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Zhang Q, Peng L, Han W, Chen H, Tang H, Chen X, Langford PR, Huang Q, Zhou R, Li L. The morphology and metabolic changes of Actinobacillus pleuropneumoniae during its growth as a biofilm. Vet Res 2023; 54:42. [PMID: 37237397 PMCID: PMC10224306 DOI: 10.1186/s13567-023-01173-x] [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: 02/28/2023] [Accepted: 04/23/2023] [Indexed: 05/28/2023] Open
Abstract
Actinobacillus pleuropneumoniae is an important swine respiratory pathogen. Previous studies have suggested that growth as a biofilm is a natural state of A. pleuropneumoniae infection. To understand the survival features involved in the biofilm state, the growth features, morphology and gene expression profiles of planktonic and biofilm A. pleuropneumoniae were compared. A. pleuropneumoniae in biofilms showed reduced viability but maintained the presence of extracellular polymeric substances (EPS) after late log-phase. Under the microscope, bacteria in biofilms formed dense aggregated structures that were connected by abundant EPS, with reduced condensed chromatin. By construction of Δpga and ΔdspB mutants, polymeric β-1,6-linked N-acetylglucosamine and dispersin B were confirmed to be critical for normal biofilm formation. RNA-seq analysis indicated that, compared to their planktonic counterparts, A. pleuropneumoniae in biofilms had an extensively altered transcriptome. Carbohydrate metabolism, energy metabolism and translation were significantly repressed, while fermentation and genes contributing to EPS synthesis and translocation were up-regulated. The regulators Fnr (HlyX) and Fis were found to be up-regulated and their binding motifs were identified in the majority of the differentially expressed genes, suggesting their coordinated global role in regulating biofilm metabolism. By comparing the transcriptome of wild-type biofilm and Δpga, the utilization of oligosaccharides, iron and sulfur and fermentation were found to be important in adhesion and aggregation during biofilm formation. Additionally, when used as inocula, biofilm bacteria showed reduced virulence in mouse, compared with planktonic grown cells. Thus, these results have identified new facets of A. pleuropneumoniae biofilm maintenance and regulation.
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Affiliation(s)
- Qiuhong Zhang
- National Key Laboratory of Agricultural Microbiology, College of Veterinary Medicine, Huazhong Agricultural University, Wuhan, 430070, Hubei, China
- Key Laboratory of Preventive Veterinary Medicine in Hubei Province, The Cooperative Innovation Center for Sustainable Pig Production, Wuhan, 430070, Hubei, China
| | - Lu Peng
- National Key Laboratory of Agricultural Microbiology, College of Veterinary Medicine, Huazhong Agricultural University, Wuhan, 430070, Hubei, China
- Key Laboratory of Preventive Veterinary Medicine in Hubei Province, The Cooperative Innovation Center for Sustainable Pig Production, Wuhan, 430070, Hubei, China
| | - Weiyao Han
- National Key Laboratory of Agricultural Microbiology, College of Veterinary Medicine, Huazhong Agricultural University, Wuhan, 430070, Hubei, China
- Key Laboratory of Preventive Veterinary Medicine in Hubei Province, The Cooperative Innovation Center for Sustainable Pig Production, Wuhan, 430070, Hubei, China
| | - Hongyu Chen
- National Key Laboratory of Agricultural Microbiology, College of Veterinary Medicine, Huazhong Agricultural University, Wuhan, 430070, Hubei, China
- Key Laboratory of Preventive Veterinary Medicine in Hubei Province, The Cooperative Innovation Center for Sustainable Pig Production, Wuhan, 430070, Hubei, China
| | - Hao Tang
- National Key Laboratory of Agricultural Microbiology, College of Veterinary Medicine, Huazhong Agricultural University, Wuhan, 430070, Hubei, China
- Key Laboratory of Preventive Veterinary Medicine in Hubei Province, The Cooperative Innovation Center for Sustainable Pig Production, Wuhan, 430070, Hubei, China
| | - Xiabing Chen
- Institute of Animal Husbandry and Veterinary Science, Wuhan Academy of Agricultural Sciences, Wuhan, 430070, Hubei, China
| | - Paul R Langford
- Section of Paediatric Infectious Disease, Imperial College London, St Mary's Campus, London, W2 1PG, UK
| | - Qi Huang
- National Key Laboratory of Agricultural Microbiology, College of Veterinary Medicine, Huazhong Agricultural University, Wuhan, 430070, Hubei, China
- Key Laboratory of Preventive Veterinary Medicine in Hubei Province, The Cooperative Innovation Center for Sustainable Pig Production, Wuhan, 430070, Hubei, China
- International Research Center for Animal Disease, Ministry of Science and Technology of the People's Republic of China, Wuhan, 430070, Hubei, China
| | - Rui Zhou
- National Key Laboratory of Agricultural Microbiology, College of Veterinary Medicine, Huazhong Agricultural University, Wuhan, 430070, Hubei, China
- Key Laboratory of Preventive Veterinary Medicine in Hubei Province, The Cooperative Innovation Center for Sustainable Pig Production, Wuhan, 430070, Hubei, China
- International Research Center for Animal Disease, Ministry of Science and Technology of the People's Republic of China, Wuhan, 430070, Hubei, China
| | - Lu Li
- National Key Laboratory of Agricultural Microbiology, College of Veterinary Medicine, Huazhong Agricultural University, Wuhan, 430070, Hubei, China.
