates Hesat is a resident prophage. Interestingly, its induction was obtained by exposing the bacterium to milk, while the conventional mitomycin C-based approach failed. The host range of phage Hesat appears to be broad, as it was able to lyse 24 out of 30 tested S. aureus isolates. Furthermore, when tested at high titer (108 PFU/ml), Hesat phage was also able to lyse a Staphylococcus muscae isolate, a coagulase-negative staphylococcal strain. KEY POINTS: • A new phage species was isolated from a Staphylococcus aureus bovine strain. • Pathogenicity island and PVL genes are encoded within phage genome. • The phage is active against most of S. aureus strains from both animal and human origins.
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Affiliation(s)
- Barbara Turchi
- Department of Veterinary Sciences, University of Pisa, Viale Delle Piagge 2, 56124, Pisa, Italy
| | - Claudia Campobasso
- Department of Biology, University of Pisa, Via San Zeno 37, 56127, Pisa, Italy
- Department of Biosystems, KU Leuven, Kasteelpark Arenberg 21, Box 2462, 3001, Louvain, Belgium
| | - Arianna Nardinocchi
- Department of Biology, University of Pisa, Via San Zeno 37, 56127, Pisa, Italy
| | - Jeroen Wagemans
- Department of Biosystems, KU Leuven, Kasteelpark Arenberg 21, Box 2462, 3001, Louvain, Belgium
| | - Beatrice Torracca
- Department of Veterinary Sciences, University of Pisa, Viale Delle Piagge 2, 56124, Pisa, Italy
| | - Cédric Lood
- Department of Biosystems, KU Leuven, Kasteelpark Arenberg 21, Box 2462, 3001, Louvain, Belgium
- Department of Microbial and Molecular Systems, Centre for Microbial and Plant Genetics, KU Leuven, Kasteelpark Arenberg 20, Box 2460, 3001, Leuven, Belgium
| | | | - Paola Nieri
- Department of Pharmacy, University of Pisa, Via Bonanno Pisano 6, 56126, Pisa, Italy
| | - Fabrizio Bertelloni
- Department of Veterinary Sciences, University of Pisa, Viale Delle Piagge 2, 56124, Pisa, Italy
| | - Luca Turini
- Department of Veterinary Sciences, University of Pisa, Viale Delle Piagge 2, 56124, Pisa, Italy
| | - Valeria Ruffo
- Department of Veterinary Sciences, University of Pisa, Viale Delle Piagge 2, 56124, Pisa, Italy
| | - Rob Lavigne
- Department of Biosystems, KU Leuven, Kasteelpark Arenberg 21, Box 2462, 3001, Louvain, Belgium
| | - Mariagrazia Di Luca
- Department of Biology, University of Pisa, Via San Zeno 37, 56127, Pisa, Italy.
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2
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Zheng T, Zhang C. Engineering strategies and challenges of endolysin as an antibacterial agent against Gram-negative bacteria. Microb Biotechnol 2024; 17:e14465. [PMID: 38593316 PMCID: PMC11003714 DOI: 10.1111/1751-7915.14465] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2024] [Revised: 03/09/2024] [Accepted: 03/21/2024] [Indexed: 04/11/2024] Open
Abstract
Bacteriophage endolysin is a novel antibacterial agent that has attracted much attention in the prevention and control of drug-resistant bacteria due to its unique mechanism of hydrolysing peptidoglycans. Although endolysin exhibits excellent bactericidal effects on Gram-positive bacteria, the presence of the outer membrane of Gram-negative bacteria makes it difficult to lyse them extracellularly, thus limiting their application field. To enhance the extracellular activity of endolysin and facilitate its crossing through the outer membrane of Gram-negative bacteria, researchers have adopted physical, chemical, and molecular methods. This review summarizes the characterization of endolysin targeting Gram-negative bacteria, strategies for endolysin modification, and the challenges and future of engineering endolysin against Gram-negative bacteria in clinical applications, to promote the application of endolysin in the prevention and control of Gram-negative bacteria.
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Affiliation(s)
- Tianyu Zheng
- Bathurst Future Agri‐Tech InstituteQingdao Agricultural UniversityQingdaoChina
| | - Can Zhang
- College of Veterinary MedicineQingdao Agricultural UniversityQingdaoChina
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3
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Ding Y, Zhang Y, Huang C, Wang J, Li H, Wang X. An electrochemical biosensor based on phage-encoded protein RBP 41 for rapid and sensitive detection of Salmonella. Talanta 2024; 270:125561. [PMID: 38128279 DOI: 10.1016/j.talanta.2023.125561] [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: 03/15/2023] [Revised: 12/13/2023] [Accepted: 12/14/2023] [Indexed: 12/23/2023]
Abstract
Salmonellosis caused by Salmonella contaminated food poses a serious threat to human health. The rapid and accurate detection of Salmonella is critical for preventing foodborne illness outbreaks. In this study, an electrochemical biosensor was developed using a newly identified biorecognition element, RBP 41, which is capable of specifically recognizing and binding to Salmonella. The biosensor was constructed through a layer-by-layer assembly of graphene oxide (GO), gold nanoparticles (GNPs), and RBP 41 on a glassy carbon electrode (GCE), with the GNPs amplifying the detection signal. The established biosensor was able to detect Salmonella in concentrations ranging from 3 to 106 CFU/mL within approximately 30 min by using differential pulse voltammetry (DPV) signal, and the estimated detection limit was to be 0.2984 Log10 CFU/mL. The biosensor demonstrated excellent specificity and was effective in detecting Salmonella in food matrices, such as skim milk and lettuce. Overall, this study highlights the potential of phage tail receptor binding proteins in biosensing and the proposed biosensor as a promising alternative for rapid and sensitive Salmonella detection in various samples.
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Affiliation(s)
- Yifeng Ding
- Key Laboratory of Environment Correlative Dietology, Huazhong Agricultural University, Wuhan, 430070, China; College of Food Science and Technology, Huazhong Agricultural University, Wuhan, 430070, China.
| | - Yiming Zhang
- Key Laboratory of Environment Correlative Dietology, Huazhong Agricultural University, Wuhan, 430070, China; College of Food Science and Technology, Huazhong Agricultural University, Wuhan, 430070, China.
| | - Chenxi Huang
- Key Laboratory of Environment Correlative Dietology, Huazhong Agricultural University, Wuhan, 430070, China; College of Food Science and Technology, Huazhong Agricultural University, Wuhan, 430070, China.
| | - Jia Wang
- Key Laboratory of Environment Correlative Dietology, Huazhong Agricultural University, Wuhan, 430070, China; College of Food Science and Technology, Huazhong Agricultural University, Wuhan, 430070, China.
| | - Huihui Li
- College of Science, Huazhong Agricultural University, Wuhan, 430070, China.
| | - Xiaohong Wang
- Key Laboratory of Environment Correlative Dietology, Huazhong Agricultural University, Wuhan, 430070, China; College of Food Science and Technology, Huazhong Agricultural University, Wuhan, 430070, China.
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4
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Roehrig C, Huemer M, Lorgé D, Arn F, Heinrich N, Selvakumar L, Gasser L, Hauswirth P, Chang CC, Schweizer TA, Eichenseher F, Lehmann S, Zinkernagel AS, Schmelcher M. MEndoB, a chimeric lysin featuring a novel domain architecture and superior activity for the treatment of staphylococcal infections. mBio 2024; 15:e0254023. [PMID: 38275913 PMCID: PMC10865858 DOI: 10.1128/mbio.02540-23] [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: 09/18/2023] [Accepted: 12/14/2023] [Indexed: 01/27/2024] Open
Abstract
Bacterial infections are a growing global healthcare concern, as an estimated annual 4.95 million deaths are associated with antimicrobial resistance (AMR). Methicillin-resistant Staphylococcus aureus is one of the deadliest pathogens and a high-priority pathogen according to the World Health Organization. Peptidoglycan hydrolases (PGHs) of phage origin have been postulated as a new class of antimicrobials for the treatment of bacterial infections, with a novel mechanism of action and no known resistances. The modular architecture of PGHs permits the creation of chimeric PGH libraries. In this study, the chimeric enzyme MEndoB was selected from a library of staphylococcal PGHs based on its rapid and sustained activity against staphylococci in human serum. The benefit of the presented screening approach was illustrated by the superiority of MEndoB in a head-to-head comparison with other PGHs intended for use against staphylococcal bacteremia. MEndoB displayed synergy with antibiotics and rapid killing in human whole blood with complete inhibition of re-growth over 24 h at low doses. Successful treatment of S. aureus-infected zebrafish larvae with MEndoB provided evidence for its in vivo effectiveness. This was further confirmed in a lethal systemic mouse infection model in which MEndoB significantly reduced S. aureus loads and tumor necrosis factor alpha levels in blood in a dose-dependent manner, which led to increased survival of the animals. Thus, the thorough lead candidate selection of MEndoB resulted in an outstanding second-generation PGH with in vitro, ex vivo, and in vivo results supporting further development.IMPORTANCEOne of the most pressing challenges of our era is the rising occurrence of bacteria that are resistant to antibiotics. Staphylococci are prominent pathogens in humans, which have developed multiple strategies to evade the effects of antibiotics. Infections caused by these bacteria have resulted in a high burden on the health care system and a significant loss of lives. In this study, we have successfully engineered lytic enzymes that exhibit an extraordinary ability to eradicate staphylococci. Our findings substantiate the importance of meticulous lead candidate selection to identify therapeutically promising peptidoglycan hydrolases with unprecedented activity. Hence, they offer a promising new avenue for treating staphylococcal infections.
