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Khairullah AR, Kurniawan SC, Puspitasari Y, Aryaloka S, Silaen OSM, Yanestria SM, Widodo A, Moses IB, Effendi MH, Afnani DA, Ramandinianto SC, Hasib A, Riwu KHP. Brucellosis: Unveiling the complexities of a pervasive zoonotic disease and its global impacts. Open Vet J 2024; 14:1081-1097. [PMID: 38938422 PMCID: PMC11199761 DOI: 10.5455/ovj.2024.v14.i5.1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2024] [Accepted: 04/08/2024] [Indexed: 06/29/2024] Open
Abstract
One zoonotic infectious animal disease is brucellosis. The bacteria that cause brucellosis belong to the genus Brucella. Numerous animal and human species are affected by brucellosis, with an estimated 500,000 human cases recorded annually worldwide. The occurrence of new areas of infection and the resurgence of infection in already infected areas indicate how dynamically brucellosis is distributed throughout different geographic regions. Bacteria originate from the blood and are found in the reticuloendothelial system, the liver, the spleen, and numerous other locations, including the joints, kidneys, heart, and genital tract. Diagnosis of this disease can be done by bacterial isolation, molecular tests, modified acid-fast stain, rose bengal test (RBT), milk ring test, complement fixation test, enzyme-linked immunosorbent assay, and serum agglutination test. The primary sign of a Brucella abortus infection is infertility, which can result in abortion and the birth of a frail fetus that may go on to infect other animals. In humans, the main symptoms are acute febrile illness, with or without localization signs, and chronic infection. Female cattle have a greater risk of contracting Brucella disease. Human populations at high risk of contracting brucellosis include those who care for cattle, veterinarians, slaughterhouse employees, and butchers. Antibiotic treatment of brucellosis is often unsuccessful due to the intracellular survival of Brucella and its adaptability in macrophages. A "one health" strategy is necessary to control illnesses like brucellosis.
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Affiliation(s)
- Aswin Rafif Khairullah
- Research Center for Veterinary Science, National Research and Innovation Agency (BRIN), Bogor, Indonesia
| | - Shendy Canadya Kurniawan
- Master Program of Animal Sciences, Department of Animal Sciences, Specialisation in Molecule, Cell and Organ Functioning, Wageningen University and Research, Wageningen, The Netherlands
| | - Yulianna Puspitasari
- Division of Veterinary Microbiology, Faculty of Veterinary Medicine, Universitas Airlangga, Surabaya, Indonesia
| | - Suhita Aryaloka
- Master Program of Veterinary Agribusiness, Faculty of Veterinary Medicine, Universitas Airlangga, Surabaya, Indonesia
| | - Otto Sahat Martua Silaen
- Doctoral Program in Biomedical Science, Faculty of Medicine, Universitas Indonesia, Jakarta, Indonesia
| | | | - Agus Widodo
- Department of Health, Faculty of Vocational Studies, Universitas Airlangga, Surabaya, Indonesia
| | - Ikechukwu Benjamin Moses
- Department of Applied Microbiology, Faculty of Science, Ebonyi State University, Abakaliki, Nigeria
| | - Mustofa Helmi Effendi
- Division of Veterinary Public Health, Faculty of Veterinary Medicine, Universitas Airlangga, Surabaya, Indonesia
| | - Daniah Ashri Afnani
- Department of Microbiology and Parasitology, Faculty of Veterinary Medicine, Universitas Pendidikan Mandalika, Mataram, Indonesia
| | | | - Abdullah Hasib
- School of Agriculture and Food Sustainability, The University of Queensland, Gatton, Queensland
| | - Katty Hendriana Priscilia Riwu
- Department of Veterinary Public Health, Faculty of Veterinary Medicine, Universitas Pendidikan Mandalika, Mataram, Indonesia
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Hao M, Wang M, Zhao D, Shi Y, Yuan Y, Li J, Zhai Y, Liu X, Zhou D, Chen H, Lin P, Tang K, Liu W, Jin Y, Wang A. Alr Gene in Brucella suis S2: Its Role in Lipopolysaccharide Biosynthesis and Bacterial Virulence in RAW264.7. Int J Mol Sci 2023; 24:10744. [PMID: 37445922 DOI: 10.3390/ijms241310744] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2023] [Revised: 06/24/2023] [Accepted: 06/25/2023] [Indexed: 07/15/2023] Open
Abstract
Brucella suis, the causative agent of brucellosis, poses a significant public health and animal husbandry threat. However, the role of the alanine racemase (alr) gene, which encodes alanine racemase in Brucella, remains unclear. Here, we analyzed an alr deletion mutant and a complemented strain of Brucella suis S2. The knockout strain displayed an unaltered, smooth phenotype in acriflavine agglutination tests but lacked the core polysaccharide portion of lipopolysaccharide (LPS). Genes involved in the LPS synthesis were significantly upregulated in the deletion mutant. The alr deletion strain exhibited reduced intracellular viability in the macrophages, increased macrophage-mediated killing, and upregulation of the apoptosis markers. Bcl2, an anti-apoptotic protein, was downregulated, while the pro-apoptotic proteins, Bax, Caspase-9, and Caspase-3, were upregulated in the macrophages infected with the deletion strain. The infected macrophages showed increased mitochondrial membrane permeability, Cytochrome C release, and reactive oxygen species, activating the mitochondrial apoptosis pathway. These findings revealed that alanine racemase was dispensable in B. suis S2 but influenced the strain's rough features and triggered the mitochondrial apoptosis pathway during macrophage invasion. The deletion of the alr gene reduced the intracellular survival and virulence. This study enhances our understanding of the molecular mechanism underlying Brucella's survival and virulence and, specifically, how alr gene affects host immune evasion by regulating bacterial LPS biosynthesis.
