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Guo F, Quan R, Cui Y, Cao X, Wen T, Xu F. Effects of OxyR regulator on oxidative stress, Apx toxin secretion and virulence of Actinobacillus pleuropneumoniae. Front Cell Infect Microbiol 2024; 13:1324760. [PMID: 38268788 PMCID: PMC10806198 DOI: 10.3389/fcimb.2023.1324760] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2023] [Accepted: 12/18/2023] [Indexed: 01/26/2024] Open
Abstract
Introduction Actinobacillus pleuropneumoniae, the causative agent of porcine pleuropneumonia, poses a significant threat to global swine populations due to its high prevalence, mortality rates, and substantial economic ramifications. Understanding the pathogen's defense mechanisms against host-produced reactive oxygen species is crucial for its survival, with OxyR, a conserved bacterial transcription factor, being pivotal in oxidative stress response. Methods This study investigated the presence and role of OxyR in A. pleuropneumoniae serovar 1-12 reference strains. Transcriptomic analysis was conducted on an oxyR disruption mutant to delineate the biological activities influenced by OxyR. Additionally, specific assays were employed to assess urease activity, catalase expression, ApxI toxin secretion, as well as adhesion and invasion abilities of the oxyR disruption mutant on porcine 3D4/21 and PT cells. A mice challenge experiment was also conducted to evaluate the impact of oxyR inactivation on A. pleuropneumoniae virulence. Results OxyR was identified as a conserved regulator present in A. pleuropneumoniae serovar 1-12 reference strains. Transcriptomic analysis revealed the involvement of OxyR in multiple biological activities. The oxyR disruption resulted in decreased urease activity, elevated catalase expression, enhanced ApxI toxin secretion-attributed to OxyR binding to the apxIBD promoter-and reduced adhesion and invasion abilities on porcine cells. Furthermore, inactivation of oxyR reduced the virulence of A. pleuropneumoniae in a mice challenge experiment. Discussion The findings highlight the pivotal role of OxyR in influencing the virulence mechanisms of A. pleuropneumoniae. The observed effects on various biological activities underscore OxyR as an essential factor contributing to the pathogenicity of this bacterium.
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Affiliation(s)
- Fangfang Guo
- Beijing Key Laboratory for Prevention and Control of Infectious Diseases in Livestock and Poultry, Institute of Animal Husbandry and Veterinary Medicine, Beijing Academy of Agriculture and Forestry Sciences, Beijing, China
| | - Rong Quan
- Beijing Key Laboratory for Prevention and Control of Infectious Diseases in Livestock and Poultry, Institute of Animal Husbandry and Veterinary Medicine, Beijing Academy of Agriculture and Forestry Sciences, Beijing, China
| | - Yifang Cui
- Beijing Key Laboratory for Prevention and Control of Infectious Diseases in Livestock and Poultry, Institute of Animal Husbandry and Veterinary Medicine, Beijing Academy of Agriculture and Forestry Sciences, Beijing, China
| | - Xiaoya Cao
- Beijing Key Laboratory for Prevention and Control of Infectious Diseases in Livestock and Poultry, Institute of Animal Husbandry and Veterinary Medicine, Beijing Academy of Agriculture and Forestry Sciences, Beijing, China
| | - Tong Wen
- Department of Biology Science and Technology, Baotou Teacher’s College, Baotou, China
| | - Fuzhou Xu
- Beijing Key Laboratory for Prevention and Control of Infectious Diseases in Livestock and Poultry, Institute of Animal Husbandry and Veterinary Medicine, Beijing Academy of Agriculture and Forestry Sciences, Beijing, China
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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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Comparative Efficacy in Challenge Dose Models of a Toxin Expressing Whole-Cell Vaccine against Eight Serovars of Actinobacillus pleuropneumoniae in Pigs. Animals (Basel) 2022; 12:ani12233244. [PMID: 36496765 PMCID: PMC9740876 DOI: 10.3390/ani12233244] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2022] [Revised: 11/19/2022] [Accepted: 11/20/2022] [Indexed: 11/24/2022] Open
Abstract
Actinobacillus pleuropneumoniae is a major economically significant bacterial respiratory pig pathogen, and whole cell vaccines are used to prevent disease. However, there is little data available on multi-serovar whole cell vaccine protection. Therefore, we determined the protective efficacies of a whole-cell A. pleuropneumoniae serovar 1 and 2 vaccine comprising ApxI-III toxins (C-vaccine, Coglapix®, Ceva, France) against serovars 1, 2, 4, 5, 6, 7, 9/11, and 13. The infection doses used induced disease representative of endemic field conditions, and standard protocols were used for all studies. Protection against homologous serovars 1 and 2 significantly reduced lung lesion scores (LLS) compared to positive controls: p = 0.00007 and p = 0.00124, respectively. The protection against heterologous serovars 4, 5, 6, 7, 9/11, and 13 also significantly reduced LLS: range p = 2.9 × 10-10 to p = 0.00953. As adjudged by the estimated random effect, reproducibility between studies was high. A highly significant serovar-independent reduction of pathological lung lesions by the C-vaccine was found for all the serovars tested (1, 2, 4, 5, 6, 7, 9/11, and 13). We conclude that the C-vaccine gives high serovar-independent protection against disease and is suitable for this use in the field.
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The ArcAB Two-Component System: Function in Metabolism, Redox Control, and Infection. Microbiol Mol Biol Rev 2022; 86:e0011021. [PMID: 35442087 PMCID: PMC9199408 DOI: 10.1128/mmbr.00110-21] [Citation(s) in RCA: 17] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023] Open
Abstract
ArcAB, also known as the Arc system, is a member of the two-component system family of bacterial transcriptional regulators and is composed of sensor kinase ArcB and response regulator ArcA. In this review, we describe the structure and function of these proteins and assess the state of the literature regarding ArcAB as a sensor of oxygen consumption. The bacterial quinone pool is the primary modulator of ArcAB activity, but questions remain for how this regulation occurs. This review highlights the role of quinones and their oxidation state in activating and deactivating ArcB and compares competing models of the regulatory mechanism. The cellular processes linked to ArcAB regulation of central metabolic pathways and potential interactions of the Arc system with other regulatory systems are also reviewed. Recent evidence for the function of ArcAB under aerobic conditions is challenging the long-standing characterization of this system as strictly an anaerobic global regulator, and the support for additional ArcAB functionality in this context is explored. Lastly, ArcAB-controlled cellular processes with relevance to infection are assessed.
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The effect of ArcA on the growth, motility, biofilm formation, and virulence of Plesiomonas shigelloides. BMC Microbiol 2021; 21:266. [PMID: 34607564 PMCID: PMC8489083 DOI: 10.1186/s12866-021-02322-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2021] [Accepted: 09/06/2021] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND The anoxic redox control binary system plays an important role in the response to oxygen as a signal in the environment. In particular, phosphorylated ArcA, as a global transcription factor, binds to the promoter regions of its target genes to regulate the expression of aerobic and anaerobic metabolism genes. However, the function of ArcA in Plesiomonas shigelloides is unknown. RESULTS In the present study, P. shigelloides was used as the research object. The differences in growth, motility, biofilm formation, and virulence between the WT strain and the ΔarcA isogenic deletion mutant strain were compared. The data showed that the absence of arcA not only caused growth retardation of P. shigelloides in the log phase, but also greatly reduced the glucose utilization in M9 medium before the stationary phase. The motility of the ΔarcA mutant strain was either greatly reduced when grown in swim agar, or basically lost when grown in swarm agar. The electrophoretic mobility shift assay results showed that ArcA bound to the promoter regions of the flaK, rpoN, and cheV genes, indicating that ArcA directly regulates the expression of these three motility-related genes in P. shigelloides. Meanwhile, the ability of the ΔarcA strain to infect Caco-2 cells was reduced by 40%; on the contrary, its biofilm formation was enhanced. Furthermore, the complementation of the WT arcA gene from pBAD33-arcA+ was constructed and all of the above features of the pBAD33-arcA+ complemented strain were restored to the WT level. CONCLUSIONS We showed the effect of ArcA on the growth, motility, biofilm formation, and virulence of Plesiomonas shigelloides, and demonstrated that ArcA functions as a positive regulator controls the motility of P. shigelloides by directly regulating the expression of flaK, rpoN and cheV genes.