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Affiliation(s)
- Christian Roehrig
- Micreos Pharmaceuticals AG, Baar, Zug, Switzerland
- Micreos GmbH, Wädenswil, Zurich, Switzerland
| | | | | | | | | | | | - Lynn Gasser
- Institute of Chemistry and Biotechnology, Zurich University of Applied Sciences (ZHAW), Wädenswil, Zurich, Switzerland
| | - Patrick Hauswirth
- Institute of Chemistry and Biotechnology, Zurich University of Applied Sciences (ZHAW), Wädenswil, Zurich, Switzerland
| | - Chun-Chi Chang
- Department of Infectious Diseases and Hospital Epidemiology, University Hospital Zurich, University of Zurich, Zurich, Switzerland
| | - Tiziano A. Schweizer
- Department of Infectious Diseases and Hospital Epidemiology, University Hospital Zurich, University of Zurich, Zurich, Switzerland
| | | | - Steffi Lehmann
- Institute of Chemistry and Biotechnology, Zurich University of Applied Sciences (ZHAW), Wädenswil, Zurich, Switzerland
| | - Annelies S. Zinkernagel
- Department of Infectious Diseases and Hospital Epidemiology, University Hospital Zurich, University of Zurich, Zurich, Switzerland
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5
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Sarr M, Alou MT, Padane A, Diouf FS, Beye M, Sokhna C, Fenollar F, Mboup S, Raoult D, Million M. A review of the literature of Listeria monocytogenes in Africa highlights breast milk as an overlooked human source. Front Microbiol 2023; 14:1213953. [PMID: 38173673 PMCID: PMC10761537 DOI: 10.3389/fmicb.2023.1213953] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2023] [Accepted: 11/29/2023] [Indexed: 01/05/2024] Open
Abstract
According to the latest WHO estimates (2015) of the global burden of foodborne diseases, Listeria monocytogenes is responsible for one of the most serious foodborne infections and commonly results in severe clinical outcomes. The 2013 French MONALISA prospective cohort identified that women born in Africa has a 3-fold increase in the risk of maternal neonatal listeriosis. One of the largest L. monocytogenes outbreaks occurred in South Africa in 2017-2018 with over 1,000 cases. Moreover, recent findings identified L. monocytogenes in human breast milk in Mali and Senegal with its relative abundance positively correlated with severe acute malnutrition. These observations suggest that the carriage of L. monocytogenes in Africa should be further explored, starting with the existing literature. For that purpose, we searched the peer-reviewed and grey literature published dating back to 1926 to date using six databases. Ultimately, 225 articles were included in this review. We highlighted that L. monocytogenes is detected in various sample types including environmental samples, food samples as well as animal and human samples. These studies were mostly conducted in five east African countries, four west African countries, four north African countries, and two Southern African countries. Moreover, only ≈ 0.2% of the Listeria monocytogenes genomes available on NCBI were obtained from African samples, contracted with its detection. The pangenome resulting from the African Listeria monocytogenes samples revealed three clusters including two from South-African strains as well as one consisting of the strains isolated from breast milk in Mali and Senegal and, a vaginal post-miscarriage sample. This suggests there was a clonal complex circulating in Mali and Senegal. As this clone has not been associated to infections, further studies should be conducted to confirm its circulation in the region and explore its association with foodborne infections. Moreover, it is apparent that more resources should be allocated to the detection of L. monocytogenes as only 15/54 countries have reported its detection in the literature. It seems paramount to map the presence and carriage of L. monocytogenes in all African countries to prevent listeriosis outbreaks and the related miscarriages and confirm its association with severe acute malnutrition.
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Affiliation(s)
- Marièma Sarr
- Aix Marseille University, IRD, AP-HM, MEPHI, Marseille, France
- IHU-Méditerranée Infection, Marseille, France
- Campus Commun UCAD-IRD of Hann, Dakar, Senegal
- Institut de Recherche en Santé, de Surveillance Épidémiologique et de Formation (IRESSEF), Dakar, Senegal
| | - Maryam Tidjani Alou
- Aix Marseille University, IRD, AP-HM, MEPHI, Marseille, France
- IHU-Méditerranée Infection, Marseille, France
| | - Abdou Padane
- Institut de Recherche en Santé, de Surveillance Épidémiologique et de Formation (IRESSEF), Dakar, Senegal
| | - Fatou Samba Diouf
- Aix Marseille University, IRD, AP-HM, MEPHI, Marseille, France
- IHU-Méditerranée Infection, Marseille, France
- Campus Commun UCAD-IRD of Hann, Dakar, Senegal
| | - Mamadou Beye
- Aix Marseille University, IRD, AP-HM, MEPHI, Marseille, France
- IHU-Méditerranée Infection, Marseille, France
| | - Cheikh Sokhna
- Campus Commun UCAD-IRD of Hann, Dakar, Senegal
- Aix Marseille University, IRD, AP-HM, SSA, VITROME, Marseille, France
| | - Florence Fenollar
- IHU-Méditerranée Infection, Marseille, France
- Aix Marseille University, IRD, AP-HM, SSA, VITROME, Marseille, France
| | - Souleymane Mboup
- Institut de Recherche en Santé, de Surveillance Épidémiologique et de Formation (IRESSEF), Dakar, Senegal
| | - Didier Raoult
- Aix Marseille University, IRD, AP-HM, MEPHI, Marseille, France
- IHU-Méditerranée Infection, Marseille, France
| | - Matthieu Million
- Aix Marseille University, IRD, AP-HM, MEPHI, Marseille, France
- IHU-Méditerranée Infection, Marseille, France
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6
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Sousa C, Ferreira R, Santos SB, Azevedo NF, Melo LDR. Advances on diagnosis of Helicobacter pylori infections. Crit Rev Microbiol 2023; 49:671-692. [PMID: 36264672 DOI: 10.1080/1040841x.2022.2125287] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2022] [Accepted: 09/12/2022] [Indexed: 11/09/2022]
Abstract
The association of Helicobacter pylori to several gastric diseases, such as chronic gastritis, peptic ulcer disease, and gastric cancer, and its high prevalence worldwide, raised the necessity to use methods for a proper and fast diagnosis and monitoring the pathogen eradication. Available diagnostic methods can be classified as invasive or non-invasive, and the selection of the best relies on the clinical condition of the patient, as well as on the sensitivity, specificity, and accessibility of the diagnostic test. This review summarises all diagnostic methods currently available, including the invasive methods: endoscopy, histology, culture, and molecular methods, and the rapid urease test (RUT), as well as the non-invasive methods urea breath test (UBT), serological assays, biosensors, and microfluidic devices and the stool antigen test (SAT). Moreover, it lists the diagnostic advantages and limitations, as well as the main advances for each methodology. In the end, research on the development of new diagnostic methods, such as bacteriophage-based H. pylori diagnostic tools, is also discussed.
