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Camilotti E, Furian TQ, Borges KA, Ortiz Granados OF, Zottis Chitolina G, de Brites Weber T, Tonini da Rocha D, Nascimento VPD, Souza Moraes HLD, Salle CTP. Galleria mellonella larvae as an alternative model to determine the pathogenicity of avian pathogenic Escherichia coli. Avian Pathol 2024:1-13. [PMID: 38845537 DOI: 10.1080/03079457.2024.2365932] [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: 03/21/2024] [Accepted: 06/05/2024] [Indexed: 06/27/2024]
Abstract
RESEARCH HIGHLIGHTS Galleria mellonella larvae are a viable model for determining APEC pathogenicity.Larval disease score is the main variable for determining APEC pathogenicity.Response variables should be evaluated up to 24 h post-inoculation.
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Affiliation(s)
- Elisar Camilotti
- Centro de Diagnóstico e Pesquisa em Patologia Aviária, Departamento de Medicina Animal, Faculdade de Medicina Veterinária, Universidade Federal do Rio Grande do Sul, Rio Grande do Sul, Brazil
| | - Thales Quedi Furian
- Centro de Diagnóstico e Pesquisa em Patologia Aviária, Departamento de Medicina Animal, Faculdade de Medicina Veterinária, Universidade Federal do Rio Grande do Sul, Rio Grande do Sul, Brazil
| | - Karen Apellanis Borges
- Centro de Diagnóstico e Pesquisa em Patologia Aviária, Departamento de Medicina Animal, Faculdade de Medicina Veterinária, Universidade Federal do Rio Grande do Sul, Rio Grande do Sul, Brazil
| | - Oscar Fernando Ortiz Granados
- Centro de Diagnóstico e Pesquisa em Patologia Aviária, Departamento de Medicina Animal, Faculdade de Medicina Veterinária, Universidade Federal do Rio Grande do Sul, Rio Grande do Sul, Brazil
| | - Gabriela Zottis Chitolina
- Centro de Diagnóstico e Pesquisa em Patologia Aviária, Departamento de Medicina Animal, Faculdade de Medicina Veterinária, Universidade Federal do Rio Grande do Sul, Rio Grande do Sul, Brazil
| | - Thaína de Brites Weber
- Centro de Diagnóstico e Pesquisa em Patologia Aviária, Departamento de Medicina Animal, Faculdade de Medicina Veterinária, Universidade Federal do Rio Grande do Sul, Rio Grande do Sul, Brazil
| | - Daniela Tonini da Rocha
- Centro de Diagnóstico e Pesquisa em Patologia Aviária, Departamento de Medicina Animal, Faculdade de Medicina Veterinária, Universidade Federal do Rio Grande do Sul, Rio Grande do Sul, Brazil
| | - Vladimir Pinheiro do Nascimento
- Centro de Diagnóstico e Pesquisa em Patologia Aviária, Departamento de Medicina Animal, Faculdade de Medicina Veterinária, Universidade Federal do Rio Grande do Sul, Rio Grande do Sul, Brazil
| | - Hamilton Luiz de Souza Moraes
- Centro de Diagnóstico e Pesquisa em Patologia Aviária, Departamento de Medicina Animal, Faculdade de Medicina Veterinária, Universidade Federal do Rio Grande do Sul, Rio Grande do Sul, Brazil
| | - Carlos Tadeu Pippi Salle
- Centro de Diagnóstico e Pesquisa em Patologia Aviária, Departamento de Medicina Animal, Faculdade de Medicina Veterinária, Universidade Federal do Rio Grande do Sul, Rio Grande do Sul, Brazil
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2
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Zhuo W, Zhao Y, Zhao X, Yao Z, Qiu X, Huang Y, Li H, Shen J, Zhu Z, Li T, Li S, Huang Q, Zhou R. Enteropathogenic Escherichia coli is a predominant pathotype in healthy pigs in Hubei Province of China. J Appl Microbiol 2023; 134:lxad260. [PMID: 37962953 DOI: 10.1093/jambio/lxad260] [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: 07/26/2023] [Revised: 10/29/2023] [Accepted: 11/13/2023] [Indexed: 11/16/2023]
Abstract
AIM This study aims to investigate the prevalence of intestinal pathogenic Escherichia coli (InPEC) in healthy pig-related samples and evaluate the potential virulence of the InPEC strains. METHODS AND RESULTS A multiplex PCR method was established to identify different pathotypes of InPEC. A total of 800 rectal swab samples and 296 pork samples were collected from pig farms and slaughterhouses in Hubei province, China. From these samples, a total of 21 InPEC strains were isolated, including 19 enteropathogenic E. coli (EPEC) and 2 shiga toxin-producing E. coli (STEC) strains. By whole-genome sequencing and in silico typing, it was shown that the sequence types and serotypes were diverse among the strains. Antimicrobial susceptibility assays showed that 90.48% of the strains were multi-drug resistant. The virulence of the strains was first evaluated using the Galleria mellonella larvae model, which showed that most of the strains possessed medium to high pathogenicity. A moderately virulent EPEC isolate was further selected to characterize its pathogenicity using a mouse model, which suggested that it could cause significant diarrhea. Bioluminescence imaging (BLI) was then used to investigate the colonization dynamics of this EPEC isolate, which showed that the EPEC strain could colonize the mouse cecum for up to 5 days.
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Affiliation(s)
- Wenxiao Zhuo
- National Key Laboratory of Agricultural Microbiology, College of Veterinary Medicine, Huazhong Agricultural University, Wuhan 430070, China
| | - Yang Zhao
- National Key Laboratory of Agricultural Microbiology, College of Veterinary Medicine, Huazhong Agricultural University, Wuhan 430070, China
| | - Xianglin Zhao
- National Key Laboratory of Agricultural Microbiology, College of Veterinary Medicine, Huazhong Agricultural University, Wuhan 430070, China
| | - Zhiming Yao
- National Key Laboratory of Agricultural Microbiology, College of Veterinary Medicine, Huazhong Agricultural University, Wuhan 430070, China
| | - Xiuxiu Qiu
- National Key Laboratory of Agricultural Microbiology, College of Veterinary Medicine, Huazhong Agricultural University, Wuhan 430070, China
| | - Yaxue Huang
- National Key Laboratory of Agricultural Microbiology, College of Veterinary Medicine, Huazhong Agricultural University, Wuhan 430070, China
| | - Huaixia Li
- National Key Laboratory of Agricultural Microbiology, College of Veterinary Medicine, Huazhong Agricultural University, Wuhan 430070, China
| | - Jing Shen
- National Key Laboratory of Agricultural Microbiology, College of Veterinary Medicine, Huazhong Agricultural University, Wuhan 430070, China
| | - Zhihao Zhu
- National Key Laboratory of Agricultural Microbiology, College of Veterinary Medicine, Huazhong Agricultural University, Wuhan 430070, China
| | - Tingting Li
- Hubei Animal Disease Prevention and Control Center, Wuhan 430070, China
| | - Shaowen Li
- National Key Laboratory of Agricultural Microbiology, College of Veterinary Medicine, Huazhong Agricultural University, Wuhan 430070, China
| | - Qi Huang
- National Key Laboratory of Agricultural Microbiology, College of Veterinary Medicine, Huazhong Agricultural University, Wuhan 430070, China
- Cooperative Innovation Center of Sustainable Pig Production, College of Veterinary Medicine, Wuhan 430070, China
- International Research Center for Animal Disease (Ministry of Science & Technology of China), College of Veterinary Medicine, Wuhan 430070, China
| | - Rui Zhou
- National Key Laboratory of Agricultural Microbiology, College of Veterinary Medicine, Huazhong Agricultural University, Wuhan 430070, China
- Cooperative Innovation Center of Sustainable Pig Production, College of Veterinary Medicine, Wuhan 430070, China
- International Research Center for Animal Disease (Ministry of Science & Technology of China), College of Veterinary Medicine, Wuhan 430070, China
- The HZAU-HVSEN Research Institute, Wuhan 430042, China
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3
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Cho THS, Pick K, Raivio TL. Bacterial envelope stress responses: Essential adaptors and attractive targets. BIOCHIMICA ET BIOPHYSICA ACTA. MOLECULAR CELL RESEARCH 2023; 1870:119387. [PMID: 36336206 DOI: 10.1016/j.bbamcr.2022.119387] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/22/2022] [Revised: 10/05/2022] [Accepted: 10/20/2022] [Indexed: 11/06/2022]
Abstract
Millions of deaths a year across the globe are linked to antimicrobial resistant infections. The need to develop new treatments and repurpose of existing antibiotics grows more pressing as the growing antimicrobial resistance pandemic advances. In this review article, we propose that envelope stress responses, the signaling pathways bacteria use to recognize and adapt to damage to the most vulnerable outer compartments of the microbial cell, are attractive targets. Envelope stress responses (ESRs) support colonization and infection by responding to a plethora of toxic envelope stresses encountered throughout the body; they have been co-opted into virulence networks where they work like global positioning systems to coordinate adhesion, invasion, microbial warfare, and biofilm formation. We highlight progress in the development of therapeutic strategies that target ESR signaling proteins and adaptive networks and posit that further characterization of the molecular mechanisms governing these essential niche adaptation machineries will be important for sparking new therapeutic approaches aimed at short-circuiting bacterial adaptation.
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Affiliation(s)
- Timothy H S Cho
- Department of Biological Sciences, University of Alberta, Edmonton, AB, Canada
| | - Kat Pick
- Department of Biological Sciences, University of Alberta, Edmonton, AB, Canada
| | - Tracy L Raivio
- Department of Biological Sciences, University of Alberta, Edmonton, AB, Canada.
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Ahlawat S, Sharma KK. Lepidopteran insects: emerging model organisms to study infection by enteropathogens. Folia Microbiol (Praha) 2022; 68:181-196. [PMID: 36417090 DOI: 10.1007/s12223-022-01014-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2022] [Accepted: 11/03/2022] [Indexed: 11/24/2022]
Abstract
The in vivo analysis of a pathogen is a critical step in gaining greater knowledge of pathogen biology and host-pathogen interactions. In the last two decades, there has been a notable rise in the number of studies on developing insects as a model for studying pathogens, which provides various benefits, such as ethical acceptability, relatively short life cycle, and cost-effective care and maintenance relative to routinely used rodent infection models. Furthermore, lepidopteran insects provide many advantages, such as easy handling and tissue extraction due to their large size relative to other invertebrate models, like Caenorhabditis elegans. Additionally, insects have an innate immune system that is highly analogous to vertebrates. In the present review, we discuss the components of the insect's larval immune system, which strengthens its usage as an alternative host, and present an updated overview of the research findings involving lepidopteran insects (Galleria mellonella, Manduca sexta, Bombyx mori, and Helicoverpa armigera) as infection models to study the virulence by enteropathogens due to the homology between insect and vertebrate gut.