- Key Laboratory of Preventive Veterinary Medicine in Hubei Province, The Cooperative Innovation Center for Sustainable Pig Production, Wuhan, 430070, Hubei, China.
- International Research Center for Animal Disease, Ministry of Science and Technology of the People's Republic of China, Wuhan, 430070, Hubei, China.
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The Metabolic Adaptation in Response to Nitrate Is Critical for Actinobacillus pleuropneumoniae Growth and Pathogenicity under the Regulation of NarQ/P. Infect Immun 2022; 90:e0023922. [PMID: 35938858 PMCID: PMC9476948 DOI: 10.1128/iai.00239-22] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Nitrate metabolism is an adaptation mechanism used by many bacteria for survival in anaerobic environments. As a by-product of inflammation, nitrate is used by the intestinal bacterial pathogens to enable gut infection. However, the responses of bacterial respiratory pathogens to nitrate are less well understood. Actinobacillus pleuropneumoniae is an important bacterial respiratory pathogen of swine. Previous studies have suggested that adaptation of A. pleuropneumoniae to anaerobiosis is important for infection. In this work, A. pleuropneumoniae growth and pathogenesis in response to the nitrate were investigated. Nitrate significantly promoted A. pleuropneumoniae growth under anaerobic conditions in vitro and lethality in mice. By using narQ and narP deletion mutants and single-residue-mutated complementary strains of ΔnarQ, the two-component system NarQ/P was confirmed to be critical for nitrate-induced growth, with Arg50 in NarQ as an essential functional residue. Transcriptome analysis showed that nitrate upregulated multiple energy-generating pathways, including nitrate metabolism, mannose and pentose metabolism, and glycerolipid metabolism via the regulation of NarQ/P. Furthermore, narQ, narP, and its target gene encoding the nitrate reductase Nap contributed to the pathogenicity of A. pleuropneumoniae. The Nap inhibitor tungstate significantly reduced the survival of A. pleuropneumoniae in vivo, suggesting that Nap is a potential drug target. These results give new insights into how the respiratory pathogen A. pleuropneumoniae utilizes the alternative electron acceptor nitrate to overcome the hypoxia microenvironment, which can occur in the inflammatory or necrotic infected tissues.
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Identification of FtpA, a Dps-like protein involved in anti-oxidative stress and virulence in Actinobacillus pleuropneumoniae. J Bacteriol 2021; 204:e0032621. [PMID: 34807725 DOI: 10.1128/jb.00326-21] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Bacteria have evolved a variety of enzymes to eliminate endogenous or host-derived oxidative stress factors. The Dps protein, first identified in Escherichia coli, contains a ferroxidase center and protects bacteria from reactive oxygen species damage. There is a lack of knowledge of the role of Dps-like proteins in bacterial pathogenesis. Actinobacillus pleuropneumoniae causes pleuropneumonia, a respiratory disease of swine. The A. pleuropneumoniae ftpA gene is up-regulated during a shift to anaerobiosis, in biofilms and, as found in this study, also by H2O2. An A. pleuropneumoniae ftpA deletion mutant (△ftpA) had increased H2O2 sensitivity, less intracellular viability in macrophages, and decreased virulence in a mouse infection model. Expression of ftpA in an E. coli dps mutant restored wild-type resistance to H2O2. FtpA possesses a conserved ferritin domain containing a ferroxidase site. Recombinant rFtpA bound and oxidized Fe2+ reversibly. Under aerobic conditions, compared with the wild-type strain, the viability of an △ftpA mutant was reduced after extended culture, transition from anaerobic to aerobic conditions, and upon supplementation with Fenton reaction substrates. Under anaerobic conditions, additional H2O2 resulted in a more severe growth defect of △ftpA than under aerobic conditions. Therefore, by oxidizing and mineralizing Fe2+, FtpA alleviates oxidative damage mediated by intracellular Fenton reactions. Furthermore, by mutational analysis, two residues were confirmed to be critical for Fe2+ binding and oxidization, as well as for A. pleuropneumoniae H2O2 resistance. Taken together, this study demonstrates that A. pleuropneumoniae FtpA is a Dps-like protein, playing critical roles in oxidative stress resistance and virulence. IMPORTANCE As a ferroxidase, Dps of Escherichia coli can protect bacteria from reactive oxygen species damage, but its role in bacterial pathogenesis has received little attention. In this study, FtpA of the swine respiratory pathogen A. pleuropneumoniae was identified as a new Dps-like protein. It facilitated A. pleuropneumoniae resistance to H2O2, survival in macrophages, and infection in vivo. FtpA could bind and oxidize Fe2+ through two important residues in its ferroxidase site and protected the bacteria from oxidative damage mediated by the intracellular Fenton reaction. These findings provide new insights into the role of the FtpA-based antioxidant system in the pathogenesis of A. pleuropneumoniae, and the conserved Fe2+ binding ligands in Dps/FtpA provide novel drug target candidates for disease prevention.
