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Wang Z, Chen R, Xia F, Jiang M, Zhu D, Zhang Y, Dai J, Zhuge X. ProQ binding to small RNA RyfA promotes virulence and biofilm formation in avian pathogenic Escherichia coli. Vet Res 2023; 54:109. [PMID: 37993891 PMCID: PMC10664665 DOI: 10.1186/s13567-023-01241-2] [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: 05/26/2023] [Accepted: 10/10/2023] [Indexed: 11/24/2023] Open
Abstract
Avian pathogenic Escherichia coli (APEC) is a notable subpathotype of the nonhuman extraintestinal pathogenic E. coli (ExPEC). Recognized as an extraintestinal foodborne pathogen, the zoonotic potential of APEC/ExPEC allows for cross-host transmission via APEC-contaminated poultry meat and eggs. ProQ, an RNA binding protein, is evolutionarily conserved in E. coli. However, its regulatory roles in the biofilm formation and virulence of APEC/ExPEC have not been explored. In this study, proQ deletion in the APEC strain FY26 significantly compromised its biofilm-forming ability. Furthermore, animal tests and cellular infection experiments showed that ProQ depletion significantly attenuated APEC virulence, thereby diminishing its capacity for bloodstream infection and effective adherence to and persistence within host cells. Transcriptome analysis revealed a decrease in the transcription level of the small RNA (sRNA) RyfA in the mutant FY26ΔproQ, suggesting a direct interaction between the sRNA RyfA and ProQ. This interaction might indicate that sRNA RyfA is a novel ProQ-associated sRNA. Moreover, the direct binding of ProQ to the sRNA RyfA was crucial for APEC biofilm formation, pathogenicity, adhesion, and intracellular survival. In conclusion, our findings provide detailed insight into the interaction between ProQ and sRNA RyfA and deepen our understanding of the regulatory elements that dictate APEC virulence and biofilm development. Such insights are instrumental in developing strategies to counteract APEC colonization within hosts and impede APEC biofilm establishment on food surfaces.
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Affiliation(s)
- Zhongxing Wang
- Department of Nutrition and Food Hygiene, School of Public Health, Nantong University, Nantong, 226019, Jiangsu, China
- MOE Joint International Research Laboratory of Animal Health and Food Safety, College of Veterinary Medicine, Nanjing Agricultural University, Nanjing, 210095, China
| | - Rui Chen
- MOE Joint International Research Laboratory of Animal Health and Food Safety, College of Veterinary Medicine, Nanjing Agricultural University, Nanjing, 210095, China
| | - Fufang Xia
- Department of Nutrition and Food Hygiene, School of Public Health, Nantong University, Nantong, 226019, Jiangsu, China
- MOE Joint International Research Laboratory of Animal Health and Food Safety, College of Veterinary Medicine, Nanjing Agricultural University, Nanjing, 210095, China
| | - Min Jiang
- MOE Joint International Research Laboratory of Animal Health and Food Safety, College of Veterinary Medicine, Nanjing Agricultural University, Nanjing, 210095, China
| | - Dongyu Zhu
- Department of Nutrition and Food Hygiene, School of Public Health, Nantong University, Nantong, 226019, Jiangsu, China
- MOE Joint International Research Laboratory of Animal Health and Food Safety, College of Veterinary Medicine, Nanjing Agricultural University, Nanjing, 210095, China
| | - Yuting Zhang
- Department of Nutrition and Food Hygiene, School of Public Health, Nantong University, Nantong, 226019, Jiangsu, China
| | - Jianjun Dai
- MOE Joint International Research Laboratory of Animal Health and Food Safety, College of Veterinary Medicine, Nanjing Agricultural University, Nanjing, 210095, China.
| | - Xiangkai Zhuge
- Department of Nutrition and Food Hygiene, School of Public Health, Nantong University, Nantong, 226019, Jiangsu, China.
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Fu D, Shao Y, Li J, Wu J, Wu X, Song X, Tu J, Qi K. LuxR family transcriptional repressor YjjQ modulates the biofilm formation and motility of avian pathogenic Escherichia coli. Res Vet Sci 2022; 152:10-19. [PMID: 35901637 DOI: 10.1016/j.rvsc.2022.07.011] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2022] [Revised: 06/09/2022] [Accepted: 07/17/2022] [Indexed: 11/27/2022]
Abstract
Avian pathogenic Escherichia coli (APEC) can cause the acute and sudden death of poultry, which leads to serious economic losses in the poultry industry. Biofilm formation contributes to the persistence of bacterial infection, drug resistance, and resistance to diverse environmental stress. Many transcription regulators in APEC play an essential role in the formation of biofilm and could provide further insights into APEC pathogenesis. YjjQ has an important role in the pathogenicity of bacteria by regulating the expression of virulence factors, such as flagellar and iron uptake. However, YjjQ regulates other virulence factors, and their role in the overall regulatory network is unclear. Here, we further evaluate the function of YjjQ on APEC biofilm formation and motility. In this study, we successfully constructed mutant (AE27∆yjjQ) and complement (AE27ΔyjjQ-comp) strains of the wild-type strain AE27. Inactivation of the yjjQ gene significantly increased biofilm-forming ability in APEC. Scanning electron microscopy showed that the biofilm formation of the AE27 was single-layered and flat, whereas that of the AE27∆yjjQ had a porous three-dimensional structure. Moreover, the deletion of the yjjQ gene inhibited the motility of APEC. RNA-sequencing was used to further investigate the regulatory mechanism of YjjQ in APEC. The results indicate that YjjQ regulates biofilm formation and flagellar genes in AE27∆yjjQ. RT-qPCR shows that YjjQ affects the transcriptional levels of genes, including flagella genes (flhD, flhC and flgE), and biofilm formation genes (pstA, uhpC, nikD, and ygcS). These results confirm that the transcription regulator YjjQ is involved in APEC biofilm formation and motility, and provide new evidence for the prevention and control of APEC.
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Affiliation(s)
- Dandan Fu
- Anhui Province Key Laboratory of Veterinary Pathobiology and Disease Control, College of Animal Science and Technology, Anhui Agricultural University, Hefei, Anhui 230036, PR China
| | - Ying Shao
- Anhui Province Key Laboratory of Veterinary Pathobiology and Disease Control, College of Animal Science and Technology, Anhui Agricultural University, Hefei, Anhui 230036, PR China
| | - Jiaxuan Li
- Anhui Province Key Laboratory of Veterinary Pathobiology and Disease Control, College of Animal Science and Technology, Anhui Agricultural University, Hefei, Anhui 230036, PR China
| | - Jianmei Wu
- Anhui Province Key Laboratory of Veterinary Pathobiology and Disease Control, College of Animal Science and Technology, Anhui Agricultural University, Hefei, Anhui 230036, PR China
| | - Xiaoyan Wu
- Anhui Province Key Laboratory of Veterinary Pathobiology and Disease Control, College of Animal Science and Technology, Anhui Agricultural University, Hefei, Anhui 230036, PR China
| | - Xiangjun Song
- Anhui Province Key Laboratory of Veterinary Pathobiology and Disease Control, College of Animal Science and Technology, Anhui Agricultural University, Hefei, Anhui 230036, PR China
| | - Jian Tu
- Anhui Province Key Laboratory of Veterinary Pathobiology and Disease Control, College of Animal Science and Technology, Anhui Agricultural University, Hefei, Anhui 230036, PR China
| | - Kezong Qi
- Anhui Province Key Laboratory of Veterinary Pathobiology and Disease Control, College of Animal Science and Technology, Anhui Agricultural University, Hefei, Anhui 230036, PR China.