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Affiliation(s)
- Mingyue Hao
- College of Veterinary Medicine, Northwest A&F University, Yangling District, Xianyang 712100, China
- Key Laboratory of Animal Biotechnology of the Ministry of Agriculture, Northwest A&F University, Yangling District, Xianyang 712100, China
| | - Minghui Wang
- College of Veterinary Medicine, Northwest A&F University, Yangling District, Xianyang 712100, China
- Key Laboratory of Animal Biotechnology of the Ministry of Agriculture, Northwest A&F University, Yangling District, Xianyang 712100, China
| | - Danyu Zhao
- College of Veterinary Medicine, Northwest A&F University, Yangling District, Xianyang 712100, China
- Key Laboratory of Animal Biotechnology of the Ministry of Agriculture, Northwest A&F University, Yangling District, Xianyang 712100, China
| | - Yong Shi
- College of Veterinary Medicine, Northwest A&F University, Yangling District, Xianyang 712100, China
- Key Laboratory of Animal Biotechnology of the Ministry of Agriculture, Northwest A&F University, Yangling District, Xianyang 712100, China
| | - Ye Yuan
- College of Veterinary Medicine, Northwest A&F University, Yangling District, Xianyang 712100, China
- Key Laboratory of Animal Biotechnology of the Ministry of Agriculture, Northwest A&F University, Yangling District, Xianyang 712100, China
| | - Junmei Li
- College of Veterinary Medicine, Northwest A&F University, Yangling District, Xianyang 712100, China
- Key Laboratory of Animal Biotechnology of the Ministry of Agriculture, Northwest A&F University, Yangling District, Xianyang 712100, China
| | - Yunyi Zhai
- College of Veterinary Medicine, Northwest A&F University, Yangling District, Xianyang 712100, China
- Key Laboratory of Animal Biotechnology of the Ministry of Agriculture, Northwest A&F University, Yangling District, Xianyang 712100, China
| | - Xiaofang Liu
- College of Veterinary Medicine, Northwest A&F University, Yangling District, Xianyang 712100, China
- Key Laboratory of Animal Biotechnology of the Ministry of Agriculture, Northwest A&F University, Yangling District, Xianyang 712100, China
| | - Dong Zhou
- College of Veterinary Medicine, Northwest A&F University, Yangling District, Xianyang 712100, China
- Key Laboratory of Animal Biotechnology of the Ministry of Agriculture, Northwest A&F University, Yangling District, Xianyang 712100, China
| | - Huatao Chen
- College of Veterinary Medicine, Northwest A&F University, Yangling District, Xianyang 712100, China
- Key Laboratory of Animal Biotechnology of the Ministry of Agriculture, Northwest A&F University, Yangling District, Xianyang 712100, China
| | - Pengfei Lin
- College of Veterinary Medicine, Northwest A&F University, Yangling District, Xianyang 712100, China
- Key Laboratory of Animal Biotechnology of the Ministry of Agriculture, Northwest A&F University, Yangling District, Xianyang 712100, China
| | - Keqiong Tang
- College of Veterinary Medicine, Northwest A&F University, Yangling District, Xianyang 712100, China
- Key Laboratory of Animal Biotechnology of the Ministry of Agriculture, Northwest A&F University, Yangling District, Xianyang 712100, China
| | - Wei Liu
- College of Veterinary Medicine, Northwest A&F University, Yangling District, Xianyang 712100, China
- Key Laboratory of Animal Biotechnology of the Ministry of Agriculture, Northwest A&F University, Yangling District, Xianyang 712100, China
| | - Yaping Jin
- College of Veterinary Medicine, Northwest A&F University, Yangling District, Xianyang 712100, China