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Nahar N, Turni C, Tram G, Blackall PJ, Atack JM. Actinobacillus pleuropneumoniae: The molecular determinants of virulence and pathogenesis. Adv Microb Physiol 2021; 78:179-216. [PMID: 34147185 DOI: 10.1016/bs.ampbs.2020.12.001] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Actinobacillus pleuropneumoniae, the causative agent of porcine pleuropneumonia, is responsible for high economic losses in swine herds across the globe. Pleuropneumonia is characterized by severe respiratory distress and high mortality. The knowledge about the interaction between bacterium and host within the porcine respiratory tract has improved significantly in recent years. A. pleuropneumoniae expresses multiple virulence factors, which are required for colonization, immune clearance, and tissue damage. Although vaccines are used to protect swine herds against A. pleuropneumoniae infection, they do not offer complete coverage, and often only protect against the serovar, or serovars, used to prepare the vaccine. This review will summarize the role of individual A. pleuropneumoniae virulence factors that are required during key stages of pathogenesis and disease progression, and highlight progress made toward developing effective and broadly protective vaccines against an organism of great importance to global agriculture and food production.
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Affiliation(s)
- Nusrat Nahar
- Institute for Glycomics, Griffith University, Gold Coast, QLD, Australia
| | - Conny Turni
- Queensland Alliance for Agriculture and Food Innovation, The University of Queensland, St. Lucia, QLD, Australia
| | - Greg Tram
- Institute for Glycomics, Griffith University, Gold Coast, QLD, Australia
| | - Patrick J Blackall
- Queensland Alliance for Agriculture and Food Innovation, The University of Queensland, St. Lucia, QLD, Australia.
| | - John M Atack
- Institute for Glycomics, Griffith University, Gold Coast, QLD, Australia.
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Exposure of Mycobacterium abscessus to Environmental Stress and Clinically Used Antibiotics Reveals Common Proteome Response among Pathogenic Mycobacteria. Microorganisms 2020; 8:microorganisms8050698. [PMID: 32397563 PMCID: PMC7285101 DOI: 10.3390/microorganisms8050698] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2020] [Revised: 05/06/2020] [Accepted: 05/07/2020] [Indexed: 12/19/2022] Open
Abstract
Mycobacterium abscessus subsp. abscessus (MAB) is a clinically important nontuberculous mycobacterium (NTM) causing pulmonary infection in patients such as cystic fibrosis and bronchiectasis. MAB is naturally resistant to the majority of available antibiotics. In attempts to identify the fundamental response of MAB to aerobic, anaerobic, and biofilm conditions (as it is encountered in patients) and during exposure to antibiotics, we studied bacterial proteome using tandem mass tag mass spectrometry sequencing. Numerous de novo synthesized proteins belonging to diverse metabolic pathways were found in anaerobic and biofilm conditions, including glycolysis/gluconeogenesis, tricarboxylic acid (TCA) cycle, oxidative phosphorylation, nitrogen metabolism, and glyoxylate and dicarboxylate metabolism. Upon exposure to amikacin and linezolid under stress environments, MAB displayed metabolic enrichment for glycerophospholipid metabolism and oxidative phosphorylation. By comparing proteomes of two significant NTMs, MAB and M. avium subsp. hominissuis, we found highly synthesized shared enzymes of oxidative phosphorylation, TCA cycle, glycolysis/gluconeogenesis, glyoxylate/dicarboxylate, nitrogen metabolism, peptidoglycan biosynthesis, and glycerophospholipid/glycerolipid metabolism. The activation of peptidoglycan and fatty acid biosynthesis pathways indicates the attempt of bacteria to modify the cell wall, influencing the susceptibility to antibiotics. This study establishes global changes in the synthesis of enzymes promoting the metabolic shift and enhancing the pathogen resistance to antibiotics within different environments.
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Aper D, Frömbling J, Bağcıoğlu M, Ehling-Schulz M, Hennig-Pauka I. Comparison of metabolic adaptation and biofilm formation of Actinobacillus pleuropneumoniae field isolates from the upper and lower respiratory tract of swine with respiratory disease. Vet Microbiol 2019; 240:108532. [PMID: 31902502 DOI: 10.1016/j.vetmic.2019.108532] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2019] [Revised: 11/25/2019] [Accepted: 11/26/2019] [Indexed: 12/27/2022]
Abstract
Most outbreaks of disease due to infection with Actinobacillus (A.) pleuropneumoniae are caused by pigs already pre-colonised in tonsillar tissue, where the pathogen is protected from exposure to antibiotic substances administered for treatment. As it has been shown recently under experimental conditions, A. pleuropneumoniae displays host tissue-specific metabolic adaptation. In this study, pairs of A. pleuropneumoniae field isolates were recovered from lung as well as from tonsillar and nasal tissue from 20 pigs suffering from acute clinical signs of pleuropneumonia and showing characteristic pathological lung alterations. Metabolic adaptation to the porcine lower and upper respiratory tract of 32 A. pleuropneumoniae serotype 2 field isolates was examined using Fourier transform infrared (FTIR) spectroscopy as a high resolution metabolic fingerprinting method. All strains showed metabolic adaptations to organ tissue reflected by hierarchical cluster analysis of FTIR spectra similar to those previously observed under experimental conditions. Notably, differences in antimicrobial resistance patterns and minimal inhibitory concentrations of isolates from different tissues in the same animal, but not in biofilm production capability in a microtiter plate assay were found. Overall, biofilm formation was observed for 71 % of the isolates, confirming that A. pleuropneumoniae field isolates are generally able to form biofilms, although rather in a serotype-specific than in an organ-specific manner. A. pleuropneumoniae serotype 6 isolates formed significantly more biofilm than the other serotypes. Furthermore, biofilm production was negatively correlated to the lung lesion scores and tonsillar isolates tended to be more susceptible to antimicrobial substances with high bioavailability than lung isolates.