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Tu J, Fu D, Gu Y, Shao Y, Song X, Xue M, Qi K. Transcription Regulator YgeK Affects the Virulence of Avian Pathogenic Escherichia coli. Animals (Basel) 2021; 11:ani11113018. [PMID: 34827751 PMCID: PMC8614350 DOI: 10.3390/ani11113018] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2021] [Revised: 10/14/2021] [Accepted: 10/15/2021] [Indexed: 11/23/2022] Open
Abstract
Simple Summary Avian pathogenic Escherichia coli (APEC) is the responsible pathogen for colibacillosis in poultry. Transcriptional regulator YgeK was a transcriptional regulator locating at E. coli type three secretion system 2 (ETT2) in APEC. However, the role of YgeK in APEC has not been reported. In this study, we found that the inactivation of YgeK in APEC decreased the flagellar formation ability, bacterial motility ability, serum sensitivity, adhesion ability, and virulence. Results suggested that the transcriptional regulator YgeK plays a crucial role in APEC virulence. Abstract Avian pathogenic Escherichia coli (APEC) is the responsible pathogen for colibacillosis in poultry, and is a potential gene source for human extraintestinal pathogenic Escherichia coli. Escherichia coli type III secretion system 2 (ETT2) is widely distributed in human and animal ExPEC isolates, and is crucial for the virulence of ExPEC. Transcriptional regulator YgeK, located in the ETT2 gene cluster, was identified as an important regulator of gene expression in enterohemorrhagic E. coli (EHEC). However, the role of YgeK in APEC has not been reported. In this study, we performed amino acid alignment analysis of YgeK among different E. coli strains and generated ygeK mutant strain AE81ΔygeK from clinical APEC strain AE81. Flagellar formation, bacterial motility, serum sensitivity, adhesion, and virulence were all significantly reduced following the inactivation of YgeK in APEC. Then, we performed transcriptome sequencing to analyze the functional pathways involved in the biological processes. Results suggested that ETT2 transcriptional regulator YgeK plays a crucial role in APEC virulence. These findings thus contribute to our understanding of the function of the ETT2 cluster, and clarify the pathogenic mechanism of APEC.
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Affiliation(s)
- Jian Tu
- Anhui Province Key Laboratory of Veterinary Pathobiology and Disease Control, College of Animal Science and Technology, Anhui Agricultural University, Hefei 230036, China; (J.T.); (D.F.); (Y.G.); (Y.S.); (X.S.)
| | - Dandan Fu
- Anhui Province Key Laboratory of Veterinary Pathobiology and Disease Control, College of Animal Science and Technology, Anhui Agricultural University, Hefei 230036, China; (J.T.); (D.F.); (Y.G.); (Y.S.); (X.S.)
| | - Yi Gu
- Anhui Province Key Laboratory of Veterinary Pathobiology and Disease Control, College of Animal Science and Technology, Anhui Agricultural University, Hefei 230036, China; (J.T.); (D.F.); (Y.G.); (Y.S.); (X.S.)
| | - Ying Shao
- Anhui Province Key Laboratory of Veterinary Pathobiology and Disease Control, College of Animal Science and Technology, Anhui Agricultural University, Hefei 230036, China; (J.T.); (D.F.); (Y.G.); (Y.S.); (X.S.)
| | - Xiangjun Song
- Anhui Province Key Laboratory of Veterinary Pathobiology and Disease Control, College of Animal Science and Technology, Anhui Agricultural University, Hefei 230036, China; (J.T.); (D.F.); (Y.G.); (Y.S.); (X.S.)
| | - Mei Xue
- Anhui Province Key Laboratory of Veterinary Pathobiology and Disease Control, College of Animal Science and Technology, Anhui Agricultural University, Hefei 230036, China; (J.T.); (D.F.); (Y.G.); (Y.S.); (X.S.)
- College of Animal Science and Food Engineering, Jinling Institute Technology, Nanjing 211169, China
- Correspondence: (M.X.); (K.Q.); Tel.: +86-551-6578-5310 (K.Q.)
| | - Kezong Qi
- Anhui Province Key Laboratory of Veterinary Pathobiology and Disease Control, College of Animal Science and Technology, Anhui Agricultural University, Hefei 230036, China; (J.T.); (D.F.); (Y.G.); (Y.S.); (X.S.)
- Correspondence: (M.X.); (K.Q.); Tel.: +86-551-6578-5310 (K.Q.)
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Xue M, Xiao Y, Fu D, Raheem MA, Shao Y, Song X, Tu J, Xue T, Qi K. Transcriptional Regulator YqeI, Locating at ETT2 Locus, Affects the Pathogenicity of Avian Pathogenic Escherichia coli. Animals (Basel) 2020; 10:ani10091658. [PMID: 32947771 PMCID: PMC7552227 DOI: 10.3390/ani10091658] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2020] [Revised: 09/02/2020] [Accepted: 09/08/2020] [Indexed: 11/16/2022] Open
Abstract
Simple Summary Avian pathogenic Escherichia coli (APEC) is the causative agent of colibacillosis, threatening the development of the poultry industry. The study on APEC’s pathogenic mechanism is of great importance. In this study, we investigated the role of YqeI, a transcriptional regulator locating at E. coli type three secretion system 2 in APEC. The transcriptional results revealed that YqeI affected the expression of the genes involving in bacterial localization, locomotion and biological adhesion. A series experiments also demonstrated that the absence of yqeI decreased the bacterial flagella formation ability, motility ability, antiserum bactericidal ability, adhesion ability and colonization ability. Our data suggested that the transcriptional regulator YqeI indeed participates in the pathogenicity of APEC. Abstract Avian pathogenic Escherichia coli (APEC) is the leading cause of systemic infections in poultry worldwide and has a hidden threat to public health. Escherichia coli type three secretion system 2 (ETT2), similar to the Salmonella pathogenicity island SPI1, is widely distributed in APEC and associated with virulence. The function of YqeI, which is one of the hypothetical transcriptional regulators locating at the ETT2 locus of APEC, is unknown. In this study, we successfully obtained the mutant strain AE81ΔyqeI of the wild type strain AE81 and performed the transcriptional profiling assays. Additionally, the transcriptional sequencing results revealed that YqeI influenced localization, locomotion and biological adhesion and so on. The transmission electron microscope observation showed that the wild type strain AE81 possessed long curved flagella, whereas the mutant strain AE81ΔyqeI hardly had any. The strain AE81ΔyqeI exhibited lower motility than AE81 after culturing the dilute bacterial suspension on a semisolid medium. It was also found that the survival ability of AE81ΔyqeI weakened significantly when AE81ΔyqeI was cultured with 0%, 10%, 20%, 30%, 40% and 50% SPF serum in PBS, and AE81ΔyqeI had decreased adherence to DF-1 cells compared with AE81 in the bacterial adhesion assay. The bacterial colonization assay indicated that the virulence of AE81ΔyqeI was reduced in the heart, liver, spleen, and lung. These results confirmed that the transcription regulator YqeI is involved in APEC’s pathogenicity, and this study provides clues for future research.
