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Mekasha S, Linke D. Secretion Systems in Gram-Negative Bacterial Fish Pathogens. Front Microbiol 2022; 12:782673. [PMID: 34975803 PMCID: PMC8714846 DOI: 10.3389/fmicb.2021.782673] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2021] [Accepted: 11/24/2021] [Indexed: 12/17/2022] Open
Abstract
Bacterial fish pathogens are one of the key challenges in the aquaculture industry, one of the fast-growing industries worldwide. These pathogens rely on arsenal of virulence factors such as toxins, adhesins, effectors and enzymes to promote colonization and infection. Translocation of virulence factors across the membrane to either the extracellular environment or directly into the host cells is performed by single or multiple dedicated secretion systems. These secretion systems are often key to the infection process. They can range from simple single-protein systems to complex injection needles made from dozens of subunits. Here, we review the different types of secretion systems in Gram-negative bacterial fish pathogens and describe their putative roles in pathogenicity. We find that the available information is fragmented and often descriptive, and hope that our overview will help researchers to more systematically learn from the similarities and differences between the virulence factors and secretion systems of the fish-pathogenic species described here.
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Affiliation(s)
- Sophanit Mekasha
- Section for Genetics and Evolutionary Biology, Department of Biosciences, University of Oslo, Oslo, Norway
| | - Dirk Linke
- Section for Genetics and Evolutionary Biology, Department of Biosciences, University of Oslo, Oslo, Norway
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2
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Bothammal P, Ganesh M, Vigneshwaran V, Anbarasu K, Ponmurugan K, Al-Dhabi NA, Natarajaseenivasan K. Construction of Genomic Library and Screening of Edwardsiella tarda Immunogenic Proteins for Their Protective Efficacy Against Edwardsiellosis. Front Immunol 2021; 12:764662. [PMID: 34868012 PMCID: PMC8636194 DOI: 10.3389/fimmu.2021.764662] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2021] [Accepted: 10/11/2021] [Indexed: 11/16/2022] Open
Abstract
Edwardsiella tarda is a severe aquaculture pathogen that can infect many hosts including humans, animals, and fish. Timely diagnosis and treatment are crucial for the control of edwardsiellosis in the aqua industry. By using rabbit polyclonal antibody, an expression gene library of virulent Edwardsiella tarda strain ED-BDU 1 isolated in south India was constructed and screened. The identified immune expressive proteins were characterized, and the corresponding coding sequences were cloned, expressed, and the purified recombinant proteins were used as antigens. The identified immunoreactive proteins namely HflC, HflK, and YhcI were studied for their immune protective potential in vivo by challenge experiments. The protective efficacy of HflC, HflK, and YhcI showed that the clearance of Edwardsiella from the host with ~ 60% survivability. Further, the immunoreactive proteins induce a strong immune response upon infection and elicit the significant production of IL-10, IFN-γ, Th1, and Th2 mediated mRNA expression and were therefore effective in vaccine production for edwardsiellosis.
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Affiliation(s)
- Palanisamy Bothammal
- Medical Microbiology Laboratory, Department of Microbiology, Center for Excellence in Life Sciences, Bharathidasan University, Tiruchirappalli, India
| | - Mohan Ganesh
- Medical Microbiology Laboratory, Department of Microbiology, Center for Excellence in Life Sciences, Bharathidasan University, Tiruchirappalli, India
| | - Vellaisamy Vigneshwaran
- Medical Microbiology Laboratory, Department of Microbiology, Center for Excellence in Life Sciences, Bharathidasan University, Tiruchirappalli, India
| | - Kumarasamy Anbarasu
- Microbial Biotechnology Laboratory, Department of Marine Biotechnology, School of Marine Sciences, Bharathidasan University, Tiruchirappalli, India
| | - Karuppiah Ponmurugan
- Department of Botany & Microbiology, College of Science, King Saud University, Riyadh, Saudi Arabia
| | - Naif Abdullah Al-Dhabi
- Department of Botany & Microbiology, College of Science, King Saud University, Riyadh, Saudi Arabia
| | - Kalimuthusamy Natarajaseenivasan
- Medical Microbiology Laboratory, Department of Microbiology, Center for Excellence in Life Sciences, Bharathidasan University, Tiruchirappalli, India
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Xu L, Che J, Xu Y, Chen Y, Li Y, Murtaza B, Wang L, Zhang M, Li X. Oral administration of microencapsulated egg yolk immunoglobulin (IgY) in turbot (Scophthalmus maximus) to combat against Edwardsiella tarda 2CDM001 infections. FISH & SHELLFISH IMMUNOLOGY 2020; 106:609-620. [PMID: 32795594 DOI: 10.1016/j.fsi.2020.08.024] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/31/2020] [Revised: 06/27/2020] [Accepted: 08/11/2020] [Indexed: 06/11/2023]
Abstract
Edwardsiellosis, an extremely harmful disease can be caused by Edwardsiella tarda, severely restricts the development of turbot (Scophthalmus maximus) farming worldwide, especially in China. This study aimed to establish an effective and feasible prophylaxis by feeding chitosan-alginate coated egg yolk immunoglobulin (IgY) against E. tarda 2CDM001 infections in the process of turbot farming. Enzyme-linked immunosorbent assays proved that the obtained specific IgY could specifically target E. tarda 2CDM001 and five other E. tarda isolates (1a5p, Hz-s, 1a1s, fs-a1 and 58p8). In-vitro, the bacteriostatic effects of specific IgY showed dose dependencies at concentrations ranging from 1 to 10 mg/mL. Moreover, E. tarda 2CDM001 incubated with 10 mg/mL specific IgY could induce the destruction of cell wall structures and significantly decrease the bacterial surface hydrophobicity (p < 0.05). In this study, turbots were challenged with 107 CFU E. tarda 2CDM001 after seven days of continuous feeding with basal diets containing microencapsulated IgYs. Survival rates of the 5%, 3% and 1% microencapsulated specific IgY groups were 63.3%, 56.7% and 20% on the tenth day post infection, respectively, while the turbots in the positive control and non-specific IgY groups all died within ten days. Oral administration of basal diets containing 5% microencapsulated specific IgY significantly reduced IL-1β, IL-8, TNF-α and C3 transcript levels in the head kidney and spleen of turbots compared with the positive and non-specific IgY groups at 24 h after E. tarda 2CDM001 challenging (p < 0.05). Pathological increase of leukocytes in the specific IgY group was significantly lower than that in the positive control and non-specific IgY groups (p < 0.05), decreasing slowly after 24 h of infection and showing a recovery trend. Erythrocyte counts and hemoglobin concentrations of turbots in positive and non-specific IgY groups showed a marked decrease compared with the negative and specific groups at 96 h after E. tarda 2CDM001 infection (p < 0.05). These results suggest that passive immunity via feeding microencapsulated specific IgY could be used as a valuable preventative in turbot against E. tarda 2CDM001 infections.