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Affiliation(s)
- Cláudia Sousa
- CEB - Centre of Biological Engineering, University of Minho, Braga, Portugal
- LABBELS - Associate Laboratory, Braga/Guimarães, Portugal
| | - Rute Ferreira
- CEB - Centre of Biological Engineering, University of Minho, Braga, Portugal
- LABBELS - Associate Laboratory, Braga/Guimarães, Portugal
- i3S - Instituto de Investigação e Inovação em Saúde, University of Porto, Porto, Portugal
| | - Sílvio B Santos
- CEB - Centre of Biological Engineering, University of Minho, Braga, Portugal
- LABBELS - Associate Laboratory, Braga/Guimarães, Portugal
| | - Nuno F Azevedo
- LEPABE - Laboratory for Process Engineering, Environment, Biotechnology and Energy, Faculty of Engineering, University of Porto, Porto, Portugal
- ALiCE - Associate Laboratory in Chemical Engineering, Faculty of Engineering, University of Porto, Porto, Portugal
| | - Luís D R Melo
- CEB - Centre of Biological Engineering, University of Minho, Braga, Portugal
- LABBELS - Associate Laboratory, Braga/Guimarães, Portugal
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7
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Wohlfarth JC, Feldmüller M, Schneller A, Kilcher S, Burkolter M, Meile S, Pilhofer M, Schuppler M, Loessner MJ. L-form conversion in Gram-positive bacteria enables escape from phage infection. Nat Microbiol 2023; 8:387-399. [PMID: 36717719 PMCID: PMC9981463 DOI: 10.1038/s41564-022-01317-3] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2022] [Accepted: 12/22/2022] [Indexed: 02/01/2023]
Abstract
At the end of a lytic bacteriophage replication cycle in Gram-positive bacteria, peptidoglycan-degrading endolysins that cause explosive cell lysis of the host can also attack non-infected bystander cells. Here we show that in osmotically stabilized environments, Listeria monocytogenes can evade phage predation by transient conversion to a cell wall-deficient L-form state. This L-form escape is triggered by endolysins disintegrating the cell wall from without, leading to turgor-driven extrusion of wall-deficient, yet viable L-form cells. Remarkably, in the absence of phage predation, we show that L-forms can quickly revert to the walled state. These findings suggest that L-form conversion represents a population-level persistence mechanism to evade complete eradication by phage attack. Importantly, we also demonstrate phage-mediated L-form switching of the urinary tract pathogen Enterococcus faecalis in human urine, which underscores that this escape route may be widespread and has important implications for phage- and endolysin-based therapeutic interventions.
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Affiliation(s)
- Jan C. Wohlfarth
- grid.5801.c0000 0001 2156 2780Institute of Food, Nutrition and Health, ETH Zurich, Zurich, Switzerland
| | - Miki Feldmüller
- grid.5801.c0000 0001 2156 2780Institute of Molecular Biology and Biophysics, ETH Zurich, Zurich, Switzerland
| | - Alissa Schneller
- grid.5801.c0000 0001 2156 2780Institute of Food, Nutrition and Health, ETH Zurich, Zurich, Switzerland
| | - Samuel Kilcher
- grid.5801.c0000 0001 2156 2780Institute of Food, Nutrition and Health, ETH Zurich, Zurich, Switzerland
| | - Marco Burkolter
- grid.5801.c0000 0001 2156 2780Institute of Food, Nutrition and Health, ETH Zurich, Zurich, Switzerland
| | - Susanne Meile
- grid.5801.c0000 0001 2156 2780Institute of Food, Nutrition and Health, ETH Zurich, Zurich, Switzerland
| | - Martin Pilhofer
- grid.5801.c0000 0001 2156 2780Institute of Molecular Biology and Biophysics, ETH Zurich, Zurich, Switzerland
| | - Markus Schuppler
- grid.5801.c0000 0001 2156 2780Institute of Food, Nutrition and Health, ETH Zurich, Zurich, Switzerland
| | - Martin J. Loessner
- grid.5801.c0000 0001 2156 2780Institute of Food, Nutrition and Health, ETH Zurich, Zurich, Switzerland
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8
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Afonnikova S, Komissarov A, Kuchur P. Unique or not unique? Comparative genetic analysis of bacterial O-antigens from the Oxalobacteraceae family. Vavilovskii Zhurnal Genet Selektsii 2022; 26:810-818. [PMID: 36694719 PMCID: PMC9834719 DOI: 10.18699/vjgb-22-98] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2022] [Revised: 10/10/2022] [Accepted: 10/26/2022] [Indexed: 01/06/2023] Open
Abstract
Many plants and animals have symbiotic relationships with microorganisms, including bacteria. The interactions between bacteria and their hosts result in different outcomes for the host organism. The outcome can be neutral, harmful or have beneficial effects for participants. Remarkably, these relationships are not static, as they change throughout an organism's lifetime and on an evolutionary scale. One of the structures responsible for relationships in bacteria is O-antigen. Depending on the characteristics of its components, the bacteria can avoid the host's immune response or establish a mutualistic relationship with it. O-antigen is a key component in Gram-negative bacteria's outer membrane. This component facilitates interaction between the bacteria and host immune system or phages. The variability of the physical structure is caused by the genomic variability of genes encoding O-antigen synthesis components. The genes and pathways of O-polysaccharide (OPS) synthesis were intensively investigated mostly for Enterobacteriaceae species. Considering high genetic and molecular diversity of this structure even between strains, these findings may not have caught the entire variety possibly presented in non-model species. The current study presents a comparative analysis of genes associated with O-antigen synthesis in bacteria of the Oxalobacteraceae family. In contrast to existing studies based on PCR methods, we use a bioinformatics approach and compare O- antigens at the level of clusters rather than individual genes. We found that the O-antigen genes of these bacteria are represented by several clusters located at a distance from each other. The greatest similarity of the clusters is observed within individual bacterial genera, which is explained by the high variability of O-antigens. The study describes similarities of OPS genes inherent to the family as a whole and also considers individual unique cases of O-antigen genetic variability inherent to individual bacteria.
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Affiliation(s)
- S.D. Afonnikova
- Institute of Cytology and Genetics of the Siberian Branch of the Russian Academy of Sciences, Novosibirsk, RussiaNovosibirsk State University, Novosibirsk, Russia
| | | | - P.D. Kuchur
- ITMO University, SCAMT Institute, St. Petersburg, Russia
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9
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Al-Hindi RR, Teklemariam AD, Alharbi MG, Alotibi I, Azhari SA, Qadri I, Alamri T, Harakeh S, Applegate BM, Bhunia AK. Bacteriophage-Based Biosensors: A Platform for Detection of Foodborne Bacterial Pathogens from Food and Environment. BIOSENSORS 2022; 12:bios12100905. [PMID: 36291042 PMCID: PMC9599427 DOI: 10.3390/bios12100905] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/20/2022] [Revised: 10/15/2022] [Accepted: 10/18/2022] [Indexed: 05/27/2023]
Abstract
Foodborne microorganisms are an important cause of human illness worldwide. Two-thirds of human foodborne diseases are caused by bacterial pathogens throughout the globe, especially in developing nations. Despite enormous developments in conventional foodborne pathogen detection methods, progress is limited by the assay complexity and a prolonged time-to-result. The specificity and sensitivity of assays for live pathogen detection may also depend on the nature of the samples being analyzed and the immunological or molecular reagents used. Bacteriophage-based biosensors offer several benefits, including specificity to their host organism, the detection of only live pathogens, and resistance to extreme environmental factors such as organic solvents, high temperatures, and a wide pH range. Phage-based biosensors are receiving increasing attention owing to their high degree of accuracy, specificity, and reduced assay times. These characteristics, coupled with their abundant supply, make phages a novel bio-recognition molecule in assay development, including biosensors for the detection of foodborne bacterial pathogens to ensure food safety. This review provides comprehensive information about the different types of phage-based biosensor platforms, such as magnetoelastic sensors, quartz crystal microbalance, and electrochemical and surface plasmon resonance for the detection of several foodborne bacterial pathogens from various representative food matrices and environmental samples.