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Zhuge X, Sun Y, Jiang M, Wang J, Tang F, Xue F, Ren J, Zhu W, Dai J. Acetate metabolic requirement of avian pathogenic Escherichia coli promotes its intracellular proliferation within macrophage. Vet Res 2019; 50:31. [PMID: 31046828 PMCID: PMC6498577 DOI: 10.1186/s13567-019-0650-2] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2018] [Accepted: 02/14/2019] [Indexed: 12/13/2022] Open
Abstract
Avian pathogenic Escherichia coli (APEC) is a facultative intracellular pathogen, and intracellular persistence in macrophages is essential for APEC extraintestinal dissemination. Until now, there is still no systematic interpretation of APEC intracellular proliferation. Intracellular survival factors, especially involved in pathometabolism, need to be further revealed. Acetate plays critical roles in supporting energy homeostasis and acts as a metabolic signal in the inflammatory response of eukaryotes. In this study, we identified that APEC acs-yjcH-actP operon, encoding acetate assimilation system, presented the host-induced transcription during its proliferation in macrophages. Our result showed that this acetate assimilation system acted as a novel intracellular survival factor to promote APEC replication within macrophages. Furthermore, deletion of acs-yjcH-actP operon in APEC decreased its cytotoxic level to macrophages. qRT-PCR results showed that the production of pro-inflammatory cytokines (IL-1β, IL-6, IL-8, IL-12β, and TNF-α) and iNOS in FY26∆acs-yjcH-actP infected macrophages were obviously down-regulated compared to that in wild-type FY26 infected cells. Deletion of actP/yjcH/acs genes attenuated APEC virulence and colonization capability in avian lungs in vivo for colibacillosis infection models. And acetate assimilation system acted as a virulence factor and conferred a fitness advantage during APEC early colonization. Taken together, our research unravelled the metabolic requirement of APEC intracellular survival/replication within macrophages, and acetate metabolic requirement acted as an important strategy of APEC pathometabolism. The intracellular acetate consumption during facultative intracellular bacteria replication within macrophages promoted immunomodulatory disorders, resulting in excessively pro-inflammatory responses of host macrophages.
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Affiliation(s)
- Xiangkai Zhuge
- MOE Joint International Research Laboratory of Animal Health and Food Safety, College of Veterinary Medicine, Nanjing Agricultural University, Nanjing, China.,Key Lab of Animal Bacteriology, Ministry of Agriculture, Nanjing Agricultural University, Nanjing, 210095, China.,China Pharmaceutical University, Nanjing, 211198, China.,Center for Post-doctoral Studies of Veterinary Medicine, College of Veterinary Medicine, Nanjing Agricultural University, Nanjing, 210095, China.,Center for Post-doctoral Studies of Animal Husbandry, College of Animal Science & Technology, Nanjing Agricultural University, Nanjing, 210095, China
| | - Yu Sun
- MOE Joint International Research Laboratory of Animal Health and Food Safety, College of Veterinary Medicine, Nanjing Agricultural University, Nanjing, China.,Key Lab of Animal Bacteriology, Ministry of Agriculture, Nanjing Agricultural University, Nanjing, 210095, China
| | - Min Jiang
- MOE Joint International Research Laboratory of Animal Health and Food Safety, College of Veterinary Medicine, Nanjing Agricultural University, Nanjing, China.,Key Lab of Animal Bacteriology, Ministry of Agriculture, Nanjing Agricultural University, Nanjing, 210095, China
| | - Juanfang Wang
- MOE Joint International Research Laboratory of Animal Health and Food Safety, College of Veterinary Medicine, Nanjing Agricultural University, Nanjing, China.,Key Lab of Animal Bacteriology, Ministry of Agriculture, Nanjing Agricultural University, Nanjing, 210095, China
| | - Fang Tang
- MOE Joint International Research Laboratory of Animal Health and Food Safety, College of Veterinary Medicine, Nanjing Agricultural University, Nanjing, China.,Key Lab of Animal Bacteriology, Ministry of Agriculture, Nanjing Agricultural University, Nanjing, 210095, China
| | - Feng Xue
- MOE Joint International Research Laboratory of Animal Health and Food Safety, College of Veterinary Medicine, Nanjing Agricultural University, Nanjing, China.,Key Lab of Animal Bacteriology, Ministry of Agriculture, Nanjing Agricultural University, Nanjing, 210095, China
| | - Jianluan Ren
- MOE Joint International Research Laboratory of Animal Health and Food Safety, College of Veterinary Medicine, Nanjing Agricultural University, Nanjing, China.,Key Lab of Animal Bacteriology, Ministry of Agriculture, Nanjing Agricultural University, Nanjing, 210095, China
| | - Weiyun Zhu
- Center for Post-doctoral Studies of Animal Husbandry, College of Animal Science & Technology, Nanjing Agricultural University, Nanjing, 210095, China
| | - Jianjun Dai
- MOE Joint International Research Laboratory of Animal Health and Food Safety, College of Veterinary Medicine, Nanjing Agricultural University, Nanjing, China. .,Key Lab of Animal Bacteriology, Ministry of Agriculture, Nanjing Agricultural University, Nanjing, 210095, China. .,China Pharmaceutical University, Nanjing, 211198, China. .,Center for Post-doctoral Studies of Veterinary Medicine, College of Veterinary Medicine, Nanjing Agricultural University, Nanjing, 210095, China.
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Host immune responses and vaccination against avian pathogenic Escherichia coli - RETRACTED. WORLD POULTRY SCI J 2017. [DOI: 10.1017/s0043933916000866] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
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Zhou Y, Zhou J, Wang D, Gao Q, Mu X, Gao S, Liu X. Evaluation of ompA and pgtE genes in determining pathogenicity in Salmonella enterica serovar Enteritidis. Vet J 2016; 218:19-26. [PMID: 27938704 DOI: 10.1016/j.tvjl.2016.10.009] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2016] [Revised: 10/27/2016] [Accepted: 10/29/2016] [Indexed: 02/02/2023]
Abstract
Salmonella enterica subsp. enterica serovar Enteritidis (S. Enteritidis) is a major causative agent of gastroenteritis in humans. This important food-borne pathogen also colonises the intestinal tracts of poultry and can spread systemically, especially in chickens. To identify the S. Enteritidis virulence genes involved in infection and colonisation of chickens, chromosomal deletion mutants of the ompA and pgtE genes, which encode essential components of omptins, were constructed. There were no significant differences between the wild-type and ompA and pgtE mutants in a series of in vitro assays, including an intracellular survival assay, survival in specific-pathogen-free (SPF) chicken serum, and in vitro competition assays. In contrast, in vivo competition assays revealed that ompA and pgtE mutants underwent attenuated growth in liver, cardiac blood, spleen, lung, and kidney compared to a wild-type strain (CVCC3378). When tested in SPF chickens, ompA or pgtE gene inactivation substantially reduced organ colonisation and delayed systemic infection compared with the wild-type strain. Colonisation was restored in S. Enteritidis mutants by reintroduction of the whole ompA or pgtE gene with the native promoters. The results of this study demonstrate that ompA and pgtE play an important role in the pathogenesis of S. Enteritidis and its ability to infect chickens.