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Affiliation(s)
- Le Xu
- School of Bioengineering, Dalian University of Technology, Dalian, 116024, China
| | - Jian Che
- Dalian Xinyulong Marine Biological Seed Technology Co., Ltd., Dalian, 116222, China; Center for Food Safety of Animal Origin, Ministry of Education, Dalian University of Technology, Dalian, 116600, China
| | - Yongping Xu
- School of Bioengineering, Dalian University of Technology, Dalian, 116024, China; Center for Food Safety of Animal Origin, Ministry of Education, Dalian University of Technology, Dalian, 116600, China
| | - Yan Chen
- School of Bioengineering, Dalian University of Technology, Dalian, 116024, China
| | - Yuan Li
- School of Bioengineering, Dalian University of Technology, Dalian, 116024, China
| | - Bilal Murtaza
- School of Bioengineering, Dalian University of Technology, Dalian, 116024, China
| | - Lili Wang
- School of Bioengineering, Dalian University of Technology, Dalian, 116024, China; Center for Food Safety of Animal Origin, Ministry of Education, Dalian University of Technology, Dalian, 116600, China
| | - Meixia Zhang
- School of Bioengineering, Dalian University of Technology, Dalian, 116024, China
| | - Xiaoyu Li
- School of Bioengineering, Dalian University of Technology, Dalian, 116024, China; Center for Food Safety of Animal Origin, Ministry of Education, Dalian University of Technology, Dalian, 116600, China.
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Trxlp, a thioredoxin-like effector from Edwardsiella piscicida inhibits cellular redox signaling and nuclear translocation of NF-κB. Int J Biol Macromol 2020; 148:89-101. [PMID: 31945434 DOI: 10.1016/j.ijbiomac.2020.01.114] [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: 10/25/2019] [Revised: 01/06/2020] [Accepted: 01/11/2020] [Indexed: 11/23/2022]
Abstract
Redox signaling and homeostasis are essential for cell survival and the immune response. Peroxiredoxin (Prx) modulates the level of H2O2 as a redox signal through H2O2 decomposition. The redox activity of thioredoxin (Trx) is required as a reducing equivalent to regenerate Prx. Edwardsiella piscicida is an opportunistic Gram-negative enteric pathogen that secretes a novel Trx-like effector protein, ETAE_2186 (Trxlp). Trxlp has unique structural properties compared with other Trx proteins. In enzymatic and binding assays, we confirmed Trxlp to be redox-inactive due to the low reactivity and flexibility of the resolving cysteine residue, C35, at the active site motif "31WCXXC35". We identified key residues near the active site that are critical for reactivity and flexibility of C35 by site-directed mutagenesis analysis. NMR titration experiment demonstrated prolong inhibitory interaction of Trxlp with Prx1 resulting in the repression of Prx1-mediated H2O2 decomposition leading to increased ROS accumulation in infected host cells. Increased ROS in turn prevented nuclear translocation of NF-κB and inhibition of NF-κB target genes, leading to bacterial survival and enhanced replication inside host cells. Targeting Trxlp-mediated virulence promises to attenuate E. piscicida infection.
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Ren Y, Liu Q, Liu H, Zhou X, Zhang Y, Cai M. Engineering substrate and energy metabolism for living cell production of cytidine-5'-diphosphocholine. Biotechnol Bioeng 2020; 117:1426-1435. [PMID: 31997310 DOI: 10.1002/bit.27291] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2019] [Revised: 12/26/2019] [Accepted: 01/28/2020] [Indexed: 12/14/2022]
Abstract
Cytidine-5'-diphosphocholine (CDP-choline) is a widely used neuroprotective drug for multiple indications. In industry, CDP-choline is synthesized by a two-step cell culture/permeabilized cell biotransformation method because substrates often do not enter cells in an efficient manner. This study develops a novel one-step living cell fermentation method for CDP-choline production. For this purpose, the feasibility of Pichia pastoris as a chassis was demonstrated by substrate feeding and CDP-choline production. Overexpression of choline phosphate cytidylyltransferase and choline kinase enhanced the choline transformation pathway and improved the biosynthesis of CDP-choline. Furthermore, co-overexpression of ScHnm1, which is a heterologous choline transporter, highly improved the utilization of choline substrates, despite its easy degradation in cells. This strategy increased CDP-choline titer by 55-folds comparing with the wild-type (WT). Overexpression of cytidine-5'-monophosphate (CMP) kinase and CDP kinase in the CMP transformation pathway showed no positive effects. An increase in the ATP production by citrate stimulation or metabolic pathway modification further improved CDP-choline biosynthesis by 120%. Finally, the orthogonal optimization of key substrates and pH was carried out, and the resulting CDP-choline titer (6.0 g/L) at optimum conditions increased 88 times the original titer in the WT. This study provides a new paradigm for CDP-choline bioproduction by living cells.