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Affiliation(s)
- Rashad R. Al-Hindi
- Department of Biological Sciences, Faculty of Science, King Abdulaziz University, Jeddah 21589, Saudi Arabia
| | - Addisu D. Teklemariam
- Department of Biological Sciences, Faculty of Science, King Abdulaziz University, Jeddah 21589, Saudi Arabia
| | - Mona G. Alharbi
- Department of Biological Sciences, Faculty of Science, King Abdulaziz University, Jeddah 21589, Saudi Arabia
| | - Ibrahim Alotibi
- Health Information Technology Department, Applied College, King Abdulaziz University, Jeddah 21589, Saudi Arabia
| | - Sheren A. Azhari
- Department of Biological Sciences, Faculty of Science, King Abdulaziz University, Jeddah 21589, Saudi Arabia
| | - Ishtiaq Qadri
- Department of Biological Sciences, Faculty of Science, King Abdulaziz University, Jeddah 21589, Saudi Arabia
| | - Turki Alamri
- Family and Community Medicine Department, Faculty of Medicine in Rabigh, King Abdulaziz University, Jeddah 21589, Saudi Arabia
| | - Steve Harakeh
- King Fahd Medical Research Center, Yousef Abdullatif Jameel Chair of Prophetic Medicine Application, Faculty of Medicine, King Abdulaziz University, Jeddah 21589, Saudi Arabia
| | - Bruce M. Applegate
- Department of Food Science, Purdue University, West Lafayette, IN 47907, USA
- Interdisciplinary Life Science Program (PULSe), Purdue University, West Lafayette, IN 47907, USA
| | - Arun K. Bhunia
- Department of Food Science, Purdue University, West Lafayette, IN 47907, USA
- Purdue Institute of Inflammation, Immunology and Infectious Disease, Purdue University, West Lafayette, IN 47907, USA
- Interdisciplinary Life Science Program (PULSe), Purdue University, West Lafayette, IN 47907, USA
- Department of Comparative Pathobiology, Purdue University, West Lafayette, IN 47907, USA
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10
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Specific Isolation of Clostridium botulinum Group I Cells by Phage Lysin Cell Wall Binding Domain with the Aid of S-Layer Disruption. Int J Mol Sci 2022; 23:ijms23158391. [PMID: 35955526 PMCID: PMC9368847 DOI: 10.3390/ijms23158391] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2022] [Revised: 07/25/2022] [Accepted: 07/26/2022] [Indexed: 02/05/2023] Open
Abstract
Clostridium botulinum is a notorious pathogen that raises health and food safety concerns by producing the potent botulinum neurotoxin and causing botulism, a potentially fatal neuroparalytic disease in humans and animals. Efficient methods for the identification and isolation of C. botulinum are warranted for laboratory diagnostics of botulism and for food safety risk assessment. The cell wall binding domains (CBD) of phage lysins are recognized by their high specificity and affinity to distinct types of bacteria, which makes them promising for the development of diagnostic tools. We previously identified CBO1751, which is the first antibotulinal phage lysin showing a lytic activity against C. botulinum Group I. In this work, we assessed the host specificity of the CBD of CBO1751 and tested its feasibility as a probe for the specific isolation of C. botulinum Group I strains. We show that the CBO1751 CBD specifically binds to C. botulinum Group I sensu lato (including C. sporogenes) strains. We also demonstrate that some C. botulinum Group I strains possess an S-layer, the disruption of which by an acid glycine treatment is required for efficient binding of the CBO1751 CBD to the cells of these strains. We further developed CBO1751 CBD-based methods using flow cytometry and magnetic separation to specifically isolate viable cells of C. botulinum Group I. These methods present potential for applications in diagnostics and risk assessment in order to control the botulism hazard.
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Novel Approaches to Environmental Monitoring and Control of Listeria monocytogenes in Food Production Facilities. Foods 2022; 11:foods11121760. [PMID: 35741961 PMCID: PMC9222551 DOI: 10.3390/foods11121760] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2022] [Revised: 06/06/2022] [Accepted: 06/10/2022] [Indexed: 11/20/2022] Open
Abstract
Listeria monocytogenes is a serious public health hazard responsible for the foodborne illness listeriosis. L. monocytogenes is ubiquitous in nature and can become established in food production facilities, resulting in the contamination of a variety of food products, especially ready-to-eat foods. Effective and risk-based environmental monitoring programs and control strategies are essential to eliminate L. monocytogenes in food production environments. Key elements of the environmental monitoring program include (i) identifying the sources and prevalence of L. monocytogenes in the production environment, (ii) verifying the effectiveness of control measures to eliminate L. monocytogenes, and (iii) identifying the areas and activities to improve control. The design and implementation of the environmental monitoring program are complex, and several different approaches have emerged for sampling and detecting Listeria monocytogenes in food facilities. Traditional detection methods involve culture methods, followed by confirmation methods based on phenotypic, biochemical, and immunological characterization. These methods are laborious and time-consuming as they require at least 2 to 3 days to obtain results. Consequently, several novel detection approaches are gaining importance due to their rapidness, sensitivity, specificity, and high throughput. This paper comprehensively reviews environmental monitoring programs and novel approaches for detection based on molecular methods, immunological methods, biosensors, spectroscopic methods, microfluidic systems, and phage-based methods. Consumers have now become more interested in buying food products that are minimally processed, free of additives, shelf-stable, and have a better nutritional and sensory value. As a result, several novel control strategies have received much attention for their less adverse impact on the organoleptic properties of food and improved consumer acceptability. This paper reviews recent developments in control strategies by categorizing them into thermal, non-thermal, biocontrol, natural, and chemical methods, emphasizing the hurdle concept that involves a combination of different strategies to show synergistic impact to control L. monocytogenes in food production environments.
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12
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Trudelle D, Bryan DW, Ray S, Munafo JP, Denes TG. Analysis of Derivatized Wall Teichoic Acids Confirms that a Mutation in Phage-Resistant Listeria monocytogenes Impacts Rhamnose Decoration. ACS OMEGA 2022; 7:17002-17013. [PMID: 35647425 PMCID: PMC9134232 DOI: 10.1021/acsomega.1c07403] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/31/2021] [Accepted: 04/26/2022] [Indexed: 06/15/2023]
Abstract
Listeria monocytogenes is a Gram-positive foodborne pathogen that causes listeriosis, an illness that may result in serious health consequences or death. Wall teichoic acids (WTAs) are external cell wall glycopolymers that play many biological roles. Here, the WTA composition was determined for several phage-resistant mutant strains of L. monocytogenes. The strains included wild-type (WT) L. monocytogenes 10403S, and three phage-resistant mutant strains derived from 10403S, consisting of two well-characterized strains and one with unknown impact on cell physiology. Several WTA monomers were prepared from WT 10403S, as analytical standards. The WTA monomer fraction was then isolated from the mutant strains and the corresponding per-trimethylsilylated derivatives were analyzed by gas chromatography-flame ionization detection. WTA monomer, GlcNAc-Rha-Rbo, was detected in 10403S, and not detected in the phage-resistant strains known to lack rhamnose and N-acetylglucosamine; although the expected monomers GlcNAc-Rbo and Rha-Rbo were detected, respectively. GlcNAc-Rha-Rbo was also detected in strain UTK P1-0001, which is known to impact phage adsorption through an undetermined mechanism, albeit at a lower intensity than the WT 10403S, which is consistent with partial loss of function through truncation in RmlC protein. WTA monomers were also detected in an unpurified cell pellet, demonstrating that the method employed in this study can be used to rapidly screen L. monocytogenes without laborious WTA purification. This study lays the groundwork for future studies on WTA compositional analysis to support genomic data, and serves as a foundation for the development of new rapid methods for WTA compositional analysis.
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13
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Abril AG, Carrera M, Notario V, Sánchez-Pérez Á, Villa TG. The Use of Bacteriophages in Biotechnology and Recent Insights into Proteomics. Antibiotics (Basel) 2022; 11:653. [PMID: 35625297 PMCID: PMC9137636 DOI: 10.3390/antibiotics11050653] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2022] [Revised: 05/11/2022] [Accepted: 05/12/2022] [Indexed: 12/10/2022] Open
Abstract
Phages have certain features, such as their ability to form protein-protein interactions, that make them good candidates for use in a variety of beneficial applications, such as in human or animal health, industry, food science, food safety, and agriculture. It is essential to identify and characterize the proteins produced by particular phages in order to use these viruses in a variety of functional processes, such as bacterial detection, as vehicles for drug delivery, in vaccine development, and to combat multidrug resistant bacterial infections. Furthermore, phages can also play a major role in the design of a variety of cheap and stable sensors as well as in diagnostic assays that can either specifically identify specific compounds or detect bacteria. This article reviews recently developed phage-based techniques, such as the use of recombinant tempered phages, phage display and phage amplification-based detection. It also encompasses the application of phages as capture elements, biosensors and bioreceptors, with a special emphasis on novel bacteriophage-based mass spectrometry (MS) applications.