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Affiliation(s)
- Doris Aper
- Field Station for Epidemiology, University of Veterinary Medicine Hannover, Foundation, D-49456 Bakum, Germany
| | - Janna Frömbling
- Institute of Microbiology, Department of Pathobiology, University of Veterinary Medicine Vienna, Veterinaerplatz 1, A-1210 Vienna, Austria
| | - Murat Bağcıoğlu
- Institute of Microbiology, Department of Pathobiology, University of Veterinary Medicine Vienna, Veterinaerplatz 1, A-1210 Vienna, Austria
| | - Monika Ehling-Schulz
- Institute of Microbiology, Department of Pathobiology, University of Veterinary Medicine Vienna, Veterinaerplatz 1, A-1210 Vienna, Austria
| | - Isabel Hennig-Pauka
- Field Station for Epidemiology, University of Veterinary Medicine Hannover, Foundation, D-49456 Bakum, Germany.
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Link between Heterotrophic Carbon Fixation and Virulence in the Porcine Lung Pathogen Actinobacillus pleuropneumoniae. Infect Immun 2019; 87:IAI.00768-18. [PMID: 31285248 DOI: 10.1128/iai.00768-18] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2018] [Accepted: 06/24/2019] [Indexed: 01/01/2023] Open
Abstract
Actinobacillus pleuropneumoniae is a capnophilic pathogen of the porcine respiratory tract lacking enzymes of the oxidative branch of the tricarboxylic acid (TCA) cycle. We previously claimed that A. pleuropneumoniae instead uses the reductive branch in order to generate energy and metabolites. Here, we show that bicarbonate and oxaloacetate supported anaerobic growth of A. pleuropneumoniae Isotope mass spectrometry revealed heterotrophic fixation of carbon from stable isotope-labeled bicarbonate by A. pleuropneumoniae, which was confirmed by nano-scale secondary ion mass spectrometry at a single-cell level. By gas chromatography-combustion-isotope ratio mass spectrometry we could further show that the labeled carbon atom is mainly incorporated into the amino acids aspartate and lysine, which are derived from the TCA metabolite oxaloacetate. We therefore suggest that carbon fixation occurs at the interface of glycolysis and the reductive branch of the TCA cycle. The heme precursor δ-aminolevulinic acid supported growth of A. pleuropneumoniae, similar to bicarbonate, implying that anaplerotic carbon fixation is needed for heme synthesis. However, deletion of potential carbon-fixing enzymes, including PEP-carboxylase (PEPC), PEP-carboxykinase (PEPCK), malic enzyme, and oxaloacetate decarboxylase, as well as various combinations thereof, did not affect carbon fixation. Interestingly, generation of a deletion mutant lacking all four enzymes was not possible, suggesting that carbon fixation in A. pleuropneumoniae is an essential metabolic pathway controlled by a redundant set of enzymes. A double deletion mutant lacking PEPC and PEPCK was not impaired in carbon fixation in vitro but showed reduction of virulence in a pig infection model.
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Actinobacillus pleuropneumoniae biofilms: Role in pathogenicity and potential impact for vaccination development. Anim Health Res Rev 2017; 19:17-30. [DOI: 10.1017/s146625231700010x] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
AbstractActinobacillus pleuropneumoniae is a Gram-negative bacterium that belongs to the family Pasteurellaceae. It is the causative agent of porcine pleuropneumonia, a highly contagious respiratory disease that is responsible for major economic losses in the global pork industry. The disease may present itself as a chronic or an acute infection characterized by severe pathology, including hemorrhage, fibrinous and necrotic lung lesions, and, in the worst cases, rapid death. A. pleuropneumoniae is transmitted via aerosol route, direct contact with infected pigs, and by the farm environment. Many virulence factors associated with this bacterium are well characterized. However, much less is known about the role of biofilm, a sessile mode of growth that may have a critical impact on A. pleuropneumoniae pathogenicity. Here we review the current knowledge on A. pleuropneumoniae biofilm, factors associated with biofilm formation and dispersion, and the impact of biofilm on the pathogenesis A. pleuropneumoniae. We also provide an overview of current vaccination strategies against A. pleuropneumoniae and consider the possible role of biofilms vaccines for controlling the disease.