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Affiliation(s)
- Yanna Ren
- State Key Laboratory of Bioreactor Engineering, East China University of Science and Technology, Shanghai, China
| | - Qi Liu
- State Key Laboratory of Bioreactor Engineering, East China University of Science and Technology, Shanghai, China
| | - Haifeng Liu
- China Resources Angde Biotech Pharmaceutical Co, Ltd, Liaocheng, China
| | - Xiangshan Zhou
- State Key Laboratory of Bioreactor Engineering, East China University of Science and Technology, Shanghai, China.,China Resources Angde Biotech Pharmaceutical Co, Ltd, Liaocheng, China
| | - Yuanxing Zhang
- State Key Laboratory of Bioreactor Engineering, East China University of Science and Technology, Shanghai, China.,Shanghai Collaborative Innovation Center for Biomanufacturing, Shanghai, China
| | - Menghao Cai
- State Key Laboratory of Bioreactor Engineering, East China University of Science and Technology, Shanghai, China
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De novo whole transcriptome profiling of Edwardsiella tarda isolated from infected fish (Labeo catla). Gene 2019; 701:152-160. [PMID: 30910556 DOI: 10.1016/j.gene.2019.03.028] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2019] [Revised: 03/05/2019] [Accepted: 03/15/2019] [Indexed: 11/22/2022]
Abstract
Edwardsiella tarda belongs to the genera of Gram negative bacterium mainly associated with edwardsiellosis, the most commonly found infectious fish disease throughout the globe. E. tarda is also a widespread pathogen which cause infections such as cellulitis or gas gangrene and generalized infections in humans. To control the escalating infection of E. trada on various species, it is essential to decoded the mysterious mechanism behind the bacterial infection at transcript level. In this present study, we carry out a de novo E. tarda Whole transcriptome sequencing, isolated from infected fish intestine using SOLiD sequencing platform. RNA-Seq data analysis was performed using various bioinformatics pipelines. Protein-protein interaction study for pathway enrichment and gene ontology study were executed for further investigation. Assembly statistics for E. tarda dataset showed that the number of transcript contigs was 9657 out of which 6749 were GO annotated whereas 1528 were not assigned any GO terms. GO analysis showed that the expressed genes were enhanced with molecular function, cellular component and biological process. A KEGG enrichment study showed that pathway's that are directly linked with immune diseases like Rheumatoid arthritis (0.2%), Tuberculosis (0.3%) Endocytosis (0.6%) was considerably enriched. Protein-protein interaction study showed that most of the expressed proteins were involved in metabolic pathways, flagellar assembly, Propanoate metabolism, Microbial metabolism in diverse environments, Butanoate metabolism and Carbon. The present study provides novel E. tarda transcriptome sequence data, allowing us to identify biologically significant genes and their functional relationship with fish diseases, and will be useful in recognize the reliable therapeutic targets in near feature.
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7
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LEE K, KIM HK, PARK SK, SOHN H, CHO Y, CHOI YM, JEONG DG, KIM JH. First report of the occurrence and whole-genome characterization of Edwardsiella tarda in the false killer whale (Pseudorca crassidens). J Vet Med Sci 2018; 80:1041-1046. [PMID: 29695679 PMCID: PMC6021894 DOI: 10.1292/jvms.17-0590] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2017] [Accepted: 04/16/2018] [Indexed: 01/22/2023] Open
Abstract
Although several Edwardsiella tarda infections have been reported, its pathogenic role in marine mammals has not been investigated at the genome level. We investigated the genome of E. tarda strain KC-Pc-HB1, isolated from the false killer whale (Pseudorca crassidens) found bycaught in South Korea. The obtained genome was similar to that of human pathogenic E. tarda strains, but distinct from other Edwardsiella species. Although type III and VI secretion systems, which are essential for the virulence of other Edwardsiella species, were absent, several virulence-related genes involved in the pathogenesis of E. tarda were found in the genome. These results provide important insights into the E. tarda infecting marine mammals and give valuable information on potential virulence factors in this pathogen.
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Affiliation(s)
- Kyunglee LEE
- Cetacean Research Institute (CRI), National Institute of
Fisheries Science (NIFS), Ulsan 44780, Republic of Korea
| | - Hye Kwon KIM
- Infectious Disease Research Center, Korea Research Institute
of Bioscience and Biotechnology, Daejeon 34141, Republic of Korea
| | - Sung-Kyun PARK
- Infectious Disease Research Center, Korea Research Institute
of Bioscience and Biotechnology, Daejeon 34141, Republic of Korea
| | - Hawsun SOHN
- Cetacean Research Institute (CRI), National Institute of
Fisheries Science (NIFS), Ulsan 44780, Republic of Korea
| | - Yuna CHO
- Cetacean Research Institute (CRI), National Institute of
Fisheries Science (NIFS), Ulsan 44780, Republic of Korea
| | - Young-Min CHOI
- Cetacean Research Institute (CRI), National Institute of
Fisheries Science (NIFS), Ulsan 44780, Republic of Korea
| | - Dae Gwin JEONG
- Infectious Disease Research Center, Korea Research Institute
of Bioscience and Biotechnology, Daejeon 34141, Republic of Korea
| | - Ji Hyung KIM
- Infectious Disease Research Center, Korea Research Institute
of Bioscience and Biotechnology, Daejeon 34141, Republic of Korea
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Lee SB, Choe Y, Chon TS, Kang HY. Analysis of zebrafish (Danio rerio) behavior in response to bacterial infection using a self-organizing map. BMC Vet Res 2015; 11:269. [PMID: 26497220 PMCID: PMC4619490 DOI: 10.1186/s12917-015-0579-2] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2015] [Accepted: 10/09/2015] [Indexed: 12/15/2022] Open
Abstract
BACKGROUND Animal behavioral responses have been recently established as a suitable tool for detecting contaminants in the environment for risk assessment in situ. In this study, we observed movement behavior of zebrafish (Danio rerio) before and after infection with Edwardsiella tarda CK41 for 3 days until death. METHODS Infection status of zebrafish was confirmed through PCR and colonization assay as time progressed and lesion development in the tails of zebrafish was also examined. Movement behaviors in response to bacterial infection were patterned by self-organizing map (SOM) based on movement parameters, including speed (mm/s), acceleration (mm/s (2) ), stop duration (t), stop number (n), locomotory rate (mm/s), turning rate (rad/s), and meander (rad/mm). RESULTS According to SOM result, clusters were identified firstly according to time and secondly according to infection. Two movement patterns were observed in the early period of infection: one group with minimum turning rate and meander (i.e., stiff movement) and the other group with maximum strop number. Late infection was characterized by long stop duration. CONCLUSION SOM was suitable for extracting complex behavioral data and thus can serve as a referencing system for diagnosing disease development in order to reveal the mechanism of the infection process.
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Affiliation(s)
- Sang-Bin Lee
- Department of Biological Sciences, Pusan National University, Busan, 609-735, Republic of Korea.
| | - Yunjeong Choe
- Department of Microbiology, Pusan National University, Busandaehak-ro, 63beon-gill, Geumjeong-gu, Busan, 609-735, Republic of Korea.
| | - Tae-Soo Chon
- Department of Biological Sciences, Pusan National University, Busan, 609-735, Republic of Korea. .,Ecology & Future Research Association (EnFRA), 21 Dusil-ro, 45 beon-gil, Geumjeong-gu, Busan, 609-802, Republic of Korea.
| | - Ho Young Kang
- Department of Microbiology, Pusan National University, Busandaehak-ro, 63beon-gill, Geumjeong-gu, Busan, 609-735, Republic of Korea.