- Key Laboratory of Animal Biotechnology of the Ministry of Agriculture, Northwest A&F University, Yangling District, Xianyang 712100, China
| | - Aihua Wang
- College of Veterinary Medicine, Northwest A&F University, Yangling District, Xianyang 712100, China
- Key Laboratory of Animal Biotechnology of the Ministry of Agriculture, Northwest A&F University, Yangling District, Xianyang 712100, China
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Li B, Chen D, Lin F, Wu C, Cao L, Chen H, Hu Y, Yin Y. Genomic Island-Mediated Horizontal Transfer of the Erythromycin Resistance Gene erm(X) among Bifidobacteria. Appl Environ Microbiol 2022; 88:e0041022. [PMID: 35477272 PMCID: PMC9128502 DOI: 10.1128/aem.00410-22] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2022] [Accepted: 04/02/2022] [Indexed: 01/20/2023] Open
Abstract
Antibiotic resistance is a serious medical issue driven by antibiotic misuse. Bifidobacteria may serve as a reservoir for antibiotic resistance genes (ARGs) that have the potential risk of transfer to pathogens. The erythromycin resistance gene erm(X) is an ARG with high abundance in bifidobacteria, especially in Bifidobacterium longum species. However, the characteristics of the spread and integration of the gene erm(X) into the bifidobacteria genome are poorly understood. In this study, 10 tetW-positive bifidobacterial strains and 1 erm(X)-positive bifidobacterial strain were used to investigate the transfer of ARGs. Conjugation assays found that the erm(X) gene could transfer to five other bifidobacterial strains. Dimethyl sulfoxide (DMSO) and vorinostat significantly promoted the transfer of the erm(X) from strain Bifidobacterium catenulatum subsp. kashiwanohense DSM 21854 to Bifidobacterium longum subsp. suis DSM 20211. Whole-genome sequencing and comparative genomic analysis revealed that the erm(X) gene was located on the genomic island BKGI1 and that BKGI1 was conjugally mobile and transferable. To our knowledge, this is the first report that a genomic island-mediated gene erm(X) transfer in bifidobacteria. Additionally, BKGI1 is very unstable in B. catenulatum subsp. kashiwanohense DSM 21854 and transconjugant D2TC and is highly excisable and has an intermediate circular formation. In silico analysis showed that the BKGI1 homologs were also present in other bifidobacterial strains and were especially abundant in B. longum strains. Thus, our results confirmed that genomic island BKGI1 was one of the vehicles for erm(X) spread. These findings suggest that genomic islands play an important role in the dissemination of the gene erm(X) among Bifidobacterium species. IMPORTANCE Bifidobacteria are a very important group of gut microbiota, and the presence of these bacteria has many beneficial effects for the host. Thus, bifidobacteria have attracted growing interest owing to their potential probiotic properties. Bifidobacteria have been widely exploited by the food industry as probiotic microorganisms, and some species have a long history of safe use in food and feed production. However, the presence of antibiotic resistance raises the risk of its application. In this study, we analyzed the transfer of the erythromycin resistance gene erm(X) and revealed that the molecular mechanism behind the spread of the gene erm(X) was mediated by genomic island BKGI1. To the best of our knowledge this is the first report to describe the transfer of the gene erm(X) via genomic islands among bifidobacteria. This may be an important way to disseminate the gene erm(X) among bifidobacteria.