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Affiliation(s)
- Y Zhou
- Jiangsu Co-Innovation Centre for Prevention and Control of Important Animal Infectious Diseases and Zoonoses, College of Veterinary Medicine, Yangzhou University, Yangzhou, Jiangsu 225009, China
| | - J Zhou
- Jiangsu Co-Innovation Centre for Prevention and Control of Important Animal Infectious Diseases and Zoonoses, College of Veterinary Medicine, Yangzhou University, Yangzhou, Jiangsu 225009, China
| | - D Wang
- Jiangsu Co-Innovation Centre for Prevention and Control of Important Animal Infectious Diseases and Zoonoses, College of Veterinary Medicine, Yangzhou University, Yangzhou, Jiangsu 225009, China
| | - Q Gao
- Jiangsu Co-Innovation Centre for Prevention and Control of Important Animal Infectious Diseases and Zoonoses, College of Veterinary Medicine, Yangzhou University, Yangzhou, Jiangsu 225009, China
| | - X Mu
- Jiangsu Co-Innovation Centre for Prevention and Control of Important Animal Infectious Diseases and Zoonoses, College of Veterinary Medicine, Yangzhou University, Yangzhou, Jiangsu 225009, China
| | - S Gao
- Jiangsu Co-Innovation Centre for Prevention and Control of Important Animal Infectious Diseases and Zoonoses, College of Veterinary Medicine, Yangzhou University, Yangzhou, Jiangsu 225009, China.
| | - X Liu
- Jiangsu Co-Innovation Centre for Prevention and Control of Important Animal Infectious Diseases and Zoonoses, College of Veterinary Medicine, Yangzhou University, Yangzhou, Jiangsu 225009, China
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Abstract
Avian pathogenic Escherichia coli (APEC) strains cause severe respiratory and systemic diseases, threatening food security and avian welfare worldwide. Intensification of poultry production and the quick expansion of free-range production systems will increase the incidence of colibacillosis through greater exposure of birds to pathogens and stress. Therapy is mainly based on antibiotherapy and current vaccines have poor efficacy. Serotyping remains the most frequently used diagnostic method, only allowing the identification of a limited number of APEC strains. Several studies have demonstrated that the most common virulence factors studied in APEC are all rarely present in the same isolate, showing that APEC strains constitute a heterogeneous group. Different isolates may harbor different associations of virulence factors, each one able to induce colibacillosis. Despite its economical relevance, pathogenesis of colibacillosis is poorly understood. Our knowledge on the host response to APEC is based on very descriptive studies, mostly restricted to bacteriological and histopathological analysis of infected organs such as lungs. Furthermore, only a small number of APEC isolates have been used in experimental studies. In the present review, we discuss current knowledge on APEC diversity and virulence, including host response to infection and the associated inflammatory response with a focus on pulmonary colibacillosis.
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Affiliation(s)
- Rodrigo Guabiraba
- INRA, UMR1282 Infectiologie et Santé Publique, 37380 Nouzilly, France Université François Rabelais de Tours, UMR1282 Infectiologie et Santé Publique, 37000 Tours, France
| | - Catherine Schouler
- INRA, UMR1282 Infectiologie et Santé Publique, 37380 Nouzilly, France Université François Rabelais de Tours, UMR1282 Infectiologie et Santé Publique, 37000 Tours, France
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ArcA Controls Metabolism, Chemotaxis, and Motility Contributing to the Pathogenicity of Avian Pathogenic Escherichia coli. Infect Immun 2015; 83:3545-54. [PMID: 26099584 DOI: 10.1128/iai.00312-15] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2015] [Accepted: 06/17/2015] [Indexed: 11/20/2022] Open
Abstract
Avian pathogenic Escherichia coli (APEC) strains cause one of the three most significant infectious diseases in the poultry industry and are also potential food-borne pathogens threating human health. In this study, we showed that ArcA (aerobic respiratory control), a global regulator important for E. coli's adaptation from anaerobic to aerobic conditions and control of that bacterium's enzymatic defenses against reactive oxygen species (ROS), is involved in the virulence of APEC. Deletion of arcA significantly attenuates the virulence of APEC in the duck model. Transcriptome sequencing (RNA-Seq) analyses comparing the APEC wild type and the arcA mutant indicate that ArcA regulates the expression of 129 genes, including genes involved in citrate transport and metabolism, flagellum synthesis, and chemotaxis. Further investigations revealed that citCEFXG contributed to APEC's microaerobic growth at the lag and log phases when cultured in duck serum and that ArcA played a dual role in the control of citrate metabolism and transportation. In addition, deletion of flagellar genes motA and motB and chemotaxis gene cheA significantly attenuated the virulence of APEC, and ArcA was shown to directly regulate the expression of motA, motB, and cheA. The combined results indicate that ArcA controls metabolism, chemotaxis, and motility contributing to the pathogenicity of APEC.
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YjjQ Represses Transcription of flhDC and Additional Loci in Escherichia coli. J Bacteriol 2015; 197:2713-20. [PMID: 26078445 DOI: 10.1128/jb.00263-15] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2015] [Accepted: 06/04/2015] [Indexed: 11/20/2022] Open
Abstract
UNLABELLED The presumptive transcriptional regulator YjjQ has been identified as being virulence associated in avian pathogenic Escherichia coli (APEC). In this work, we characterize YjjQ as transcriptional repressor of the flhDC operon, encoding the master regulator of flagellar synthesis, and of additional loci. The latter include gfc (capsule 4 synthesis), ompC (outer membrane porin C), yfiRNB (regulated c-di-GMP synthesis), and loci of poorly defined function (ybhL and ymiA-yciX). We identify the YjjQ DNA-binding sites at the flhDC and gfc promoters and characterize a DNA-binding sequence motif present at all promoters found to be repressed by YjjQ. At the flhDC promoter, the YjjQ DNA-binding site overlaps the RcsA-RcsB DNA-binding site. RcsA-RcsB likewise represses the flhDC promoter, but the repression by YjjQ and that by RcsA-RcsB are independent of each other. These data suggest that YjjQ is an additional regulator involved in the complex control of flhDC at the level of transcription initiation. Furthermore, we show that YjjQ represses motility of the E. coli K-12 laboratory strain and of uropathogenic E. coli (UPEC) strains CFT073 and 536. Regulation of flhDC, yfiRNB, and additional loci by YjjQ may be features relevant for pathogenicity. IMPORTANCE Escherichia coli is a commensal and pathogenic bacterium causing intra- and extraintestinal infections in humans and farm animals. The pathogenicity of E. coli strains is determined by their particular genome content, which includes essential and associated virulence factors that control the cellular physiology in the host environment. However, the gene pools of commensal and pathogenic E. coli are not clearly differentiated, and the function of virulence-associated loci needs to be characterized. In this study, we characterize the function of yjjQ, encoding a transcription regulator that was identified as being virulence associated in avian pathogenic E. coli (APEC). We characterize YjjQ as transcriptional repressor of flagellar motility and of additional loci related to pathogenicity.
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Wang X, Cao C, Huan H, Zhang L, Mu X, Gao Q, Dong X, Gao S, Liu X. Isolation, identification, and pathogenicity of O142 avian pathogenic Escherichia coli causing black proventriculus and septicemia in broiler breeders. INFECTION GENETICS AND EVOLUTION 2015; 32:23-9. [PMID: 25709068 DOI: 10.1016/j.meegid.2015.02.013] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/05/2014] [Revised: 02/11/2015] [Accepted: 02/15/2015] [Indexed: 10/24/2022]
Abstract
Avian colibacillosis, characterized by black proventriculus and caused by avian pathogenic Escherichia coli (APEC) with an uncommon O142 serogroup, was diagnosed in young broiler breeders. Colonization and persistence assays performed in 7-day-old broilers showed that the bacterial load of the APEC 4d/9-1 O142 proventricular isolate in the lung was about 10-fold higher than that of the APEC 4d/9-1 O142 heart blood isolate (P<0.01), and about 100-fold higher in the heart blood, livers, spleens, kidneys, and proventriculi of inoculated broilers (P<0.001). When 32 common virulence genes of APEC were tested, the two isolates had nearly identical profiles, except that only the APEC 4d/9-1 O142 proventricular isolate carried the feoB gene. Furthermore, 100% mortality was observed in both 1-day-old Arbor Acres (AA) broilers and 1-day-old specific-pathogen-free (SPF) chickens inoculated with 10(6) colony-forming units of the APEC 4d/9-1 O142 proventricular isolate. However, black proventriculus was only observed in the dead AA broilers, consistent with the clinical occurrence of the disease. This implies that the black proventriculi seen in the dead birds, caused by the APEC 4d/9-1 O142 proventricular isolate, was breed-specific. Both the APEC 4d/9-1 O142 proventricular and heart blood isolates belong to phylogroup B2. However, the former was assigned to ST131 and the latter to ST2704 with multilocus sequence typing, demonstrating the genetic heterogeneity of these two bacterial isolates, although they were derived from the same dead broiler. These results suggest that the O142 APEC isolate was the main pathogenic agent for black proventriculi in 7-day-old broiler breeders.