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Yang W, Wang L, Zhang L, Qu J, Wang Q, Zhang Y. An invasive and low virulent Edwardsiella tarda esrB mutant promising as live attenuated vaccine in aquaculture. Appl Microbiol Biotechnol 2014; 99:1765-77. [DOI: 10.1007/s00253-014-6214-5] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2014] [Revised: 11/03/2014] [Accepted: 11/04/2014] [Indexed: 10/24/2022]
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Gao D, Cheng J, Zheng E, Li Y, Shao Z, Xu Z, Lu C. Eha, a transcriptional regulator of hemolytic activity ofEdwardsiella tarda. FEMS Microbiol Lett 2014; 353:132-40. [DOI: 10.1111/1574-6968.12420] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2013] [Revised: 03/02/2014] [Accepted: 03/07/2014] [Indexed: 11/29/2022] Open
Affiliation(s)
- Daqing Gao
- Department of Pathogenic Microbiology and Immunology; Southeast University School of Medicine; Nanjing China
| | - Jing Cheng
- JiangSu University School of Medicine; Zhenjiang China
| | - Enjin Zheng
- Department of Pathogenic Microbiology and Immunology; Southeast University School of Medicine; Nanjing China
| | - Yuhong Li
- Department of Pathogenic Microbiology and Immunology; Southeast University School of Medicine; Nanjing China
| | - Zeye Shao
- Department of Clinical Lab; Southeast University School of Medicine; Nanjing China
| | - Zeyan Xu
- JiangSu University School of Medicine; Zhenjiang China
| | - Chengping Lu
- NanJing Agricultural University, College of Veterinary Medicine; Nanjing China
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Dong X, Fan X, Wang B, Shi X, Zhang XH. Invasin of Edwardsiella tarda
is essential for its haemolytic activity, biofilm formation and virulence towards fish. J Appl Microbiol 2013; 115:12-9. [DOI: 10.1111/jam.12198] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2013] [Revised: 03/13/2013] [Accepted: 03/14/2013] [Indexed: 12/01/2022]
Affiliation(s)
- X. Dong
- College of Marine Life Sciences; Ocean University of China; Qingdao China
| | - X. Fan
- College of Marine Life Sciences; Ocean University of China; Qingdao China
| | - B. Wang
- College of Marine Life Sciences; Ocean University of China; Qingdao China
| | - X. Shi
- College of Marine Life Sciences; Ocean University of China; Qingdao China
| | - X.-H. Zhang
- College of Marine Life Sciences; Ocean University of China; Qingdao China
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12
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Pathogenesis of and strategies for preventing Edwardsiella tarda infection in fish. Vet Res 2012; 43:67. [PMID: 23035843 PMCID: PMC3479428 DOI: 10.1186/1297-9716-43-67] [Citation(s) in RCA: 185] [Impact Index Per Article: 15.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2012] [Accepted: 09/07/2012] [Indexed: 01/29/2023] Open
Abstract
Edwardsiella tarda is one of the serious fish pathogens, infecting both cultured and wild fish species. Research on edwardsiellosis has revealed that E. tarda has a broad host range and geographic distribution, and contains important virulence factors that enhance bacterial survival and pathogenesis in hosts. Although recent progress in edwardsiellosis research has enabled the development of numerous, highly effective vaccine candidates, these efforts have not been translated into a commercialized vaccine. The present review aims to provide an overview of the identification, pathology, diagnosis and virulence factors of E. tarda in fish, and describe recent strategies for developing vaccines against edwardsiellosis. The hope is that this presentation will be useful not only from the standpoint of understanding the pathogenesis of E. tarda, but also from the perspective of facilitating the development of effective vaccines.
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Xiao J, Chen T, Yang M, Zhang Y, Wang Q. Identification of qseEGF genetic locus and its roles in controlling hemolytic activity and invasion in fish pathogen Edwardsiella tarda. Lett Appl Microbiol 2012; 55:91-8. [PMID: 22694092 DOI: 10.1111/j.1472-765x.2012.03260.x] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
AIMS The aims of this study were to reveal the roles of the gene locus qseEGF in the pathogenesis of Edwardsiella tarda. METHODS AND RESULTS Genome sequencing of fish pathogen E. tarda EIB202 reveals that the gene locus qseEGF, which encodes a novel two-component system QseEF, were located in E. tarda. The transcription of qseE, qseF and qseG was firstly characterized to be cotranscribed by reverse-transcribed PCR (RT-PCR). The mutant strains ΔqseE, ΔqseF and ΔqseG were constructed with in-frame deletion strategy. Compared with the wild type, all of the mutants showed attenuated virulence and impaired intracellular survival capabilities. Deletion in qseE, qseF and qseG resulted in different effects on hemolysin production in E. tarda. qRT-PCR results indicated that QseEF played a role in regulation of secretion systems, which in turn affected the virulence of E. tarda. CONCLUSIONS The results manifested that QseEF system affected the virulence in E. tarda EIB202 by controlling the secretion system and hemolysin production. QseE, QseG and QseF in E. tarda serve for the physiological fitness and pathogenesis related to the bacterial survival in macrophage and in vivo of fish. SIGNIFICANCE AND IMPACT The present results suggested that the important role of two-component system QseEF in regulation of E. tarda pathogenesis and its potential for attenuated live vaccine construction.
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Affiliation(s)
- Jingfan Xiao
- State Key Laboratory of Bioreactor Engineering, East China University of Science and Technology, Shanghai, China
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14
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Wang K, Liu E, Song S, Wang X, Zhu Y, Ye J, Zhang H. Characterization of Edwardsiella tarda rpoN: roles in σ70 family regulation, growth, stress adaption and virulence toward fish. Arch Microbiol 2012; 194:493-504. [DOI: 10.1007/s00203-011-0786-6] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2011] [Revised: 12/15/2011] [Accepted: 12/23/2011] [Indexed: 12/26/2022]
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15
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Wang YM, Wang QY, Xiao JF, Liu Q, Wu HZ, Zhang YX. Genetic relationships of Edwardsiella strains isolated in China aquaculture revealed by rep-PCR genomic fingerprinting and investigation of Edwardsiella virulence genes. J Appl Microbiol 2011; 111:1337-48. [DOI: 10.1111/j.1365-2672.2011.05166.x] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
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16
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Ceuppens S, Rajkovic A, Heyndrickx M, Tsilia V, Van De Wiele T, Boon N, Uyttendaele M. Regulation of toxin production by Bacillus cereus and its food safety implications. Crit Rev Microbiol 2011; 37:188-213. [PMID: 21417966 DOI: 10.3109/1040841x.2011.558832] [Citation(s) in RCA: 88] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
Toxin expression is of utmost importance for the food-borne pathogen B. cereus, both in food poisoning and non-gastrointestinal host infections as well as in interbacterial competition. Therefore it is no surprise that the toxin gene expression is tightly regulated by various internal and environmental signals. An overview of the current knowledge regarding emetic and diarrheal toxin transcription and expression is presented in this review. The food safety aspects and management tools such as temperature control, food preservatives and modified atmosphere packaging are discussed specifically for B. cereus emetic and diarrheal toxin production.