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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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Xi D, Yang S, Liu Q, Li Y, Li Y, Yan J, Wang X, Ning K, Cao B. The response regulator ArcA enhances biofilm formation in the vpsT manner under the anaerobic condition in Vibrio cholerae. Microb Pathog 2020; 144:104197. [PMID: 32283260 DOI: 10.1016/j.micpath.2020.104197] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2019] [Revised: 04/04/2020] [Accepted: 04/06/2020] [Indexed: 12/27/2022]
Abstract
Vibrio cholerae, the agent of severe diarrheal disease cholera, is known to form biofilm to persist in the environmental and the host,s intestines. The bacteria execute a complex regulatory pathway producing virulence factors that allow colonization and cause disease in response to environmental signals in the intestine, including low oxygen-limited condition. VpsR and VpsT are primary regulators of the biofilm formation-regulatory network. In this study, we determined that anaerobic induction enhanced biofilm formation via the two component system, ArcB/A, which functions as a positive regulator of toxT expression. The biofilm formation has reduced approximately 2.4-fold in the ΔarcA mutant compared to the wild type in anaerobic condition. Chip-qPCR and EMSA assays confirmed that ArcA can bind directly to the vpsT promoter and then activates the expression of biofilm formation related genes, vpsA-K and vpsL-Q. Meanwhile, the ΔarcA mutant decreased the ability of colonization in intestine with CI (competition index) of 0.27 compared to wild type strain. These results suggest that ArcA links the expression of virulence and biofilm synthesis genes during anaerobic condition, and contributes to understand the complex relationship between biofilm formation and the intestinal signals during infection.
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Affiliation(s)
- Daoyi Xi
- TEDA Institute of Biological Sciences and Biotechnology, Nankai University, Tianjin, 300457, China; Key Laboratory of Molecular Microbiology and Technology of the Ministry of Education, Nankai University, Tianjin, 300457, China; Tianjin Key Laboratory of Microbial Functional Genomics, TEDA College, Nankai University, Tianjin, 300457, China
| | - Shuang Yang
- TEDA Institute of Biological Sciences and Biotechnology, Nankai University, Tianjin, 300457, China; Key Laboratory of Molecular Microbiology and Technology of the Ministry of Education, Nankai University, Tianjin, 300457, China; Tianjin Key Laboratory of Microbial Functional Genomics, TEDA College, Nankai University, Tianjin, 300457, China
| | - Qian Liu
- TEDA Institute of Biological Sciences and Biotechnology, Nankai University, Tianjin, 300457, China; Key Laboratory of Molecular Microbiology and Technology of the Ministry of Education, Nankai University, Tianjin, 300457, China; Tianjin Key Laboratory of Microbial Functional Genomics, TEDA College, Nankai University, Tianjin, 300457, China
| | - Yujia Li
- TEDA Institute of Biological Sciences and Biotechnology, Nankai University, Tianjin, 300457, China; Key Laboratory of Molecular Microbiology and Technology of the Ministry of Education, Nankai University, Tianjin, 300457, China; Tianjin Key Laboratory of Microbial Functional Genomics, TEDA College, Nankai University, Tianjin, 300457, China
| | - Yuehua Li
- TEDA Institute of Biological Sciences and Biotechnology, Nankai University, Tianjin, 300457, China; Key Laboratory of Molecular Microbiology and Technology of the Ministry of Education, Nankai University, Tianjin, 300457, China; Tianjin Key Laboratory of Microbial Functional Genomics, TEDA College, Nankai University, Tianjin, 300457, China
| | - Junxiang Yan
- TEDA Institute of Biological Sciences and Biotechnology, Nankai University, Tianjin, 300457, China; Key Laboratory of Molecular Microbiology and Technology of the Ministry of Education, Nankai University, Tianjin, 300457, China; Tianjin Key Laboratory of Microbial Functional Genomics, TEDA College, Nankai University, Tianjin, 300457, China
| | - Xiaochen Wang
- TEDA Institute of Biological Sciences and Biotechnology, Nankai University, Tianjin, 300457, China; Key Laboratory of Molecular Microbiology and Technology of the Ministry of Education, Nankai University, Tianjin, 300457, China; Tianjin Key Laboratory of Microbial Functional Genomics, TEDA College, Nankai University, Tianjin, 300457, China
| | - Kexin Ning
- TEDA Institute of Biological Sciences and Biotechnology, Nankai University, Tianjin, 300457, China; Key Laboratory of Molecular Microbiology and Technology of the Ministry of Education, Nankai University, Tianjin, 300457, China; Tianjin Key Laboratory of Microbial Functional Genomics, TEDA College, Nankai University, Tianjin, 300457, China
| | - Boyang Cao
- TEDA Institute of Biological Sciences and Biotechnology, Nankai University, Tianjin, 300457, China; Key Laboratory of Molecular Microbiology and Technology of the Ministry of Education, Nankai University, Tianjin, 300457, China; Tianjin Key Laboratory of Microbial Functional Genomics, TEDA College, Nankai University, Tianjin, 300457, China.
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Degraded neutrophil extracellular traps promote the growth of Actinobacillus pleuropneumoniae. Cell Death Dis 2019; 10:657. [PMID: 31506432 PMCID: PMC6736959 DOI: 10.1038/s41419-019-1895-4] [Citation(s) in RCA: 31] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2019] [Revised: 08/03/2019] [Accepted: 08/12/2019] [Indexed: 12/21/2022]
Abstract
Actinobacillus pleuropneumoniae (A.pp) causes severe pneumonia associated with enormous economic loss in pigs. Peracute diseased pigs die in <24 h with pneumonia. Neutrophils are the prominent innate immune cell in this infection that massively infiltrate the infected lung. Here we show that neutrophils release neutrophil extracellular traps (NETs) as response to A.pp infection. Numerous NET-markers were identified in bronchoalveolar lavage fluid (BALF) of A.pp-infected piglets in vivo, however, most NET fibers are degraded. Importantly, A.pp is able to enhance its growth rate in the presence of NETs that have been degraded by nucleases efficiently. A.pp itself releases no nuclease, but we identified host nucleases as sources that degrade NETs after A.pp infection. Furthermore, the nucleases of co-infecting pathogens like Streptococcus suis increase growth of A.pp in presence of porcine NETs. Thus, A.pp is not only evading the antimicrobial activity of NETs, A.pp is rather additionally using parts of NETs as growth factor thereby taking advantage of host nucleases as DNase1 or nucleases of co-infecting bacteria, which degrade NETs. This effect can be diminished by inhibiting the bacterial adenosine synthase indicating that degraded NETs serve as a source for NAD, which is required by A.pp for its growth. A similar phenotype was found for the human pathogen Haemophilus (H.) influenzae and its growth in the presence of human neutrophils. H. influenzae benefits from host nucleases in the presence of neutrophils. These data shed light on the detrimental effects of NETs during host immune response against certain bacterial species that require and/or efficiently take advantage of degraded DNA material, which has been provided by host nuclease or nucleases of other co-infecting bacteria, as growth source.
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Zhang Q, Huang Q, Fang Q, Li H, Tang H, Zou G, Wang D, Li S, Bei W, Chen H, Li L, Zhou R. Identification of genes regulated by the two-component system response regulator NarP of Actinobacillus pleuropneumoniae via DNA-affinity-purified sequencing. Microbiol Res 2019; 230:126343. [PMID: 31539852 DOI: 10.1016/j.micres.2019.126343] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2019] [Revised: 09/08/2019] [Accepted: 09/09/2019] [Indexed: 01/21/2023]
Abstract
Identifying the direct target genes of response regulators (RRs) of a bacterial two-component system (TCS) is critical to understand the roles of TCS in bacterial environmental adaption and pathogenesis. Actinobacillus pleuropneumoniae is an important respiratory bacterial pathogen that causes considerable economic losses to swine industry worldwide. The targets of A. pleuropneumoniae NarP (nitrate/nitrite RR), which is the cognate RR of the nitrate/nitrite sensor histidine kinase NarQ, are still unknown. In the present study, a DNA-affinity-purified sequencing (DAP-Seq) approach was established. The upstream regions of a total of 131 candidate genes from the genome of A. pleuropneumoniae were co-purified with the activated NarP protein. Electrophoretic mobility shift assay (EMSA) results confirmed the interactions of NarP with the promoter regions of five selected target genes, including dmsA, pgaA, ftpA, cstA and ushA. The EMSA-confirmed target genes were significantly up-regulated in the narP-deleted mutant in the presence of additional nitrate, whilst the transcriptional changes were restored in the complemented strain. The NarP binding motif in the upstream regions of the target genes dmsA and ftpA were further identified and confirmed by EMSA using the truncated binding motif. The NarP binding sites were present in a total of 25.2% of the DNA fragments captured by DAP-Seq. These results demonstrated that the established DAP-Seq method is effective for exploring the direct targets of RRs of bacterial TCSs and that the A. pleuropneumoniae NarP could be a repressor in response to nitrate.