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Affiliation(s)
- Baiyuan Li
- Key Laboratory of Comprehensive Utilization of Advantage Plant Resources in Hunan South, College of Chemistry and Bioengineering, Hunan University of Science and Engineering, Yongzhou, Hunan, China
| | - Dan Chen
- Key Laboratory of Comprehensive Utilization of Advantage Plant Resources in Hunan South, College of Chemistry and Bioengineering, Hunan University of Science and Engineering, Yongzhou, Hunan, China
| | - Fan Lin
- Key Laboratory of Comprehensive Utilization of Advantage Plant Resources in Hunan South, College of Chemistry and Bioengineering, Hunan University of Science and Engineering, Yongzhou, Hunan, China
| | - Chuanyu Wu
- Key Laboratory of Comprehensive Utilization of Advantage Plant Resources in Hunan South, College of Chemistry and Bioengineering, Hunan University of Science and Engineering, Yongzhou, Hunan, China
| | - Linyan Cao
- Key Laboratory of Comprehensive Utilization of Advantage Plant Resources in Hunan South, College of Chemistry and Bioengineering, Hunan University of Science and Engineering, Yongzhou, Hunan, China
| | - Huahai Chen
- Key Laboratory of Comprehensive Utilization of Advantage Plant Resources in Hunan South, College of Chemistry and Bioengineering, Hunan University of Science and Engineering, Yongzhou, Hunan, China
| | - Yunfei Hu
- Key Laboratory of Comprehensive Utilization of Advantage Plant Resources in Hunan South, College of Chemistry and Bioengineering, Hunan University of Science and Engineering, Yongzhou, Hunan, China
| | - Yeshi Yin
- Key Laboratory of Comprehensive Utilization of Advantage Plant Resources in Hunan South, College of Chemistry and Bioengineering, Hunan University of Science and Engineering, Yongzhou, Hunan, China
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Moreno E, Blasco JM, Moriyón I. Facing the Human and Animal Brucellosis Conundrums: The Forgotten Lessons. Microorganisms 2022; 10:942. [PMID: 35630386 PMCID: PMC9144488 DOI: 10.3390/microorganisms10050942] [Citation(s) in RCA: 15] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2022] [Revised: 03/22/2022] [Accepted: 04/28/2022] [Indexed: 11/17/2022] Open
Abstract
Brucellosis is a major zoonotic disease caused by Brucella species. Historically, the disease received over fifty names until it was recognized as a single entity, illustrating its protean manifestations and intricacies, traits that generated conundrums that have remained or re-emerged since they were first described. Here, we examine confusions concerning the clinical picture, serological diagnosis, and incidence of human brucellosis. We also discuss knowledge gaps and prevalent confusions about animal brucellosis, including brucellosis control strategies, the so-called confirmatory tests, and assumptions about the primary-binding assays and DNA detection methods. We describe how doubtfully characterized vaccines have failed to control brucellosis and emphasize how the requisites of controlled safety and protection experiments are generally overlooked. Finally, we briefly discuss the experience demonstrating that S19 remains the best cattle vaccine, while RB51 fails to validate its claimed properties (protection, differentiating infected and vaccinated animals (DIVA), and safety), offering a strong argument against its current widespread use. These conundrums show that knowledge dealing with brucellosis is lost, and previous experience is overlooked or misinterpreted, as illustrated in a significant number of misguided meta-analyses. In a global context of intensifying livestock breeding, such recurrent oversights threaten to increase the impact of brucellosis.
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Affiliation(s)
- Edgardo Moreno
- Tropical Disease Research Program, National University, Heredia 40104, Costa Rica;
| | | | - Ignacio Moriyón
- Institute for Tropical Health and Department of Microbiology and Parasitology, Medical School, University of Navarra and IdISNA, 31008 Pamplona, Spain
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5
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Whole Genome Sequence Analysis of Brucella melitensis Phylogeny and Virulence Factors. MICROBIOLOGY RESEARCH 2021. [DOI: 10.3390/microbiolres12030050] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Abstract
Brucellosis has a wide range of clinical severity in humans that remains poorly understood. Whole genome sequencing (WGS) analysis may be able to detect variation in virulence genes. We used Brucella melitensis sequences in the NCBI Sequence Read Archive (SRA) database to assemble 248 whole genomes, and additionally, assembled 27 B. melitensis genomes from samples of human patients in Southern Israel. We searched the 275 assembled genomes for the 43 B. melitensis virulence genes in the Virulence Factors of Pathogenic Bacteria Database (VFDB) and 10 other published putative virulence genes. We explored pan-genome variation across the genomes and in a pilot analysis, explored single nucleotide polymorphism (SNP) variation among the ten putative virulence genes. More than 99% of the genomes had sequences for all Brucella melitensis virulence genes included in the VFDB. The 10 other virulence genes of interest were present across all the genomes, but three of these genes had SNP variation associated with particular Brucella melitensis genotypes. SNP variation was also seen within the Israeli genomes obtained from a small geographic region. While the Brucella genome is highly conserved, this novel and large whole genome study of Brucella demonstrates the ability of whole genome and pan-genome analysis to screen multiple genomes and identify SNP variation in both known and novel virulence genes that could be associated with differential disease virulence. Further development of whole genome techniques and linkage with clinical metadata on disease outcomes could shed light on whether such variation in the Brucella genome plays a role in pathogenesis.