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Affiliation(s)
- Shruti Ahlawat
- Department of Microbiology, Faculty of Allied Health Sciences, SGT University, Gurgaon-Badli Road Chandu, Budhera, Gurugram, 122505, Haryana, India.
| | - Krishna Kant Sharma
- Laboratory of Enzymology and Recombinant DNA Technology, Department of Microbiology, Maharshi Dayanand University, Rohtak, 124001, Haryana, India
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Fitness Trade-Offs in Phage Cocktail-Resistant Salmonella enterica Serovar Enteritidis Results in Increased Antibiotic Susceptibility and Reduced Virulence. Microbiol Spectr 2022; 10:e0291422. [PMID: 36165776 PMCID: PMC9603643 DOI: 10.1128/spectrum.02914-22] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023] Open
Abstract
The rapid emergence of phage-resistant bacterial mutants is a major challenge for phage therapy. Phage cocktails have been considered one approach to mitigate this issue. However, the synergistic effect of randomly selected phages in the cocktails is ambiguous. Here, we rationally designed a phage cocktail consisting of four phages that utilize the lipopolysaccharide (LPS) O antigen, the LPS outer core, the LPS inner core, and the outer membrane proteins BtuB and TolC on the Salmonella enterica serovar Enteritidis cell surface as receptors. We demonstrated that the four-phage cocktail could significantly delay the emergence of phage-resistant bacterial mutants compared to the single phage. To investigate the fitness costs associated with phage resistance, we characterized a total of 80 bacterial mutants resistant to a single phage or the four-phage cocktail. We observed that mutants resistant to the four-phage cocktail were more sensitive to several antibiotics than the single-phage-resistant mutants. In addition, all mutants resistant to the four-phage cocktail had significantly reduced virulence compared to wild-type strains. Our mouse model of Salmonella Enteritidis infection also indicated that the four-phage cocktail exhibited an enhanced therapeutic effect. Together, our work demonstrates an efficient strategy to design phage cocktails by combining phages with different bacterial receptors, which can steer the evolution of phage-resistant strains toward clinically exploitable phenotypes. IMPORTANCE The selection pressure of phage promotes bacterial mutation, which results in a fitness cost. Such fitness trade-offs are related to the host receptor of the phage; therefore, we can utilize knowledge of bacterial receptors used by phages as a criterion for designing phage cocktails. Here, we evaluated the efficacy of a phage cocktail made up of phages that target four different receptors on Salmonella Enteritidis through in vivo and in vitro experiments. Importantly, we found that pressure from phage cocktails with different receptors can drive phage-resistant bacterial mutants to evolve in a direction that entails more severe fitness costs, resulting in reduced virulence and increased susceptibility to antibiotics. These findings suggest that phage cocktail therapy using combinations of phages targeting different important receptors (e.g., LPS or the efflux pump AcrAB-TolC) on the host surface can steer the host bacteria toward more detrimental surface mutations than single-phage therapy, resulting in more favorable therapeutic outcomes.
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6
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Prakoso D, Zhu X, Rajeev S. Galleria mellonella infection model to evaluate pathogenic and nonpathogenic Leptospira strains. Vet Microbiol 2022; 264:109295. [PMID: 34875420 DOI: 10.1016/j.vetmic.2021.109295] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2021] [Revised: 11/22/2021] [Accepted: 11/23/2021] [Indexed: 01/21/2023]
Abstract
The Galleria mellonella larvae infection model is emerging as a valuable tool for studying various characteristics of infectious agents and host-pathogen interaction. This system has been widely recognized as a high throughput, ethical, and cost-effective invertebrate infection model to study the virulence and pathogenesis of various bacterial pathogens. In this study, we compared the effect of Leptospira infection in G. mellonella larvae infected with Leptospira interrogans serovar Copenhageni (pathogenic) or Leptospira biflexa serovar Patoc (saprophytic) strains. We observed significant pathologic changes such as decreased activity, complete melanization, and lower survival rate in the G. mellonella larvae infected with a pathogenic strain L. interrogans serovar Copenhageni compared to those infected with a nonpathogenic strain L. biflexa serovar Patoc. Our study demonstrates the feasibility and the potential of using G. mellonella larvae as an alternative model to study virulence mechanisms and pathogenesis of Leptospira strains. Once optimized, the G. mellonella infection model can be a potential substitute for hamsters to explore various host and pathogen-related mechanistic events in Leptospira infection.
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Affiliation(s)
- Dhani Prakoso
- Department of Biomedical and Diagnostic Sciences, College of Veterinary Medicine, University of Tennessee, 2407 River Drive, 37996, Knoxville, TN, United States
| | - Xiaojuan Zhu
- Office of Information Technology, University of Tennessee, Knoxville, TN, United States
| | - Sreekumari Rajeev
- Department of Biomedical and Diagnostic Sciences, College of Veterinary Medicine, University of Tennessee, 2407 River Drive, 37996, Knoxville, TN, United States.
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7
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Chen RY, Keddie BA. Galleria mellonella (Lepidoptera: Pyralidae) Hemocytes Release Extracellular Traps That Confer Protection Against Bacterial Infection in the Hemocoel. JOURNAL OF INSECT SCIENCE (ONLINE) 2021; 21:6449199. [PMID: 34865034 PMCID: PMC8643984 DOI: 10.1093/jisesa/ieab092] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/14/2021] [Indexed: 05/06/2023]
Abstract
Extracellular traps (ETs) released from vertebrate and invertebrate immune cells consist of chromatin and toxic granule contents that are capable of immobilizing and killing microbes. This recently described innate immune response is not well documented in insects. The present study found that ETs were released by hemocytes of Galleria mellonella (Linnaeus) (Lepidoptera: Pyralidae) in vivo and ex vivo after bacterial stimulation. ET release (ETosis), hemolymph coagulation, and melanization likely contributed to the immobilization and killing of the bacteria. The injection of G. mellonella hemocyte deoxyribonucleic acid (DNA) in the presence of bacteria increased bacterial clearance rate and prolonged insect survival. Taken together, these results indicate the presence of insect hemocyte extracellular traps (IHETs) that protect the insect against microbial infection in the hemocoel and represent the first documentation of ETs in insects in vivo.
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Affiliation(s)
- Robin Y Chen
- Department of Biological Sciences, University of Alberta, Edmonton, AB T6G 2E9, Canada
- Corresponding author, e-mail:
| | - B Andrew Keddie
- Department of Biological Sciences, University of Alberta, Edmonton, AB T6G 2E9, Canada
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8
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Fei K, Chao HJ, Hu Y, Francis MS, Chen S. CpxR regulates the Rcs phosphorelay system in controlling the Ysc-Yop type III secretion system in Yersinia pseudotuberculosis. MICROBIOLOGY-SGM 2021; 167. [PMID: 33295859 DOI: 10.1099/mic.0.000998] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
The CpxRA two-component regulatory system and the Rcs phosphorelay system are both employed by the Enterobacteriaceae family to preserve bacterial envelope integrity and function when growing under stress. Although both systems regulate several overlapping physiological processes, evidence demonstrating a molecular connection between Cpx and Rcs signalling outputs is scarce. Here, we show that CpxR negatively regulates the transcription of the rcsB gene in the Rcs phosphorelay system in Yersinia pseudotuberculosis. Interestingly, transcription of rcsB is under the control of three promoters, which were all repressed by CpxR. Critically, synthetic activation of Cpx signalling through mislocalization of the NlpE lipoprotein to the inner membrane resulted in an active form of CpxR that repressed activity of rcsB promoters. On the other hand, a site-directed mutation of the phosphorylation site at residue 51 in CpxR generated an inactive non-phosphorylated variant that was unable to regulate output from these rcsB promoters. Importantly, CpxR-mediated inhibition of rcsB transcription in turn restricted activation of the Ysc-Yop type III secretion system (T3SS). Moreover, active CpxR blocks zinc-mediated activation of Rcs signalling and the subsequent activation of lcrF transcription. Our results demonstrate a novel regulatory cascade linking CpxR-RcsB-LcrF to control production of the Ysc-Yop T3SS.
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Affiliation(s)
- Keke Fei
- University of Chinese Academy of Sciences, Beijing, PR China.,Key Laboratory of Special Pathogens and Biosafety, Wuhan Institute of Virology, Center for Biosafety Mega-Science, Chinese Academy of Sciences, Wuhan, PR China
| | - Hong-Jun Chao
- Present address: School of Biological & pharmaceutical Engineering, Wuhan Polytechnic University, Wuhan, PR China.,Key Laboratory of Special Pathogens and Biosafety, Wuhan Institute of Virology, Center for Biosafety Mega-Science, Chinese Academy of Sciences, Wuhan, PR China
| | - Yangbo Hu
- Key Laboratory of Special Pathogens and Biosafety, Wuhan Institute of Virology, Center for Biosafety Mega-Science, Chinese Academy of Sciences, Wuhan, PR China
| | - Matthew S Francis
- Department of Molecular Biology, Umeå University, Umeå, Sweden; Umeå Centre for Microbial Research, Umeå University, Umeå, Sweden
| | - Shiyun Chen
- Key Laboratory of Special Pathogens and Biosafety, Wuhan Institute of Virology, Center for Biosafety Mega-Science, Chinese Academy of Sciences, Wuhan, PR China
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9
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Chen RY, Keddie BA. The Galleria mellonella-Enteropathogenic Escherichia coli Model System: Characterization of Pathogen Virulence and Insect Immune Responses. JOURNAL OF INSECT SCIENCE (ONLINE) 2021; 21:6329131. [PMID: 34314494 PMCID: PMC8315237 DOI: 10.1093/jisesa/ieab046] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/18/2021] [Indexed: 05/22/2023]
Abstract
The use of Galleria mellonella (Linnaeus) (Lepidoptera: Pyralidae), an economical insect model, for the study of enteropathogenic Escherichia coli (Migula) (EPEC), a diarrheagenic human pathogen, has been demonstrated previously but remains poorly understood. The present study characterizes the Galleria-EPEC system extensively for future studies using this system. We found that EPEC causes disease in G. mellonella larvae when injected intrahemocoelically but not orally. Disease manifests as increased mortality, decreased survival time, delayed pupation, decreased pupal mass, increased pupal duration, and hemocytopenia. Disease symptoms are dose-dependent and can be used as metrics for measuring EPEC virulence in future studies. The type III secretion system was only partially responsible for EPEC virulence in G. mellonella while the majority of the virulence remains unknown in origin. EPEC elicits insect anti-bacterial immune responses including melanization, hemolymph coagulation, nodulation, and phagocytosis. The immune responses were unable to control EPEC replication in the early stage of infection (≤3 h post-injection). EPEC clearance from the hemocoel does not guarantee insect survival. Overall, this study provided insights into EPEC virulence and pathogenesis in G. mellonella and identified areas of future research using this system.
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Affiliation(s)
- Robin Y Chen
- Department of Biological Sciences, University of Alberta, Edmonton, AB T6G 2E9, Canada
- Corresponding author, e-mail:
| | - B Andrew Keddie
- Department of Biological Sciences, University of Alberta, Edmonton, AB T6G 2E9, Canada
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10
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Hesketh-Best PJ, Mouritzen MV, Shandley-Edwards K, Billington RA, Upton M. Galleria mellonella larvae exhibit a weight-dependent lethal median dose when infected with methicillin-resistant Staphylococcus aureus. Pathog Dis 2021; 79:6121426. [PMID: 33503238 DOI: 10.1093/femspd/ftab003] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2020] [Accepted: 01/11/2021] [Indexed: 12/13/2022] Open
Abstract
Galleria mellonella is a recognised model to study antimicrobial efficacy; however, standardisation across the scientific field and investigations of methodological components are needed. Here, we investigate the impact of weight on mortality following infection with Methicillin-resistant Staphylococcus aureus (MRSA). Larvae were separated into six weight groups (180-300 mg at 20 mg intervals) and infected with a range of doses of MRSA to determine the 50% lethal dose (LD50), and the 'lipid weight' of larvae post-infection was quantified. A model of LD50 values correlated with weight was developed. The LD50 values, as estimated by our model, were further tested in vivo to prove our model. We establish a weight-dependent LD50 in larvae against MRSA and demonstrate that G. mellonella is a stable model within 180-260 mg. We present multiple linear models correlating weight with: LD50, lipid weight, and larval length. We demonstrate that the lipid weight is reduced as a result of MRSA infection, identifying a potentially new measure in which to understand the immune response. Finally, we demonstrate that larval length can be a reasonable proxy for weight. Refining the methodologies in which to handle and design experiments involving G. mellonella, we can improve the reliability of this powerful model.