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Sassu EL, Bossé JT, Tobias TJ, Gottschalk M, Langford PR, Hennig-Pauka I. Update on Actinobacillus pleuropneumoniae-knowledge, gaps and challenges. Transbound Emerg Dis 2017; 65 Suppl 1:72-90. [PMID: 29083117 DOI: 10.1111/tbed.12739] [Citation(s) in RCA: 109] [Impact Index Per Article: 15.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2017] [Indexed: 12/15/2022]
Abstract
Porcine pleuropneumonia, caused by the bacterial porcine respiratory tract pathogen Actinobacillus pleuropneumoniae, leads to high economic losses in affected swine herds in most countries of the world. Pigs affected by peracute and acute disease suffer from severe respiratory distress with high lethality. The agent was first described in 1957 and, since then, knowledge about the pathogen itself, and its interactions with the host, has increased continuously. This is, in part, due to the fact that experimental infections can be studied in the natural host. However, the fact that most commercial pigs are colonized by this pathogen has hampered the applicability of knowledge gained under experimental conditions. In addition, several factors are involved in development of disease, and these have often been studied individually. In a DISCONTOOLS initiative, members from science, industry and clinics exchanged their expertise and empirical observations and identified the major gaps in knowledge. This review sums up published results and expert opinions, within the fields of pathogenesis, epidemiology, transmission, immune response to infection, as well as the main means of prevention, detection and control. The gaps that still remain to be filled are highlighted, and present as well as future challenges in the control of this disease are addressed.
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Affiliation(s)
- E L Sassu
- Department of Pathobiology, Institute of Immunology, University of Veterinary Medicine, Vienna, Austria
| | - J T Bossé
- Section of Paediatrics, Department of Medicine, Imperial College London, London, UK
| | - T J Tobias
- Department of Farm Animal Health, Faculty of Veterinary Medicine, Utrecht University, Utrecht, The Netherlands
| | - M Gottschalk
- Department of Pathology and Microbiology, Faculty of Veterinary Medicine, University of Montreal, Saint-Hyacinthe, QC, Canada
| | - P R Langford
- Section of Paediatrics, Department of Medicine, Imperial College London, London, UK
| | - I Hennig-Pauka
- Field Station for Epidemiology, University of Veterinary Medicine Hannover, Foundation, Bakum, Germany
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Sassu EL, Ladinig A, Talker SC, Stadler M, Knecht C, Stein H, Frömbling J, Richter B, Spergser J, Ehling-Schulz M, Graage R, Hennig-Pauka I, Gerner W. Frequency of Th17 cells correlates with the presence of lung lesions in pigs chronically infected with Actinobacillus pleuropneumoniae. Vet Res 2017; 48:4. [PMID: 28166835 PMCID: PMC5294905 DOI: 10.1186/s13567-017-0411-z] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2016] [Accepted: 01/03/2017] [Indexed: 12/21/2022] Open
Abstract
Porcine contagious pleuropneumonia caused by Actinobacillus pleuropneumoniae (APP) remains one of the major causes of poor growth performance and respiratory disease in pig herds. While the role of antibodies against APP has been intensely studied, the porcine T cell response remains poorly characterized. To address this, pigs were intranasally infected with APP serotype 2 and euthanized during the acute phase [6-10 days post-infection (dpi)] or the chronic phase of APP infection (27-31 dpi). Lymphocytes isolated from blood, tonsils, lung tissue and tracheobronchial lymph nodes were analyzed by intracellular cytokine staining (ICS) for IL-17A, IL-10 and TNF-α production after in vitro stimulation with crude capsular extract (CCE) of the APP inoculation strain. This was combined with cell surface staining for the expression of CD4, CD8α and TCR-γδ. Clinical records, microbiological investigations and pathological findings confirmed the induction of a subclinical APP infection. ICS-assays revealed the presence of APP-CCE specific CD4+CD8αdim IL-17A-producing T cells in blood and lung tissue in most infected animals during the acute and chronic phase of infection and a minor fraction of these cells co-produced TNF-α. APP-CCE specific IL-17A-producing γδ T cells could not be found and APP-CCE specific IL-10-producing CD4+ T cells were present in various organs but only in a few infected animals. The frequency of identified putative Th17 cells (CD4+CD8αdimIL-17A+) in lung and blood correlated positively with lung lesion scores and APP-specific antibody titers during the chronic phase. These results suggest a potential role of Th17 cells in the immune pathogenesis of APP infection.