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Stranahan LW, Arenas-Gamboa AM. When the Going Gets Rough: The Significance of Brucella Lipopolysaccharide Phenotype in Host-Pathogen Interactions. Front Microbiol 2021; 12:713157. [PMID: 34335551 PMCID: PMC8319746 DOI: 10.3389/fmicb.2021.713157] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2021] [Accepted: 06/22/2021] [Indexed: 01/18/2023] Open
Abstract
Brucella is a facultatively intracellular bacterial pathogen and the cause of worldwide zoonotic infections, infamous for its ability to evade the immune system and persist chronically within host cells. Despite the frequent association with attenuation in other Gram-negative bacteria, a rough lipopolysaccharide phenotype is retained by Brucella canis and Brucella ovis, which remain fully virulent in their natural canine and ovine hosts, respectively. While these natural rough strains lack the O-polysaccharide they, like their smooth counterparts, are able to evade and manipulate the host immune system by exhibiting low endotoxic activity, resisting destruction by complement and antimicrobial peptides, entering and trafficking within host cells along a similar pathway, and interfering with MHC-II antigen presentation. B. canis and B. ovis appear to have compensated for their roughness by alterations to their outer membrane, especially in regards to outer membrane proteins. B. canis, in particular, also shows evidence of being less proinflammatory in vivo, suggesting that the rough phenotype may be associated with an enhanced level of stealth that could allow these pathogens to persist for longer periods of time undetected. Nevertheless, much additional work is required to understand the correlates of immune protection against the natural rough Brucella spp., a critical step toward development of much-needed vaccines. This review will highlight the significance of rough lipopolysaccharide in the context of both natural disease and host–pathogen interactions with an emphasis on natural rough Brucella spp. and the implications for vaccine development.
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Affiliation(s)
- Lauren W Stranahan
- Department of Veterinary Pathobiology, College of Veterinary Medicine and Biomedical Sciences, Texas A&M University, College Station, TX, United States
| | - Angela M Arenas-Gamboa
- Department of Veterinary Pathobiology, College of Veterinary Medicine and Biomedical Sciences, Texas A&M University, College Station, TX, United States
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Vassen V, Valotteau C, Feuillie C, Formosa-Dague C, Dufrêne YF, De Bolle X. Localized incorporation of outer membrane components in the pathogen Brucella abortus. EMBO J 2019; 38:e100323. [PMID: 30635335 PMCID: PMC6396147 DOI: 10.15252/embj.2018100323] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2018] [Revised: 11/29/2018] [Accepted: 12/04/2018] [Indexed: 12/21/2022] Open
Abstract
The zoonotic pathogen Brucella abortus is part of the Rhizobiales, which are alpha-proteobacteria displaying unipolar growth. Here, we show that this bacterium exhibits heterogeneity in its outer membrane composition, with clusters of rough lipopolysaccharide co-localizing with the essential outer membrane porin Omp2b, which is proposed to allow facilitated diffusion of solutes through the porin. We also show that the major outer membrane protein Omp25 and peptidoglycan are incorporated at the new pole and the division site, the expected growth sites. Interestingly, lipopolysaccharide is also inserted at the same growth sites. The absence of long-range diffusion of main components of the outer membrane could explain the apparent immobility of the Omp2b clusters, as well as unipolar and mid-cell localizations of newly incorporated outer membrane proteins and lipopolysaccharide. Unipolar growth and limited mobility of surface structures also suggest that new surface variants could arise in a few generations without the need of diluting pre-existing surface antigens.