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Affiliation(s)
- Ana G. Abril
- Department of Microbiology and Parasitology, Faculty of Pharmacy, University of Santiago de Compostela, 15898 Santiago de Compostela, Spain;
- Department of Food Technology, Spanish National Research Council (CSIC), Marine Research Institute (IIM), 36208 Vigo, Spain;
| | - Mónica Carrera
- Department of Food Technology, Spanish National Research Council (CSIC), Marine Research Institute (IIM), 36208 Vigo, Spain;
| | - Vicente Notario
- Lombardi Comprehensive Cancer Center, Georgetown University, Washington, DC 20057, USA;
| | - Ángeles Sánchez-Pérez
- Sydney School of Veterinary Science, Faculty of Science, University of Sydney, Sydney, NSW 2006, Australia;
| | - Tomás G. Villa
- Department of Microbiology and Parasitology, Faculty of Pharmacy, University of Santiago de Compostela, 15898 Santiago de Compostela, Spain;
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14
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Filik K, Szermer-Olearnik B, Oleksy S, Brykała J, Brzozowska E. Bacteriophage Tail Proteins as a Tool for Bacterial Pathogen Recognition—A Literature Review. Antibiotics (Basel) 2022; 11:antibiotics11050555. [PMID: 35625199 PMCID: PMC9137617 DOI: 10.3390/antibiotics11050555] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2022] [Revised: 04/13/2022] [Accepted: 04/19/2022] [Indexed: 12/23/2022] Open
Abstract
In recent years, a number of bacterial detection methods have been developed to replace time-consuming culture methods. One interesting approach is to mobilize the ability of phage tail proteins to recognize and bind to bacterial hosts. In this paper, the authors provide an overview of the current methodologies in which phage proteins play major roles in detecting pathogenic bacteria. Authors focus on proteins capable of recognizing highly pathogenic strains, such as Acinetobacter baumannii, Campylobacter spp., Yersinia pestis, Pseudomonas aeruginosa, Listeria monocytogenes, Staphylococcus aureus, Enterococcus spp., Salmonella spp., and Shigella. These pathogens may be diagnosed by capture-based detection methods involving the use of phage protein-coated nanoparticles, ELISA (enzyme-linked immunosorbent assay)-based methods, or biosensors. The reviewed studies show that phage proteins are becoming an important diagnostic tool due to the discovery of new phages and the increasing knowledge of understanding the specificity and functions of phage tail proteins.
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15
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Liu S, He X, Zhang T, Zhao K, Xiao C, Tong Z, Jin L, He N, Deng Y, Li S, Guo Y, Chen Z. Highly sensitive smartphone-based detection of Listeria monocytogenes using SYTO9. CHINESE CHEM LETT 2022. [DOI: 10.1016/j.cclet.2021.11.051] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
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16
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Abstract
The field of metagenomics has rapidly expanded to become the go-to method for complex microbial community analyses. However, there is currently no straightforward route from metagenomics to traditional culture-based methods of strain isolation, particularly in (bacterio)phage biology, leading to an investigative bottleneck. Here, we describe a method that exploits specific phage receptor binding protein (RBP)-host cell surface receptor interaction enabling isolation of phage-host combinations from an environmental sample. The method was successfully applied to two complex sample types-a dairy-derived whey sample and an infant fecal sample, enabling retrieval of specific and culturable phage hosts. IMPORTANCE PhRACS aims to bridge the current divide between in silico genetic analyses (i.e., phageomic studies) and traditional culture-based methodology. Through the labeling of specific bacterial hosts with fluorescently tagged recombinant phage receptor binding proteins and the isolation of tagged cells using flow cytometry, PhRACS allows the full potential of phageomic data to be realized in the wet laboratory.
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17
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Liu B, Guo X, Wang J, Wu P, Li S, Feng L, Liu B, Wang L. Development of a Molecular Serotyping Scheme for Morganella morganii. Front Microbiol 2021; 12:791165. [PMID: 34887844 PMCID: PMC8649690 DOI: 10.3389/fmicb.2021.791165] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2021] [Accepted: 11/02/2021] [Indexed: 12/02/2022] Open
Abstract
Morganella morganii, which is often regarded as a human commensal organism, can be an opportunistic pathogen, causing a variety of clinical infections with serious morbidity and mortality. An efficient and convenient method for subtyping and identifying M. morganii strains in epidemiological surveillance and control is urgently needed. Serotyping based on bacterial surface polysaccharide antigens (O-antigen or K-antigens) is a standard subtyping method for many gram-negative bacteria. Here, through whole genome sequencing and comparative genomics analysis of 27 strains, we developed a molecular serotyping scheme based on the genetic variation of O-antigen gene clusters (O-AGC) in M. morganii, and 11 distinct O-AGC types were identified. A conventional serotyping scheme was also developed by the production of antisera and agglutination experiments, which was shown to be perfectly consistent with the molecular serotyping scheme, confirming that the variation in M. morganii O-AGC correlated with phenotypic O-antigen diversification. Furthermore, a microsphere-based suspension array (MSA) with high specificity was developed based on the specific genes within each O-AGC type. The sensitivity of MSA was determined to be 0.1 ng of genomic DNA and 103 CFU of pure culture. We further analyzed 104 M. morganii genomes available in GenBank, and an additional six novel O-AGC types were identified, indicating that the extension of this molecular serotyping scheme is convenient. Our work provides an important tool for the detection and epidemiological surveillance of M. morganii, and this method has the potential to be widely utilized, especially for bacterial genera/species without an efficient typing approach.
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Affiliation(s)
- Bin Liu
- Tianjin Union Medical Center, TEDA Institute of Biological Sciences and Biotechnology, The Institute of Translational Medicine Research, Nankai University, Tianjin, China.,Key Laboratory of Molecular Microbiology and Technology, Nankai University, Ministry of Education, Tianjin, China
| | - Xi Guo
- Tianjin Union Medical Center, TEDA Institute of Biological Sciences and Biotechnology, The Institute of Translational Medicine Research, Nankai University, Tianjin, China.,Key Laboratory of Molecular Microbiology and Technology, Nankai University, Ministry of Education, Tianjin, China
| | - Jing Wang
- Tianjin Union Medical Center, TEDA Institute of Biological Sciences and Biotechnology, The Institute of Translational Medicine Research, Nankai University, Tianjin, China
| | - Pan Wu
- Tianjin Union Medical Center, TEDA Institute of Biological Sciences and Biotechnology, The Institute of Translational Medicine Research, Nankai University, Tianjin, China
| | - Shujie Li
- Tianjin Union Medical Center, TEDA Institute of Biological Sciences and Biotechnology, The Institute of Translational Medicine Research, Nankai University, Tianjin, China
| | - Lu Feng
- Tianjin Union Medical Center, TEDA Institute of Biological Sciences and Biotechnology, The Institute of Translational Medicine Research, Nankai University, Tianjin, China.,Key Laboratory of Molecular Microbiology and Technology, Nankai University, Ministry of Education, Tianjin, China
| | - Bin Liu
- Tianjin Union Medical Center, TEDA Institute of Biological Sciences and Biotechnology, The Institute of Translational Medicine Research, Nankai University, Tianjin, China.,Key Laboratory of Molecular Microbiology and Technology, Nankai University, Ministry of Education, Tianjin, China
| | - Lei Wang
- Tianjin Union Medical Center, TEDA Institute of Biological Sciences and Biotechnology, The Institute of Translational Medicine Research, Nankai University, Tianjin, China.,Key Laboratory of Molecular Microbiology and Technology, Nankai University, Ministry of Education, Tianjin, China
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18
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Glucose Decoration on Wall Teichoic Acid Is Required for Phage Adsorption and InlB-Mediated Virulence in Listeria ivanovii. J Bacteriol 2021; 203:e0013621. [PMID: 34096780 PMCID: PMC8297528 DOI: 10.1128/jb.00136-21] [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] [Indexed: 12/30/2022] Open
Abstract
Listeria ivanovii (Liv) is an intracellular Gram-positive pathogen that primarily infects ruminants but also occasionally causes enteric infections in humans. Albeit rare, this bacterium possesses the capacity to cross the intestinal epithelium of humans, similar to its more frequently pathogenic cousin, Listeria monocytogenes (Lmo). Recent studies in Lmo have shown that specific glycosyl modifications on the cell wall-associated glycopolymers (termed wall teichoic acid [WTA]) of Lmo are responsible for bacteriophage adsorption and retention of the major virulence factor internalin B (InlB). However, the relationship between InlB and WTA in Liv remains unclear. Here, we report the identification of the unique gene liv1070, which encodes a putative glucosyltransferase in the polycistronic WTA gene cluster of the Liv WSLC 3009 genome. We found that in-frame deletion of liv1070 led to loss of the glucose substitution on WTA, as revealed by ultraperformance liquid chromatography-mass spectrometry (UPLC-MS) analysis. Interestingly, the glucose-deficient mutant became resistant to phage B025 infection due to an inability of the phage to adsorb to the bacterial surface, a binding process mediated by the receptor-binding protein B025_Gp17. As expected, deletion of liv1070 led to loss of InlB retention on the bacterial cell wall, which corresponded to a drastic decrease in cellular invasion. Genetic complementation of liv1070 restored the characteristic phenotypes, including glucose decoration, phage adsorption, and cellular invasion. Taken together, our data demonstrate that an interplay between phage, bacteria, and host cells also exists in Listeria ivanovii, suggesting that the trade-off between phage resistance and virulence attenuation may be a general feature in the genus Listeria. IMPORTANCE Listeria ivanovii is a Gram-positive bacterial pathogen known to cause enteric infection in rodents and ruminants and occasionally in immunocompromised humans. Recent investigations revealed that in its better-known cousin Listeria monocytogenes, strains develop resistance to bacteriophage attack due to loss of glycosylated surface receptors, which subsequently results in disconnection of one of the bacterium's major virulence factors, InlB. However, the situation in L. ivanovii remains unclear. Here, we show that L. ivanovii acquires phage resistance following deletion of a unique glycosyltransferase. This deletion also leads to dysfunction of InlB, making the resulting strain unable to invade host cells. Overall, this study suggests that the interplay between phage, bacteria, and the host may be a feature common to the genus Listeria.