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Affiliation(s)
- Elena L Sassu
- University Clinic for Swine, Department of Farm Animals and Veterinary Public Health, University of Veterinary Medicine, Vienna, Austria
| | - Andrea Ladinig
- University Clinic for Swine, Department of Farm Animals and Veterinary Public Health, University of Veterinary Medicine, Vienna, Austria
| | - Stephanie C Talker
- Institute of Immunology, Department of Pathobiology, University of Veterinary Medicine Vienna, Vienna, Austria
| | - Maria Stadler
- Institute of Immunology, Department of Pathobiology, University of Veterinary Medicine Vienna, Vienna, Austria
| | - Christian Knecht
- University Clinic for Swine, Department of Farm Animals and Veterinary Public Health, University of Veterinary Medicine, Vienna, Austria
| | - Heiko Stein
- University Clinic for Swine, Department of Farm Animals and Veterinary Public Health, University of Veterinary Medicine, Vienna, Austria
| | - Janna Frömbling
- Functional Microbiology, Institute of Microbiology, Department of Pathobiology, University of Veterinary Medicine Vienna, Vienna, Austria
| | - Barbara Richter
- Institute of Pathology and Forensic Veterinary Medicine, Department of Pathobiology, University of Veterinary Medicine Vienna, Vienna, Austria
| | - Joachim Spergser
- Functional Microbiology, Institute of Microbiology, Department of Pathobiology, University of Veterinary Medicine Vienna, Vienna, Austria
| | - Monika Ehling-Schulz
- Functional Microbiology, Institute of Microbiology, Department of Pathobiology, University of Veterinary Medicine Vienna, Vienna, Austria
| | - Robert Graage
- Division of Swine Medicine, Department of Farm Animals, University of Zurich, Vetsuisse Faculty, Zurich, Switzerland
| | - Isabel Hennig-Pauka
- University Clinic for Swine, Department of Farm Animals and Veterinary Public Health, University of Veterinary Medicine, Vienna, Austria
| | - Wilhelm Gerner
- Institute of Immunology, Department of Pathobiology, University of Veterinary Medicine Vienna, Vienna, Austria.
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Su Z, Zhu J, Xu Z, Xiao R, Zhou R, Li L, Chen H. A Transcriptome Map of Actinobacillus pleuropneumoniae at Single-Nucleotide Resolution Using Deep RNA-Seq. PLoS One 2016; 11:e0152363. [PMID: 27018591 PMCID: PMC4809551 DOI: 10.1371/journal.pone.0152363] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2015] [Accepted: 03/13/2016] [Indexed: 12/21/2022] Open
Abstract
Actinobacillus pleuropneumoniae is the pathogen of porcine contagious pleuropneumoniae, a highly contagious respiratory disease of swine. Although the genome of A. pleuropneumoniae was sequenced several years ago, limited information is available on the genome-wide transcriptional analysis to accurately annotate the gene structures and regulatory elements. High-throughput RNA sequencing (RNA-seq) has been applied to study the transcriptional landscape of bacteria, which can efficiently and accurately identify gene expression regions and unknown transcriptional units, especially small non-coding RNAs (sRNAs), UTRs and regulatory regions. The aim of this study is to comprehensively analyze the transcriptome of A. pleuropneumoniae by RNA-seq in order to improve the existing genome annotation and promote our understanding of A. pleuropneumoniae gene structures and RNA-based regulation. In this study, we utilized RNA-seq to construct a single nucleotide resolution transcriptome map of A. pleuropneumoniae. More than 3.8 million high-quality reads (average length ~90 bp) from a cDNA library were generated and aligned to the reference genome. We identified 32 open reading frames encoding novel proteins that were mis-annotated in the previous genome annotations. The start sites for 35 genes based on the current genome annotation were corrected. Furthermore, 51 sRNAs in the A. pleuropneumoniae genome were discovered, of which 40 sRNAs were never reported in previous studies. The transcriptome map also enabled visualization of 5'- and 3'-UTR regions, in which contained 11 sRNAs. In addition, 351 operons covering 1230 genes throughout the whole genome were identified. The RNA-Seq based transcriptome map validated annotated genes and corrected annotations of open reading frames in the genome, and led to the identification of many functional elements (e.g. regions encoding novel proteins, non-coding sRNAs and operon structures). The transcriptional units described in this study provide a foundation for future studies concerning the gene functions and the transcriptional regulatory architectures of this pathogen.