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Affiliation(s)
- Siele Ceuppens
- Ghent University, Faculty of Bioscience Engineering, Laboratory of Food Microbiology and Food Preservation, Ghent, Belgium
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17
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Li GY, Li J, Xiao P, Guo YH, Mo ZL. Detection of type III secretion gene as an indicator for pathogenic Edwardsiella tarda. Lett Appl Microbiol 2011; 52:213-9. [PMID: 21219368 DOI: 10.1111/j.1472-765x.2010.02984.x] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
AIMS To differentiate pathogenic and nonpathogenic Edwardsiella tarda strains based on the detection of type III secretion system (T3SS) gene using polymerase chain reaction (PCR). METHODS AND RESULTS Primers were designed to amplify Edw. tarda T3SS component gene esaV, catalase gene katB, haemolysin gene hlyA and 16S rRNA gene as an internal positive control. Genomic DNAs were extracted using a commercial isolation kit from 36 Edw. tarda strains consisting of 18 pathogenic and 18 nonpathogenic strains, and 50 ng of each DNA was used as the template for PCR amplification. PCR was performed with a thermocycler (TaKaRa TP600) in a 25-μl volume. Products of esaV were detected in all pathogenic strains, but not in nonpathogenic strains; katB was detected in all pathogenic strains and one of nonpathogenic strains; hlyA was not detected in any strains. CONCLUSIONS The detection of esaV gene can be used for the assessment of pathogenic Edw. tarda strains. SIGNIFICANCE AND IMPACT OF THE STUDY The strategy using T3SS gene as the virulence indicator provides a useful tool for the clinical assessment of pathogenic Edw. tarda strains and prediction of edwardsiellosis risk in fish culture environments.
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Affiliation(s)
- G Y Li
- Key Laboratory of Experimental Marine Biology, Institute of Oceanology, Chinese Academy of Sciences, Qingdao, China
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18
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Wang B, Mo ZL, Xiao P, Li J, Zou YX, Hao B, Li GY. EseD, a putative T3SS translocon component of Edwardsiella tarda, contributes to virulence in fish and is a candidate for vaccine development. MARINE BIOTECHNOLOGY (NEW YORK, N.Y.) 2010; 12:678-685. [PMID: 20072793 DOI: 10.1007/s10126-009-9255-5] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/22/2009] [Accepted: 12/11/2009] [Indexed: 05/28/2023]
Abstract
Edwardsiella tarda has a type III secretion system (T3SS) essential for pathogenesis. EseD, together with EseB and EseC, has been suggested to form a putative T3SS translocon complex, although its further function is unclear. To investigate the physiological role of EseD, a mutant strain of E. tarda was constructed with an in-frame deletion of the entire eseD gene. One finding was that the ∆eseD mutant decreased the secretion levels of EseC and EseB proteins. Additionally, the ∆eseD mutant showed attenuated swarming and contact-hemolysis abilities. However, the ∆eseD mutant showed increased biofilm formation. Complementation of the mutant strain with eseD restored these phenotypes to those similar to the wild-type strain. Furthermore, infection experiments in fish showed that the ∆eseD mutant exhibited slower proliferation and a tenfold decrease in virulence in fish. These results indicate a specific role of EseD in the pathogenesis of E. tarda. Finally, recombinant EseD protein elicited high antibody titers in immunized fish and various levels of protection against lethal challenge with the wild-type strain. These results indicate that EseD protein may be a candidate antigen for development of a subunit vaccine against Edwardsiellosis.
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Affiliation(s)
- Bo Wang
- Key Lab of Experimental Marine Biology, Institute of Oceanology, Chinese Academy of Sciences, 7 Nanhai Road, Qingdao 266071, China
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Xu L, Wang Q, Xiao J, Liu Q, Wang X, Chen T, Zhang Y. Characterization of Edwardsiella tarda waaL: roles in lipopolysaccharide biosynthesis, stress adaptation, and virulence toward fish. Arch Microbiol 2010; 192:1039-47. [PMID: 20938646 DOI: 10.1007/s00203-010-0635-z] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2010] [Revised: 08/12/2010] [Accepted: 09/23/2010] [Indexed: 12/29/2022]
Abstract
Edwardsiella tarda is the causative agent of edwardsiellosis in fish. The genome sequence of a virulent strain EIB202 has been determined. According to the genome sequence, the lipopolysaccharide (LPS) synthesis cluster containing a putative O-antigen ligase gene waaL was identified. Here, the in-frame deletion mutant ΔwaaL was constructed to analyze the function of WaaL in E. tarda EIB202. The ΔwaaL mutant displayed absence in O-antigen side chains in the LPS production. The ΔwaaL mutant exhibited an increased sensitivity to hydrogen peroxide indicating that the LPS was involved in the endurance to the oxidative stress in hosts during infection. In addition, the resistance of ΔwaaL to serum and polymyxin B decreased remarkably. The ΔwaaL mutant was also attenuated in virulence, showed an impaired ability in internalization of epithelioma papulosum cyprinid (EPC) cells and a comparatively poor ability of proliferation in vivo, which was in line with the increased LD(50) value. These results indicated that waaL gene was a functional member of the gene cluster involved in LPS synthesis and highlighted the importance of the O-antigen side chains to stress adaption and virulence in E. tarda, signifying the gene as a potential target for live attenuated vaccine against this bacterium.
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Affiliation(s)
- Lili Xu
- State Key Laboratory of Bioreactor Engineering, East China University of Science and Technology, 200237 Shanghai, People's Republic of China
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20
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Sakai T, Matsuyama T, Nishioka T, Nakayasu C, Kamaishi T, Yamaguchi K, Iida T. Identification of Major Antigenic Proteins of Edwardsiella Tarda Recognized by Japanese Flounder Antibody. J Vet Diagn Invest 2009; 21:504-9. [DOI: 10.1177/104063870902100412] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Abstract
Edwardsiella tarda is a fish pathogen that causes systemic infections in fresh water and marine fish. Determining the antigenic proteins is important for the development of an immunodiagnostic tests and a vaccine for effective infection control in fish. In the current study, antigens were detected by immunoblotting and affinity column chromatography using a Japanese flounder ( Paralichthys olivaceus) antibody produced by experimental infection with E. tarda. GroEL, glyceraldehyde-3-phosphate dehydrogenase (GAPDH), outer membrane protein A, filament protein, 30S ribosomal protein S6, 50S ribosomal protein L9, cold shock protein, and carbon storage protein were identified as antigens of E. tarda through biochemical analyses of the molecular weights, isoelectric points, and N-terminal amino-acid sequences. These proteins can be easily detected in flounder infected with E. tarda and are potential diagnostic markers.