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Affiliation(s)
- Poppy J Hesketh-Best
- School of Biological and Marine Sciences, University of Plymouth, Drake Circus, Plymouth, PL4 8AA, UK
| | - Michelle V Mouritzen
- School of Biomedical Sciences, University of Plymouth, Derriford Research Facility, Plymouth Science Park, Plymouth, PL6 8BT, UK
| | - Kayleigh Shandley-Edwards
- School of Biological and Marine Sciences, University of Plymouth, Drake Circus, Plymouth, PL4 8AA, UK
| | - Richard A Billington
- School of Biological and Marine Sciences, University of Plymouth, Drake Circus, Plymouth, PL4 8AA, UK
| | - Mathew Upton
- School of Biomedical Sciences, University of Plymouth, Derriford Research Facility, Plymouth Science Park, Plymouth, PL6 8BT, UK
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11
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Monitoring Gene Expression during a Galleria mellonella Bacterial Infection. Microorganisms 2020; 8:microorganisms8111798. [PMID: 33207842 PMCID: PMC7697238 DOI: 10.3390/microorganisms8111798] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2020] [Revised: 11/12/2020] [Accepted: 11/13/2020] [Indexed: 12/05/2022] Open
Abstract
Galleria mellonella larvae are an alternative in vivo model that has been extensively used to study the virulence and pathogenicity of different bacteria due to its practicality and lack of ethical constraints. However, the larvae possess intrinsic autofluorescence that obstructs the use of fluorescent proteins to study bacterial infections, hence better methodologies are needed. Here, we report the construction of a promoter probe vector with bioluminescence expression as well as the optimization of a total bacterial RNA extraction protocol to enhance the monitoring of in vivo infections. By employing the vector to construct different gene promoter fusions, variable gene expression levels were efficiently measured in G. mellonella larvae at various time points during the course of infection and without much manipulation of the larvae. Additionally, our optimized RNA extraction protocol facilitates the study of transcriptional gene levels during an in vivo infection. The proposed methodologies will greatly benefit bacterial infection studies as they can contribute to a better understanding of the in vivo infection processes and pathogen–mammalian host interactions.
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12
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Piatek M, Sheehan G, Kavanagh K. UtilisingGalleria mellonella larvae for studying in vivo activity of conventional and novel antimicrobial agents. Pathog Dis 2020; 78:5917982. [DOI: 10.1093/femspd/ftaa059] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2020] [Accepted: 10/02/2020] [Indexed: 12/15/2022] Open
Abstract
ABSTRACTThe immune response of insects displays many structural and functional similarities to the innate immune response of mammals. As a result of these conserved features, insects may be used for evaluating microbial virulence or for testing the in vivo efficacy and toxicity of antimicrobial compounds and results show strong similarities to those from mammals. Galleria mellonella larvae are widely used in this capacity and have the advantage of being easy to use, inexpensive to purchase and house, and being free from the ethical and legal restrictions that relate to the use of mammals in these tests. Galleria mellonella larvae may be used to assess the in vivo toxicity and efficacy of novel antimicrobial compounds. A wide range of antibacterial and antifungal therapies have been evaluated in G. mellonella larvae and results have informed subsequent experiments in mammals. While insect larvae are a convenient and reproducible model to use, care must be taken in their use to ensure accuracy of results. The objective of this review is to provide a comprehensive account of the use of G. mellonella larvae for assessing the in vivo toxicity and efficacy of a wide range of antibacterial and antifungal agents.
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Affiliation(s)
- Magdalena Piatek
- SSPC Pharma Research Centre, Department of Biology, Maynooth University, Co. Kildare W23 F2H6, Ireland
| | - Gerard Sheehan
- Institute of Microbiology and Infection, University of Birmingham, Birmingham B15 2TT, UK
| | - Kevin Kavanagh
- SSPC Pharma Research Centre, Department of Biology, Maynooth University, Co. Kildare W23 F2H6, Ireland
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A CpxR-Regulated zapD Gene Involved in Biofilm Formation of Uropathogenic Proteus mirabilis. Infect Immun 2020; 88:IAI.00207-20. [PMID: 32284373 DOI: 10.1128/iai.00207-20] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2020] [Accepted: 04/08/2020] [Indexed: 02/07/2023] Open
Abstract
Proteus mirabilis, a frequent uropathogen, forms extensive biofilms on catheters that are infamously difficult to treat. To explore the mechanisms of biofilm formation by P. mirabilis, we performed in vivo transposon mutagenesis. A mutant with impaired biofilm formation was isolated. The mutant was found to have Tn5 inserted in the zapD gene, encoding an outer membrane protein of the putative type 1 secretion system ZapBCD. zapBCD and its upstream zapA gene, encoding a protease, constitute an operon under the control of CpxR, a two-component regulator. The cpxR mutant and zapA mutant strains also had a biofilm-forming defect. CpxR positively regulates the promoter activities of zapABCD, cpxP, and cpxR An electrophoretic mobility shift assay revealed that CpxR binds zapA promoter DNA. The loss of zapD reduced CpxR-regulated gene expression of cpxR, zapA, cpxP, and mrpA, the mannose-resistant Proteus-like (MR/P) fimbrial major subunit gene. The restoration of biofilm formation in the zapD mutant with a CpxR-expressing plasmid reinforces the idea that CpxR-mediated gene expression contributes to zapD-involved biofilm formation. In trans expression of zapBCD from a zapBCD-expressing plasmid also reestablished the biofilm formation ability of the cpxR mutant to a certain level. The zapD and cpxR mutants had significantly lower protease activity, adhesion, and autoaggregation ability and production of exopolysaccharides and extracellular DNA (eDNA) than did the wild type. Finally, we identified copper as a signal for CpxR to increase biofilm formation. The loss of cpxR or zapD abolished the copper-mediated biofilm upshift. CpxR was required for copper-induced expression of zapA and cpxR Taken together, these data highlight the important role of CpxR-regulated zapD in biofilm formation and the underlying mechanisms in P. mirabilis.
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Bonfiglio G, Neroni B, Radocchia G, Pompilio A, Mura F, Trancassini M, Di Bonaventura G, Pantanella F, Schippa S. Growth Control of Adherent-Invasive Escherichia coli (AIEC) by the Predator Bacteria Bdellovibrio bacteriovorus: A New Therapeutic Approach for Crohn's Disease Patients. Microorganisms 2019; 8:microorganisms8010017. [PMID: 31861852 PMCID: PMC7023281 DOI: 10.3390/microorganisms8010017] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2019] [Revised: 12/05/2019] [Accepted: 12/17/2019] [Indexed: 01/10/2023] Open
Abstract
In Crohn’s disease (CD) patients, intestinal dysbiosis with an overgrowth of Proteobacteria, mainly Escherichia coli, has been reported. A new pathotype of E. coli, the adherent-invasive Escherichia coli strain (AIEC), has been isolated from the mucosae of CD patients. AIEC strains play an important role in CD pathogenesis, increasing intestinal mucosa damage and inflammation. Several studies have been undertaken to find possible strategies/treatments aimed at AIEC strain reduction/elimination from CD patients’ intestinal mucosae. To date, a truly effective strategy against AIEC overgrowth is not yet available, and as such, further investigations are warranted. Bdellovibrio bacteriovorus is a predator bacterium which lives by invading Gram-negative bacteria, and is usually present both in natural and human ecosystems. The aim of this study was to evaluate a novel possible strategy to treat CD patients’ mucosae when colonized by AIEC strains, based on the utilization of the Gram-negative predatory bacteria, B. bacteriovorus. The overall results indicate that B. bacteriovorus is able to interfere with important steps in the dynamics of pathogenicity of AIEC strains by its predatory activity. We indicate, for the first time, the possibility of counteracting AIEC strain overgrowth by exploiting what naturally occurs in microbial ecosystems (i.e., predation).
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Affiliation(s)
- Giulia Bonfiglio
- Department of Public Health and Infectious Diseases, Microbiology section, Sapienza University of Rome, 00185 Roma, Italy; (G.B.); (B.N.); (G.R.); (M.T.); (F.P.)
| | - Bruna Neroni
- Department of Public Health and Infectious Diseases, Microbiology section, Sapienza University of Rome, 00185 Roma, Italy; (G.B.); (B.N.); (G.R.); (M.T.); (F.P.)
| | - Giulia Radocchia
- Department of Public Health and Infectious Diseases, Microbiology section, Sapienza University of Rome, 00185 Roma, Italy; (G.B.); (B.N.); (G.R.); (M.T.); (F.P.)
| | - Arianna Pompilio
- Department of Medical, Oral and Biotechnological Sciences, and Center for Advanced Studies and Technology (CAST), University “G. d’Annunzio” of Chieti-Pescara, 66100 Chieti, Italy; (A.P.); (G.D.B.)
| | - Francesco Mura
- Electrical and Energy Engineering, Sapienza Nanoscience & Nanotechnology Laboratories (SNN-Lab), ‘Sapienza’ University of Rome, 00185 Roma, Italy;
| | - Maria Trancassini
- Department of Public Health and Infectious Diseases, Microbiology section, Sapienza University of Rome, 00185 Roma, Italy; (G.B.); (B.N.); (G.R.); (M.T.); (F.P.)
| | - Giovanni Di Bonaventura
- Department of Medical, Oral and Biotechnological Sciences, and Center for Advanced Studies and Technology (CAST), University “G. d’Annunzio” of Chieti-Pescara, 66100 Chieti, Italy; (A.P.); (G.D.B.)
| | - Fabrizio Pantanella
- Department of Public Health and Infectious Diseases, Microbiology section, Sapienza University of Rome, 00185 Roma, Italy; (G.B.); (B.N.); (G.R.); (M.T.); (F.P.)
| | - Serena Schippa
- Department of Public Health and Infectious Diseases, Microbiology section, Sapienza University of Rome, 00185 Roma, Italy; (G.B.); (B.N.); (G.R.); (M.T.); (F.P.)
- Correspondence:
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Hotinger JA, May AE. Animal Models of Type III Secretion System-Mediated Pathogenesis. Pathogens 2019; 8:pathogens8040257. [PMID: 31766664 PMCID: PMC6963218 DOI: 10.3390/pathogens8040257] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2019] [Revised: 11/18/2019] [Accepted: 11/20/2019] [Indexed: 01/22/2023] Open
Abstract
The type III secretion system (T3SS) is a conserved virulence factor used by many Gram-negative pathogenic bacteria and has become an important target for anti-virulence drugs. Most T3SS inhibitors to date have been discovered using in vitro screening assays. Pharmacokinetics and other important characteristics of pharmaceuticals cannot be determined with in vitro assays alone. In vivo assays are required to study pathogens in their natural environment and are an important step in the development of new drugs and vaccines. Animal models are also required to understand whether T3SS inhibition will enable the host to clear the infection. This review covers selected animal models (mouse, rat, guinea pig, rabbit, cat, dog, pig, cattle, primates, chicken, zebrafish, nematode, wax moth, flea, fly, and amoeba), where T3SS activity and infectivity have been studied in relation to specific pathogens (Escherichia coli, Salmonella spp., Pseudomonas spp., Shigella spp., Bordetella spp., Vibrio spp., Chlamydia spp., and Yersinia spp.). These assays may be appropriate for those researching T3SS inhibition.