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19
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Cunha AP, Henriques R, Cardoso S, Freitas PP, Carvalho CM. Rapid and multiplex detection of nosocomial pathogens on a phage-based magnetoresistive lab-on-chip platform. Biotechnol Bioeng 2021; 118:3164-3174. [PMID: 34037981 DOI: 10.1002/bit.27841] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2021] [Revised: 05/06/2021] [Accepted: 05/16/2021] [Indexed: 11/11/2022]
Abstract
Nosocomial or hospital-acquired infections (HAIs) have a major impact on mortality worldwide. Enterococcus and Staphylococcus are among the leading causes of HAIs and thus are important pathogens to control mainly due to their increased antibiotic resistance. The gold-standard diagnostic methods for HAIs are time-consuming, which hinders timely and adequate treatment. Therefore, the development of fast and accurate diagnostic tools is an urgent demand. In this study, we combined the sensitivity of magnetoresistive (MR) sensors, the portability of a lab-on-chip platform, and the specificity of phage receptor binding proteins (RBPs) as probes for the rapid and multiplex detection of Enterococcus and Staphylococcus. For this, bacterial cells were firstly labelled with magnetic nanoparticles (MNPs) functionalized with RBPs and then measured on the MR sensors. The results indicate that the RBP-MNPS provided a specific individual and simultaneous capture of more than 70% of Enterococcus and Staphylococcus cells. Moreover, high signals from the MR sensors were obtained for these samples, providing the detection of both pathogens at low concentrations (10 CFU/ml) in less than 2 h. Overall, the lab-on-chip MR platform herein presented holds great potential to be used as a point-of-care for the rapid, sensitive and specific multiplex diagnosis of bacterial infections.
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Affiliation(s)
- Alexandra P Cunha
- International Iberian Nanotechnology Laboratory (INL), Braga, Portugal.,Centre of Biological Engineering (CEB), University of Minho, Braga, Portugal
| | - Raquel Henriques
- Instituto de Engenharia de Sistemas e Computadores - Microsistemas e Nanotecnologias (INESC MN) and IN - Institute of Nanoscience and Nanotechnology, Lisbon, Portugal
| | - Susana Cardoso
- Instituto de Engenharia de Sistemas e Computadores - Microsistemas e Nanotecnologias (INESC MN) and IN - Institute of Nanoscience and Nanotechnology, Lisbon, Portugal
| | - Paulo P Freitas
- International Iberian Nanotechnology Laboratory (INL), Braga, Portugal.,Instituto de Engenharia de Sistemas e Computadores - Microsistemas e Nanotecnologias (INESC MN) and IN - Institute of Nanoscience and Nanotechnology, Lisbon, Portugal
| | - Carla M Carvalho
- International Iberian Nanotechnology Laboratory (INL), Braga, Portugal
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20
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Witte S, Zinsli LV, Gonzalez-Serrano R, Matter CI, Loessner MJ, van Mierlo JT, Dunne M. Structural and functional characterization of the receptor binding proteins of Escherichia coli O157 phages EP75 and EP335. Comput Struct Biotechnol J 2021; 19:3416-3426. [PMID: 34194667 PMCID: PMC8217332 DOI: 10.1016/j.csbj.2021.06.001] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2020] [Revised: 05/31/2021] [Accepted: 06/01/2021] [Indexed: 12/16/2022] Open
Abstract
Bacteriophages (phages) are widely used as biocontrol agents in food and as antibacterial agents for treatment of food production plant surfaces. An important feature of such phages is broad infectivity towards a given pathogenic species. Phages attach to the surfaces of bacterial cells using receptor binding proteins (RBPs), namely tail fibers or tailspikes (TSPs). The binding range of RBPs is the primary determinant of phage host range and infectivity, and therefore dictates a phage's suitability as an antibacterial agent. Phages EP75 and EP335 broadly infect strains of E. coli serotype O157. To better understand host recognition by both phages, here we focused on characterizing the structures and functions of their RBPs. We identified two distinct tail fibers in the genome of the podovirus EP335: gp12 and gp13. Using fluorescence microscopy, we reveal how gp13 recognizes strains of E. coli serotypes O157 and O26. Phage EP75 belongs to the Kuttervirus genus within the Ackermannviridae family and features a four TSP complex (TSPs 1-4) that is universal among such phages. We demonstrate enzymatic activity of TSP1 (gp167) and TSP2 (gp168) toward the O18A and O157 O-antigens of E. coli, respectively, as well as TSP3 activity (gp169.1) against O4, O7, and O9 Salmonella O-antigens. TSPs of EP75 present high similarity to TSPs from E. coli phages CBA120 (TSP2) and HK620 (TSP1) and Salmonella myovirus Det7 (TSP3), which helps explain the cross-genus infectivity observed for EP75.
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Affiliation(s)
- Sander Witte
- Micreos Food Safety B.V., Wageningen, Nieuwe Kanaal 7P, 6709PA, The Netherlands
| | - Léa V. Zinsli
- Institute of Food Nutrition and Health, ETH Zürich, Schmelzbergstrasse 7, 8092 Zürich, Switzerland
| | | | - Cassandra I. Matter
- Institute of Food Nutrition and Health, ETH Zürich, Schmelzbergstrasse 7, 8092 Zürich, Switzerland
| | - Martin J. Loessner
- Institute of Food Nutrition and Health, ETH Zürich, Schmelzbergstrasse 7, 8092 Zürich, Switzerland
| | - Joël T. van Mierlo
- Micreos Food Safety B.V., Wageningen, Nieuwe Kanaal 7P, 6709PA, The Netherlands
| | - Matthew Dunne
- Institute of Food Nutrition and Health, ETH Zürich, Schmelzbergstrasse 7, 8092 Zürich, Switzerland
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21
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Hassan AY, Lin JT, Ricker N, Anany H. The Age of Phage: Friend or Foe in the New Dawn of Therapeutic and Biocontrol Applications? Pharmaceuticals (Basel) 2021; 14:199. [PMID: 33670836 PMCID: PMC7997343 DOI: 10.3390/ph14030199] [Citation(s) in RCA: 30] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2021] [Revised: 02/22/2021] [Accepted: 02/25/2021] [Indexed: 02/07/2023] Open
Abstract
Extended overuse and misuse of antibiotics and other antibacterial agents has resulted in an antimicrobial resistance crisis. Bacteriophages, viruses that infect bacteria, have emerged as a legitimate alternative antibacterial agent with a wide scope of applications which continue to be discovered and refined. However, the potential of some bacteriophages to aid in the acquisition, maintenance, and dissemination of negatively associated bacterial genes, including resistance and virulence genes, through transduction is of concern and requires deeper understanding in order to be properly addressed. In particular, their ability to interact with mobile genetic elements such as plasmids, genomic islands, and integrative conjugative elements (ICEs) enables bacteriophages to contribute greatly to bacterial evolution. Nonetheless, bacteriophages have the potential to be used as therapeutic and biocontrol agents within medical, agricultural, and food processing settings, against bacteria in both planktonic and biofilm environments. Additionally, bacteriophages have been deployed in developing rapid, sensitive, and specific biosensors for various bacterial targets. Intriguingly, their bioengineering capabilities show great promise in improving their adaptability and effectiveness as biocontrol and detection tools. This review aims to provide a balanced perspective on bacteriophages by outlining advantages, challenges, and future steps needed in order to boost their therapeutic and biocontrol potential, while also providing insight on their potential role in contributing to bacterial evolution and survival.