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Affiliation(s)
- Takamitsu Sakai
- National Research Institute of Aquaculture, Fisheries Research Agency, Minami-Ise, Mie
- Japan
| | - Tomomasa Matsuyama
- National Research Institute of Aquaculture, Fisheries Research Agency, Minami-Ise, Mie
- Japan
| | - Toyohiro Nishioka
- National Research Institute of Aquaculture, Fisheries Research Agency, Minami-Ise, Mie
- Japan
| | - Chihaya Nakayasu
- Inland Station, National Research Institute of Aquaculture, Fisheries Research Agency, Tamaki, Mie
- Japan
| | - Takashi Kamaishi
- National Research Institute of Aquaculture, Fisheries Research Agency, Minami-Ise, Mie
- Japan
| | | | - Takaji Iida
- National Research Institute of Aquaculture, Fisheries Research Agency, Minami-Ise, Mie
- Japan
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21
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Wang B, Mo ZL, Mao YX, Zou YX, Xiao P, Li J, Yang JY, Ye XH, Leung KY, Zhang PJ. Investigation of EscA as a chaperone for the Edwardsiella tarda type III secretion system putative translocon component EseC. MICROBIOLOGY-SGM 2009; 155:1260-1271. [PMID: 19332827 DOI: 10.1099/mic.0.021865-0] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Edwardsiella tarda is an important Gram-negative enteric pathogen affecting both animals and humans. It possesses a type III secretion system (T3SS) essential for pathogenesis. EseB, EseC and EseD have been shown to form a translocon complex after secretion, while EscC functions as a T3SS chaperone for EseB and EseD. In this paper we identify EscA, a protein required for accumulation and proper secretion of another translocon component, EseC. The escA gene is located upstream of eseC and the EscA protein has the characteristics of T3SS chaperones. Cell fractionation experiments indicated that EscA is located in the cytoplasm and on the cytoplasmic membrane. Mutation with in-frame deletion of escA greatly decreased the secretion of EseC, while complementation of escA restored the wild-type secretion phenotype. The stabilization and accumulation of EseC in the cytoplasm were also affected in the absence of EscA. Mutation of escA did not affect the transcription of eseC but reduced the accumulation level of EseC as measured by using an EseC-LacZ fusion protein in Ed. tarda. Co-purification and co-immunoprecipitation studies demonstrated a specific interaction between EscA and EseC. Further analysis showed that residues 31-137 of EseC are required for EseC-EscA interaction. Mutation of EseC residues 31-137 reduced the secretion and accumulation of EseC in Ed. tarda. Finally, infection experiments showed that mutations of EscA and residues 31-137 of EseC increased the LD(50) by approximately 10-fold in blue gourami fish. These results indicated that EscA functions as a specific chaperone for EseC and contributes to the virulence of Ed. tarda.
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Affiliation(s)
- Bo Wang
- Graduate University of Chinese Academy of Sciences, Beijing 100049, PR China.,Institute of Oceanology, Chinese Academy of Sciences, Qingdao 266071, PR China
| | - Zhao Lan Mo
- Institute of Oceanology, Chinese Academy of Sciences, Qingdao 266071, PR China
| | | | - Yu Xia Zou
- Institute of Oceanology, Chinese Academy of Sciences, Qingdao 266071, PR China
| | - Peng Xiao
- Graduate University of Chinese Academy of Sciences, Beijing 100049, PR China.,Institute of Oceanology, Chinese Academy of Sciences, Qingdao 266071, PR China
| | - Jie Li
- Ocean University of China, Qingdao 266003, PR China
| | - Jia Yin Yang
- Graduate University of Chinese Academy of Sciences, Beijing 100049, PR China.,Institute of Oceanology, Chinese Academy of Sciences, Qingdao 266071, PR China
| | - Xu Hong Ye
- Ocean University of China, Qingdao 266003, PR China
| | - Ka Yin Leung
- Department of Biological Sciences, Faculty of Science, National University of Singapore, 117543 Singapore
| | - Pei Jun Zhang
- Institute of Oceanology, Chinese Academy of Sciences, Qingdao 266071, PR China
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22
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Sakai T, Matsuyama T, Sano M, Iida T. Identification of novel putative virulence factors, adhesin AIDA and type VI secretion system, in atypical strains of fish pathogenic Edwardsiella tarda by genomic subtractive hybridization. Microbiol Immunol 2009; 53:131-9. [DOI: 10.1111/j.1348-0421.2009.00108.x] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
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23
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Abstract
Edwardsiellosis is one of the most important bacterial diseases in fish. Scientific work on this disease started more than forty years ago and numerous workers around the world are continually adding to the knowledge of the disease. In spite of this, not a single article that reviews the enormous scientific data thus generated is available in the English language. This article briefly discusses some of the recent research on edwardsiellosis, describing the pathogen's interaction with the host and environment, its pathogenesis and pathology as well as diagnostic, preventive and control measures.
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Affiliation(s)
- B R Mohanty
- Central Institute of Freshwater Aquaculture, Kausalyaganga, Bhubaneswar 751 002, India
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24
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Verjan N, Hirono I, Aoki T. Genetic loci of major antigenic protein genes of Edwardsiella tarda. Appl Environ Microbiol 2005; 71:5654-8. [PMID: 16151172 PMCID: PMC1214691 DOI: 10.1128/aem.71.9.5654-5658.2005] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Seven antigenic proteins of Edwardsiella tarda were identified by using a rabbit polyclonal antiserum. Four of these proteins also reacted with a Japanese flounder antiserum. The amino acid sequences had identity to lipoproteins, periplasmic proteins, and exported and secreted proteins with roles in transport of metabolites across the cell membrane, stress response, and motility. These genes and their products are useful for developing DNA or recombinant subunit vaccines to control edwardsiellosis.