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Affiliation(s)
- Zhipeng Su
- State Key Laboratory of Agricultural Microbiology, College of Veterinary Medicine, Huazhong Agricultural University, Wuhan 430070, China
| | - Jiawen Zhu
- State Key Laboratory of Agricultural Microbiology, College of Veterinary Medicine, Huazhong Agricultural University, Wuhan 430070, China
| | - Zhuofei Xu
- State Key Laboratory of Agricultural Microbiology, College of Veterinary Medicine, Huazhong Agricultural University, Wuhan 430070, China
| | - Ran Xiao
- State Key Laboratory of Agricultural Microbiology, College of Veterinary Medicine, Huazhong Agricultural University, Wuhan 430070, China
| | - Rui Zhou
- State Key Laboratory of Agricultural Microbiology, College of Veterinary Medicine, Huazhong Agricultural University, Wuhan 430070, China
- Cooperative Innovation Center of Sustainable Pig Production, Wuhan 430070, China
| | - Lu Li
- State Key Laboratory of Agricultural Microbiology, College of Veterinary Medicine, Huazhong Agricultural University, Wuhan 430070, China
- Cooperative Innovation Center of Sustainable Pig Production, Wuhan 430070, China
- * E-mail: (HC); (LL)
| | - Huanchun Chen
- State Key Laboratory of Agricultural Microbiology, College of Veterinary Medicine, Huazhong Agricultural University, Wuhan 430070, China
- Cooperative Innovation Center of Sustainable Pig Production, Wuhan 430070, China
- * E-mail: (HC); (LL)
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Hu X, Yan H, Liu K, Hu J, Qi C, Yang J, Liu Y, Zhao J, Liu J. Identification and characterization of a novel stress-responsive outer membrane protein Lip40 from Actinobacillus pleuropneumoniae. BMC Biotechnol 2015; 15:106. [PMID: 26608465 PMCID: PMC4660844 DOI: 10.1186/s12896-015-0199-8] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2015] [Accepted: 08/29/2015] [Indexed: 01/30/2023] Open
Abstract
Background Actinobacillus pleuropneumoniae, a Gram-negative bacterium, is the causative agent of porcine pleuropneumonia, a highly contagious and often fatal disease. Because current vaccines confer limited protection against A. pleuropneumoniae infection, the development of more effective vaccines is urgently required. The identification of immunogenic and protective antigens, such as an outer-membrane lipoprotein, will advance this purpose. Results Sixty putative lipoproteins were predicted from the genomic sequence of A. pleuropneumoniae using multiple algorithms. Here, we focused on the characteristics of the putative lipoprotein Lip40 from A. pleuropneumoniae strain SLW01 (serovar 1). Lip40 shares sequence similarity with many bacterial lipoproteins, and the structural prediction of Lip40 suggests that it is similar to A. pleuropneumoniae TbpB. The N-terminus of Lip40 contains an interesting tandemly repeated sequence, Q(E/D/P)QPK. Real-time RT–PCR indicated that the expression of lip40 was significantly upregulated at 42 °C, at 16 °C, and under anaerobic conditions. Recombinant Lip40 (rLip40) produced in Escherichia coli BL21(DE3) was specifically recognized by porcine convalescent serum directed against A. pleuropneumoniae. Lip40 was confirmed to localize at the bacterial outer membrane, and its expression was significantly stimulated when A. pleuropneumoniae was cultured under various stress conditions. Lip40 also protected 75 % of mice from fatal virulent A. pleuropneumoniae infection. Conclusions The immunogenic outer-membrane protein Lip40 is stress responsive, protects mice against infection, and might be a virulence determinant. Further investigation of Lip40 should expedite vaccine development and provide insight into the pathogenesis of A. pleuropneumoniae. Electronic supplementary material The online version of this article (doi:10.1186/s12896-015-0199-8) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Xuehe Hu
- College of Life Sciences, Central China Normal University, Wuhan, Hubei, 430079, China.
| | - Hao Yan
- College of Life Sciences, Central China Normal University, Wuhan, Hubei, 430079, China.
| | - Ke Liu
- College of Life Sciences, Central China Normal University, Wuhan, Hubei, 430079, China.
| | - Jiansheng Hu
- College of Life Sciences, Central China Normal University, Wuhan, Hubei, 430079, China.
| | - Chao Qi
- College of Life Sciences, Central China Normal University, Wuhan, Hubei, 430079, China.
| | - Jihong Yang
- College of Life Sciences, Central China Normal University, Wuhan, Hubei, 430079, China.
| | - Yanli Liu
- College of Life Sciences, Central China Normal University, Wuhan, Hubei, 430079, China.
| | - Jin Zhao
- College of Life Sciences, Central China Normal University, Wuhan, Hubei, 430079, China.
| | - Jinlin Liu
- College of Life Sciences, Central China Normal University, Wuhan, Hubei, 430079, China.
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Encyclopedia of bacterial gene circuits whose presence or absence correlate with pathogenicity--a large-scale system analysis of decoded bacterial genomes. BMC Genomics 2015; 16:773. [PMID: 26459834 PMCID: PMC4603813 DOI: 10.1186/s12864-015-1957-7] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2015] [Accepted: 09/28/2015] [Indexed: 12/26/2022] Open
Abstract
BACKGROUND Bacterial infections comprise a global health challenge as the incidences of antibiotic resistance increase. Pathogenic potential of bacteria has been shown to be context dependent, varying in response to environment and even within the strains of the same genus. RESULTS We used the KEGG repository and extensive literature searches to identify among the 2527 bacterial genomes in the literature those implicated as pathogenic to the host, including those which show pathogenicity in a context dependent manner. Using data on the gene contents of these genomes, we identified sets of genes highly abundant in pathogenic but relatively absent in commensal strains and vice versa. In addition, we carried out genome comparison within a genus for the seventeen largest genera in our genome collection. We projected the resultant lists of ortholog genes onto KEGG bacterial pathways to identify clusters and circuits, which can be linked to either pathogenicity or synergy. Gene circuits relatively abundant in nonpathogenic bacteria often mediated biosynthesis of antibiotics. Other synergy-linked circuits reduced drug-induced toxicity. Pathogen-abundant gene circuits included modules in one-carbon folate, two-component system, type-3 secretion system, and peptidoglycan biosynthesis. Antibiotics-resistant bacterial strains possessed genes modulating phagocytosis, vesicle trafficking, cytoskeletal reorganization, and regulation of the inflammatory response. Our study also identified bacterial genera containing a circuit, elements of which were previously linked to Alzheimer's disease. CONCLUSIONS Present study produces for the first time, a signature, in the form of a robust list of gene circuitry whose presence or absence could potentially define the pathogenicity of a microbiome. Extensive literature search substantiated a bulk majority of the commensal and pathogenic circuitry in our predicted list. Scanning microbiome libraries for these circuitry motifs will provide further insights into the complex and context dependent pathogenicity of bacteria.