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Affiliation(s)
- Ahmad Y. Hassan
- Guelph Research and Development Centre, Agriculture and Agri-Food Canada, Guelph, ON N1G 5C9, Canada;
- Department of Molecular and Cellular Biology, College of Biological Science, University of Guelph, Guelph, ON N1G 2W1, Canada;
| | - Janet T. Lin
- Department of Molecular and Cellular Biology, College of Biological Science, University of Guelph, Guelph, ON N1G 2W1, Canada;
| | - Nicole Ricker
- Department of Pathobiology, Ontario Veterinary College, University of Guelph, Guelph, ON N1G 2W1, Canada;
| | - Hany Anany
- Guelph Research and Development Centre, Agriculture and Agri-Food Canada, Guelph, ON N1G 5C9, Canada;
- Department of Food Science, Ontario Agricultural College, University of Guelph, Guelph, ON N1G 2W1, Canada
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22
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Whole Genome Sequence Analysis of Phage-Resistant Listeria monocytogenes Serotype 1/2a Strains from Turkey Processing Plants. Pathogens 2021; 10:pathogens10020199. [PMID: 33668492 PMCID: PMC7922946 DOI: 10.3390/pathogens10020199] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/01/2021] [Revised: 01/26/2021] [Accepted: 02/09/2021] [Indexed: 12/17/2022] Open
Abstract
Listeria monocytogenes is a Gram-positive bacterial pathogen and the causative agent of listeriosis, a severe foodborne infection. L. monocytogenes is notorious for its ability to persist in food processing environments (FPEs) via a variety of adaptive traits. Even though traits such as cold tolerance, biofilm formation and sanitizer resistance have been extensively investigated for their roles in persistence of L. monocytogenes in FPEs, much less is known about resistance to bacteriophages. Previous studies explored phage resistance mechanisms in laboratory-created mutants but it is imperative to investigate phage resistance that is naturally exhibited in FPE-derived strains. Here, we integrated the analysis of whole genome sequence data from a panel of serotype 1/2a strains of sequence types 321 and 391 from turkey processing plants, with the determination of cell surface substituents required for phage adsorption and phage infection assays with the four wide-host-range phages A511, P100, 20422-1 and 805405-1. Using a specific set of recombinant phage protein probes, we discovered that phage-resistant strains lacked one or both of the serogroup 1/2-specific wall teichoic acid carbohydrate decorations, N-acetylglucosamine and rhamnose. Furthermore, these phage-resistant strains harbored substitutions in lmo1080, lmo1081, and lmo2550, which mediate carbohydrate decoration of the wall teichoic acids.
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23
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Complete Genome Sequences of Three Listeria monocytogenes Bacteriophage Propagation Strains. Microbiol Resour Announc 2021; 10:10/1/e01159-20. [PMID: 33414304 PMCID: PMC8407704 DOI: 10.1128/mra.01159-20] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023] Open
Abstract
Bacteriophages can be used as a biocontrol for the foodborne pathogen Listeria monocytogenes. Propagation of phages is a necessary step for their use in experimental studies and biocontrol applications. Here, we present the complete genomes of three Listeria monocytogenes strains commonly used as propagation hosts for Listeria phages. Bacteriophages can be used as a biocontrol for the foodborne pathogen Listeria monocytogenes. Propagation of phages is a necessary step for their use in experimental studies and biocontrol applications. Here, we present the complete genomes of three Listeria monocytogenes strains commonly used as propagation hosts for Listeria phages.
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24
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Beyond antibacterials - exploring bacteriophages as antivirulence agents. Curr Opin Biotechnol 2020; 68:166-173. [PMID: 33333352 DOI: 10.1016/j.copbio.2020.11.004] [Citation(s) in RCA: 23] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2020] [Revised: 10/28/2020] [Accepted: 11/09/2020] [Indexed: 01/10/2023]
Abstract
Life-threatening infections caused by multidrug-resistant bacteria are becoming increasingly difficult to treat. There is growing interest in exploiting bacteriophages (or phages) to combat bacterial infections. Phages often target bacterial surface structures that may also be important for virulence. Upon phage challenge, these molecules may be lost or modified, resulting in phage resistance and possibly phenotypical conversion. Importantly, possible trade-offs may include lower fitness, increased sensitivity to antibiotics and immune defense mechanisms, and virulence attenuation. Although evolution of phage-resistance may be difficult to prevent, the trade-off phenomenon carries potential for antibacterial therapy. Here we present some insights into the molecular principles and significance of this coincidental interplay between phages, bacteria, and immune cells, and discuss the prospect of developing phage-derived products as antivirulence agents.
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Mutant and Recombinant Phages Selected from In Vitro Coevolution Conditions Overcome Phage-Resistant Listeria monocytogenes. Appl Environ Microbiol 2020; 86:AEM.02138-20. [PMID: 32887717 DOI: 10.1128/aem.02138-20] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2020] [Accepted: 08/31/2020] [Indexed: 12/17/2022] Open
Abstract
Bacteriophages (phages) are currently available for use by the food industry to control the foodborne pathogen Listeria monocytogenes Although phage biocontrols are effective under specific conditions, their use can select for phage-resistant bacteria that repopulate phage-treated environments. Here, we performed short-term coevolution experiments to investigate the impact of single phages and a two-phage cocktail on the regrowth of phage-resistant L. monocytogenes and the adaptation of the phages to overcome this resistance. We used whole-genome sequencing to identify mutations in the target host that confer phage resistance and in the phages that alter host range. We found that infections with Listeria phages LP-048, LP-125, or a combination of both select for different populations of phage-resistant L. monocytogenes bacteria with different regrowth times. Phages isolated from the end of the coevolution experiments were found to have gained the ability to infect phage-resistant mutants of L. monocytogenes and L. monocytogenes strains previously found to be broadly resistant to phage infection. Phages isolated from coinfected cultures were identified as recombinants of LP-048 and LP-125. Interestingly, recombination events occurred twice independently in a locus encoding two proteins putatively involved in DNA binding. We show that short-term coevolution of phages and their hosts can be utilized to obtain mutant and recombinant phages with adapted host ranges. These laboratory-evolved phages may be useful for limiting the emergence of phage resistance and for targeting strains that show general resistance to wild-type (WT) phages.IMPORTANCE Listeria monocytogenes is a life-threatening bacterial foodborne pathogen that can persist in food processing facilities for years. Phages can be used to control L. monocytogenes in food production, but phage-resistant bacterial subpopulations can regrow in phage-treated environments. Coevolution experiments were conducted on a Listeria phage-host system to provide insight into the genetic variation that emerges in both the phage and bacterial host under reciprocal selective pressure. As expected, mutations were identified in both phage and host, but additionally, recombination events were shown to have repeatedly occurred between closely related phages that coinfected L. monocytogenes This study demonstrates that in vitro evolution of phages can be utilized to expand the host range and improve the long-term efficacy of phage-based control of L. monocytogenes This approach may also be applied to other phage-host systems for applications in biocontrol, detection, and phage therapy.