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Affiliation(s)
- Noel Verjan
- Laboratory of Genome Science, Graduate School of Marine Science and Technology, Tokyo University of Marine Science and Technology, 4-5-7 Konan, Minato, Tokyo 108-8477, Japan
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25
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Tan YP, Zheng J, Tung SL, Rosenshine I, Leung KY. Role of type III secretion in Edwardsiella tarda virulence. Microbiology (Reading) 2005; 151:2301-2313. [PMID: 16000720 DOI: 10.1099/mic.0.28005-0] [Citation(s) in RCA: 121] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
Abstract
Edwardsiella tarda is a Gram-negative enteric bacterium affecting both animals and humans. Recently, a type III secretion system (TTSS) was found in Ed. tarda. Such systems are generally used by bacterial pathogens to deliver virulence factors into host cells to subvert normal cell functions. Genome-walking was performed from the eseB and esrB genes (homologues of Salmonella sseB and ssrB, respectively) identified in previous studies, to determine the sequences of the TTSS. Thirty-five ORFs were identified which encode the TTSS apparatus, chaperones, effectors and regulators. Mutants affected in genes representing each category were generated and found to have decreased survival and growth in fish phagocytes. LD50 values of the mutants were increased by at least 10-fold in comparison to those of the wild-type strain. The adherence and invasion rates of the esrA and esrB mutants were enhanced while those of the other mutants remained similar to the wild-type. The eseC and eseD mutants showed slight autoaggregation in Dulbecco's Modified Eagle Medium, whereas the rest of the mutants failed to autoaggregate. Regulation of the TTSS was found to involve the two-component regulatory system esrA–esrB. This study showed that the TTSS is important for Ed. tarda pathogenesis. An understanding of this system will provide greater insight into the virulence mechanisms of this bacterial pathogen.
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Affiliation(s)
- Y P Tan
- Department of Biological Sciences, Faculty of Science, National University of Singapore, Science Drive 4, Singapore 117543
| | - J Zheng
- Department of Biological Sciences, Faculty of Science, National University of Singapore, Science Drive 4, Singapore 117543
| | - S L Tung
- Department of Biological Sciences, Faculty of Science, National University of Singapore, Science Drive 4, Singapore 117543
| | - I Rosenshine
- Department of Molecular Genetics and Biotechnology, Faculty of Medicine, The Hebrew University, PO Box 12272, Jerusalem 91120, Israel
| | - K Y Leung
- Department of Biological Sciences, Faculty of Science, National University of Singapore, Science Drive 4, Singapore 117543
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26
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Savan R, Igarashi A, Matsuoka S, Sakai M. Sensitive and rapid detection of edwardsiellosis in fish by a loop-mediated isothermal amplification method. Appl Environ Microbiol 2004; 70:621-4. [PMID: 14711699 PMCID: PMC321279 DOI: 10.1128/aem.70.1.621-624.2004] [Citation(s) in RCA: 55] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Here we report a rapid and sensitive method (using loop-mediated isothermal amplification [LAMP]) for the diagnosis of edwardsiellosis, a fish disease caused by Edwardsiella tarda, in Japanese flounder. A set of four primers was designed, and conditions for the detection were optimized for the detection of E. tarda in 45 min at 65 degrees C. No amplification of the target hemolysin gene was detected in other related bacteria. When the LAMP primers were used, detection of edwardsiellosis in infected Japanese flounder kidney, and spleen and seawater cultures was possible. We have developed a rapid and sensitive diagnostic protocol for edwardsiellosis detection in fish. This is the first report of the application of LAMP for the diagnosis of a fish pathogen.
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Affiliation(s)
- Ram Savan
- United Graduate School of Agricultural Sciences, Kagoshima University, Kagoshima 890-0065, Japan
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27
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Walker G, Hertle R, Braun V. Activation of Serratia marcescens hemolysin through a conformational change. Infect Immun 2004; 72:611-4. [PMID: 14688146 PMCID: PMC343996 DOI: 10.1128/iai.72.1.611-614.2004] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
For Serratia marcescens, secreted hemolysin/cytotoxin is not only secreted but also activated by an outer membrane protein. Excluding posttranslational processing by mass spectrometry, the conformation of active and inactive ShlA derivatives strongly differed in electrophoretic mobilities, gel permeation chromatography, sensitivity to trypsin, circular dichroism, and intrinsic fluorescence. We concluded that ShlB interacts with ShlA during secretion and imposes a conformational change in ShlA to form the active hemolysin.
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Affiliation(s)
- Georg Walker
- Mikrobiologie/Membranphysiologie, Universität Tübingen, Tübingen, Germany
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28
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Sakai T, Kanai K, Osatomi K, Yoshikoshi K. Identification of a 19.3-kDa protein in MRHA-positive Edwardsiella tarda: putative fimbrial major subunit. FEMS Microbiol Lett 2003; 226:127-33. [PMID: 13129618 DOI: 10.1016/s0378-1097(03)00608-6] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The hemagglutinating properties of Edwardsiella tarda isolated from fish were investigated. Hemagglutination of E. tarda was not inhibited by D-mannose but was strongly inhibited by fetuin and N-acetylneuraminic acid. Extraction of hemagglutinating activity from bacterial cells was achieved using n-octyl-beta-D-thioglucoside (NOTG), and the NOTG extracts were fractionated by sucrose density gradient ultracentrifugation. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis analysis of the fractions revealed that a 19.3-kDa protein band appeared in the fractions exhibiting highest hemagglutinating activity. In an immunoblot analysis of NOTG extracts from 18 strains of E. tarda, the 19.3-kDa protein was detected only in the extracts possessing hemagglutinating activity. The predicted amino acid sequence of a 534-bp gene encoding the 19.3-kDa protein was identical to fimbrial subunit (FimA) of E. tarda by FASTA homology search. These findings suggest that fimbriae are implicated in the hemagglutination of E. tarda.
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Affiliation(s)
- Takamitsu Sakai
- Graduate School of Science and Technology, Nagasaki University, Bunkyo Machi 1-14, 852-8521, Nagasaki, Japan
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29
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Mathew JA, Tan YP, Srinivasa Rao PS, Lim TM, Leung KY. Edwardsiella tarda mutants defective in siderophore production, motility, serum resistance and catalase activity. MICROBIOLOGY (READING, ENGLAND) 2001; 147:449-457. [PMID: 11158362 DOI: 10.1099/00221287-147-2-449] [Citation(s) in RCA: 52] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Edwardsiella tarda is a Gram-negative bacterium that causes a systemic infection, edwardsiellosis, in fish. The virulence factors of this pathogen and its genetic determinants have not been systematically examined. In this study, TnphoA transposon mutagenesis was used to construct a library of 440 alkaline phosphatase (PhoA(+)) fusion mutants from a total of 400000 transconjugants derived from Ed. tarda PPD130/91. This library included genes for secreted and membrane-associated proteins normally involved in virulence. The library was screened for four virulence factors: siderophore production, motility, serum resistance and catalase production. Eight mutants deficient in one or more of these phenotypes were grouped into four classes. They were further characterized for their stimulation of reactive oxygen intermediate production by fish phagocytes, for their adhesion to and internalization into EPC (epithelioma papillosum of carp) cells, and for attenuation of virulence in blue gourami. Mutants 2A and 34 were highly attenuated in fish, with LD(50) values about 10 times higher than for the wild-type. These strains had mutations in the genes encoding arylsulfate sulfotransferase (mutant 2A) and a catalase precursor protein (mutant 34). One hyperinvasive/adhesive mutant and four pst mutants that were pleiotropic and slightly attenuated in fish were also isolated.