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Abstract
Bacterial cells respond to changes in the environment by adjusting their physiological reactions. In cascades of cellular responses to stresses of various origins, rapid modulation of RNA function is known to be an effective biochemical adaptation. Among many factors affecting RNA function, RNase III, a member of the phylogenetically highly conserved endoribonuclease III family, plays a key role in posttranscriptional regulatory pathways in Escherichia coli. In this review, we provide an overview of the factors affecting RNase III activity in E. coli.
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Brogaard L, Klitgaard K, Heegaard PMH, Hansen MS, Jensen TK, Skovgaard K. Concurrent host-pathogen gene expression in the lungs of pigs challenged with Actinobacillus pleuropneumoniae. BMC Genomics 2015; 16:417. [PMID: 26018580 PMCID: PMC4446954 DOI: 10.1186/s12864-015-1557-6] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2014] [Accepted: 04/20/2015] [Indexed: 12/22/2022] Open
Abstract
Background Actinobacillus pleuropneumoniae causes pleuropneumonia in pigs, a disease which is associated with high morbidity and mortality, as well as impaired animal welfare. To obtain in-depth understanding of this infection, the interplay between virulence factors of the pathogen and defense mechanisms of the porcine host needs to be elucidated. However, research has traditionally focused on either bacteriology or immunology; an unbiased picture of the transcriptional responses can be obtained by investigating both organisms in the same biological sample. Results Host and pathogen responses in pigs experimentally infected with A. pleuropneumoniae were analyzed by high-throughput RT-qPCR. This approach allowed concurrent analysis of selected genes encoding proteins known or hypothesized to be important in the acute phase of this infection. The expression of 17 bacterial and 31 porcine genes was quantified in lung samples obtained within the first 48 hours of infection. This provided novel insight into the early time course of bacterial genes involved in synthesis of pathogen-associated molecular patterns (lipopolysaccharide, peptidoglycan, lipoprotein) and genes involved in pattern recognition (TLR4, CD14, MD2, LBP, MYD88) in response to A. pleuropneumoniae. Significant up-regulation of proinflammatory cytokines such as IL1B, IL6, and IL8 was observed, correlating with protein levels, infection status and histopathological findings. Host genes encoding proteins involved in iron metabolism, as well as bacterial genes encoding exotoxins, proteins involved in adhesion, and iron acquisition were found to be differentially expressed according to disease progression. By applying laser capture microdissection, porcine expression of selected genes could be confirmed in the immediate surroundings of the invading pathogen. Conclusions Microbial pathogenesis is the product of interactions between host and pathogen. Our results demonstrate the applicability of high-throughput RT-qPCR for the elucidation of dual-organism gene expression analysis during infection. We showed differential expression of 12 bacterial and 24 porcine genes during infection and significant correlation of porcine and bacterial gene expression. This is the first study investigating the concurrent transcriptional response of both bacteria and host at the site of infection during porcine respiratory infection. Electronic supplementary material The online version of this article (doi:10.1186/s12864-015-1557-6) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Louise Brogaard
- Innate Immunology Group, Section of Immunology and Vaccinology, National Veterinary Institute, Technical University of Denmark, Bülowsvej 27, 1870, Frederiksberg C, Denmark.
| | - Kirstine Klitgaard
- Section of Bacteriology, Pathology and Parasitology, National Veterinary Institute, Technical University of Denmark, Bülowsvej 27, 1870, Frederiksberg C, Denmark.
| | - Peter M H Heegaard
- Innate Immunology Group, Section of Immunology and Vaccinology, National Veterinary Institute, Technical University of Denmark, Bülowsvej 27, 1870, Frederiksberg C, Denmark.
| | - Mette Sif Hansen
- Section of Bacteriology, Pathology and Parasitology, National Veterinary Institute, Technical University of Denmark, Bülowsvej 27, 1870, Frederiksberg C, Denmark.
| | - Tim Kåre Jensen
- Section of Bacteriology, Pathology and Parasitology, National Veterinary Institute, Technical University of Denmark, Bülowsvej 27, 1870, Frederiksberg C, Denmark.
| | - Kerstin Skovgaard
- Innate Immunology Group, Section of Immunology and Vaccinology, National Veterinary Institute, Technical University of Denmark, Bülowsvej 27, 1870, Frederiksberg C, Denmark.
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