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Guerrieri CG, Pereira MF, Galdino ACM, Dos Santos ALS, Elias WP, Schuenck RP, Spano LC. Typical and Atypical Enteroaggregative Escherichia coli Are Both Virulent in the Galleria mellonella Model. Front Microbiol 2019; 10:1791. [PMID: 31456762 PMCID: PMC6700222 DOI: 10.3389/fmicb.2019.01791] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2019] [Accepted: 07/19/2019] [Indexed: 12/16/2022] Open
Abstract
Enteroaggregative Escherichia coli (EAEC) is an emerging pathotype responsible for acute and persistent diarrhea. It can be classified as typical and atypical strains, respectively, based on the presence or absence of the AggR regulon, suggesting a higher virulence for typical EAEC. This study aims to evaluate in the Galleria mellonella model if there are differences in the virulence profiles among clinical strains of typical and atypical EAEC, prototype strains EAEC C1096, 042 and its aggR mutant. The clinical EAEC strains (n = 20) were analyzed for the presence of 22 putative virulence factors of EAEC or extraintestinal E. coli by PCR, as well as phenotypic characteristics of virulence (enzymes, siderophore, and biofilm). The survival of the larvae was analyzed after inoculation of 104-107 CFU/larva; the monitoring of bacterial growth in vivo and hemocyte quantification was determined after inoculation of the prototype strains (105 CFU/larva) at different periods after infection. The strains of typical and atypical EAEC presented the same virulence profile for the larva, regardless of the amount or type of genes and phenotypic aspects of virulence analyzed. In addition, the EAEC 042 aggR mutant strain showed a significant reduction in the mortality of the inoculated larvae compared to the wild-type strain. In conclusion, the results obtained herein demonstrate that the virulence of EAEC seems to be related to the AggR regulon, but not exclusively, and atypical EAEC strains may be as virulent as typical ones in vivo in the G. mellonella model.
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Affiliation(s)
- Caroline Gastaldi Guerrieri
- Laboratory of Virology and Infectious Gastroenteritis, Department of Pathology, Health Sciences Center, Federal University of Espírito Santo, Vitória, Brazil
| | - Monalessa Fábia Pereira
- Laboratory of Virology and Infectious Gastroenteritis, Department of Pathology, Health Sciences Center, Federal University of Espírito Santo, Vitória, Brazil
| | - Anna Clara Milesi Galdino
- Laboratory of Advanced Studies of Emerging and Resistant Microorganisms, Department of General Microbiology, Institute of Microbiology Paulo de Góes, Federal University of Rio de Janeiro, Rio de Janeiro, Brazil
| | - André Luis Souza Dos Santos
- Laboratory of Advanced Studies of Emerging and Resistant Microorganisms, Department of General Microbiology, Institute of Microbiology Paulo de Góes, Federal University of Rio de Janeiro, Rio de Janeiro, Brazil
| | | | - Ricardo Pinto Schuenck
- Laboratory of Virology and Infectious Gastroenteritis, Department of Pathology, Health Sciences Center, Federal University of Espírito Santo, Vitória, Brazil
| | - Liliana Cruz Spano
- Laboratory of Virology and Infectious Gastroenteritis, Department of Pathology, Health Sciences Center, Federal University of Espírito Santo, Vitória, Brazil
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Yi Z, Wang D, Xin S, Zhou D, Li T, Tian M, Qi J, Ding C, Wang S, Yu S. The CpxR regulates type VI secretion system 2 expression and facilitates the interbacterial competition activity and virulence of avian pathogenic Escherichia coli. Vet Res 2019; 50:40. [PMID: 31126325 PMCID: PMC6534853 DOI: 10.1186/s13567-019-0658-7] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2019] [Accepted: 05/08/2019] [Indexed: 11/18/2022] Open
Abstract
Systemic infections caused by avian pathogenic Escherichia coli (APEC) are economically devastating to poultry industries worldwide and are also potentially threatening to human health. Pathogens must be able to precisely modulate gene expression to facilitate their survival and the successful infection. The Cpx two-component signal transduction system (TCS) regulates surface structure assembly and virulence factors implicated in Gram-negative bacterial pathogenesis. However, the roles of the Cpx TCS in bacterial fitness and pathogenesis during APEC infection are not completely understood. Here, we show that the Cpx TCS response regulator CpxR is critical to the survival and virulence of APEC. Inactivation of cpxR leads to significant defects in the interbacterial competition activity, invasion and survival of APEC in vitro and in vivo. Moreover, activation of CpxR positive regulates the expression of the APEC type VI secretion system 2 (T6SS2). Further investigations revealed that phosphorylated CpxR directly bound to the T6SS2 hcp2B promoter region. Taken together, our results demonstrated that CpxR contributes to the pathogensis of APEC at least through directly regulating the expression and function of T6SS2. This study broadens understanding of the regulatory effect of Cpx TCS, thus elucidating the mechanisms through which Cpx TCS involved in bacterial virulence.
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Affiliation(s)
- Zhengfei Yi
- Shanghai Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Shanghai, 200241, China
| | - Dong Wang
- Shanghai Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Shanghai, 200241, China
| | - Suhua Xin
- Shanghai Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Shanghai, 200241, China
| | - Dongliang Zhou
- Shanghai Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Shanghai, 200241, China
| | - Tao Li
- Shanghai Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Shanghai, 200241, China
| | - Mingxing Tian
- Shanghai Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Shanghai, 200241, China
| | - Jingjing Qi
- Shanghai Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Shanghai, 200241, China
| | - Chan Ding
- Shanghai Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Shanghai, 200241, China
| | - Shaohui Wang
- Shanghai Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Shanghai, 200241, China.
| | - Shengqing Yu
- Shanghai Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Shanghai, 200241, China.
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Rossoni RD, Ribeiro FDC, dos Santos HFS, dos Santos JD, Oliveira NDS, Dutra MTDS, de Lapena SAB, Junqueira JC. Galleria mellonella as an experimental model to study human oral pathogens. Arch Oral Biol 2019; 101:13-22. [DOI: 10.1016/j.archoralbio.2019.03.002] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2018] [Revised: 02/27/2019] [Accepted: 03/03/2019] [Indexed: 12/28/2022]
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Genome-Wide Identification of Fitness Factors in Mastitis-Associated Escherichia coli. Appl Environ Microbiol 2018; 84:AEM.02190-17. [PMID: 29101196 DOI: 10.1128/aem.02190-17] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2017] [Accepted: 10/27/2017] [Indexed: 12/31/2022] Open
Abstract
Virulence factors of mammary pathogenic Escherichia coli (MPEC) have not been identified, and it is not known how bacterial gene content influences the severity of mastitis. Here, we report a genome-wide identification of genes that contribute to fitness of MPEC under conditions relevant to the natural history of the disease. A highly virulent clinical isolate (M12) was identified that killed Galleria mellonella at low infectious doses and that replicated to high numbers in mouse mammary glands and spread to spleens. Genome sequencing was combined with transposon insertion site sequencing to identify MPEC genes that contribute to growth in unpasteurized whole milk, as well as during G. mellonella and mouse mastitis infections. These analyses show that strain M12 possesses a unique genomic island encoding a group III polysaccharide capsule that greatly enhances virulence in G. mellonella Several genes appear critical for MPEC survival in both G. mellonella and in mice, including those for nutrient-scavenging systems and resistance to cellular stress. Insertions in the ferric dicitrate receptor gene fecA caused significant fitness defects under all conditions (in milk, G. mellonella, and mice). This gene was highly expressed during growth in milk. Targeted deletion of fecA from strain M12 caused attenuation in G. mellonella larvae and reduced growth in unpasteurized cow's milk and lactating mouse mammary glands. Our results confirm that iron scavenging by the ferric dicitrate receptor, which is strongly associated with MPEC strains, is required for MPEC growth and may influence disease severity in mastitis infections.IMPORTANCE Mastitis caused by E. coli inflicts substantial burdens on the health and productivity of dairy animals. Strains causing mastitis may express genes that distinguish them from other E. coli strains and promote infection of mammary glands, but these have not been identified. Using a highly virulent strain, we employed genome-wide mutagenesis and sequencing to discover genes that contribute to mastitis. This extensive data set represents a screen for mastitis-associated E. coli fitness factors and provides the following contributions to the field: (i) global comparison of genes required for different aspects of mastitis infection, (ii) discovery of a unique capsule that contributes to virulence, and (iii) conclusive evidence for the crucial role of iron-scavenging systems in mastitis, particularly the ferric dicitrate transport system. Similar approaches applied to other mastitis-associated strains will uncover conserved targets for prevention or treatment and provide a better understanding of their relationship to other E. coli pathogens.
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Younas M, Siddiqui F, Noreen Z, Bokhari SS, Gomez-Duarte OG, Wren BW, Bokhari H. Characterization of enteropathogenic Escherichia coli of clinical origin from the pediatric population in Pakistan. Trans R Soc Trop Med Hyg 2017; 110:414-20. [PMID: 27496516 DOI: 10.1093/trstmh/trw047] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2016] [Accepted: 06/13/2016] [Indexed: 12/24/2022] Open
Abstract
BACKGROUND Enteropathogenic Escherichia coli (EPEC) is one of the leading causes of watery diarrhea among children. METHODS In this study EPEC isolates from the pediatric population of Pakistan (2010-2012) were subjected to phylotyping, antibiotic susceptibility, extended-spectrum beta-lactamase (ESBL) profiling and evaluation of one representative strain from each panel of phylotypesin Galleria mellonella, infection model. RESULTS A total of 46/225 (20.4%) stool samples were positive for EPEC. Isolates mainly belong to D phylogroup (18, 39%) followed by nontypeable (10, 22%), B1 (9, 20%), B2 (8, 17%) and A (1, 2%). High resistance was observed for ampicillin (42, 91%), erythromycin (41, 89%), cefaclor (37, 80%), trimethoprim/sulfamethoxazole (36, 78%), tetracycline (36, 78%). Among nalidixic acid resistant isolates 13 (28%) showed presence of single nucleotide polymorphism (SNP) in parC (C330-T330) whereas 1 (2%) isolate showed gyrB (A660-T660) SNP. Furthermore, 27 (59%) isolates were ESBL producers. Representative isolates of phlyotypes A and B2 showed enhance killing of G. mellonella compared to ones belonging to phylotypes B1 and D. CONCLUSIONS Non-typeable EPEC strains were frequently observed. ESBL production in ESBL producers was found to be plasmid mediated. No significant association of antibiotic resistance profile with specific phylogroup of EPEC was found, however G. mellonella infection model differentiated representative phylotypes.
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Affiliation(s)
- Mahwish Younas
- Department of Biosciences, COMSATS Institute of Information Technology, Park Road, 44000, Islamabad, Pakistan
| | - Fariha Siddiqui
- Department of Biosciences, COMSATS Institute of Information Technology, Park Road, 44000, Islamabad, Pakistan
| | - Zobia Noreen
- Department of Biosciences, COMSATS Institute of Information Technology, Park Road, 44000, Islamabad, Pakistan
| | | | - Oscar G Gomez-Duarte
- Division of Pediatric Infectious Diseases, Department of Pediatrics, Vanderbilt University School of Medicine, Nashville, TN, USA
| | - Brendan W Wren
- Department of Pathogen Molecular Biology, London School of Hygiene & Tropical Medicine, London, UK
| | - Habib Bokhari
- Department of Biosciences, COMSATS Institute of Information Technology, Park Road, 44000, Islamabad, Pakistan
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Jønsson R, Struve C, Jenssen H, Krogfelt KA. The wax moth Galleria mellonella as a novel model system to study Enteroaggregative Escherichia coli pathogenesis. Virulence 2017; 8:1894-1899. [PMID: 27824518 PMCID: PMC5810504 DOI: 10.1080/21505594.2016.1256537] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Affiliation(s)
- Rie Jønsson
- a Department of Science and Environment , Roskilde University , Roskilde , Denmark.,b Department of Microbiology and Infection Control , Statens Serum Institut , Copenhagen , Denmark
| | - Carsten Struve
- b Department of Microbiology and Infection Control , Statens Serum Institut , Copenhagen , Denmark
| | - Håvard Jenssen
- a Department of Science and Environment , Roskilde University , Roskilde , Denmark
| | - Karen A Krogfelt
- b Department of Microbiology and Infection Control , Statens Serum Institut , Copenhagen , Denmark
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Galleria mellonella is low cost and suitable surrogate host for studying virulence of human pathogenic Vibrio cholerae. Gene 2017; 628:1-7. [PMID: 28698162 DOI: 10.1016/j.gene.2017.07.019] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2017] [Revised: 07/04/2017] [Accepted: 07/07/2017] [Indexed: 01/05/2023]
Abstract
Vibrio cholerae causes a severe diarrheal disease affecting millions of people worldwide, particularly in low income countries. V. cholerae successfully persist in aquatic environment and its pathogenic strains results in sever enteric disease in humans. This dual life style contributes towards its better survival and persistence inside host gut and in the environment. Alternative animal replacement models are of great value in studying host-pathogen interaction and for quick screening of various pathogenic strains. One such model is Galleria mellonella, a wax moth which has a complex innate immune system and here we investigate its suitability as a model for clinical human isolates of O1 El TOR, Ogawa serotype belonging to two genetically distinct subclades found in Pakistan (PSC-1 and PSC-2). We demonstrate that the PSC-2 strain D59 frequently isolated from inland areas, was more virulent than PSC-1 strain K7 mainly isolated from coastal areas (p=0.0001). In addition, we compared the relative biofilm capability of the representative strains as indicators of their survival and persistence in the environment and K7 showed enhanced biofilm forming capabilities (p=0.004). Finally we present the annotated genomes of the strains D59 and K7, and compared them with the reference strain N16961.