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Affiliation(s)
- Xiaobo Wang
- Jiangsu Co-Innovation Center for the Prevention and Control of Important Animal Infectious Diseases and Zoonoses, Yangzhou/College of Veterinary Medicine, Yangzhou University, 225009, China
| | - Chunguang Cao
- Jiangsu Co-Innovation Center for the Prevention and Control of Important Animal Infectious Diseases and Zoonoses, Yangzhou/College of Veterinary Medicine, Yangzhou University, 225009, China
| | - Haixia Huan
- Huaiyin Normal University School of Life Science, 223001, China
| | - Liuli Zhang
- Jiangsu Co-Innovation Center for the Prevention and Control of Important Animal Infectious Diseases and Zoonoses, Yangzhou/College of Veterinary Medicine, Yangzhou University, 225009, China
| | - Xiaohui Mu
- Jiangsu Co-Innovation Center for the Prevention and Control of Important Animal Infectious Diseases and Zoonoses, Yangzhou/College of Veterinary Medicine, Yangzhou University, 225009, China
| | - Qingqing Gao
- Jiangsu Co-Innovation Center for the Prevention and Control of Important Animal Infectious Diseases and Zoonoses, Yangzhou/College of Veterinary Medicine, Yangzhou University, 225009, China
| | - Xianglei Dong
- Jiangsu Co-Innovation Center for the Prevention and Control of Important Animal Infectious Diseases and Zoonoses, Yangzhou/College of Veterinary Medicine, Yangzhou University, 225009, China
| | - Song Gao
- Jiangsu Co-Innovation Center for the Prevention and Control of Important Animal Infectious Diseases and Zoonoses, Yangzhou/College of Veterinary Medicine, Yangzhou University, 225009, China.
| | - Xiufan Liu
- Jiangsu Co-Innovation Center for the Prevention and Control of Important Animal Infectious Diseases and Zoonoses, Yangzhou/College of Veterinary Medicine, Yangzhou University, 225009, China
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Bacterial resistance to Quaternary Ammonium Compounds (QAC) disinfectants. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2014; 808:1-13. [PMID: 24595606 DOI: 10.1007/978-81-322-1774-9_1] [Citation(s) in RCA: 43] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Control of bacterial diseases has, for many years, been dependent on the use of antibiotics. Due to the high levels of efficacy of antibiotics in the past other disease control options have, to a large extent, been neglected. Mankind is now facing an increasing problem with antibiotic resistance. In an effort to retain some antibiotics for human use, there are moves afoot to limit or even ban the use of antibiotics in animal production. The use of antibiotics as growth promoters have been banned in the European Union and the USA. The potential ban on the use of antibiotics to treat diseases in production animals creates a dilemma for man-suffer significant problem with bacterial infection or suffer from a severe shortage of food! There are other options for the control of bacterial diseases. These include vaccine development, bacteriophage therapy, and improved biosecurity. Vaccine development against bacterial pathogens, particularly opportunistic pathogens, is often very challenging, as in many cases the molecular basis of the virulence is not always clearly understood. This is particularly true for Escherichia coli. Biosecurity (disinfection) has been a highly neglected area in disease control. With the ever-increasing problems with antibiotic resistance-the focus should return to improvements in biosecurity. As with antibiotics, bacteria also have mechanisms for resistance to disinfectants. To ensure that we do not replace one set of problems (increasing antibiotic resistance) with another (increasing resistance to disinfectants) we need to fully understand the modes of action of disinfectants and how the bacteria develop resistance to these disinfectants. Molecular studies have been undertaken to relate the presence of QAC resistance genes in bacteria to their levels of sensitivity to different generations of QAC-based products. The mode of action of QAC on bacteria has been studied using NanoSAM technology, where it was revealed that the QAC causes disruption of the bacterial cell wall and leaking of the cytoplasm out of the cells. Our main focus is on the control of bacterial and viral diseases in the poultry industry in a post-antibiotic era, but the principles remain similar for disease control in any veterinary field as well as in human medicine.
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Salscheider SL, Jahn A, Schnetz K. Transcriptional regulation by BglJ-RcsB, a pleiotropic heteromeric activator in Escherichia coli. Nucleic Acids Res 2013; 42:2999-3008. [PMID: 24335284 PMCID: PMC3950696 DOI: 10.1093/nar/gkt1298] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Abstract
The bacterial Rcs phosphorelay signals perturbations of the bacterial cell envelope to its response regulator RcsB, which regulates transcription of multiple loci related to motility, biofilm formation and various stress responses. RcsB is unique, as its set of target loci is modulated by interaction with auxiliary regulators including BglJ. The BglJ–RcsB heteromer is known to activate the HNS repressed leuO and bgl loci independent of RcsB phosphorylation. Here, we show that BglJ–RcsB activates the promoters of 10 additional loci (chiA, molR, sfsB, yecT, yqhG, ygiZ, yidL, ykiA, ynbA and ynjI). Furthermore, we mapped the BglJ–RcsB binding site at seven loci and propose a consensus sequence motif. The data suggest that activation by BglJ–RcsB is DNA phasing dependent at some loci, a feature reminiscent of canonical transcriptional activators, while at other loci BglJ–RcsB activation may be indirect by inhibition of HNS-mediated repression. In addition, we show that BglJ–RcsB activates transcription of bgl synergistically with CRP where it shifts the transcription start by 20 bp from a position typical for class I CRP-dependent promoters to a position typical for class II CRP-dependent promoters. Thus, BglJ–RcsB is a pleiotropic transcriptional activator that coordinates regulation with global regulators including CRP, LeuO and HNS.