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Affiliation(s)
- Victoria Vassen
- Research Unit in Biology of Microorganisms (URBM), Narilis University of Namur (UNamur), Namur, Belgium
| | - Claire Valotteau
- Louvain Institute of Biomolecular Science and Technology, Université catholique de Louvain (UCL), Louvain-la-Neuve, Belgium
| | - Cécile Feuillie
- Louvain Institute of Biomolecular Science and Technology, Université catholique de Louvain (UCL), Louvain-la-Neuve, Belgium
| | - Cécile Formosa-Dague
- Louvain Institute of Biomolecular Science and Technology, Université catholique de Louvain (UCL), Louvain-la-Neuve, Belgium
| | - Yves F Dufrêne
- Louvain Institute of Biomolecular Science and Technology, Université catholique de Louvain (UCL), Louvain-la-Neuve, Belgium
- Walloon Excellence in Life Sciences and Biotechnology (WELBIO), Wavre, Belgium
| | - Xavier De Bolle
- Research Unit in Biology of Microorganisms (URBM), Narilis University of Namur (UNamur), Namur, Belgium
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Ducrotoy MJ, Conde-Álvarez R, Blasco JM, Moriyón I. A review of the basis of the immunological diagnosis of ruminant brucellosis. Vet Immunol Immunopathol 2016; 171:81-102. [DOI: 10.1016/j.vetimm.2016.02.002] [Citation(s) in RCA: 48] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2015] [Revised: 01/07/2016] [Accepted: 02/02/2016] [Indexed: 01/18/2023]
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Fontana C, Conde-Álvarez R, Ståhle J, Holst O, Iriarte M, Zhao Y, Arce-Gorvel V, Hanniffy S, Gorvel JP, Moriyón I, Widmalm G. Structural Studies of Lipopolysaccharide-defective Mutants from Brucella melitensis Identify a Core Oligosaccharide Critical in Virulence. J Biol Chem 2016; 291:7727-41. [PMID: 26867577 PMCID: PMC4817197 DOI: 10.1074/jbc.m115.701540] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2015] [Indexed: 11/07/2022] Open
Abstract
The structures of the lipooligosaccharides from Brucella melitensis mutants affected in the WbkD and ManBcore proteins have been fully characterized using NMR spectroscopy. The results revealed that disruption of wbkD gives rise to a rough lipopolysaccharide (R-LPS) with a complete core structure (β-d-Glcp-(1→4)-α-Kdop-(2→4)[β-d-GlcpN-(1→6)-β-d-GlcpN-(1→4)[β-d-GlcpN-(1→6)]-β-d-GlcpN-(1→3)-α-d-Manp-(1→5)]-α-Kdop-(2→6)-β-d-GlcpN3N4P-(1→6)-α-d-GlcpN3N1P), in addition to components lacking one of the terminal β-d-GlcpN and/or the β-d-Glcp residues (48 and 17%, respectively). These structures were identical to those of the R-LPS from B. melitensis EP, a strain simultaneously expressing both smooth and R-LPS, also studied herein. In contrast, disruption of manBcore gives rise to a deep-rough pentasaccharide core (β-d-Glcp-(1→4)-α-Kdop-(2→4)-α-Kdop-(2→6)-β-d-GlcpN3N4P-(1→6)-α-d-GlcpN3N1P) as the major component (63%), as well as a minor tetrasaccharide component lacking the terminal β-d-Glcp residue (37%). These results are in agreement with the predicted functions of the WbkD (glycosyltransferase involved in the biosynthesis of the O-antigen) and ManBcore proteins (phosphomannomutase involved in the biosynthesis of a mannosyl precursor needed for the biosynthesis of the core and O-antigen). We also report that deletion of B. melitensis wadC removes the core oligosaccharide branch not linked to the O-antigen causing an increase in overall negative charge of the remaining LPS inner section. This is in agreement with the mannosyltransferase role predicted for WadC and the lack of GlcpN residues in the defective core oligosaccharide. Despite carrying the O-antigen essential in B. melitensis virulence, the core deficiency in the wadC mutant structure resulted in a more efficient detection by innate immunity and attenuation, proving the role of the β-d-GlcpN-(1→6)-β-d-GlcpN-(1→4)[β-d-GlcpN-(1→6)]-β-d-GlcpN-(1→3)-α-d-Manp-(1→5) structure in virulence.
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Affiliation(s)
- Carolina Fontana
- From the Department of Organic Chemistry, Arrhenius Laboratory, Stockholm University, S-106 91 Stockholm, Sweden
| | - Raquel Conde-Álvarez
- the Instituto de Salud Tropical, Instituto de Investigación Sanitaria de Navarra, and Departamento de Microbiología y Parasitología, Universidad de Navarra, c/Irunlarrea 1, 31008 Pamplona, Spain
| | - Jonas Ståhle
- From the Department of Organic Chemistry, Arrhenius Laboratory, Stockholm University, S-106 91 Stockholm, Sweden
| | - Otto Holst
- the Division of Structural Biochemistry, Leibniz-Center for Medicine and Biosciences, Priority Area Asthma and Allergy, Research Center Borstel, Airway Research Center North, Member of the German Center for Lung Research, D-23845 Borstel, Germany
| | - Maite Iriarte
- the Instituto de Salud Tropical, Instituto de Investigación Sanitaria de Navarra, and Departamento de Microbiología y Parasitología, Universidad de Navarra, c/Irunlarrea 1, 31008 Pamplona, Spain
| | - Yun Zhao
- the Centre d'Immunologie de Marseille-Luminy Aix-Marseille University, UM2 Marseille, France