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Scalfaro C, Iacobino A, Nardis C, Franciosa G. Galleria mellonella as an in vivo model for assessing the protective activity of probiotics against gastrointestinal bacterial pathogens. FEMS Microbiol Lett 2017; 364:3078546. [PMID: 28369512 DOI: 10.1093/femsle/fnx064] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2017] [Accepted: 03/20/2017] [Indexed: 12/18/2022] Open
Abstract
The antagonistic activity against gastrointestinal bacterial pathogens is an important property of probiotic bacteria and a desirable feature for pre-selection of novel strains with probiotic potential. Pre-screening of candidate probiotics for antibacterial activity should be based on in vitro and in vivo tests. This study investigated whether the protective activity of probiotic bacteria against gastrointestinal bacterial pathogens can be evaluated using Galleria mellonella larvae as an in vivo model. Larvae were pre-inoculated with either of two widely used probiotic bacteria, Lactobacillus rhamnosus GG or Clostridium butyricum Miyairi 588, and then challenged with Salmonella enterica Typhimurium, enteropathogenic Escherichia coli or Listeria monocytogenes. Survival rates increased in the probiotic pretreated larvae compared with control larvae inoculated with pathogens only. The hemocyte density increased as well in the probiotic pretreated larvae, indicating that both probiotics induce an immune response in the larvae. The antibacterial activity of probiotics against the pathogens was also assayed by an in vitro agar spot test: results were partially consistent with those obtained by the G. mellonella protection assay. The results obtained, as a whole, suggest that G. mellonella larvae are a potentially useful in vivo model that can complement in vitro assays for pre-screening of candidate probiotics.
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Affiliation(s)
- Concetta Scalfaro
- Department of Food Safety and Veterinary Public Health, Istituto Superiore di Sanità, Viale Regina Elena 299, 00161 Rome, Italy
| | - Angelo Iacobino
- Department of Infectious, Parasitic and Immunomediated Diseases, Istituto Superiore di Sanità, Viale Regina Elena 299, 00161 Rome, Italy
| | - Chiara Nardis
- Department of Food Safety and Veterinary Public Health, Istituto Superiore di Sanità, Viale Regina Elena 299, 00161 Rome, Italy
| | - Giovanna Franciosa
- Department of Food Safety and Veterinary Public Health, Istituto Superiore di Sanità, Viale Regina Elena 299, 00161 Rome, Italy
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Gaytán MO, Martínez-Santos VI, Soto E, González-Pedrajo B. Type Three Secretion System in Attaching and Effacing Pathogens. Front Cell Infect Microbiol 2016; 6:129. [PMID: 27818950 PMCID: PMC5073101 DOI: 10.3389/fcimb.2016.00129] [Citation(s) in RCA: 115] [Impact Index Per Article: 14.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2016] [Accepted: 09/27/2016] [Indexed: 02/06/2023] Open
Abstract
Enteropathogenic Escherichia coli and enterohemorrhagic E. coli are diarrheagenic bacterial human pathogens that cause severe gastroenteritis. These enteric pathotypes, together with the mouse pathogen Citrobacter rodentium, belong to the family of attaching and effacing pathogens that form a distinctive histological lesion in the intestinal epithelium. The virulence of these bacteria depends on a type III secretion system (T3SS), which mediates the translocation of effector proteins from the bacterial cytosol into the infected cells. The core architecture of the T3SS consists of a multi-ring basal body embedded in the bacterial membranes, a periplasmic inner rod, a transmembrane export apparatus in the inner membrane, and cytosolic components including an ATPase complex and the C-ring. In addition, two distinct hollow appendages are assembled on the extracellular face of the basal body creating a channel for protein secretion: an approximately 23 nm needle, and a filament that extends up to 600 nm. This filamentous structure allows these pathogens to get through the host cells mucus barrier. Upon contact with the target cell, a translocation pore is assembled in the host membrane through which the effector proteins are injected. Assembly of the T3SS is strictly regulated to ensure proper timing of substrate secretion. The different type III substrates coexist in the bacterial cytoplasm, and their hierarchical secretion is determined by specialized chaperones in coordination with two molecular switches and the so-called sorting platform. In this review, we present recent advances in the understanding of the T3SS in attaching and effacing pathogens.
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Affiliation(s)
- Meztlli O Gaytán
- Departamento de Genética Molecular, Instituto de Fisiología Celular, Universidad Nacional Autónoma de México Ciudad de México, Mexico
| | - Verónica I Martínez-Santos
- Departamento de Genética Molecular, Instituto de Fisiología Celular, Universidad Nacional Autónoma de México Ciudad de México, Mexico
| | - Eduardo Soto
- Departamento de Genética Molecular, Instituto de Fisiología Celular, Universidad Nacional Autónoma de México Ciudad de México, Mexico
| | - Bertha González-Pedrajo
- Departamento de Genética Molecular, Instituto de Fisiología Celular, Universidad Nacional Autónoma de México Ciudad de México, Mexico
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Mahmoud RY, Li W, Eldomany RA, Emara M, Yu J. The Shigella ProU system is required for osmotic tolerance and virulence. Virulence 2016; 8:362-374. [PMID: 27558288 DOI: 10.1080/21505594.2016.1227906] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
To cope with hyperosmotic stress encountered in the environments and in the host, the pathogenic as well as non-pathogenic microbes use diverse transport systems to obtain osmoprotectants. To study the role of Shigella sonnei ProU system in response to hyperosmotic stress and virulence, we constructed deletion and complementation strains of proV and used an RNAi approach to silence the whole ProU operon. We compared the response between wild type and the mutants to the hyperosmotic pressure in vitro, and assessed virulence properties of the mutants using gentamicin protection assay as well as Galleria mellonella moth larvae model. In response to osmotic stress by either NaCl or KCl, S. sonnei highly up-regulates transcription of proVWX genes. Supplementation of betaine greatly elevates the growth of the wild type S. sonnei but not the proV mutants in M9 medium containing 0.2 M NaCl or 0.2 M KCl. The proV mutants are also defective in intracellular growth compared with the wild type. The moth larvae model of G. mellonella shows that either deletion of proV gene or knockdown of proVWX transcripts by RNAi significantly attenuates virulence. ProU system in S. sonnei is required to cope with osmotic stress for survival and multiplication in vitro, and for infection.
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Affiliation(s)
- Rasha Y Mahmoud
- a Strathclyde Institute of Pharmacy and Biomedical Sciences (SIPBS) , University of Strathclyde , Glasgow , Scotland , UK.,b Department of Microbiology and Immunology, Faculty of Pharmacy , Helwan University , Cairo , Egypt
| | - Wenqin Li
- a Strathclyde Institute of Pharmacy and Biomedical Sciences (SIPBS) , University of Strathclyde , Glasgow , Scotland , UK
| | - Ramadan A Eldomany
- c Department of Microbiology and Immunology, Faculty of Pharmacy , Kafr Elsheikh University , Kafr Elsheikh , Egypt
| | - Mohamed Emara
- b Department of Microbiology and Immunology, Faculty of Pharmacy , Helwan University , Cairo , Egypt
| | - Jun Yu
- a Strathclyde Institute of Pharmacy and Biomedical Sciences (SIPBS) , University of Strathclyde , Glasgow , Scotland , UK
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Khalil U, Younus M, Asghar N, Siddiqui F, Gómez-Duarte OG, Wren BW, Bokhari H. Phenotypic and genotypic characterization of enteroaggregative Escherichia coli isolates from pediatric population in Pakistan. APMIS 2016; 124:872-80. [PMID: 27485156 DOI: 10.1111/apm.12577] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2016] [Accepted: 06/13/2016] [Indexed: 11/30/2022]
Abstract
Enteroaggregative Escherichia coli (EAEC) are a leading cause of diarrhea among children. The objective of this study was to define the frequency of EAEC among diarrheal children from flood-affected areas as well as sporadic cases, determine multidrug resistance, and evaluation of virulence using an in vivo model of pathogenesis. Stool samples were collected from 225 diarrheal children from 2010 to 2011 from flood-affected areas as well as from sporadic cases in Pakistan. Identified EAEC isolates were characterized by phylogrouping, antibiotic resistance patterns including the extended-spectrum beta lactamase spectrum, single nucleotide polymorphism detection in gyrA and parC, and virulence potential using wax worm, G. mellonella. A total of 35 (12.5%) confirmed EAEC isolates were identified among 225 E. coli isolates. EAEC isolates displayed high resistance to tetracycline, ampicillin, and cefaclor. A total of 34.28% were ESBL positive. Single nucleotide polymorphism detection revealed 37.14% and 68.57% isolates were positive for SNPs in gyrA (A660 -T660 ) and parC (C330 -T330 ), respectively. Phylogrouping revealed that B2 phylogroup was more prevalent among all EAEC isolates tested followed by D, A, B1, and non-typeable (NT). Infection of G. mellonella with EAEC showed that killing infective dose was 100% higher than E. coli DH5 alpha control. EAEC are prevalent among Pakistani children with diarrhea, they are highly resistant to antibiotics, and predominantly fall into B2 phylogroup. Epidemiologic surveillance of EAEC and other E. coli pathotypes is critical to assess not only the role of these pathogens in diarrheal disease but also to determine the extent of multidrug resistance among the population.
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Affiliation(s)
- Uzma Khalil
- COMSATS Institute of Information Technology, Islamabad, Pakistan
| | - Mahwish Younus
- COMSATS Institute of Information Technology, Islamabad, Pakistan
| | - Naeem Asghar
- Biological Production Division, National Institute of Health, Islamabad, Pakistan
| | - Fariha Siddiqui
- COMSATS Institute of Information Technology, Islamabad, Pakistan
| | - Oscar G Gómez-Duarte
- Division of Pediatric Infectious Diseases, Department of Pediatrics, Vanderbilt University School of Medicine, Nashville, TN, USA
| | - Brendan W Wren
- Department of Pathogen Molecular Biology, London School of Hygiene and Tropical Medicine, London, UK
| | - Habib Bokhari
- COMSATS Institute of Information Technology, Islamabad, Pakistan.
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Role of the Gram-Negative Envelope Stress Response in the Presence of Antimicrobial Agents. Trends Microbiol 2016; 24:377-390. [PMID: 27068053 DOI: 10.1016/j.tim.2016.03.001] [Citation(s) in RCA: 55] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/02/2016] [Revised: 03/01/2016] [Accepted: 03/01/2016] [Indexed: 01/10/2023]
Abstract
Bacterial survival necessitates endurance of many types of antimicrobial compound. Many Gram-negative envelope stress responses, which must contend with an outer membrane and a dense periplasm containing the cell wall, have been associated with the status of protein folding, membrane homeostasis, and physiological functions such as efflux and the proton motive force (PMF). In this review, we discuss evidence that indicates an emerging role for Gram-negative envelope stress responses in enduring exposure to diverse antimicrobial substances, focusing on recent studies of the γ-proteobacterial Cpx envelope stress response.