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Affiliation(s)
- Silja Lucia Salscheider
- Institute for Genetics, University of Cologne, Zülpicher Strasse 47a, 50674 Cologne, Germany
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Xu H, Ling J, Gao Q, He H, Mu X, Yan Z, Gao S, Liu X. Role of the lpxM lipid A biosynthesis pathway gene in pathogenicity of avian pathogenic Escherichia coli strain E058 in a chicken infection model. Vet Microbiol 2013; 166:516-26. [DOI: 10.1016/j.vetmic.2013.05.030] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2012] [Revised: 04/25/2013] [Accepted: 05/23/2013] [Indexed: 10/26/2022]
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15
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Ling J, Pan H, Gao Q, Xiong L, Zhou Y, Zhang D, Gao S, Liu X. Aerobactin synthesis genes iucA and iucC contribute to the pathogenicity of avian pathogenic Escherichia coli O2 strain E058. PLoS One 2013; 8:e57794. [PMID: 23460907 PMCID: PMC3584046 DOI: 10.1371/journal.pone.0057794] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2012] [Accepted: 01/29/2013] [Indexed: 11/18/2022] Open
Abstract
Aerobactin genes are known to be present in virulent strains and absent from avirulent strains, but contributions of iucC and iucA, which are involved in aerobactin synthesis, to the pathogenicity of avian pathogenic Escherichia coli (APEC) have not been clarified. In this study, effects of double mutants (iucA/iutA or iucC/iutA) compared to those of single mutants (iucA, iucC or iutA) of aerobactin genes on the virulence of APEC strain E058 were examined both in vitro (aerobactin production, ingestion into HD-11 cells, survival in chicken serum) and in vivo (competitive growth against parental strain, colonization and persistence). In competitive co-infection assays, compared to the E058 parental strain, the E058ΔiucA mutant was significantly reduced in the liver, kidney, spleen (all P<0.01), heart and lung (both P<0.001). The E058ΔiutA mutant also was significantly reduced in the liver, lung, kidney (all P<0.01), heart and spleen (both P<0.001). The E058ΔiucC mutant was significantly attenuated in the heart and kidney (both P<0.05) and showed a remarkable reduction in the liver, spleen and lung (P<0.01); meanwhile, both E058ΔiucAΔiutA and E058ΔiucCΔiutA double mutants were sharply reduced as well (P<0.001). In colonization and persistence assays, compared with E058, recovered colonies of E058ΔiucA were significantly reduced from the lung, liver, spleen and kidney (P<0.01) and significantly reduced in the heart (P<0.001). E058ΔiutA was significantly reduced from the heart, lung, liver, spleen and kidney (P<0.01). E058ΔiucC, E058ΔiucAΔiutA and E058ΔiucCΔiutA were significantly decreased in all organs tested (P<0.001). These results suggest that iutA, iucA and iucC play important roles in the pathogenicity of APEC E058.
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Affiliation(s)
- Jielu Ling
- Animal Infectious Disease Laboratory, Ministry of Agriculture, College of Veterinary Medicine, Yangzhou University, Yangzhou, Jiangsu, People's Republic of China
| | - Haizhu Pan
- Animal Infectious Disease Laboratory, Ministry of Agriculture, College of Veterinary Medicine, Yangzhou University, Yangzhou, Jiangsu, People's Republic of China
| | - Qingqing Gao
- Animal Infectious Disease Laboratory, Ministry of Agriculture, College of Veterinary Medicine, Yangzhou University, Yangzhou, Jiangsu, People's Republic of China
| | - Liping Xiong
- Animal Infectious Disease Laboratory, Ministry of Agriculture, College of Veterinary Medicine, Yangzhou University, Yangzhou, Jiangsu, People's Republic of China
| | - Yefei Zhou
- Animal Infectious Disease Laboratory, Ministry of Agriculture, College of Veterinary Medicine, Yangzhou University, Yangzhou, Jiangsu, People's Republic of China
| | - Debao Zhang
- Animal Infectious Disease Laboratory, Ministry of Agriculture, College of Veterinary Medicine, Yangzhou University, Yangzhou, Jiangsu, People's Republic of China
| | - Song Gao
- Animal Infectious Disease Laboratory, Ministry of Agriculture, College of Veterinary Medicine, Yangzhou University, Yangzhou, Jiangsu, People's Republic of China
- * E-mail:
| | - Xiufan Liu
- Animal Infectious Disease Laboratory, Ministry of Agriculture, College of Veterinary Medicine, Yangzhou University, Yangzhou, Jiangsu, People's Republic of China
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Sequencing and functional annotation of avian pathogenic Escherichia coli serogroup O78 strains reveal the evolution of E. coli lineages pathogenic for poultry via distinct mechanisms. Infect Immun 2012; 81:838-49. [PMID: 23275093 DOI: 10.1128/iai.00585-12] [Citation(s) in RCA: 68] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Avian pathogenic Escherichia coli (APEC) causes respiratory and systemic disease in poultry. Sequencing of a multilocus sequence type 95 (ST95) serogroup O1 strain previously indicated that APEC resembles E. coli causing extraintestinal human diseases. We sequenced the genomes of two strains of another dominant APEC lineage (ST23 serogroup O78 strains χ7122 and IMT2125) and compared them to each other and to the reannotated APEC O1 sequence. For comparison, we also sequenced a human enterotoxigenic E. coli (ETEC) strain of the same ST23 serogroup O78 lineage. Phylogenetic analysis indicated that the APEC O78 strains were more closely related to human ST23 ETEC than to APEC O1, indicating that separation of pathotypes on the basis of their extraintestinal or diarrheagenic nature is not supported by their phylogeny. The accessory genome of APEC ST23 strains exhibited limited conservation of APEC O1 genomic islands and a distinct repertoire of virulence-associated loci. In light of this diversity, we surveyed the phenotype of 2,185 signature-tagged transposon mutants of χ7122 following intra-air sac inoculation of turkeys. This procedure identified novel APEC ST23 genes that play strain- and tissue-specific roles during infection. For example, genes mediating group 4 capsule synthesis were required for the virulence of χ7122 and were conserved in IMT2125 but absent from APEC O1. Our data reveal the genetic diversity of E. coli strains adapted to cause the same avian disease and indicate that the core genome of the ST23 lineage serves as a chassis for the evolution of E. coli strains adapted to cause avian or human disease via acquisition of distinct virulence genes.
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van der Westhuizen WA, Bragg RR. Multiplex polymerase chain reaction for screening avian pathogenic Escherichia coli for virulence genes. Avian Pathol 2012; 41:33-40. [PMID: 22845319 DOI: 10.1080/03079457.2011.631982] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/28/2022]
Abstract
Colibacillosis is a disease in poultry caused by avian pathogenic Escherichia coli (APEC) strains which leads to great economic losses in the poultry industry. These E. coli strains contain various virulence genes which grant the bacteria the ability to proliferate in the poultry host and cause disease. Many genes which can contribute to virulence have been identified and can be used to screen E. coli strains to infer pathogenicity and aid in the identification and classification of APEC. Multiplex polymerase chain reaction methods were designed and optimized to rapidly detect 18 different virulence genes in E. coli strains that were isolated in South Africa and Zimbabwe from various sources, including from chickens showing signs of colibacillosis. Virulence gene profiles were constructed for each E. coli isolate from the multiplex data for the comparison of the colibacillosis isolates with the other isolates. The South African E. coli isolated from chickens with signs of colibacillosis showed higher virulence gene prevalence in comparison with the Zimbabwean and other samples except those isolated from chicken faeces. The multiplex polymerase chain reaction designed in the present study successfully screened E. coli isolates for various APEC-related virulence genes, including genes recently described in the literature.