| | - Vilma Arce-Gorvel
- the Centre d'Immunologie de Marseille-Luminy Aix-Marseille University, UM2 Marseille, France, INSERM, U1104 Marseille, France, and CNRS, UMR7280 Marseille, France
| | - Seán Hanniffy
- the Centre d'Immunologie de Marseille-Luminy Aix-Marseille University, UM2 Marseille, France, INSERM, U1104 Marseille, France, and CNRS, UMR7280 Marseille, France
| | - Jean-Pierre Gorvel
- the Centre d'Immunologie de Marseille-Luminy Aix-Marseille University, UM2 Marseille, France, INSERM, U1104 Marseille, France, and CNRS, UMR7280 Marseille, France
| | - Ignacio Moriyón
- the Instituto de Salud Tropical, Instituto de Investigación Sanitaria de Navarra, and Departamento de Microbiología y Parasitología, Universidad de Navarra, c/Irunlarrea 1, 31008 Pamplona, Spain
| | - Göran Widmalm
- From the Department of Organic Chemistry, Arrhenius Laboratory, Stockholm University, S-106 91 Stockholm, Sweden,
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Mancilla M. Smooth to Rough Dissociation in Brucella: The Missing Link to Virulence. Front Cell Infect Microbiol 2016; 5:98. [PMID: 26779449 PMCID: PMC4700419 DOI: 10.3389/fcimb.2015.00098] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2015] [Accepted: 12/10/2015] [Indexed: 11/24/2022] Open
Abstract
Dissociation encompasses changes in a series of phenotypes: colony and cell morphology, inmunological and biochemical reactions and virulence. The concept is generally associated to the in vitro transition between smooth (S) and rough (R) colonies, a phenotypic observation in Gram-negative bacteria commonly made since the beginning of microbiology as a science. It is also well known that the loss of the O-polysaccharide, the most external lipopolysaccharide (LPS) moiety, triggers the change in the colony phenotype. Although dissociation is related to one of the most basic features used to distinguish between species, i.e., colony morphology, and, in the case of pathogens, predict their virulence behavior, it has been considered a laboratory artifact and thus did not gain further attention. However, recent insights into genetics and pathogenesis of members of Brucella, causative agents of brucellosis, have brought a new outlook on this experimental fact, suggesting that it plays a role beyond the laboratory observations. In this perspective article, the current knowledge on Brucella LPS genetics and its connection with dissociation in the frame of evolution is discussed. Latest reports support the notion that, by means of a better understanding of genetic pathways linked to R phenotype and the biological impact of this intriguing "old" phenomenon, unexpected applications can be achieved.
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Affiliation(s)
- Marcos Mancilla
- Research and Development Department, ADL Diagnostic Chile Ltd.Puerto Montt, Chile
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Brucella canis is an intracellular pathogen that induces a lower proinflammatory response than smooth zoonotic counterparts. Infect Immun 2015; 83:4861-70. [PMID: 26438796 DOI: 10.1128/iai.00995-15] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2015] [Accepted: 09/29/2015] [Indexed: 01/18/2023] Open
Abstract
Canine brucellosis caused by Brucella canis is a disease of dogs and a zoonotic risk. B. canis harbors most of the virulence determinants defined for the genus, but its pathogenic strategy remains unclear since it has not been demonstrated that this natural rough bacterium is an intracellular pathogen. Studies of B. canis outbreaks in kennel facilities indicated that infected dogs displaying clinical signs did not present hematological alterations. A virulent B. canis strain isolated from those outbreaks readily replicated in different organs of mice for a protracted period. However, the levels of tumor necrosis factor alpha, interleukin-6 (IL-6), and IL-12 in serum were close to background levels. Furthermore, B. canis induced lower levels of gamma interferon, less inflammation of the spleen, and a reduced number of granulomas in the liver in mice than did B. abortus. When the interaction of B. canis with cells was studied ex vivo, two patterns were observed, a predominant scattered cell-associated pattern of nonviable bacteria and an infrequent intracellular replicative pattern of viable bacteria in a perinuclear location. The second pattern, responsible for the increase in intracellular multiplication, was dependent on the type IV secretion system VirB and was seen only if the inoculum used for cell infections was in early exponential phase. Intracellular replicative B. canis followed an intracellular trafficking route undistinguishable from that of B. abortus. Although B. canis induces a lower proinflammatory response and has a stealthier replication cycle, it still displays the pathogenic properties of the genus and the ability to persist in infected organs based on the ability to multiply intracellularly.