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Chen S, Thompson KM, Francis MS. Environmental Regulation of Yersinia Pathophysiology. Front Cell Infect Microbiol 2016; 6:25. [PMID: 26973818 PMCID: PMC4773443 DOI: 10.3389/fcimb.2016.00025] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2015] [Accepted: 02/15/2016] [Indexed: 12/26/2022] Open
Abstract
Hallmarks of Yersinia pathogenesis include the ability to form biofilms on surfaces, the ability to establish close contact with eukaryotic target cells and the ability to hijack eukaryotic cell signaling and take over control of strategic cellular processes. Many of these virulence traits are already well-described. However, of equal importance is knowledge of both confined and global regulatory networks that collaborate together to dictate spatial and temporal control of virulence gene expression. This review has the purpose to incorporate historical observations with new discoveries to provide molecular insight into how some of these regulatory mechanisms respond rapidly to environmental flux to govern tight control of virulence gene expression by pathogenic Yersinia.
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Affiliation(s)
- Shiyun Chen
- Key Laboratory of Special Pathogens and Biosafety, Wuhan Institute of Virology, Chinese Academy of Sciences Wuhan, China
| | - Karl M Thompson
- Department of Microbiology, College of Medicine, Howard University Washington, DC, USA
| | - Matthew S Francis
- Umeå Centre for Microbial Research, Umeå UniversityUmeå, Sweden; Department of Molecular Biology, Umeå UniversityUmeå, Sweden
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29
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Effective immunosuppression with dexamethasone phosphate in the Galleria mellonella larva infection model resulting in enhanced virulence of Escherichia coli and Klebsiella pneumoniae. Med Microbiol Immunol 2016; 205:333-43. [PMID: 26920133 PMCID: PMC4939170 DOI: 10.1007/s00430-016-0450-5] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2015] [Accepted: 02/11/2016] [Indexed: 01/19/2023]
Abstract
The aim was to evaluate whether immunosuppression with dexamethasone 21-phosphate could be applied to the Galleria mellonella in vivo infection model. Characterised clinical isolates of Escherichia coli or Klebsiella pneumoniae were employed, and G. mellonella larvae were infected with increasing doses of each strain to investigate virulence in vivo. Virulence was then compared with larvae exposed to increasing doses of dexamethasone 21-phosphate. The effect of dexamethasone 21-phosphate on larval haemocyte phagocytosis in vitro was determined via fluorescence microscopy and a burden assay measured the growth of infecting bacteria inside the larvae. Finally, the effect of dexamethasone 21-phosphate treatment on the efficacy of ceftazidime after infection was also noted. The pathogenicity of K. pneumoniae or E. coli in G. mellonella larvae was dependent on high inoculum numbers such that virulence could not be attributed specifically to infection by live bacteria but also to factors associated with dead cells. Thus, for these strains, G. mellonella larvae do not constitute an ideal infection model. Treatment of larvae with dexamethasone 21-phosphate enhanced the lethality induced by infection with E. coli or K. pneumoniae in a dose- and inoculum size-dependent manner. This correlated with proliferation of bacteria in the larvae that could be attributed to dexamethasone inhibiting haemocyte phagocytosis and acting as an immunosuppressant. Notably, prior exposure to dexamethasone 21-phosphate reduced the efficacy of ceftazidime in vivo. In conclusion, demonstration of an effective immunosuppressant regimen can improve the specificity and broaden the applications of the G. mellonella model to address key questions regarding infection.
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De la Cruz MA, Morgan JK, Ares MA, Yáñez-Santos JA, Riordan JT, Girón JA. The Two-Component System CpxRA Negatively Regulates the Locus of Enterocyte Effacement of Enterohemorrhagic Escherichia coli Involving σ(32) and Lon protease. Front Cell Infect Microbiol 2016; 6:11. [PMID: 26904510 PMCID: PMC4742615 DOI: 10.3389/fcimb.2016.00011] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2015] [Accepted: 01/18/2016] [Indexed: 12/05/2022] Open
Abstract
Enterohemorrhagic Escherichia coli (EHEC) is a significant cause of serious human gastrointestinal disease worldwide. EHEC strains contain a pathogenicity island called the locus of enterocyte effacement (LEE), which encodes virulence factors responsible for damaging the gut mucosa. The Cpx envelope stress response of E. coli is controlled by a two-component system (TCS) consisting of a sensor histidine kinase (CpxA) and a cytoplasmic response regulator (CpxR). In this study, we investigated the role of CpxRA in the expression of LEE-encoded virulence factors of EHEC. We found that a mutation in cpxA significantly affected adherence of EHEC to human epithelial cells. Analysis of this mutant revealed the presence of high levels of CpxR which repressed transcription of grlA and ler, the main positive virulence regulators of the LEE, and influenced negatively the production of the type 3 secretion system–associated EspABD translocator proteins. It is known that CpxR activates rpoH (Sigma factor 32), which in turns activates transcription of the lon protease gene. We found that transcription levels of ler and grlA were significantly increased in the lon and cpxA lon mutants suggesting that lon is involved in down-regulating LEE genes. In addition, the Galleria mellonella model of infection was used to analyze the effect of the loss of the cpx and lon genes in EHEC's ability to kill the larvae. We found that the cpxA mutant was significantly deficient at killing the larvae however, the cpxA lon mutant which overexpresses LEE genes in vitro, was unable to kill the larvae, suggesting that virulence in the G. mellonella model is T3SS independent and that CpxA modulates virulence through a yet unknown EHEC-specific factor. Our data provides new insights and broadens our scope into the complex regulatory network of the LEE in which the CpxA sensor kinase plays an important role in a cascade involving both global and virulence regulators.
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Affiliation(s)
- Miguel A De la Cruz
- Unidad de Investigación Médica en Enfermedades Infecciosas y Parasitarias, Centro Médico Nacional Siglo XXI-IMSSMexico City, Mexico; Emerging Pathogens Institute, University of FloridaGainesville, FL, USA
| | - Jason K Morgan
- Department of Cell Biology, Microbiology, and Molecular Biology, University of South Florida Tampa, FL, USA
| | - Miguel A Ares
- Unidad de Investigación Médica en Enfermedades Infecciosas y Parasitarias, Centro Médico Nacional Siglo XXI-IMSS Mexico City, Mexico
| | - Jorge A Yáñez-Santos
- Facultad de Estomatología, Benemerita Universidad Autonoma de Puebla Puebla, Mexico
| | - James T Riordan
- Department of Cell Biology, Microbiology, and Molecular Biology, University of South Florida Tampa, FL, USA
| | - Jorge A Girón
- Emerging Pathogens Institute, University of FloridaGainesville, FL, USA; Centro de Deteccion Biomolecular, Benemerita Universidad Autonoma de PueblaPuebla, Mexico
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Tsai CJY, Loh JMS, Proft T. Galleria mellonella infection models for the study of bacterial diseases and for antimicrobial drug testing. Virulence 2016; 7:214-29. [PMID: 26730990 PMCID: PMC4871635 DOI: 10.1080/21505594.2015.1135289] [Citation(s) in RCA: 445] [Impact Index Per Article: 55.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
Galleria mellonella (greater wax moth or honeycomb moth) has been introduced as an alternative model to study microbial infections. G. mellonella larvae can be easily and inexpensively obtained in large numbers and are simple to use as they don't require special lab equipment. There are no ethical constraints and their short life cycle makes them ideal for large-scale studies. Although insects lack an adaptive immune response, their innate immune response shows remarkable similarities with the immune response in vertebrates. This review gives a current update of what is known about the immune system of G. mellonella and provides an extensive overview of how G. mellonella is used to study the virulence of Gram-positive and Gram-negative bacteria. In addition, the use of G. mellonella to evaluate the efficacy of antimicrobial agents and experimental phage therapy are also discussed. The review concludes with a critical assessment of the current limitatons of G. mellonella infection models.
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Affiliation(s)
- Catherine Jia-Yun Tsai
- a Department of Molecular Medicine & Pathology , School of Medical Sciences, University of Auckland , Auckland , New Zealand.,b Maurice Wilkins Center, University of Auckland , Auckland , New Zealand
| | - Jacelyn Mei San Loh
- a Department of Molecular Medicine & Pathology , School of Medical Sciences, University of Auckland , Auckland , New Zealand.,b Maurice Wilkins Center, University of Auckland , Auckland , New Zealand
| | - Thomas Proft
- a Department of Molecular Medicine & Pathology , School of Medical Sciences, University of Auckland , Auckland , New Zealand.,b Maurice Wilkins Center, University of Auckland , Auckland , New Zealand
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32
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Mahmoud RY, Stones DH, Li W, Emara M, El-Domany RA, Wang D, Wang Y, Krachler AM, Yu J. The Multivalent Adhesion Molecule SSO1327 plays a key role in Shigella sonnei pathogenesis. Mol Microbiol 2015; 99:658-73. [PMID: 26481305 DOI: 10.1111/mmi.13255] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 10/19/2015] [Indexed: 12/30/2022]
Abstract
Shigella sonnei is a bacterial pathogen and causative agent of bacillary dysentery. It deploys a type III secretion system to inject effector proteins into host epithelial cells and macrophages, an essential step for tissue invasion and immune evasion. Although the arsenal of bacterial effectors and their cellular targets have been studied extensively, little is known about the prerequisites for deployment of type III secreted proteins during infection. Here, we describe a novel S. sonnei adhesin, SSO1327 which is a multivalent adhesion molecule (MAM) required for invasion of epithelial cells and macrophages and for infection in vivo. The S. sonnei MAM mediates intimate attachment to host cells, which is required for efficient translocation of type III effectors into host cells. SSO1327 is non-redundant to IcsA; its activity is independent of type III secretion. In contrast to the up-regulation of IcsA-dependent and independent attachment and invasion by deoxycholate in Shigella flexneri, deoxycholate negatively regulates IcsA and MAM in S. sonnei resulting in reduction in attachment and invasion and virulence attenuation in vivo. A strain deficient for SSO1327 is avirulent in vivo, but still elicits a host immune response.