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Affiliation(s)
- W A van der Westhuizen
- Department of Microbial, Biochemical and Food Biotechnology, University of the Free State, Bloemfontein, South Africa
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18
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Construction of iucB and iucBiutA mutants of avian pathogenic Escherichia coli and evaluation of their pathogenicity. Vet Microbiol 2012; 159:420-31. [DOI: 10.1016/j.vetmic.2012.04.024] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2010] [Revised: 04/14/2012] [Accepted: 04/20/2012] [Indexed: 11/20/2022]
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19
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Proteome response of an extraintestinal pathogenic Escherichia coli strain with zoonotic potential to human and chicken sera. J Proteomics 2012; 75:4853-62. [PMID: 22677113 DOI: 10.1016/j.jprot.2012.05.044] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2012] [Revised: 05/20/2012] [Accepted: 05/29/2012] [Indexed: 12/29/2022]
Abstract
A subset of extraintestinal pathogenic Escherichia coli is zoonotic and has developed strategies to adapt to different host-specific environments. However, the underlying mechanisms of these adaptive strategies have yet to be discerned. Here, the proteomic response of an avian pathogenic E. coli strain, which appears indistinguishable from neonatal meningitis E. coli, was compared following growth in human and avian sera to determine whether it uses the same mechanisms to overcome the antibacterial effects of sera from different host species. Proteins involved in biosynthesis of iron receptors were up-regulated under both sera, suggesting that serum, regardless of the host of origin, is an iron-limited environment. However, several proteins involved in synthesis of nucleic acids, sulfur-containing amino acids and fatty acids, were differentially expressed in response to the sera from different hosts. Mutational analysis showed that this APEC strain required nucleotide biosynthesis during incubation in human, but not avian serum, and deletion of genes involved in the biosynthesis of sulfur-containing amino acids increased its resistance to human serum. Continued investigation of the proteome of 'zoonotic' ExPEC strains, grown under other 'dual' host conditions, will contribute to our understanding of ExPEC pathogenesis and host specificity and development of effective therapies and control strategies.
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20
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Transcriptome analysis of avian pathogenic Escherichia coli O1 in chicken serum reveals adaptive responses to systemic infection. Infect Immun 2011; 79:1951-60. [PMID: 21357721 DOI: 10.1128/iai.01230-10] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Infections of avian pathogenic Escherichia coli (APEC) result in annual multimillion-dollar losses to the poultry industry. Despite this, little is known about the mechanisms by which APEC survives and grows in the bloodstream. Thus, the aim of this study was to identify molecular mechanisms enabling APEC to survive and grow in this critical host environment. To do so, we compared the transcriptome of APEC O1 during growth in Luria-Bertani broth and chicken serum. Several categories of genes, predicted to contribute to adaptation and growth in the avian host, were identified. These included several known virulence genes and genes involved in adaptive metabolism, protein transport, biosynthesis pathways, stress resistance, and virulence regulation. Several genes with unknown function, which were localized to pathogenicity islands or APEC O1's large virulence plasmid, pAPEC-O1-ColBM, were also identified, suggesting that they too contribute to survival in serum. The significantly upregulated genes dnaK, dnaJ, phoP, and ybtA were subsequently subjected to mutational analysis to confirm their role in conferring a competitive advantage during infection. This genome-wide analysis provides novel insight into processes that are important to the pathogenesis of APEC O1.
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BglJ-RcsB heterodimers relieve repression of the Escherichia coli bgl operon by H-NS. J Bacteriol 2010; 192:6456-64. [PMID: 20952573 DOI: 10.1128/jb.00807-10] [Citation(s) in RCA: 57] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
RcsB is the response regulator of the complex Rcs two-component system, which senses perturbations in the outer membrane and peptidoglycan layer. BglJ is a transcriptional regulator whose constitutive expression causes activation of the H-NS- and StpA-repressed bgl (aryl-β,D-glucoside) operon in Escherichia coli. RcsB and BglJ both belong to the LuxR-type family of transcriptional regulators with a characteristic C-terminal DNA-binding domain. Here, we show that BglJ and RcsB interact and form heterodimers that presumably bind upstream of the bgl promoter, as suggested by mutation of a sequence motif related to the consensus sequence for RcsA-RcsB heterodimers. Heterodimerization of BglJ-RcsB and relief of H-NS-mediated repression of bgl by BglJ-RcsB are apparently independent of RcsB phosphorylation. In addition, we show that LeuO, a pleiotropic LysR-type transcriptional regulator, likewise binds to the bgl upstream regulatory region and relieves repression of bgl independently of BglJ-RcsB. Thus, LeuO can affect bgl directly, as shown here, and indirectly by activating the H-NS-repressed yjjQ-bglJ operon, as shown previously. Taken together, heterodimer formation of RcsB and BglJ expands the role of the Rcs two-component system and the network of regulators affecting the bgl promoter.
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AatA is a novel autotransporter and virulence factor of avian pathogenic Escherichia coli. Infect Immun 2009; 78:898-906. [PMID: 20028805 DOI: 10.1128/iai.00513-09] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Autotransporters (AT) are widespread in Gram-negative bacteria, and many of them are involved in virulence. An open reading frame (APECO1_O1CoBM96) encoding a novel AT was located in the pathogenicity island of avian pathogenic Escherichia coli (APEC) O1's virulence plasmid, pAPEC-O1-ColBM. This 3.5-kb APEC autotransporter gene (aatA) is predicted to encode a 123.7-kDa protein with a 25-amino-acid signal peptide, an 857-amino-acid passenger domain, and a 284-amino-acid beta domain. The three-dimensional structure of AatA was also predicted by the threading method using the I-TASSER online server and then was refined using four-body contact potentials. Molecular analysis of AatA revealed that it is translocated to the cell surface, where it elicits antibody production in infected chickens. Gene prevalence analysis indicated that aatA is strongly associated with E. coli from avian sources but not with E. coli isolated from human hosts. Also, AatA was shown to enhance adhesion of APEC to chicken embryo fibroblast cells and to contribute to APEC virulence.
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23
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Antão EM, Ewers C, Gürlebeck D, Preisinger R, Homeier T, Li G, Wieler LH. Signature-tagged mutagenesis in a chicken infection model leads to the identification of a novel avian pathogenic Escherichia coli fimbrial adhesin. PLoS One 2009; 4:e7796. [PMID: 19907658 PMCID: PMC2771359 DOI: 10.1371/journal.pone.0007796] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2009] [Accepted: 10/07/2009] [Indexed: 11/23/2022] Open
Abstract
The extraintestinal pathogen, avian pathogenic E. coli (APEC), known to cause systemic infections in chickens, is responsible for large economic losses in the poultry industry worldwide. In order to identify genes involved in the early essential stages of pathogenesis, namely adhesion and colonization, Signature-tagged mutagenesis (STM) was applied to a previously established lung colonization model of infection by generating and screening a total of 1,800 mutants of an APEC strain IMT5155 (O2:K1:H5; Sequence type complex 95). The study led to the identification of new genes of interest, including two adhesins, one of which coded for a novel APEC fimbrial adhesin (Yqi) not described for its role in APEC pathogenesis to date. Its gene product has been temporarily designated ExPEC Adhesin I (EA/I) until the adhesin-specific receptor is identified. Deletion of the ExPEC adhesin I gene resulted in reduced colonization ability by APEC strain IMT5155 both in vitro and in vivo. Furthermore, complementation of the adhesin gene restored its ability to colonize epithelial cells in vitro. The ExPEC adhesin I protein was successfully expressed in vitro. Electron microscopy of an afimbriate strain E. coli AAEC189 over-expressed with the putative EA/I gene cluster revealed short fimbrial-like appendages protruding out of the bacterial outer membrane. We observed that this adhesin coding gene yqi is prevalent among extraintestinal pathogenic E. coli (ExPEC) isolates, including APEC (54.4%), uropathogenic E. coli (UPEC) (65.9%) and newborn meningitic E. coli (NMEC) (60.0%), and absent in all of the 153 intestinal pathogenic E. coli strains tested, thereby validating the designation of the adhesin as ExPEC Adhesin I. In addition, prevalence of EA/I was most frequently associated with the B2 group of the EcoR classification and ST95 complex of the multi locus sequence typing (MLST) scheme, with evidence of a positive selection within this highly pathogenic complex. This is the first report of the newly identified and functionally characterized ExPEC adhesin I and its significant role during APEC infection in chickens.