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Affiliation(s)
- J A Mathew
- Department of Biological Sciences, Faculty of Science, National University of Singapore, 10 Kent Ridge Crescent, Singapore1192601
| | - Y P Tan
- Department of Biological Sciences, Faculty of Science, National University of Singapore, 10 Kent Ridge Crescent, Singapore1192601
| | - P S Srinivasa Rao
- Department of Biological Sciences, Faculty of Science, National University of Singapore, 10 Kent Ridge Crescent, Singapore1192601
| | - T M Lim
- Department of Biological Sciences, Faculty of Science, National University of Singapore, 10 Kent Ridge Crescent, Singapore1192601
| | - K Y Leung
- Department of Biological Sciences, Faculty of Science, National University of Singapore, 10 Kent Ridge Crescent, Singapore1192601
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30
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Yang FL, Braun V. ShlB mutants of Serratia marcescens allow uncoupling of activation and secretion of the ShlA hemolysin. Int J Med Microbiol 2000; 290:529-38. [PMID: 11100827 DOI: 10.1016/s1438-4221(00)80018-1] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
The ShlB protein in the outer membrane of Serratia marcescens secretes hemolytic ShlA protein into the culture medium. In the absence of ShlB, nonhemolytic ShlA remains in the periplasm. ShlB mutants were isolated in which secretion was uncoupled from activation. Mutants with a tetrapeptide insertion after residues 136 or 224 of mature ShlB and a mutant with an insertion after residue 154 and a deletion secreted inactive ShlA. In vitro, secreted nonhemolytic ShlA was converted into hemolytic ShlA by isolated wild-type ShlB and by complementation with an N-terminal ShlA fragment of 255 residues (ShlA-255). The isolation of secretion-competent, but activation-negative mutants indicates that secretion alone is not sufficient for activation of ShlA. Rather, ShlB is required for activation and secretion, and the mutants define sites in ShlB which are involved in activation. According to a predicted transmembrane model of ShlB, the mutations that retain secretion competence but abolish activation competence are located in the most prominent surface loop and the following transmembrane loop. In one tetrapeptide insertion mutant, ShlB-332, most of the ShlA remained cell-associated in an inactive form and low amounts (6%) were hemolytic. Secreted inactive ShlA(o) was completely degraded by trypsin, in contrast to hemolytic ShlA, which was cleaved into two fragments of 60 and 100 kDa. This result indicates that the conformational change from a highly trypsin-sensitive to a highly trypsin-resistant protein with only a single cleavage site in a polypeptide of 1,578 residues occurs upon activation of ShlA and not during secretion.
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Affiliation(s)
- F L Yang
- Mikrobiologie/Membranphsiologie, Universität Tübingen, Germany
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31
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Granum PE, O'Sullivan K, Lund T. The sequence of the non-haemolytic enterotoxin operon from Bacillus cereus. FEMS Microbiol Lett 1999; 177:225-9. [PMID: 10474188 DOI: 10.1111/j.1574-6968.1999.tb13736.x] [Citation(s) in RCA: 151] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022] Open
Abstract
The non-haemolytic enterotoxin from Bacillus cereus has been sequenced. It is composed of three components, non-haemolytic enterotoxin A, B and C of 41.0, 39.8 and 36.5 kDa, respectively. Transcription of the operon seems to be positively regulated by plcR, a gene that also regulates phospholipase C expression. There is substantial similarity between the three proteins of non-haemolytic enterotoxin and between the non-haemolytic enterotoxin and haemolytic enterotoxin proteins.
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Affiliation(s)
- P E Granum
- Department of Pharmacology, Microbiology and Food Hygiene, Norwegian School of Veterinary Science, Oslo, Norway.
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32
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Strauss EJ, Ghori N, Falkow S. An Edwardsiella tarda strain containing a mutation in a gene with homology to shlB and hpmB is defective for entry into epithelial cells in culture. Infect Immun 1997; 65:3924-32. [PMID: 9284172 PMCID: PMC175559 DOI: 10.1128/iai.65.9.3924-3932.1997] [Citation(s) in RCA: 55] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
Edwardsiella tarda is an enteric pathogen that causes diarrhea, wound infections, and death due to septicemia. This species is capable of invading human epithelial cell lines, and we have now been able to follow the entry and replication of E. tarda within tissue culture host cells. E. tarda escapes from the endocytic vacuole within minutes of entry and then replicates within the cytoplasm. Unlike other well-studied bacteria that replicate and reside in the cytoplasm, we never observed this organism moving directly from cell to cell; instead the bacteria spread by lysing the plasma membrane after several rounds of replication. Efforts to study the interactions of E. tarda with tissue culture cells are complicated by the presence of a potent cytotoxin that the bacterium produces. Using transposon mutagenesis, we isolated a noncytotoxic strain of E. tarda. This mutant is also defective for hemolysin production. The dual phenotype of this strain is consistent with the hypothesis that cytotoxicity is due to the previously characterized E. tarda hemolysin activity. The nonhemolytic strain is also unable to enter HEp-2 cells. The disrupted gene has sequence similarity to members of a family of genes required for transport and activation of the hemolysin genes, shlA and hpmA. A cosmid bearing 40 kb of E. tarda DNA, including wild-type copies of the E. tarda homologs of the transporter-activator protein and the hemolysin itself, confers hemolytic, cytotoxic, and invasive abilities upon normally nonhemolytic, noncytotoxic, and noninvasive strains of Escherichia coli. Sequence data indicate that the genes required for hemolytic activity are linked to a transposable element, suggesting that they arose in the E. tarda genome by horizontal transfer.
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Affiliation(s)
- E J Strauss
- Department of Microbiology and Immunology, Stanford University School of Medicine, California 94305-5402, USA.
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