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Affiliation(s)
- Rasha Y Mahmoud
- Strathclyde Institute of Pharmacy and Biomedical Sciences (SIPBS), University of Strathclyde, Glasgow, UK.,Department of Microbiology and Immunology, Faculty of Pharmacy, Helwan University, Cairo, Egypt
| | - Daniel Henry Stones
- Institute of Microbiology and Infection, School of Biosciences, University of Birmingham, Edgbaston, Birmingham, B15 2TT, UK
| | - Wenqin Li
- Strathclyde Institute of Pharmacy and Biomedical Sciences (SIPBS), University of Strathclyde, Glasgow, UK
| | - Mohamed Emara
- Department of Microbiology and Immunology, Faculty of Pharmacy, Helwan University, Cairo, Egypt
| | - Ramadan A El-Domany
- Department of Microbiology and Immunology, Faculty of Pharmacy, Helwan University, Cairo, Egypt
| | - Depu Wang
- The center of Translational Medicine, The First Affiliated Hospital, Xi'an Jiao Tong University, Xi'an, China
| | - Yili Wang
- Institute for Cancer Research, School of Basic Medical Science, Health Science Center, Xi'an Jiao Tong University, Xi'an, China
| | - Anne Marie Krachler
- Institute of Microbiology and Infection, School of Biosciences, University of Birmingham, Edgbaston, Birmingham, B15 2TT, UK
| | - Jun Yu
- Strathclyde Institute of Pharmacy and Biomedical Sciences (SIPBS), University of Strathclyde, Glasgow, UK
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33
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The CpxRA two-component system is essential for Citrobacter rodentium virulence. Infect Immun 2015; 83:1919-28. [PMID: 25712925 DOI: 10.1128/iai.00194-15] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2015] [Accepted: 02/16/2015] [Indexed: 12/29/2022] Open
Abstract
Citrobacter rodentium is a murine intestinal pathogen used as a model for the foodborne human pathogens enterohemorrhagic Escherichia coli and enteropathogenic E. coli. During infection, these pathogens use two-component signal transduction systems to detect and adapt to changing environmental conditions. In E. coli, the CpxRA two-component signal transduction system responds to envelope stress by modulating the expression of a myriad of genes. Quantitative real-time PCR showed that cpxRA was expressed in the colon of C57BL/6J mice infected with C. rodentium. To determine whether CpxRA plays a role during C. rodentium infection, a cpxRA deletion strain was generated and found to have a colonization defect during infection. This defect was independent of an altered growth rate or a defective type III secretion system, and single-copy chromosomal complementation of cpxRA restored virulence. The C. rodentium strains were then tested in C3H/HeJ mice, a lethal intestinal infection model. Mice infected with the ΔcpxRA strain survived infection, whereas mice infected with the wild-type or complemented strains succumbed to infection. Furthermore, we found that the cpxRA expression level was higher during early infection than at a later time point. Taken together, these data demonstrate that the CpxRA two-component signal transduction system is essential for the in vivo virulence of C. rodentium. In addition, these data suggest that fine-tuned cpxRA expression is important for infection. This is the first study that identifies a C. rodentium two-component transduction system required for pathogenesis. This study further indicates that CpxRA is an interesting target for therapeutics against enteric pathogens.
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Morgan JK, Ortiz JA, Riordan JT. The role for TolA in enterohemorrhagic Escherichia coli pathogenesis and virulence gene transcription. Microb Pathog 2014; 77:42-52. [DOI: 10.1016/j.micpath.2014.10.010] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2014] [Revised: 10/14/2014] [Accepted: 10/21/2014] [Indexed: 01/16/2023]
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Alghoribi MF, Gibreel TM, Dodgson AR, Beatson SA, Upton M. Galleria mellonella infection model demonstrates high lethality of ST69 and ST127 uropathogenic E. coli. PLoS One 2014; 9:e101547. [PMID: 25061819 PMCID: PMC4111486 DOI: 10.1371/journal.pone.0101547] [Citation(s) in RCA: 50] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2014] [Accepted: 06/09/2014] [Indexed: 01/09/2023] Open
Abstract
Galleria mellonella larvae are an alternative in vivo model for investigating bacterial pathogenicity. Here, we examined the pathogenicity of 71 isolates from five leading uropathogenic E. coli (UPEC) lineages using G. mellonella larvae. Larvae were challenged with a range of inoculum doses to determine the 50% lethal dose (LD50) and for analysis of survival outcome using Kaplan-Meier plots. Virulence was correlated with carriage of a panel of 29 virulence factors (VF). Larvae inoculated with ST69 and ST127 isolates (104 colony-forming units/larvae) showed significantly higher mortality rates than those infected with ST73, ST95 and ST131 isolates, killing 50% of the larvae within 24 hours. Interestingly, ST131 isolates were the least virulent. We observed that ST127 isolates are significantly associated with a higher VF-score than isolates of all other STs tested (P≤0.0001), including ST69 (P<0.02), but one ST127 isolate (strain EC18) was avirulent. Comparative genomic analyses with virulent ST127 strains revealed an IS1 mediated deletion in the O-antigen cluster in strain EC18, which is likely to explain the lack of virulence in the larvae infection model. Virulence in the larvae was not correlated with serotype or phylogenetic group. This study illustrates that G. mellonella are an excellent tool for investigation of the virulence of UPEC strains. The findings also support our suggestion that the incidence of ST127 strains should be monitored, as these isolates have not yet been widely reported, but they clearly have a pathogenic potential greater than that of more widely recognised clones, including ST73, ST95 or ST131.
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Affiliation(s)
- Majed F. Alghoribi
- Microbiology and Virology Unit, School of Medicine, University of Manchester, Manchester, United Kingdom
- King Abdullah International Medical Research Center, King Saud bin Abdulaziz University for Health Sciences, Riyadh, Saudi Arabia
| | - Tarek M. Gibreel
- Microbiology and Virology Unit, School of Medicine, University of Manchester, Manchester, United Kingdom
| | | | - Scott A. Beatson
- Australian Infectious Disease Centre, School of Chemistry & Molecular Biosciences, University of Queensland, Queensland, Australia
| | - Mathew Upton
- Microbiology and Virology Unit, School of Medicine, University of Manchester, Manchester, United Kingdom
- School of Biomedical and Healthcare Science, Plymouth University Peninsula Schools of Medicine and Dentistry, Plymouth, United Kingdom
- * E-mail:
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Reciprocal regulation of resistance-nodulation-division efflux systems and the Cpx two-component system in Vibrio cholerae. Infect Immun 2014; 82:2980-91. [PMID: 24799626 DOI: 10.1128/iai.00025-14] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
The Cpx two-component regulatory system has been shown in Escherichia coli to alleviate stress caused by misfolded cell envelope proteins. The Vibrio cholerae Cpx system was previously found to respond to cues distinct from those in the E. coli system, suggesting that this system fulfills a different physiological role in the cholera pathogen. Here, we used microarrays to identify genes that were regulated by the V. cholerae Cpx system. Our observations suggest that the activation of the V. cholerae Cpx system does not induce expression of genes involved in the mitigation of stress generated by misfolded cell envelope proteins but promotes expression of genes involved in antimicrobial resistance. In particular, activation of the Cpx system induced expression of the genes encoding the VexAB and VexGH resistance-nodulation-division (RND) efflux systems and their cognate outer membrane pore protein TolC. The promoters for these loci contained putative CpxR consensus binding sites, and ectopic cpxR expression activated transcription from the promoters for the RND efflux systems. CpxR was not required for intrinsic antimicrobial resistance, but CpxR activation enhanced resistance to antimicrobial substrates of VexAB and VexGH. Mutations that inactivated VexAB or VexGH efflux activity resulted in the activation of the Cpx response, suggesting that vexAB and vexGH and the cpxP-cpxRA system are reciprocally regulated. We speculate that the reciprocal regulation of the V. cholerae RND efflux systems and the Cpx two-component system is mediated by the intracellular accumulation of an endogenously produced metabolic by-product that is normally extruded from the cell by the RND efflux systems.
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Vogt SL, Raivio TL. Hfq reduces envelope stress by controlling expression of envelope-localized proteins and protein complexes in enteropathogenic Escherichia coli. Mol Microbiol 2014; 92:681-97. [PMID: 24628810 DOI: 10.1111/mmi.12581] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 03/13/2014] [Indexed: 12/25/2022]
Abstract
Gram-negative bacteria possess several envelope stress responses that detect and respond to damage to this critical cellular compartment. The σ(E) envelope stress response senses the misfolding of outer membrane proteins (OMPs), while the Cpx two-component system is believed to detect the misfolding of periplasmic and inner membrane proteins. Recent studies in several Gram-negative organisms found that deletion of hfq, encoding a small RNA chaperone protein, activates the σ(E) envelope stress response. In this study, we assessed the effects of deleting hfq upon activity of the σ(E) and Cpx responses in non-pathogenic and enteropathogenic (EPEC) strains of Escherichia coli. We found that the σ(E) response was activated in Δhfq mutants of all E. coli strains tested, resulting from the misregulation of OMPs. The Cpx response was activated by loss of hfq in EPEC, but not in E. coli K-12. Cpx pathway activation resulted in part from overexpression of the bundle-forming pilus (BFP) in EPEC Δhfq. We found that Hfq repressed expression of the BFP via PerA, a master regulator of virulence in EPEC. This study shows that Hfq has a more extensive role in regulating the expression of envelope proteins and horizontally acquired virulence genes in E. coli than previously recognized.
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Affiliation(s)
- Stefanie L Vogt
- Department of Biological Sciences, University of Alberta, Edmonton, Alberta, Canada, T6G 2E9
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38
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Affiliation(s)
- Sheila Nathan
- School of Biosciences & Biotechnology; Faculty of Science & Technology; Universiti Kebangsaan Malaysia; Bangi, Selangor, Malaysia
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39
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Williamson DA, Mills G, Johnson JR, Porter S, Wiles S. In vivo correlates of molecularly inferred virulence among extraintestinal pathogenic Escherichia coli (ExPEC) in the wax moth Galleria mellonella model system. Virulence 2014; 5:388-93. [PMID: 24518442 DOI: 10.4161/viru.27912] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
In contrast to commensal Escherichia coli, extraintestinal pathogenic E. coli (ExPEC) strains possess an array of virulence-associated genes. We sought to establish the feasibility of using the invertebrate Galleria mellonella (greater wax moth) for assessing ExPEC virulence and to investigate the correlation between genotypic determinants of virulence and in vivo pathogenicity. We observed a correlation between the number of virulence genes and larval survival, such that ExPEC isolates with higher virulence scores killed larvae significantly faster than isolates with lower virulence scores. By correlating genotypic and phenotypic virulence, we provide preliminary validation of this model for future studies investigating ExPEC virulence.
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Affiliation(s)
- Deborah A Williamson
- Faculty of Medical and Health Sciences; University of Auckland; Auckland, New Zealand; Institute of Environmental Science and Research; Wellington, New Zealand; Maurice Wilkins Centre for Molecular Biodiscovery; University of Auckland; Auckland, New Zealand
| | - Grant Mills
- Faculty of Medical and Health Sciences; University of Auckland; Auckland, New Zealand
| | | | | | - Siouxsie Wiles
- Faculty of Medical and Health Sciences; University of Auckland; Auckland, New Zealand; Maurice Wilkins Centre for Molecular Biodiscovery; University of Auckland; Auckland, New Zealand
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40
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Alshareef F, Robson GD. Genetic and virulence variation in an environmental population of the opportunistic pathogen Aspergillus fumigatus. MICROBIOLOGY-SGM 2014; 160:742-751. [PMID: 24464798 DOI: 10.1099/mic.0.072520-0] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Environmental populations of the opportunistic pathogen Aspergillus fumigatus have been shown to be genotypically diverse and to contain a range of isolates with varying pathogenic potential. In this study, we combined two RAPD primers to investigate the genetic diversity of environmental isolates from Manchester collected monthly over 1 year alongside Dublin environmental isolates and clinical isolates from patients. RAPD analysis revealed a diverse genotype, but with three major clinical isolate clusters. When the pathogenicity of clinical and Dublin isolates was compared with a random selection of Manchester isolates in a Galleria mellonella larvae model, as a group, clinical isolates were significantly more pathogenic than environmental isolates. Moreover, when relative pathogenicity of individual isolates was compared, clinical isolates were the most pathogenic, Dublin isolates were the least pathogenic and Manchester isolates showed a range in pathogenicity. Overall, this suggests that the environmental population is genetically diverse, displaying a range in pathogenicity, and that the most pathogenic strains from the environment are selected during patient infection.