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Affiliation(s)
- Esther-Maria Antão
- Institut für Mikrobiologie und Tierseuchen, Freie Universität Berlin, Berlin, Germany.
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Rouquet G, Porcheron G, Barra C, Répérant M, Chanteloup NK, Schouler C, Gilot P. A metabolic operon in extraintestinal pathogenic Escherichia coli promotes fitness under stressful conditions and invasion of eukaryotic cells. J Bacteriol 2009; 191:4427-40. [PMID: 19376853 PMCID: PMC2698472 DOI: 10.1128/jb.00103-09] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2009] [Accepted: 04/14/2009] [Indexed: 11/20/2022] Open
Abstract
We identified a carbohydrate metabolic operon (frz) that is highly associated with extraintestinal pathogenic Escherichia coli (ExPEC) strains. The frz operon codes for three subunits of a phosphoenolpyruvate:carbohydrate phosphotransferase system (PTS) transporter of the fructose subfamily, for a transcriptional activator of PTSs of the MgA family, for two type II ketose-1,6-bisphosphate aldolases, for a sugar-specific kinase (repressor, open reading frame, kinase family [ROK]), and for a protein of the cupin superfamily. We proved that the frz operon promotes bacterial fitness under stressful conditions, such as oxygen restriction, late stationary phase of growth, or growth in serum or in the intestinal tract. Furthermore, we showed that frz is involved in adherence to and internalization in human type II pneumocytes, human enterocytes, and chicken liver cells by favoring the ON orientation of the fim operon promoter and thus acting on the expression of type 1 fimbriae, which are the major ExPEC adhesins. Both the PTS activator and the metabolic enzymes encoded by the frz operon are involved in these phenotypes.
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Affiliation(s)
- Géraldine Rouquet
- INRA, UR1282, Unité d'Infectiologie Animale et de Santé Publique, Laboratoire de Pathogénie Bactérienne, Centre de Recherche de Tours, Nouzilly, France
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Sankar TS, Neelakanta G, Sangal V, Plum G, Achtman M, Schnetz K. Fate of the H-NS-repressed bgl operon in evolution of Escherichia coli. PLoS Genet 2009; 5:e1000405. [PMID: 19266030 PMCID: PMC2646131 DOI: 10.1371/journal.pgen.1000405] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2008] [Accepted: 02/05/2009] [Indexed: 11/18/2022] Open
Abstract
In the enterobacterial species Escherichia coli and Salmonella enterica, expression of horizontally acquired genes with a higher than average AT content is repressed by the nucleoid-associated protein H-NS. A classical example of an H-NS–repressed locus is the bgl (aryl-β,D-glucoside) operon of E. coli. This locus is “cryptic,” as no laboratory growth conditions are known to relieve repression of bgl by H-NS in E. coli K12. However, repression can be relieved by spontaneous mutations. Here, we investigated the phylogeny of the bgl operon. Typing of bgl in a representative collection of E. coli demonstrated that it evolved clonally and that it is present in strains of the phylogenetic groups A, B1, and B2, while it is presumably replaced by a cluster of ORFans in the phylogenetic group D. Interestingly, the bgl operon is mutated in 20% of the strains of phylogenetic groups A and B1, suggesting erosion of bgl in these groups. However, bgl is functional in almost all B2 isolates and, in approximately 50% of them, it is weakly expressed at laboratory growth conditions. Homologs of bgl genes exist in Klebsiella, Enterobacter, and Erwinia species and also in low GC-content Gram-positive bacteria, while absent in E. albertii and Salmonella sp. This suggests horizontal transfer of bgl genes to an ancestral Enterobacterium. Conservation and weak expression of bgl in isolates of phylogenetic group B2 may indicate a functional role of bgl in extraintestinal pathogenic E. coli. Horizontal gene transfer, an important mechanism in bacterial adaptation and evolution, requires mechanisms to avoid uncontrolled and possibly disadvantageous expression of the transferred genes. Recently, it was shown that the protein H-NS selectively silences genes gained by horizontal transfer in enteric bacteria. Regulated expression of these genes can then evolve and be integrated into the regulatory network of the new host. Our analysis of the catabolic bgl (aryl-β,D-glucoside) operon, which is silenced by H-NS in E. coli, provides a snapshot on the evolution of such a locus. Genes of the bgl operon were presumably gained by horizontal transfer from Gram-positive bacteria to ancestral enteric bacteria. In E. coli, the bgl operon co-evolved with the diversification of the species into four phylogenetic groups. In one phylogenetic group the bgl operon is functional. However, in two other phylogenetic groups, bgl accumulates disrupting mutations, and it is absent in the fourth group. This indicates that the H-NS–silenced bgl operon evolved differently in E. coli and is presumably positively selected in one phylogenetic group, while it is neutrally or negatively selected in the other groups.
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Affiliation(s)
| | | | - Vartul Sangal
- Department of Molecular Biology, Max-Planck Institute for Infection Biology, Berlin, Germany
- Department of Microbiology and Environmental Research Institute, University College Cork, Cork, Ireland
| | - Georg Plum
- Institute for Medical Microbiology, Immunology, and Hygiene, University of Cologne, Cologne, Germany
| | - Mark Achtman
- Department of Microbiology and Environmental Research Institute, University College Cork, Cork, Ireland
| | - Karin Schnetz
- Institute for Genetics, University of Cologne, Cologne, Germany
- * E-mail:
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Intestine and environment of the chicken as reservoirs for extraintestinal pathogenic Escherichia coli strains with zoonotic potential. Appl Environ Microbiol 2008; 75:184-92. [PMID: 18997030 DOI: 10.1128/aem.01324-08] [Citation(s) in RCA: 163] [Impact Index Per Article: 10.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Although research has increasingly focused on the pathogenesis of avian pathogenic Escherichia coli (APEC) infections and the "APEC pathotype" itself, little is known about the reservoirs of these bacteria. We therefore compared outbreak strains isolated from diseased chickens (n = 121) with nonoutbreak strains, including fecal E. coli strains from clinically healthy chickens (n = 211) and strains from their environment (n = 35) by determining their virulence gene profiles, phylogenetic backgrounds, responses to chicken serum, and in vivo pathogenicities in a chicken infection model. In general, by examining 46 different virulence-associated genes we were able to distinguish the three groups of avian strains, but some specific fecal and environmental isolates had a virulence gene profile that was indistinguishable from that determined for outbreak strains. In addition, a substantial number of phylogenetic EcoR group B2 strains, which are known to include potent human and animal extraintestinal pathogenic E. coli (ExPEC) strains, were identified among the APEC strains (44.5%) as well as among the fecal E. coli strains from clinically healthy chickens (23.2%). Comparably high percentages (79.2 to 89.3%) of serum-resistant strains were identified for all three groups of strains tested, bringing into question the usefulness of this phenotype as a principal marker for extraintestinal virulence. Intratracheal infection of 5-week-old chickens corroborated the pathogenicity of a number of nonoutbreak strains. Multilocus sequence typing data revealed that most strains that were virulent in chicken infection experiments belonged to sequence types that are almost exclusively associated with extraintestinal diseases not only in birds but also in humans, like septicemia, urinary tract infection, and newborn meningitis, supporting the hypothesis that not the ecohabitat but the phylogeny of E. coli strains determines virulence. These data provide strong evidence for an avian intestinal reservoir hypothesis which could be used to develop intestinal intervention strategies. These strains pose a zoonotic risk because either they could be transferred directly from birds to humans or they could serve as a genetic pool for ExPEC strains.
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