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Shen Y, Kalograiaki I, Prunotto A, Dunne M, Boulos S, Taylor NMI, Sumrall ET, Eugster MR, Martin R, Julian-Rodero A, Gerber B, Leiman PG, Menéndez M, Peraro MD, Cañada FJ, Loessner MJ. Structural basis for recognition of bacterial cell wall teichoic acid by pseudo-symmetric SH3b-like repeats of a viral peptidoglycan hydrolase. Chem Sci 2020; 12:576-589. [PMID: 34163788 PMCID: PMC8179006 DOI: 10.1039/d0sc04394j] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
Endolysins are bacteriophage-encoded peptidoglycan hydrolases targeting the cell wall of host bacteria via their cell wall-binding domains (CBDs). The molecular basis for selective recognition of surface carbohydrate ligands by CBDs remains elusive. Here, we describe, in atomic detail, the interaction between the Listeria phage endolysin domain CBD500 and its cell wall teichoic acid (WTA) ligands. We show that 3′O-acetylated GlcNAc residues integrated into the WTA polymer chain are the key epitope recognized by a CBD binding cavity located at the interface of tandem copies of beta-barrel, pseudo-symmetric SH3b-like repeats. This cavity consists of multiple aromatic residues making extensive interactions with two GlcNAc acetyl groups via hydrogen bonds and van der Waals contacts, while permitting the docking of the diastereomorphic ligands. Our multidisciplinary approach tackled an extremely challenging protein–glycopolymer complex and delineated a previously unknown recognition mechanism by which a phage endolysin specifically recognizes and targets WTA, suggesting an adaptable model for regulation of endolysin specificity. Combining genetic, biochemical and computational approaches, we elucidated the molecular mechanisms underlying the recognition of Listeria wall teichoic acid by bacteriophage-encoded SH3b repeats.![]()
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Affiliation(s)
- Yang Shen
- Institute of Food, Nutrition and Health, ETH Zurich Schmelzbergstrasse 7 8092 Zurich Switzerland
| | - Ioanna Kalograiaki
- Centro de Investigaciones Biológicas, Margarita Salas, Consejo Superior de Investigaciones Científicas Ramiro de Maeztu 9 28040 Madrid Spain.,Centro de Investigación Biomédica en Red-Enfermedades Respiratorias (CIBERES) Avenida de Monforte de Lemos 3-5 28029 Madrid Spain
| | - Alessio Prunotto
- Laboratory for Biomolecular Modeling, EPFL IBI-SV Station 19 1015 Lausanne Switzerland
| | - Matthew Dunne
- Institute of Food, Nutrition and Health, ETH Zurich Schmelzbergstrasse 7 8092 Zurich Switzerland
| | - Samy Boulos
- Institute of Food, Nutrition and Health, ETH Zurich Schmelzbergstrasse 9 8092 Zurich Switzerland
| | - Nicholas M I Taylor
- Structural Biology of Molecular Machines Group, Protein Structure & Function Programme, Novo Nordisk Foundation Center for Protein Research, Faculty of Health and Medical Sciences, University of Copenhagen Blegdamsvej 3B Copenhagen 2200 Denmark
| | - Eric T Sumrall
- Institute of Food, Nutrition and Health, ETH Zurich Schmelzbergstrasse 7 8092 Zurich Switzerland
| | - Marcel R Eugster
- Institute of Food, Nutrition and Health, ETH Zurich Schmelzbergstrasse 7 8092 Zurich Switzerland
| | - Rebecca Martin
- Institute of Food, Nutrition and Health, ETH Zurich Schmelzbergstrasse 7 8092 Zurich Switzerland
| | - Alicia Julian-Rodero
- Institute of Food, Nutrition and Health, ETH Zurich Schmelzbergstrasse 7 8092 Zurich Switzerland
| | - Benjamin Gerber
- Institute of Food, Nutrition and Health, ETH Zurich Schmelzbergstrasse 7 8092 Zurich Switzerland
| | - Petr G Leiman
- University of Texas Medical Branch, Department of Biochemistry and Molecular Biology, Sealy Center for Structural Biology and Molecular Biophysics 301 University Blvd Galveston TX 77555-0647 USA
| | - Margarita Menéndez
- Centro de Investigación Biomédica en Red-Enfermedades Respiratorias (CIBERES) Avenida de Monforte de Lemos 3-5 28029 Madrid Spain.,Instituto de Química-Física Rocasolano, Consejo Superior de Investigaciones Cientificas Serrano 119 28006 Madrid Spain
| | - Matteo Dal Peraro
- Laboratory for Biomolecular Modeling, EPFL IBI-SV Station 19 1015 Lausanne Switzerland
| | - Francisco Javier Cañada
- Centro de Investigaciones Biológicas, Margarita Salas, Consejo Superior de Investigaciones Científicas Ramiro de Maeztu 9 28040 Madrid Spain.,Centro de Investigación Biomédica en Red-Enfermedades Respiratorias (CIBERES) Avenida de Monforte de Lemos 3-5 28029 Madrid Spain
| | - Martin J Loessner
- Institute of Food, Nutrition and Health, ETH Zurich Schmelzbergstrasse 7 8092 Zurich Switzerland
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Reporter Phage-Based Detection of Bacterial Pathogens: Design Guidelines and Recent Developments. Viruses 2020; 12:v12090944. [PMID: 32858938 PMCID: PMC7552063 DOI: 10.3390/v12090944] [Citation(s) in RCA: 34] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2020] [Revised: 08/10/2020] [Accepted: 08/25/2020] [Indexed: 02/06/2023] Open
Abstract
Fast and reliable detection of bacterial pathogens in clinical samples, contaminated food products, and water supplies can drastically improve clinical outcomes and reduce the socio-economic impact of disease. As natural predators of bacteria, bacteriophages (phages) have evolved to bind their hosts with unparalleled specificity and to rapidly deliver and replicate their viral genome. Not surprisingly, phages and phage-encoded proteins have been used to develop a vast repertoire of diagnostic assays, many of which outperform conventional culture-based and molecular detection methods. While intact phages or phage-encoded affinity proteins can be used to capture bacteria, most phage-inspired detection systems harness viral genome delivery and amplification: to this end, suitable phages are genetically reprogrammed to deliver heterologous reporter genes, whose activity is typically detected through enzymatic substrate conversion to indicate the presence of a viable host cell. Infection with such engineered reporter phages typically leads to a rapid burst of reporter protein production that enables highly sensitive detection. In this review, we highlight recent advances in infection-based detection methods, present guidelines for reporter phage construction, outline technical aspects of reporter phage engineering, and discuss some of the advantages and pitfalls of phage-based pathogen detection. Recent improvements in reporter phage construction and engineering further substantiate the potential of these highly evolved nanomachines as rapid and inexpensive detection systems to replace or complement traditional diagnostic approaches.
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Santos SB, Cunha AP, Macedo M, Nogueira CL, Brandão A, Costa SP, Melo LDR, Azeredo J, Carvalho CM. Bacteriophage‐receptor binding proteins for multiplex detection of
Staphylococcus
and
Enterococcus
in blood. Biotechnol Bioeng 2020; 117:3286-3298. [DOI: 10.1002/bit.27489] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2020] [Revised: 06/23/2020] [Accepted: 07/10/2020] [Indexed: 02/06/2023]
Affiliation(s)
- Sílvio B. Santos
- Centre of Biological Engineering University of Minho Braga Portugal
| | | | - Mariana Macedo
- Centre of Biological Engineering University of Minho Braga Portugal
| | - Catarina L. Nogueira
- International Iberian Nanotechnology Laboratory Braga Portugal
- Instituto de Engenharia de Sistemas e Computadores – Microsistemas e Nanotecnologias (INESC MN) and IN – Institute of Nanoscience and Nanotechnolnology Lisbon Portugal
| | - Ana Brandão
- Centre of Biological Engineering University of Minho Braga Portugal
| | - Susana P. Costa
- Centre of Biological Engineering University of Minho Braga Portugal
- International Iberian Nanotechnology Laboratory Braga Portugal
- Instituto de Engenharia de Sistemas e Computadores – Microsistemas e Nanotecnologias (INESC MN) and IN – Institute of Nanoscience and Nanotechnolnology Lisbon Portugal
| | - Luís D. R. Melo
- Centre of Biological Engineering University of Minho Braga Portugal
| | - Joana Azeredo
- Centre of Biological Engineering University of Minho Braga Portugal
| | - Carla M. Carvalho
- Centre of Biological Engineering University of Minho Braga Portugal
- International Iberian Nanotechnology Laboratory Braga Portugal
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Rapid Microscopic Detection of Bacillus anthracis by Fluorescent Receptor Binding Proteins of Bacteriophages. Microorganisms 2020; 8:microorganisms8060934. [PMID: 32575866 PMCID: PMC7356292 DOI: 10.3390/microorganisms8060934] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2020] [Revised: 06/18/2020] [Accepted: 06/19/2020] [Indexed: 12/19/2022] Open
Abstract
Bacillus anthracis, the etiological agent of anthrax disease, is typically diagnosed by immunological and molecular methods such as polymerase chain reaction (PCR). Alternatively, mass spectrometry techniques may aid in confirming the presence of the pathogen or its toxins. However, because of the close genetic relationship between B. anthracis and other members of the Bacillus cereus sensu lato group (such as Bacillus cereus or Bacillus thuringiensis) mis- or questionable identification occurs frequently. Also, bacteriophages such as phage gamma (which is highly specific for B. anthracis) have been in use for anthrax diagnostics for many decades. Here we employed host cell-specific receptor binding proteins (RBP) of (pro)-phages, also known as tail or head fibers, to develop a microscopy-based approach for the facile, rapid and unambiguous detection of B. anthracis cells. For this, the genes of (putative) RBP from Bacillus phages gamma, Wip1, AP50c and from lambdoid prophage 03 located on the chromosome of B. anthracis were selected. Respective phage genes were heterologously expressed in Escherichia coli and purified as fusions with fluorescent proteins. B. anthracis cells incubated with either of the reporter fusion proteins were successfully surface-labeled. Binding specificity was confirmed as RBP fusion proteins did not bind to most isolates of a panel of other B. cereus s.l. species or to more distantly related bacteria. Remarkably, RBP fusions detected encapsulated B. anthracis cells, thus RBP were able to penetrate the poly-γ-d-glutamate capsule of B. anthracis. From these results we anticipate this RBP-reporter assay may be useful for rapid confirmative identification of B. anthracis.
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