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Affiliation(s)
- Fadwa Alshareef
- Faculty of Life Sciences, Michael Smith Building, University of Manchester, Manchester M16 8QW, UK
| | - Geoffrey D Robson
- Faculty of Life Sciences, Michael Smith Building, University of Manchester, Manchester M16 8QW, UK
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Kirchner M, AbuOun M, Mafura M, Bagnall M, Hunt T, Thomas C, Weile J, Anjum MF. Cefotaxime resistant Escherichia coli collected from a healthy volunteer; characterisation and the effect of plasmid loss. PLoS One 2013; 8:e84142. [PMID: 24386342 PMCID: PMC3873979 DOI: 10.1371/journal.pone.0084142] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2013] [Accepted: 11/12/2013] [Indexed: 11/18/2022] Open
Abstract
In this study 6 CTX-M positive E. coli isolates collected during a clinical study examining the effect of antibiotic use in a human trial were analysed. The aim of the study was to analyse these isolates and assess the effect of full or partial loss of plasmid genes on bacterial fitness and pathogenicity. A DNA array was utilised to assess resistance and virulence gene carriage. Plasmids were characterised by PCR-based replicon typing and addiction system multiplex PCR. A phenotypic array and insect virulence model were utilised to assess the effect of plasmid-loss in E. coli of a large multi-resistance plasmid. All six E. coli carrying blaCTX-M-14 were detected from a single participant and were identical by pulse field gel electrophoresis and MLST. Plasmid profiling and arrays indicated absence of a large multi-drug resistance (MDR) F-replicon plasmid carrying blaTEM, aadA4, strA, strB, dfrA17/19, sul1, and tetB from one isolate. Although this isolate partially retained the plasmid it showed altered fitness characteristics e.g. inability to respire in presence of antiseptics, similar to a plasmid-cured strain. However, unlike the plasmid-cured or plasmid harbouring strains, the survival rate for Galleria mellonella infected by the former strain was approximately 5-times lower, indicating other possible changes accompanying partial plasmid loss. In conclusion, our results demonstrated that an apparently healthy individual can harbour blaCTX-M-14E. coli strains. In one such strain, isolated from the same individual, partial absence of a large MDR plasmid resulted in altered fitness and virulence characteristics, which may have implications in the ability of this strain to infect and any subsequent treatment.
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Affiliation(s)
- Miranda Kirchner
- Department of Bacteriology and Food Safety, Animal Health and Veterinary Laboratories Agency, Addlestone, Surrey, United Kingdom
| | - Manal AbuOun
- Department of Bacteriology and Food Safety, Animal Health and Veterinary Laboratories Agency, Addlestone, Surrey, United Kingdom
| | - Muriel Mafura
- Department of Bacteriology and Food Safety, Animal Health and Veterinary Laboratories Agency, Addlestone, Surrey, United Kingdom
| | - Mary Bagnall
- Department of Bacteriology and Food Safety, Animal Health and Veterinary Laboratories Agency, Addlestone, Surrey, United Kingdom
| | - Theresa Hunt
- Department of Bacteriology and Food Safety, Animal Health and Veterinary Laboratories Agency, Addlestone, Surrey, United Kingdom
| | - Christopher Thomas
- School of Biosciences, University of Birmingham, Edgbaston, Birmingham, United Kingdom
| | - Jan Weile
- Institute for Laboratory and Transfusion Medicine at the Heart and Diabetes Centre, University Hospital of the Ruhr University, Bochum, Germany
| | - Muna F. Anjum
- Department of Bacteriology and Food Safety, Animal Health and Veterinary Laboratories Agency, Addlestone, Surrey, United Kingdom
- * E-mail:
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Wand ME, McCowen JWI, Nugent PG, Sutton JM. Complex interactions of Klebsiella pneumoniae with the host immune system in a Galleria mellonella infection model. J Med Microbiol 2013; 62:1790-1798. [DOI: 10.1099/jmm.0.063032-0] [Citation(s) in RCA: 46] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Worldwide, Klebsiella pneumoniae is an increasingly problematic opportunistic pathogen, with the emergence of carbapenem-resistant isolates of special importance. The mechanisms of virulence are poorly understood, and the current study utilized the invertebrate model Galleria mellonella to investigate facets of the virulence process. A range of UK clinical isolates and reference strains was assessed in Galleria by measuring survival as an end point. The clinical strains showed a range of virulence, with the majority of strains (68 %) causing greater than 50 % mortality at a challenge dose of 1×105 c.f.u. Three additional intermediate read-outs were developed to allow the mechanisms of virulence of Klebsiella to be dissected further. The release of lactate dehydrogenase as a marker of cell damage was the best predictor of virulence. Melanization as a marker of the insect innate immune system and ability to proliferate within Galleria as a marker of immune evasion also broadly correlated with survival but with some notable exceptions. No direct correlation was observed between virulence and either K1 or other defined capsular types, the carriage of defined virulence factors or particular functional phenotypes. Overall, the study showed that Galleria can provide significant insights into the mechanisms of virulence, and that this can be applied to the study of opportunistic human pathogens.
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Affiliation(s)
- Matthew E. Wand
- Public Health England, Microbiology Services Division, Porton Down, Salisbury, Wiltshire SP4 0JG, UK
| | - James W. I. McCowen
- Public Health England, Microbiology Services Division, Porton Down, Salisbury, Wiltshire SP4 0JG, UK
| | - Philip G. Nugent
- Public Health England, Microbiology Services Division, Porton Down, Salisbury, Wiltshire SP4 0JG, UK
| | - J. Mark Sutton
- Public Health England, Microbiology Services Division, Porton Down, Salisbury, Wiltshire SP4 0JG, UK
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Common duckweed (Lemna minor) is a versatile high-throughput infection model for the Burkholderia cepacia complex and other pathogenic bacteria. PLoS One 2013; 8:e80102. [PMID: 24223216 PMCID: PMC3819297 DOI: 10.1371/journal.pone.0080102] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2013] [Accepted: 10/07/2013] [Indexed: 01/05/2023] Open
Abstract
Members of the Burkholderia cepacia complex (Bcc) have emerged in recent decades as problematic pulmonary pathogens of cystic fibrosis (CF) patients, with severe infections progressing to acute necrotizing pneumonia and sepsis. This study presents evidence that Lemna minor (Common duckweed) is useful as a plant model for the Bcc infectious process, and has potential as a model system for bacterial pathogenesis in general. To investigate the relationship between Bcc virulence in duckweed and Galleria mellonella (Greater wax moth) larvae, a previously established Bcc infection model, a duckweed survival assay was developed and used to determine LD50 values. A strong correlation (R2 = 0.81) was found between the strains’ virulence ranks in the two infection models, suggesting conserved pathways in these vastly different hosts. To broaden the application of the duckweed model, enteropathogenic Escherichia coli (EPEC) and five isogenic mutants with previously established LD50 values in the larval model were tested against duckweed, and a strong correlation (R2 = 0.93) was found between their raw LD50 values. Potential virulence factors in B. cenocepacia K56-2 were identified using a high-throughput screen against single duckweed plants. In addition to the previously characterized antifungal compound (AFC) cluster genes, several uncharacterized genes were discovered including a novel lysR regulator, a histidine biosynthesis gene hisG, and a gene located near the gene encoding the recently characterized virulence factor SuhBBc. Finally, to demonstrate the utility of this model in therapeutic applications, duckweed was rescued from Bcc infection by treating with bacteriophage at 6-h intervals. It was observed that phage application became ineffective at a timepoint that coincided with a sharp increase in bacterial invasion of plant tissue. These results indicate that common duckweed can serve as an effective infection model for the investigation of bacterial virulence factors and therapeutic strategies to combat them.
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Affiliation(s)
- John K Crane
- Department of Medicine; Division of Infectious Diseases; University at Buffalo; Buffalo, NY USA
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45
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Choosing an appropriate infection model to study quorum sensing inhibition in Pseudomonas infections. Int J Mol Sci 2013; 14:19309-40. [PMID: 24065108 PMCID: PMC3794835 DOI: 10.3390/ijms140919309] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2013] [Revised: 09/13/2013] [Accepted: 09/17/2013] [Indexed: 02/07/2023] Open
Abstract
Bacteria, although considered for decades to be antisocial organisms whose sole purpose is to find nutrients and multiply are, in fact, highly communicative organisms. Referred to as quorum sensing, cell-to-cell communication mechanisms have been adopted by bacteria in order to co-ordinate their gene expression. By behaving as a community rather than as individuals, bacteria can simultaneously switch on their virulence factor production and establish successful infections in eukaryotes. Understanding pathogen-host interactions requires the use of infection models. As the use of rodents is limited, for ethical considerations and the high costs associated with their use, alternative models based on invertebrates have been developed. Invertebrate models have the benefits of low handling costs, limited space requirements and rapid generation of results. This review presents examples of such models available for studying the pathogenicity of the Gram-negative bacterium Pseudomonas aeruginosa. Quorum sensing interference, known as quorum quenching, suggests a promising disease-control strategy since quorum-quenching mechanisms appear to play important roles in microbe-microbe and host-pathogen interactions. Examples of natural and synthetic quorum sensing inhibitors and their potential as antimicrobials in Pseudomonas-related infections are discussed in the second part of this review.
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46
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Junqueira JC. Galleria mellonella as a model host for human pathogens: recent studies and new perspectives. Virulence 2013; 3:474-6. [PMID: 23211681 PMCID: PMC3524145 DOI: 10.4161/viru.22493] [Citation(s) in RCA: 65] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The number of studies using G. mellonella as a model host for human pathogens has increased significantly in the last few years. Important studies were published from different countries for evaluating the pathogenesis of bacterial and fungal infections and for exploring the host defenses against pathogens. Therefore, standardized conditions for the use of G. melonella larvae need to be established. Recent research showed that the deprivation of G. mellonella larvae of food during the experiment caused a reduction in immune responses and an increased susceptibility to infection, suggesting that incubating of larvae in the presence or absence of nutrition may affect the results and comparisons among different laboratories.
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Affiliation(s)
- Juliana Campos Junqueira
- Department of Biosciences and Oral Diagnosis, São José dos Campos Dental School, Universidade Estadual Paulista/UNESP, São Paulo, Brazil.
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The Cpx stress response system potentiates the fitness and virulence of uropathogenic Escherichia coli. Infect Immun 2013; 81:1450-9. [PMID: 23429541 DOI: 10.1128/iai.01213-12] [Citation(s) in RCA: 50] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
Strains of uropathogenic Escherichia coli (UPEC) are the primary cause of urinary tract infections, representing one of the most widespread and successful groups of pathogens on the planet. To colonize and persist within the urinary tract, UPEC must be able to sense and respond appropriately to environmental stresses, many of which can compromise the bacterial envelope. The Cpx two-component envelope stress response system is comprised of the inner membrane histidine kinase CpxA, the cytosolic response regulator CpxR, and the periplasmic auxiliary factor CpxP. Here, by using deletion mutants along with mouse and zebrafish infection models, we show that the Cpx system is critical to the fitness and virulence of two reference UPEC strains, the cystitis isolate UTI89 and the urosepsis isolate CFT073. Specifically, deletion of the cpxRA operon impaired the ability of UTI89 to colonize the murine bladder and greatly reduced the virulence of CFT073 during both systemic and localized infections within zebrafish embryos. These defects coincided with diminished host cell invasion by UTI89 and increased sensitivity of both strains to complement-mediated killing and the aminoglycoside antibiotic amikacin. Results obtained with the cpxP deletion mutants were more complicated, indicating variable strain-dependent and niche-specific requirements for this well-conserved auxiliary factor.
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48
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Utility of insects for studying human pathogens and evaluating new antimicrobial agents. ADVANCES IN BIOCHEMICAL ENGINEERING/BIOTECHNOLOGY 2013; 135:1-25. [PMID: 23604210 DOI: 10.1007/10_2013_194] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/06/2022]
Abstract
Insect models, such as Galleria mellonella and Drosophila melanogaster have significant ethical, logistical, and economic advantages over mammalian models for the studies of infectious diseases. Using these models, various pathogenic microbes have been studied and many novel virulence genes have been identified. Notably, because insects are susceptible to a wide variety of human pathogens and have immune responses similar to those of mammals, they offer the opportunity to understand innate immune responses against human pathogens better. It is important to note that insect pathosystems have also offered a simple strategy to evaluate the efficacy and toxicity of many antimicrobial agents. Overall, insect models provide a rapid, inexpensive, and reliable way as complementary hosts to conventional vertebrate animal models to study pathogenesis and antimicrobial agents.
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