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Affiliation(s)
- Qiuhong Zhang
- State Key Laboratory of Agricultural Microbiology, College of Veterinary Medicine, Huazhong Agricultural University, Wuhan, Hubei, 430070, China; Key Laboratory of Preventive Veterinary Medicine in Hubei Province, The Cooperative Innovation Center for Sustainable Pig Production, Wuhan, Hubei, 430070, China
| | - Qi Huang
- State Key Laboratory of Agricultural Microbiology, College of Veterinary Medicine, Huazhong Agricultural University, Wuhan, Hubei, 430070, China; Key Laboratory of Preventive Veterinary Medicine in Hubei Province, The Cooperative Innovation Center for Sustainable Pig Production, Wuhan, Hubei, 430070, China
| | - Qiong Fang
- State Key Laboratory of Agricultural Microbiology, College of Veterinary Medicine, Huazhong Agricultural University, Wuhan, Hubei, 430070, China; Key Laboratory of Preventive Veterinary Medicine in Hubei Province, The Cooperative Innovation Center for Sustainable Pig Production, Wuhan, Hubei, 430070, China
| | - Haotian Li
- State Key Laboratory of Agricultural Microbiology, College of Veterinary Medicine, Huazhong Agricultural University, Wuhan, Hubei, 430070, China; Key Laboratory of Preventive Veterinary Medicine in Hubei Province, The Cooperative Innovation Center for Sustainable Pig Production, Wuhan, Hubei, 430070, China
| | - Hao Tang
- State Key Laboratory of Agricultural Microbiology, College of Veterinary Medicine, Huazhong Agricultural University, Wuhan, Hubei, 430070, China; Key Laboratory of Preventive Veterinary Medicine in Hubei Province, The Cooperative Innovation Center for Sustainable Pig Production, Wuhan, Hubei, 430070, China
| | - Geng Zou
- State Key Laboratory of Agricultural Microbiology, College of Veterinary Medicine, Huazhong Agricultural University, Wuhan, Hubei, 430070, China; Key Laboratory of Preventive Veterinary Medicine in Hubei Province, The Cooperative Innovation Center for Sustainable Pig Production, Wuhan, Hubei, 430070, China
| | - Dong Wang
- State Key Laboratory of Agricultural Microbiology, College of Veterinary Medicine, Huazhong Agricultural University, Wuhan, Hubei, 430070, China; Key Laboratory of Preventive Veterinary Medicine in Hubei Province, The Cooperative Innovation Center for Sustainable Pig Production, Wuhan, Hubei, 430070, China
| | - Siqi Li
- State Key Laboratory of Agricultural Microbiology, College of Veterinary Medicine, Huazhong Agricultural University, Wuhan, Hubei, 430070, China; Key Laboratory of Preventive Veterinary Medicine in Hubei Province, The Cooperative Innovation Center for Sustainable Pig Production, Wuhan, Hubei, 430070, China
| | - Weicheng Bei
- State Key Laboratory of Agricultural Microbiology, College of Veterinary Medicine, Huazhong Agricultural University, Wuhan, Hubei, 430070, China; Key Laboratory of Preventive Veterinary Medicine in Hubei Province, The Cooperative Innovation Center for Sustainable Pig Production, Wuhan, Hubei, 430070, China; Key Laboratory of Development of Veterinary Diagnostic Products, Ministry of Agriculture and Rural Affairs of the People's Republic of China, Wuhan, Hubei, 430070, China; International Research Center for Animal Disease, Ministry of Science and Technology of the People's Republic of China, Wuhan, Hubei, 430070, China
| | - Huanchun Chen
- State Key Laboratory of Agricultural Microbiology, College of Veterinary Medicine, Huazhong Agricultural University, Wuhan, Hubei, 430070, China; Key Laboratory of Preventive Veterinary Medicine in Hubei Province, The Cooperative Innovation Center for Sustainable Pig Production, Wuhan, Hubei, 430070, China; Key Laboratory of Development of Veterinary Diagnostic Products, Ministry of Agriculture and Rural Affairs of the People's Republic of China, Wuhan, Hubei, 430070, China; International Research Center for Animal Disease, Ministry of Science and Technology of the People's Republic of China, Wuhan, Hubei, 430070, China
| | - Lu Li
- State Key Laboratory of Agricultural Microbiology, College of Veterinary Medicine, Huazhong Agricultural University, Wuhan, Hubei, 430070, China; Key Laboratory of Preventive Veterinary Medicine in Hubei Province, The Cooperative Innovation Center for Sustainable Pig Production, Wuhan, Hubei, 430070, China; Key Laboratory of Development of Veterinary Diagnostic Products, Ministry of Agriculture and Rural Affairs of the People's Republic of China, Wuhan, Hubei, 430070, China; International Research Center for Animal Disease, Ministry of Science and Technology of the People's Republic of China, Wuhan, Hubei, 430070, China.
| | - Rui Zhou
- State Key Laboratory of Agricultural Microbiology, College of Veterinary Medicine, Huazhong Agricultural University, Wuhan, Hubei, 430070, China; Key Laboratory of Preventive Veterinary Medicine in Hubei Province, The Cooperative Innovation Center for Sustainable Pig Production, Wuhan, Hubei, 430070, China; Key Laboratory of Development of Veterinary Diagnostic Products, Ministry of Agriculture and Rural Affairs of the People's Republic of China, Wuhan, Hubei, 430070, China; International Research Center for Animal Disease, Ministry of Science and Technology of the People's Republic of China, Wuhan, Hubei, 430070, China.
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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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Mohamed AM, Vladimirovna SN, Grigorievich ZV, Borisovna PA, Ivanovich SV. Sodium Oleate Increases Ampicillin Sensitivity in Methylophilus quaylei Biofilms on Teflon and Polypropylene. Curr Pharm Biotechnol 2019; 20:261-270. [DOI: 10.2174/1389201020666190222191656] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2018] [Revised: 01/14/2019] [Accepted: 02/14/2019] [Indexed: 01/22/2023]
Abstract
Background:Drug combination is a new therapy to improve antibiotic deficiency treatment towards biofilm resistance.Objective:This study was conducted to determine the potential effect of sodium oleate to inhibit established biofilms of two strains, methylotrophic bacteria Methylophilus quaylei in combination with ampicillin. Minimum inhibitory concentration (MIC) of ampicillin was determined and added in combination with sodium oleate and examined on planktonic and established biofilms of two strains M. quaylei were characterized by different properties of cell surface hydrophobicity.Methods:The effect on biofilms was evaluated by the number of colony forming units (CFUs), crystal violet assay, light and scanning electron microscopy.Results:The study demonstrates that sodium oleate has a promoting activity against planktonic growth of M. quaylei strains and has a slight inhibitory effect on biofilm. Addition of sodium oleate enhances the bactericidal effect of ampicillin against biofilm cells. Combination of ampicillin 0.1 mg/ml (MIC) and sodium oleate 0.03 mg/ml showed a remarkable destruction effect on established biofilms.Discussion:Combination of ampicillin 0.1 mg/ml (MIC) and sodium oleate 0.03 mg/ml showed a remarkable destruction effect on established biofilms. Overall, results indicated that sodium oleate in combination with ampicillin enhances the inhibition of M. quaylei biofilms and this combination can be utilized for combating bacterial biofilm resistance.Conclusion:Overall, results indicated that sodium oleate in combination with ampicillin enhances the inhibition of M. quaylei biofilms and this combination can be utilized for combating bacterial biofilm resistance.
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Affiliation(s)
- Abir M.H.A. Mohamed
- Department of Biotechnology and Industrial Pharmacy, M.V. Lomonosov Institute of Fine Chemical Technologies, MIREA-Russian Technological University, 119571 Moscow, Russian Federation
| | - Shevlyagina N. Vladimirovna
- Gamaleya Federal Research Centre for Microbiology and Immunology of the Ministry of Public Health, Moscow, Russian Federation
| | - Zhukhovitsky V. Grigorievich
- Gamaleya Federal Research Centre for Microbiology and Immunology of the Ministry of Public Health, Moscow, Russian Federation
| | - Pshenichnikova A. Borisovna
- Department of Biotechnology and Industrial Pharmacy, M.V. Lomonosov Institute of Fine Chemical Technologies, MIREA-Russian Technological University, 119571 Moscow, Russian Federation
| | - Shvets V. Ivanovich
- Department of Biotechnology and Industrial Pharmacy, M.V. Lomonosov Institute of Fine Chemical Technologies, MIREA-Russian Technological University, 119571 Moscow, Russian Federation
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Co-regulation of CodY and (p)ppGpp synthetases on morphology and pathogenesis of Streptococcus suis. Microbiol Res 2019; 223-225:88-98. [PMID: 31178056 DOI: 10.1016/j.micres.2019.04.001] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2018] [Revised: 02/28/2019] [Accepted: 04/06/2019] [Indexed: 01/04/2023]
Abstract
CodY and (p)ppGpp synthetases are two important global regulators of bacteria. In some pathogens, such as Listeria monocytogenes, the GTP pool links these two regulatory systems, and introducing a codY mutant into the ΔrelA strain restored the pathogenicity of the attenuated ΔrelA mutant. In previous studies, we identified the (p)ppGpp synthetases (RelA and RelQ) and CodY of Streptococcus suis. To understand the interrelationships between these two regulators in S. suis, a ΔrelAΔrelQΔcodY mutant was constructed, and its growth, morphology, and pathogenicity were evaluated. Compared with ΔrelAΔrelQ, ΔcodY, its growth was very slow, but its chain length was partly restored to the wild-type length and its capsule became thick and rough. The adherence, invasion ability, and resistance to whole-blood killing in vitro of ΔrelAΔrelQΔcodY and its lethality and colonization ability in mice were clearly reduced, which differs from the effects of these mutations in L. monocytogenes. An analysis of gene expression showed that CodY interacted with the relA promoter in a GTP-independent manner to positively regulate the expression of relA. The introduction of a codY mutant into the ΔrelAΔrelQ strain further reduced the expression of virulence factors, which suggests a novel interaction between the (p)ppGpp synthetases and CodY. This study extends our understanding of the relationship between the (p)ppGpp-mediated stringent response and the regulation of CodY in S. suis.
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Stumpp NS, Konze SA, Gerardy-Schahn R, Stiesch M, Buettner FFR. A single-step transconjugation system for gene deletion in Aggregatibacter actinomycetemcomitans. J Microbiol Methods 2018; 148:74-77. [PMID: 29627600 DOI: 10.1016/j.mimet.2018.04.002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2018] [Revised: 04/03/2018] [Accepted: 04/03/2018] [Indexed: 11/25/2022]
Abstract
Aggregatibacter (A.) actinomycetemcomitans is a periodontopathogenic bacterium causing aggressive periodontitis. Here we describe a single-step transconjugation system as novel and easily applicable protocol for site-specific genetic manipulation of A. actinomycetemcomitans. Deletion of PgaC, which is involved in the synthesis of biofilm matrix, led to a reduced biofilm formation.
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Affiliation(s)
- Nico S Stumpp
- Department of Prosthetic Dentistry and Biomedical Materials Science, Hannover Medical School, Germany
| | - Sarah A Konze
- Institute of Clinical Biochemistry, Hannover Medical School, Germany
| | | | - Meike Stiesch
- Department of Prosthetic Dentistry and Biomedical Materials Science, Hannover Medical School, Germany.
| | - Falk F R Buettner
- Institute of Clinical Biochemistry, Hannover Medical School, Germany.
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Yuan F, Liu J, You W, Bei W, Wang C, Zhao J, Tian Y, Liu S. Generation, safety and immunogenicity of an Actinobacillus pleuropneumoniae quintuple deletion mutant SLW07 (ΔapxICΔapxIICΔorf1ΔcpxARΔarcA). Vaccine 2018; 36:1830-1836. [PMID: 29486946 DOI: 10.1016/j.vaccine.2018.02.083] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2017] [Revised: 02/05/2018] [Accepted: 02/19/2018] [Indexed: 10/18/2022]
Abstract
We inactivated a virulence determinant, ArcA, in an Actinobacillus pleuropneumoniae quadruple deletion mutant SLW06 (ΔapxICΔapxIICΔorf1ΔcpxAR, serovar 1), and a quintuple deletion mutant SLW07 was generated. SLW07 showed decreased adherence to and invasion of host cells, compared to its parent strain SLW06. SLW07 was more sensitive in RAW264.7 macrophage-mediated phagocytosis and clearance. SLW07 was less virulent in mice. An immunization assay indicated that both SLW07 and SLW06 preferentially stimulated T helper cell type 2 response in mice. Live vaccines induced the production of interleukin-6 and tumor necrosis factor-α by splenic lymphocytes. Furthermore, the protective immunity of SLW07 was not affected after ArcA mutation. Immunization with SLW07 could provide a complete protection following virulent A. pleuropneumoniae challenge in mice. Our results suggest that SLW07 is a promising live vaccine candidate, which is further attenuated from and shares similar protective efficacy with its quadruple deletion parent SLW06.
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Affiliation(s)
- Fangyan Yuan
- Institute of Animal Husbandry and Veterinary Sciences, Hubei Academy of Agricultural Sciences, Key Laboratory of Prevention and Control Agents for Animal Bacteriosis (Ministry of Agriculture), Hubei Key Laboratory of Animal Embryo and Molecular Breeding, Wuhan, Hubei 430064, China
| | - Jinlin Liu
- College of Life Sciences, Central China Normal University, Wuhan, Hubei 430079, China
| | - Wujin You
- State Key Laboratory of Agricultural Microbiology, The Cooperative Innovation Center for Sustainable Pig Production, College of Veterinary Medicine, Huazhong Agricultural University, Wuhan, Hubei 430070, China
| | - Weicheng Bei
- State Key Laboratory of Agricultural Microbiology, The Cooperative Innovation Center for Sustainable Pig Production, College of Veterinary Medicine, Huazhong Agricultural University, Wuhan, Hubei 430070, China
| | - Chunlai Wang
- State Key Laboratory of Veterinary Biotechnology, Harbin Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Harbin 150001, China
| | - Jin Zhao
- College of Life Sciences, Central China Normal University, Wuhan, Hubei 430079, China
| | - Yiongxiang Tian
- Institute of Animal Husbandry and Veterinary Sciences, Hubei Academy of Agricultural Sciences, Key Laboratory of Prevention and Control Agents for Animal Bacteriosis (Ministry of Agriculture), Hubei Key Laboratory of Animal Embryo and Molecular Breeding, Wuhan, Hubei 430064, China.
| | - Siguo Liu
- State Key Laboratory of Veterinary Biotechnology, Harbin Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Harbin 150001, China.
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15
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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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16
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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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17
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Ding L, Wen X, He L, Yan X, Wen Y, Cao S, Huang X, Wu R, Wen Y. The arcA gene contributes to the serum resistance and virulence of Haemophilus parasuis serovar 13 clinical strain EP3. Vet Microbiol 2016; 196:67-71. [PMID: 27939158 DOI: 10.1016/j.vetmic.2016.10.011] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2016] [Revised: 08/25/2016] [Accepted: 10/09/2016] [Indexed: 10/20/2022]
Abstract
As a global transcriptional factor, ArcA regulates the expression of hundreds of genes involved in aerobic and anaerobic metabolism. Here we deleted arcA gene and investigated the biological characteristics of arcA deletion mutant (ΔarcA) in Haemophilus parasuis (H. parasuis) serovar 13 clinical strain EP3. Results indicated that deletion of arcA impaired growth of EP3 strain under anaerobic condition, and reduced virulence of EP3 strain in mice. Additionally, the ΔarcA strain showed greater sensitivity in porcine serum and produced less biofilm mass than the EP3 strain. Taken together, these findings suggested that the arcA gene may be involved in pathogenesis in Haemophilus parasuis.
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Affiliation(s)
- Lingqiang Ding
- Research Center of Swine Disease, College of Veterinary Medicine, Sichuan Agricultural University, Chengdu 611130, China.
| | - Xintian Wen
- Research Center of Swine Disease, College of Veterinary Medicine, Sichuan Agricultural University, Chengdu 611130, China.
| | - Lvqin He
- Research Center of Swine Disease, College of Veterinary Medicine, Sichuan Agricultural University, Chengdu 611130, China.
| | - Xuefeng Yan
- Research Center of Swine Disease, College of Veterinary Medicine, Sichuan Agricultural University, Chengdu 611130, China.
| | - Yongping Wen
- Research Center of Swine Disease, College of Veterinary Medicine, Sichuan Agricultural University, Chengdu 611130, China.
| | - Sanjie Cao
- Research Center of Swine Disease, College of Veterinary Medicine, Sichuan Agricultural University, Chengdu 611130, China.
| | - Xiaobo Huang
- Research Center of Swine Disease, College of Veterinary Medicine, Sichuan Agricultural University, Chengdu 611130, China.
| | - Rui Wu
- Research Center of Swine Disease, College of Veterinary Medicine, Sichuan Agricultural University, Chengdu 611130, China.
| | - Yiping Wen
- Research Center of Swine Disease, College of Veterinary Medicine, Sichuan Agricultural University, Chengdu 611130, China.
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Qin W, Wang L, Zhai R, Ma Q, Liu J, Bao C, Zhang H, Sun C, Feng X, Gu J, Du C, Han W, Langford PR, Lei L. Trimeric autotransporter adhesins contribute to Actinobacillus pleuropneumoniae pathogenicity in mice and regulate bacterial gene expression during interactions between bacteria and porcine primary alveolar macrophages. Antonie van Leeuwenhoek 2015; 109:51-70. [PMID: 26494209 DOI: 10.1007/s10482-015-0609-x] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/20/2015] [Accepted: 10/14/2015] [Indexed: 11/27/2022]
Abstract
Actinobacillus pleuropneumoniae is an important pathogen that causes respiratory disease in pigs. Trimeric autotransporter adhesin (TAA) is a recently discovered bacterial virulence factor that mediates bacterial adhesion and colonization. Two TAA coding genes have been found in the genome of A. pleuropneumoniae strain 5b L20, but whether they contribute to bacterial pathogenicity is unclear. In this study, we used homologous recombination to construct a double-gene deletion mutant, ΔTAA, in which both TAA coding genes were deleted and used it in in vivo and in vitro studies to confirm that TAAs participate in bacterial auto-aggregation, biofilm formation, cell adhesion and virulence in mice. A microarray analysis was used to determine whether TAAs can regulate other A. pleuropneumoniae genes during interactions with porcine primary alveolar macrophages. The results showed that deletion of both TAA coding genes up-regulated 36 genes, including ene1514, hofB and tbpB2, and simultaneously down-regulated 36 genes, including lgt, murF and ftsY. These data illustrate that TAAs help to maintain full bacterial virulence both directly, through their bioactivity, and indirectly by regulating the bacterial type II and IV secretion systems and regulating the synthesis or secretion of virulence factors. This study not only enhances our understanding of the role of TAAs but also has significance for those studying A. pleuropneumoniae pathogenesis.
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Affiliation(s)
- Wanhai Qin
- College of Veterinary Medicine, Jilin University, Changchun, People's Republic of China
| | - Lei Wang
- College of Veterinary Medicine, Jilin University, Changchun, People's Republic of China.,College of Animal Science, Henan Institute of Science and Technology, Xinxiang, People's Republic of China
| | - Ruidong Zhai
- College of Veterinary Medicine, Jilin University, Changchun, People's Republic of China
| | - Qiuyue Ma
- College of Veterinary Medicine, Jilin University, Changchun, People's Republic of China
| | - Jianfang Liu
- College of Veterinary Medicine, Jilin University, Changchun, People's Republic of China
| | - Chuntong Bao
- College of Veterinary Medicine, Jilin University, Changchun, People's Republic of China
| | - Hu Zhang
- School of Public Health, Jilin University, Changchun, People's Republic of China
| | - Changjiang Sun
- College of Veterinary Medicine, Jilin University, Changchun, People's Republic of China
| | - Xin Feng
- College of Veterinary Medicine, Jilin University, Changchun, People's Republic of China
| | - Jingmin Gu
- College of Veterinary Medicine, Jilin University, Changchun, People's Republic of China
| | - Chongtao Du
- College of Veterinary Medicine, Jilin University, Changchun, People's Republic of China
| | - Wenyu Han
- College of Veterinary Medicine, Jilin University, Changchun, People's Republic of China
| | - P R Langford
- Section of Paediatrics, Imperial College London, London, UK
| | - Liancheng Lei
- College of Veterinary Medicine, Jilin University, Changchun, People's Republic of China.
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Liu J, Hu L, Xu Z, Tan C, Yuan F, Fu S, Cheng H, Chen H, Bei W. Actinobacillus pleuropneumoniae two-component system QseB/QseC regulates the transcription of PilM, an important determinant of bacterial adherence and virulence. Vet Microbiol 2015; 177:184-92. [PMID: 25796134 DOI: 10.1016/j.vetmic.2015.02.033] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2014] [Revised: 02/23/2015] [Accepted: 02/28/2015] [Indexed: 01/01/2023]
Abstract
QseB/QseC is one of the five predicted two-component systems (TCSs) in Actinobacillus pleuropneumoniae. To understand the roles of this TCS in A. pleuropneumoniae, a markerless gene-deletion mutant ΔqseBC was constructed. Differentially expressed (DE) genes in ΔqseBC were filtered by microarray analysis. A total of 44 DE genes were found to be regulated by QseB/QseC system. The transcriptional profile of A. pleuropneumoniae ΔqseBC was compared with that of ΔluxS and catecholamine (CA) stimulations, 13 genes regulated by QseB/QseC were found also regulated by LuxS, and 3 Qse-regulons were co-regulated by CA stimulations, respectively. Binding of QseB to the promoters of three regulons (pilM, glpK and hugZ), which were co-regulated by QseB/QseC and LuxS, was evaluated by electrophoretic mobility-shift assay. Results indicated that pilM was directly regulated by phosphorylated-QseB. Then the pilM deletion mutant ΔpilM was constructed and characterized. Data presented here revealed that adherence ability of ΔpilM to St. Jude porcine lung cells was significantly decreased, and ΔpilM exhibited reduced virulence in pigs, suggesting PilM contributes to the process of A. pleuropneumoniae infection.
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Affiliation(s)
- Jinlin Liu
- State Key Laboratory of Agricultural Microbiology, College of Veterinary Medicine, Huazhong Agricultural University, Wuhan, Hubei 430070, China; College of Life Sciences, Central China Normal University, Wuhan, Hubei 430079, China
| | - Linlin Hu
- State Key Laboratory of Agricultural Microbiology, College of Veterinary Medicine, Huazhong Agricultural University, Wuhan, Hubei 430070, China
| | - Zhuofei Xu
- State Key Laboratory of Agricultural Microbiology, College of Veterinary Medicine, Huazhong Agricultural University, Wuhan, Hubei 430070, China
| | - Chen Tan
- State Key Laboratory of Agricultural Microbiology, College of Veterinary Medicine, Huazhong Agricultural University, Wuhan, Hubei 430070, China
| | - Fangyan Yuan
- Hubei Key Laboratory of Animal Embryo and Molecular Breeding, Institute of Animal Husbandry and Veterinary Sciences, Hubei Academy of Agricultural Sciences, Wuhan 430064, China
| | - Shulin Fu
- State Key Laboratory of Agricultural Microbiology, College of Veterinary Medicine, Huazhong Agricultural University, Wuhan, Hubei 430070, China
| | - Hui Cheng
- State Key Laboratory of Agricultural Microbiology, College of Veterinary Medicine, Huazhong Agricultural University, Wuhan, Hubei 430070, China
| | - Huanchun Chen
- State Key Laboratory of Agricultural Microbiology, College of Veterinary Medicine, Huazhong Agricultural University, Wuhan, Hubei 430070, China
| | - Weicheng Bei
- State Key Laboratory of Agricultural Microbiology, College of Veterinary Medicine, Huazhong Agricultural University, Wuhan, Hubei 430070, China.
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The generation of successive unmarked mutations and chromosomal insertion of heterologous genes in Actinobacillus pleuropneumoniae using natural transformation. PLoS One 2014; 9:e111252. [PMID: 25409017 PMCID: PMC4237320 DOI: 10.1371/journal.pone.0111252] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2014] [Accepted: 09/26/2014] [Indexed: 12/24/2022] Open
Abstract
We have developed a simple method of generating scarless, unmarked mutations in Actinobacillus pleuropneumoniae by exploiting the ability of this bacterium to undergo natural transformation, and with no need to introduce plasmids encoding recombinases or resolvases. This method involves two successive rounds of natural transformation using linear DNA: the first introduces a cassette carrying cat (which allows selection by chloramphenicol) and sacB (which allows counter-selection using sucrose) flanked by sequences to either side of the target gene; the second transformation utilises the flanking sequences ligated directly to each other in order to remove the cat-sacB cassette. In order to ensure efficient uptake of the target DNA during transformation, A. pleuropneumoniae uptake sequences are added into the constructs used in both rounds of transformation. This method can be used to generate multiple successive deletions and can also be used to introduce targeted point mutations or insertions of heterologous genes into the A. pleuropneumoniae chromosome for development of live attenuated vaccine strains. So far, we have applied this method to highly transformable isolates of serovars 8 (MIDG2331), which is the most prevalent in the UK, and 15 (HS143). By screening clinical isolates of other serovars, it should be possible to identify other amenable strains.
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Green J, Rolfe MD, Smith LJ. Transcriptional regulation of bacterial virulence gene expression by molecular oxygen and nitric oxide. Virulence 2014; 5:794-809. [PMID: 25603427 PMCID: PMC4601167 DOI: 10.4161/viru.27794] [Citation(s) in RCA: 59] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
Molecular oxygen (O2) and nitric oxide (NO) are diatomic gases that play major roles in infection. The host innate immune system generates reactive oxygen species and NO as bacteriocidal agents and both require O2 for their production. Furthermore, the ability to adapt to changes in O2 availability is crucial for many bacterial pathogens, as many niches within a host are hypoxic. Pathogenic bacteria have evolved transcriptional regulatory systems that perceive these gases and respond by reprogramming gene expression. Direct sensors possess iron-containing co-factors (iron–sulfur clusters, mononuclear iron, heme) or reactive cysteine thiols that react with O2 and/or NO. Indirect sensors perceive the physiological effects of O2 starvation. Thus, O2 and NO act as environmental cues that trigger the coordinated expression of virulence genes and metabolic adaptations necessary for survival within a host. Here, the mechanisms of signal perception by key O2- and NO-responsive bacterial transcription factors and the effects on virulence gene expression are reviewed, followed by consideration of these aspects of gene regulation in two major pathogens, Staphylococcus aureus and Mycobacterium tuberculosis.
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Key Words
- AIP, autoinducer peptide
- Arc, Aerobic respiratory control
- FNR
- FNR, fumarate nitrate reduction regulator
- GAF, cGMP-specific phosphodiesterase-adenylyl cyclase-FhlA domain
- Isc, iron–sulfur cluster biosynthesis machinery
- Mycobacterium tuberculosis
- NOX, NADPH oxidase
- PAS, Per-Amt-Sim domain
- RNS, reactive nitrogen species
- ROS, reactive oxygen species
- Staphylococcus aureus
- TB, tuberculosis
- WhiB-like proteins
- iNOS, inducible nitric oxide synthase
- iron–sulfur cluster
- nitric oxide sensors
- oxygen sensors
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Affiliation(s)
- Jeffrey Green
- a Krebs Institute; Molecular Biology & Biotechnology; University of Sheffield ; Western Bank , Sheffield , UK
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Li L, Zhu J, Yang K, Xu Z, Liu Z, Zhou R. Changes in gene expression of Actinobacillus pleuropneumoniae in response to anaerobic stress reveal induction of central metabolism and biofilm formation. J Microbiol 2014; 52:473-81. [DOI: 10.1007/s12275-014-3456-y] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2013] [Revised: 12/23/2013] [Accepted: 01/03/2014] [Indexed: 01/07/2023]
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The RNA chaperone Hfq promotes fitness of Actinobacillus pleuropneumoniae during porcine pleuropneumonia. Infect Immun 2013; 81:2952-61. [PMID: 23732171 DOI: 10.1128/iai.00392-13] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
Actinobacillus pleuropneumoniae is the etiological agent of porcine pleuropneumonia, an economically important disease of pigs. The hfq gene in A. pleuropneumoniae, encoding the RNA chaperone and posttranscriptional regulator Hfq, is upregulated during infection of porcine lungs. To investigate the role of this in vivo-induced gene in A. pleuropneumoniae, an hfq mutant strain was constructed. The hfq mutant was defective in biofilm formation on abiotic surfaces. The level of pgaC transcript, encoding the biosynthesis of poly-β-1,6-N-acetylglucosamine (PNAG), a major biofilm matrix component, was lower and PNAG content was 10-fold lower in the hfq mutant than in the wild-type strain. When outer membrane proteins were examined, cysteine synthase, implicated in resistance to oxidative stress and tellurite, was not found at detectable levels in the absence of Hfq. The hfq mutant displayed enhanced sensitivity to superoxide generated by methyl viologen and tellurite. These phenotypes were readily reversed by complementation with the hfq gene expressed from its native promoter. The role of Hfq in the fitness of A. pleuropneumoniae was assessed in a natural host infection model. The hfq mutant failed to colonize porcine lungs and was outcompeted by the wild-type strain (median competitive index of 2 × 10(-5)). Our data demonstrate that the in vivo-induced gene hfq is involved in the regulation of PNAG-dependent biofilm formation, resistance to superoxide stress, and the fitness and virulence of A. pleuropneumoniae in pigs and begin to elucidate the role of an in vivo-induced gene in the pathogenesis of pleuropneumonia.
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Tremblay YDN, Deslandes V, Jacques M. Actinobacillus pleuropneumoniae genes expression in biofilms cultured under static conditions and in a drip-flow apparatus. BMC Genomics 2013; 14:364. [PMID: 23725589 PMCID: PMC3671958 DOI: 10.1186/1471-2164-14-364] [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] [Received: 01/30/2013] [Accepted: 05/14/2013] [Indexed: 12/13/2022] Open
Abstract
Background Actinobacillus pleuropneumoniae is the Gram-negative bacterium responsible for porcine pleuropneumonia. This respiratory infection is highly contagious and characterized by high morbidity and mortality. The objectives of our study were to study the transcriptome of A. pleuropneumoniae biofilms at different stages and to develop a protocol to grow an A. pleuropneumoniae biofilm in a drip-flow apparatus. This biofilm reactor is a system with an air-liquid interface modeling lung-like environment. Bacteria attached to a surface (biofilm) and free floating bacteria (plankton) were harvested for RNA isolation. Labelled cDNA was hybridized to a microarray to compare the expression profiles of planktonic cells and biofilm cells. Results It was observed that 47 genes were differentially expressed (22 up, 25 down) in a 4 h-static growing/maturing biofilm and 117 genes were differentially expressed (49 up, 68 down) in a 6h-static dispersing biofilm. The transcriptomes of a 4 h biofilm and a 6 h biofilm were also compared and 456 genes (235 up, 221 down) were identified as differently expressed. Among the genes identified in the 4 h vs 6h biofilm experiment, several regulators of stress response were down-regulated and energy metabolism associated genes were up-regulated. Biofilm bacteria cultured using the drip-flow apparatus differentially expressed 161 genes (68 up, 93 down) compared to the effluent bacteria. Cross-referencing of differentially transcribed genes in the different assays revealed that drip-flow biofilms shared few differentially expressed genes with static biofilms (4 h or 6 h) but shared several differentially expressed genes with natural or experimental infections in pigs. Conclusion The formation of a static biofilm by A. pleuropneumoniae strain S4074 is a rapid process and transcriptional analysis indicated that dispersal observed at 6 h is driven by nutritional stresses. Furthermore, A. pleuropneumoniae can form a biofilm under low-shear force in a drip-flow apparatus and analyses indicated that the formation of a biofilm under low-shear force requires a different sub-set of genes than a biofilm grown under static conditions. The drip-flow apparatus may represent the better in vitro model to investigate biofilm formation of A. pleuropneumoniae.
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Affiliation(s)
- Yannick D N Tremblay
- Groupe de recherche sur les maladies infectieuses du porc, Faculté de médecine vétérinaire, Université de Montréal, 3200 Sicotte, St-Hyacinthe, Québec J2S 7C6, Canada
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Xie F, Zhang Y, Li G, Zhou L, Liu S, Wang C. The ClpP protease is required for the stress tolerance and biofilm formation in Actinobacillus pleuropneumoniae. PLoS One 2013; 8:e53600. [PMID: 23326465 PMCID: PMC3543445 DOI: 10.1371/journal.pone.0053600] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2012] [Accepted: 11/30/2012] [Indexed: 01/12/2023] Open
Abstract
In the respiratory tract and lung tissue, a balanced physiological response is essential for Actinobacillus pleuropneumoniae to survive various types of challenges. ClpP, the catalytic core of the Clp proteolytic complex, is involved in various stresses response and regulation of biofilm formation in many pathogenic bacteria. To investigate the role of ClpP in the virulence of A. pleuropneumoniae, the clpP gene was deleted by homologous recombination, resulting in the mutant strain S8ΔclpP. The reduced growth of S8ΔclpP mutant at high temperatures and under several other stress conditions suggests that the ClpP protein is required for the stress tolerance of A. pleuropneumoniae. Interestingly, we observed that the S8ΔclpP mutant exhibited an increased ability to take up iron in vitro compared to the wild-type strain. We also found that the cells without ClpP displayed rough and irregular surfaces and increased cell volume relative to the wild-type strain using scanning electron microscopy (SEM). Confocal laser scanning microscopy (CLSM) revealed that the S8ΔclpP mutant showed decreased biofilm formation compared to the wild-type strain. We examined the transcriptional profiles of the wild type S8 and the S8ΔclpP mutant strains of A. pleuropneumoniae using RNA sequencing. Our analysis revealed that the expression of 16 genes was changed by the deletion of the clpP gene. The data presented in this study illustrate the important role of ClpP protease in the stress response, iron acquisition, cell morphology and biofilm formation related to A. pleuropneumoniae and further suggest a putative role of ClpP protease in virulence regulation.
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Affiliation(s)
- Fang Xie
- State Key Laboratory of Veterinary Biotechnology, Division of Bacterial Diseases, Harbin Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Harbin, People's Republic of China
| | - Yanhe Zhang
- State Key Laboratory of Veterinary Biotechnology, Division of Bacterial Diseases, Harbin Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Harbin, People's Republic of China
| | - Gang Li
- State Key Laboratory of Veterinary Biotechnology, Division of Bacterial Diseases, Harbin Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Harbin, People's Republic of China
| | - Long Zhou
- State Key Laboratory of Veterinary Biotechnology, Division of Bacterial Diseases, Harbin Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Harbin, People's Republic of China
| | - Siguo Liu
- State Key Laboratory of Veterinary Biotechnology, Division of Bacterial Diseases, Harbin Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Harbin, People's Republic of China
| | - Chunlai Wang
- State Key Laboratory of Veterinary Biotechnology, Division of Bacterial Diseases, Harbin Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Harbin, People's Republic of China
- * E-mail:
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Giaouris E, Samoilis G, Chorianopoulos N, Ercolini D, Nychas GJ. Differential protein expression patterns between planktonic and biofilm cells of Salmonella enterica serovar Enteritidis PT4 on stainless steel surface. Int J Food Microbiol 2013; 162:105-13. [PMID: 23376784 DOI: 10.1016/j.ijfoodmicro.2012.12.023] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2012] [Revised: 12/27/2012] [Accepted: 12/28/2012] [Indexed: 10/27/2022]
Abstract
In the present study, the proteome of a strain of S. enterica serovar Enteritidis PT4, grown either as biofilm on stainless steel surface or as free-floating (planktonic) in Brain Heart (BH) broth, was investigated in order to detect the strong differences in whole-cell protein expression patterns between the two growth styles. The proteins extracted from both types of cells were subjected to 2-D PAGE, followed by in-gel tryptic digestion, extraction, subsequent MALDI-TOF mass spectrometry (MS) analysis and finally database searches for protein identification. Using this approach, 30 proteins were identified as differentially expressed between the two growth modes on an "on-off" basis, that is, proteins that were detected in one case but not in the other. In particular, 20 and 10 proteins were identified in biofilm and planktonic-grown cells, respectively. The group of proteins whose expression was visible only during biofilm growth included proteins involved in global regulation and stress response (ArcA, BtuE, Dps, OsmY, SspA, TrxA, YbbN and YhbO), nutrient transport (Crr, DppA, Fur and SufC), degradation and energy metabolism (GcvT, GpmA, RibB), detoxification (SseA and YibF), DNA metabolism (SSB), curli production (CsgF), and murein synthesis (MipA). To summarize, this study demonstrates that biofilm growth of S. Enteritidis causes distinct changes in protein expression and offers valuable new data regarding some of the proteins presumably involved in this process. The putative role of these proteins in the maintenance of a biofilm community in Salmonella and other bacteria is discussed.
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Affiliation(s)
- Efstathios Giaouris
- Department of Food Science and Nutrition, University of the Aegean, Mitropoliti Ioakeim 2, Myrina, 81400 Lemnos, Greece.
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Global effects of catecholamines on Actinobacillus pleuropneumoniae gene expression. PLoS One 2012; 7:e31121. [PMID: 22347439 PMCID: PMC3275570 DOI: 10.1371/journal.pone.0031121] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2011] [Accepted: 01/03/2012] [Indexed: 11/26/2022] Open
Abstract
Bacteria can use mammalian hormones to modulate pathogenic processes that play essential roles in disease development. Actinobacillus pleuropneumoniae is an important porcine respiratory pathogen causing great economic losses in the pig industry globally. Stress is known to contribute to the outcome of A. pleuropneumoniae infection. To test whether A. pleuropneumoniae could respond to stress hormone catecholamines, gene expression profiles after epinephrine (Epi) and norepinephrine (NE) treatment were compared with those from untreated bacteria. The microarray results showed that 158 and 105 genes were differentially expressed in the presence of Epi and NE, respectively. These genes were assigned to various functional categories including many virulence factors. Only 18 genes were regulated by both hormones. These genes included apxIA (the ApxI toxin structural gene), pgaB (involved in biofilm formation), APL_0443 (an autotransporter adhesin) and genes encoding potential hormone receptors such as tyrP2, the ygiY-ygiX (qseC-qseB) operon and narQ-narP (involved in nitrate metabolism). Further investigations demonstrated that cytotoxic activity was enhanced by Epi but repressed by NE in accordance with apxIA gene expression changes. Biofilm formation was not affected by either of the two hormones despite pgaB expression being affected. Adhesion to host cells was induced by NE but not by Epi, suggesting that the hormones affect other putative adhesins in addition to APL_0443. This study revealed that A. pleuropneumoniae gene expression, including those encoding virulence factors, was altered in response to both catecholamines. The differential regulation of A. pleuropneumoniae gene expression by the two hormones suggests that this pathogen may have multiple responsive systems for the two catecholamines.
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Novel genes associated with biofilm formation of Actinobacillus pleuropneumoniae. Vet Microbiol 2011; 153:134-43. [DOI: 10.1016/j.vetmic.2011.03.029] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2010] [Revised: 03/14/2011] [Accepted: 03/23/2011] [Indexed: 12/15/2022]
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ArcA-regulated glycosyltransferase lic2B promotes complement evasion and pathogenesis of nontypeable Haemophilus influenzae. Infect Immun 2011; 79:1971-83. [PMID: 21357723 DOI: 10.1128/iai.01269-10] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023] Open
Abstract
Signaling mechanisms used by Haemophilus influenzae to adapt to conditions it encounters during stages of infection and pathogenesis are not well understood. The ArcAB two-component signal transduction system controls gene expression in response to respiratory conditions of growth and contributes to resistance to bactericidal effects of serum and to bloodstream infection by H. influenzae. We show that ArcA of nontypeable H. influenzae (NTHI) activates expression of a glycosyltransferase gene, lic2B. Structural comparison of the lipooligosaccharide (LOS) of a lic2B mutant to that of the wild-type strain NT127 revealed that lic2B is required for addition of a galactose residue to the LOS outer core. The lic2B gene was crucial for optimal survival of NTHI in a mouse model of bacteremia and for evasion of serum complement. The results demonstrate that ArcA, which controls cellular metabolism in response to environmental reduction and oxidation (redox) conditions, also coordinately controls genes that are critical for immune evasion, providing evidence that NTHI integrates redox signals to regulate specific countermeasures against host defense.
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Li L, Xu Z, Zhou Y, Li T, Sun L, Chen H, Zhou R. Analysis on Actinobacillus pleuropneumoniae LuxS regulated genes reveals pleiotropic roles of LuxS/AI-2 on biofilm formation, adhesion ability and iron metabolism. Microb Pathog 2011; 50:293-302. [PMID: 21320583 DOI: 10.1016/j.micpath.2011.02.002] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2010] [Revised: 01/31/2011] [Accepted: 02/04/2011] [Indexed: 12/20/2022]
Abstract
LuxS is an enzyme involved in the activated methyl cycle and the by-product autoinducer-2 (AI-2) was a quorum sensing signal in some species. In our previous study, the functional LuxS in AI-2 production was verified in the porcine respiratory pathogen Actinobacillus pleuropneumoniae. Enhanced biofilm formation and reduced virulence were observed in the luxS mutant. To comprehensively understand the luxS function, in this study, the transcriptional profiles were compared between the A. pleuropneumoniae luxS mutant and its parental strain in four different growth phases using microarray. Many genes associated with infection were differentially expressed. The biofilm formation genes pgaABC in the luxS mutant were up-regulated in early exponential phase, while 9 genes associated with adhesion were down-regulated in late exponential phase. A group of genes involved in iron acquisition and metabolism were regulated in four growth phases. Phenotypic investigations using luxS mutant and both genetic and chemical (AI-2) complementation on these virulence traits were performed. The results demonstrated that the luxS mutant showed enhanced biofilm formation and reduced adhesion ability and these effects were not due to lack of AI-2. But AI-2 could increase biofilm formation and adhesion of A. pleuropneumoniae independent of LuxS. Growth under iron restricted condition could be controlled by LuxS through AI-2 production. These results revealed pleiotropic roles of LuxS and AI-2 on A. pleuropneumoniae virulence traits.
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Affiliation(s)
- Lu Li
- Division of Animal Infectious Diseases, State Key Laboratory of Agricultural Microbiology, College of Veterinary Medicine, Huazhong Agricultural University, Shizishan Street 1, Wuhan 430070, China
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Abstract
Bacterial biofilms are structured communities of bacterial cells enclosed in a self-produced polymer matrix that is attached to a surface. Biofilms protect and allow bacteria to survive and thrive in hostile environments. Bacteria within biofilms can withstand host immune responses, and are much less susceptible to antibiotics and disinfectants when compared with their planktonic counterparts. The ability to form biofilms is now considered a universal attribute of micro-organisms. Diseases associated with biofilms require novel methods for their prevention, diagnosis and treatment; this is largely due to the properties of biofilms. Surprisingly, biofilm formation by bacterial pathogens of veterinary importance has received relatively little attention. Here, we review the current knowledge of bacterial biofilms as well as studies performed on animal pathogens.
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Chiers K, De Waele T, Pasmans F, Ducatelle R, Haesebrouck F. Virulence factors of Actinobacillus pleuropneumoniae involved in colonization, persistence and induction of lesions in its porcine host. Vet Res 2010; 41:65. [PMID: 20546697 PMCID: PMC2899255 DOI: 10.1051/vetres/2010037] [Citation(s) in RCA: 148] [Impact Index Per Article: 10.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2009] [Accepted: 06/10/2010] [Indexed: 12/17/2022] Open
Abstract
Actinobacillus pleuropneumoniae is the causative agent of porcine pleuropneumonia. The virulence factors of this microorganism involved in colonization and the induction of lung lesions have been thoroughly studied and some have been well characterized. A. pleuropneumoniae binds preferentially to cells of the lower respiratory tract in a process involving different adhesins and probably biofilm formation. Apx toxins and lipopolysaccharides exert pathogenic effects on several host cells, resulting in typical lung lesions. Lysis of host cells is essential for the bacterium to obtain nutrients from the environment and A. pleuropneumoniae has developed several uptake mechanisms for these nutrients. In addition to persistence in lung lesions, colonization of the upper respiratory tract – and of the tonsils in particular – may also be important for long-term persistent asymptomatic infection. Information on virulence factors involved in tonsillar and nasal cavity colonization and persistence is scarce, but it can be speculated that similar features as demonstrated for the lung may play a role.
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Affiliation(s)
- Koen Chiers
- Department of Pathology, Bacteriology and Poultry Diseases, Faculty of Veterinary Medicine, Ghent University, Ghent, Belgium.
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Labrie J, Pelletier-Jacques G, Deslandes V, Ramjeet M, Auger E, Nash JHE, Jacques M. Effects of growth conditions on biofilm formation by Actinobacillus pleuropneumoniae. Vet Res 2009; 41:3. [PMID: 19737507 PMCID: PMC2762130 DOI: 10.1051/vetres/2009051] [Citation(s) in RCA: 52] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2009] [Accepted: 09/08/2009] [Indexed: 11/26/2022] Open
Abstract
Biofilm formation is an important virulence trait of many bacterial pathogens. It has been reported in the literature that only two of the reference strains of the swine pathogen Actinobacillus pleuropneumoniae, representing serotypes 5b and 11, were able to form biofilm in vitro. In this study, we compared biofilm formation by the serotype 1 reference strain S4074 of A. pleuropneumoniae grown in five different culture media. We observed that strain S4074 of A. pleuropneumoniae is able to form biofilms after growth in one of the culture conditions tested brain heart infusion (BHI medium, supplier B). Confocal laser scanning microscopy using a fluorescent probe specific to the poly-N-acetylglucosamine (PGA) polysaccharide further confirmed biofilm formation. In accordance, biofilm formation was susceptible to dispersin B, a PGA hydrolase. Transcriptional profiles of A. pleuropneumoniae S4074 following growth in BHI-B, which allowed a robust biofilm formation, and in BHI-A, in which only a slight biofilm formation was observed, were compared. Genes such as tadC, tadD, genes with homology to autotransporter adhesins as well as genes pgaABC involved in PGA biosynthesis and genes involved in zinc transport were up-regulated after growth in BHI-B. Interestingly, biofilm formation was inhibited by zinc, which was found to be more present in BHI-A (no or slight biofilm) than in BHI-B. We also observed biofilm formation in reference strains representing serotypes 3, 4, 5a, 12 and 14 as well as in 20 of the 37 fresh field isolates tested. Our data indicate that A. pleuropneumoniae has the ability to form biofilms under appropriate growth conditions and transition from a biofilm-positive to a biofilm-negative phenotype was reversible.
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Affiliation(s)
- Josée Labrie
- Groupe de recherche sur les maladies infectieuses du porc et Centre de recherche en infectiologie porcine, Faculté de médecine vétérinaire, Université de Montréal, 3200 Sicotte, St-Hyacinthe, Québec, Canada
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An isogenic Actinobacillus pleuropneumoniae AasP mutant exhibits altered biofilm formation but retains virulence. Vet Microbiol 2009; 137:392-6. [DOI: 10.1016/j.vetmic.2009.01.026] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2008] [Revised: 01/13/2009] [Accepted: 01/19/2009] [Indexed: 11/20/2022]
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Buettner FFR, Bendalla IM, Bossé JT, Meens J, Nash JHE, Härtig E, Langford PR, Gerlach GF. Analysis of the
Actinobacillus pleuropneumoniae
HlyX (FNR) regulon and identification of iron-regulated protein B as an essential virulence factor. Proteomics 2009; 9:2383-98. [DOI: 10.1002/pmic.200800439] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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Dalai B, Zhou R, Wan Y, Kang M, Li L, Li T, Zhang S, Chen H. Histone-like protein H-NS regulates biofilm formation and virulence of Actinobacillus pleuropneumoniae. Microb Pathog 2008; 46:128-34. [PMID: 19095055 DOI: 10.1016/j.micpath.2008.11.005] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2008] [Revised: 11/18/2008] [Accepted: 11/21/2008] [Indexed: 10/21/2022]
Abstract
Actinobacillus pleuropneumoniae is the causative agent of porcine contagious pleuropneumonia, a very important swine respiratory infectious disease causing great economic losses worldwide. The pathogenesis of this disease is still not completely understood. Biofilm formation contributes to full virulence in many Gram-negative bacterial pathogens. In the present study, two biofilm-producing mutants were identified from the transposon mutagenesis mutant pools of A. pleuropneumoniae strain 4074 of serovar 1 (a non-biofilm forming strain). Inverse PCR and sequencing analysis revealed that the hns gene encoding the histone-like nucleoid structuring protein (H-NS) was inactivated by the mini-Tn10 transposon in both mutant strains. Further analysis revealed that the virulence was attenuated in the mutant strains when their haemolytic activity and 50% lethal doses in mice were compared with the parental strain. Real-time RT-PCR analysis suggested that the down-regulation of the exotoxin genes in the hns mutants may partly contribute to the virulence attenuation. Our data indicate that H-NS plays important roles in regulating biofilm formation and virulence in A. pleuropneumoniae.
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Affiliation(s)
- Baolige Dalai
- Division of Animal Infectious Diseases, State Key Laboratory of Agricultural Microbiology, College of Veterinary Medicine, Huazhong Agricultural University, Shizishan Street 1, Wuhan 430070, China
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Liu J, Tan C, Li J, Chen H, Xu P, He Q, Bei W, Chen H. Characterization of ISApl1, an insertion element identified from Actinobacillus pleuropneumoniae field isolate in China. Vet Microbiol 2008; 132:348-54. [DOI: 10.1016/j.vetmic.2008.05.031] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2008] [Revised: 05/15/2008] [Accepted: 05/20/2008] [Indexed: 10/22/2022]
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Functional characterization of AasP, a maturation protease autotransporter protein of Actinobacillus pleuropneumoniae. Infect Immun 2008; 76:5608-14. [PMID: 18852244 DOI: 10.1128/iai.00085-08] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023] Open
Abstract
Actinobacillus pleuropneumoniae is the etiological agent of porcine pleuropneumonia, a highly contagious respiratory infection in pigs. AasP, a putative subtilisin-like serine protease autotransporter, has recently been identified in A. pleuropneumoniae. We hypothesized that, similarly to other autotransporters of this type, AasP may undergo autocatalytic cleavage resulting in release of the passenger domain of the protein. Furthermore, AasP may be responsible for cleavage of other A. pleuropneumoniae outer membrane proteins. To address these hypotheses, the aasP gene was cloned and the expressed recombinant AasP protein used to raise monospecific rabbit antiserum. Immunoblot analysis of whole-cell lysates and secreted proteins demonstrated that AasP does not undergo proteolytic cleavage. Immunoblot analysis also confirmed that AasP is universally expressed by A. pleuropneumoniae. Confirmation of the maturation protease function of AasP was obtained through phenotypic analysis of an A. pleuropneumoniae aasP deletion mutant and by functional complementation. Comparison of the secreted proteins of the wild type, an aasP mutant derivative, and an aasP mutant complemented in trans led to the identification of OmlA protein fragments that were present only in the secreted-protein preparations of the wild-type and complemented strains, indicating that AasP is involved in modification of OmlA. This is the first demonstration of a function for any autotransporter protein in Actinobacillus pleuropneumoniae.
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Buettner FFR, Bendallah IM, Bosse JT, Dreckmann K, Nash JHE, Langford PR, Gerlach GF. Analysis of the Actinobacillus pleuropneumoniae ArcA regulon identifies fumarate reductase as a determinant of virulence. Infect Immun 2008; 76:2284-95. [PMID: 18378638 PMCID: PMC2423083 DOI: 10.1128/iai.01540-07] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2007] [Revised: 01/10/2008] [Accepted: 03/23/2008] [Indexed: 11/20/2022] Open
Abstract
The ability of the bacterial pathogen Actinobacillus pleuropneumoniae to grow anaerobically allows the bacterium to persist in the lung. The ArcAB two-component system is crucial for metabolic adaptation in response to anaerobic conditions, and we recently showed that an A. pleuropneumoniae arcA mutant had reduced virulence compared to the wild type (F. F. Buettner, A. Maas, and G.-F. Gerlach, Vet. Microbiol. 127:106-115, 2008). In order to understand the attenuated phenotype, we investigated the ArcA regulon of A. pleuropneumoniae by using a combination of transcriptome (microarray) and proteome (two-dimensional difference gel electrophoresis and subsequent mass spectrometry) analyses. We show that ArcA negatively regulates the expression of many genes, including those encoding enzymes which consume intermediates during fumarate synthesis. Simultaneously, the expression of glycerol-3-phosphate dehydrogenase, a component of the respiratory chain serving as a direct reduction equivalent for fumarate reductase, was upregulated. This result, together with the in silico analysis finding that A. pleuropneumoniae has no oxidative branch of the citric acid cycle, led to the hypothesis that fumarate reductase might be crucial for virulence by providing (i) energy via fumarate respiration and (ii) succinate and other essential metabolic intermediates via the reductive branch of the citric acid cycle. To test this hypothesis, an isogenic A. pleuropneumoniae fumarate reductase deletion mutant was constructed and studied by using a pig aerosol infection model. The mutant was shown to be significantly attenuated, thereby strongly supporting a crucial role for fumarate reductase in the pathogenesis of A. pleuropneumoniae infection.
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Affiliation(s)
- Falk F R Buettner
- Department of Infectious Diseases, Institute for Microbiology, University of Veterinary Medicine Hannover, Hannover, Germany
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