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Phenotypic and genotypic characterization of Brucella strains isolated from autochthonous livestock reveals the dominance of B. abortus biovar 3a in Nigeria. Vet Microbiol 2015; 180:103-8. [DOI: 10.1016/j.vetmic.2015.08.014] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2015] [Revised: 07/30/2015] [Accepted: 08/14/2015] [Indexed: 12/31/2022]
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Pei J, Kahl-McDonagh M, Ficht TA. Brucella dissociation is essential for macrophage egress and bacterial dissemination. Front Cell Infect Microbiol 2014; 4:23. [PMID: 24634889 PMCID: PMC3942807 DOI: 10.3389/fcimb.2014.00023] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2013] [Accepted: 02/10/2014] [Indexed: 12/24/2022] Open
Abstract
It has long been observed that smooth Brucella can dissociate into rough mutants that are cytotoxic to macrophages. However, the in vivo biological significance and/or mechanistic details of Brucella dissociation and cytotoxicity remain incomplete. In the current report, a plaque assay was developed using Brucella strains exhibiting varying degrees of cytotoxicity. Infected monolayers were observed daily using phase contrast microscopy for plaque formation while Brucella uptake and replication were monitored using an immunofluorescence assay (IFA). Visible plaques were detected at 4-5 days post infection (p.i.) with cytotoxic Brucella 16MΔmanBA at an MOI of 0.1. IFA staining demonstrated that the plaques consisted of macrophages with replicating Brucella. Visible plaques were not detected in monolayers infected with non-cytotoxic 16MΔmanBAΔvirB2 at an MOI of 0.1. However, IFA staining did reveal small groups of macrophages (foci) with replicating Brucella in the monolayers infected with 16MΔmanBAΔvirB2. The size of the foci observed in macrophage monolayers infected with rough Brucella correlated directly with cytotoxicity measured in liquid culture, suggesting that cytotoxicity was essential for Brucella egress and dissemination. In monolayers infected with 16M, small and large foci were observed. Double antibody staining revealed spontaneous rough mutants within the large, but not the small foci in 16M infected monolayers. Furthermore, plaque formation was observed in the large foci derived from 16M infections. Finally, the addition of gentamicin to the culture medium inhibited plaque formation, suggesting that cell-to-cell spread occurred only following release of the organisms from the cells. Taken together, these results demonstrate that Brucella-induced cytotoxicity is critical for Brucella egress and dissemination.
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Affiliation(s)
| | | | - Thomas A. Ficht
- Department of Veterinary Pathobiology, Texas A&M University and Texas Agricultural Experiment StationCollege Station, TX, USA
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Mancilla M, Grilló MJ, de Miguel MJ, López-Goñi I, San-Román B, Zabalza-Baranguá A, Moriyón I. Deletion of the GI-2 integrase and the wbkA flanking transposase improves the stability of Brucella melitensis Rev 1 vaccine. Vet Res 2013; 44:105. [PMID: 24176078 PMCID: PMC4176087 DOI: 10.1186/1297-9716-44-105] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2013] [Accepted: 10/21/2013] [Indexed: 12/17/2022] Open
Abstract
Brucella melitensis Rev 1 is the best vaccine available for the prophylaxis of small ruminant brucellosis and, indirectly, for reducing human brucellosis. However, Rev 1 shows anomalously high rates of spontaneous dissociation from smooth (S) to rough (R) bacteria, the latter being inefficacious as vaccines. This S-R instability results from the loss of the O-polysaccharide. To overcome this problem, we investigated whether some recently described mechanisms promoting mutations in O-polysaccharide genes were involved in Rev 1 S-R dissociation. We found that a proportion of Rev 1 R mutants result from genome rearrangements affecting the wbo O-polysaccharide loci of genomic island GI-2 and the wbkA O-polysaccharide glycosyltransferase gene of the wbk region. Accordingly, we mutated the GI-2 int gene and the wbk IS transposase involved in those arrangements, and found that these Rev 1 mutants maintained the S phenotype and showed lower dissociation levels. Combining these two mutations resulted in a strain (Rev 2) displaying a 95% decrease in dissociation with respect to parental Rev 1 under conditions promoting dissociation. Rev 2 did not differ from Rev 1 in the characteristics used in Rev 1 typing (growth rate, colonial size, reactivity with O-polysaccharide antibodies, phage, dye and antibiotic susceptibility). Moreover, Rev 2 and Rev 1 showed similar attenuation and afforded similar protection in the mouse model of brucellosis vaccines. We conclude that mutations targeting genes and DNA sequences involved in spontaneous O-polysaccharide loss enhance the stability of a critical vaccine phenotype and complement the empirical stabilization precautions taken during S Brucella vaccine production.
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Affiliation(s)
- Marcos Mancilla
- Departamento de Microbiología y Parasitología e Instituto de Salud Tropical, Universidad de Navarra, C/ Irunlarrea, 1, 31008 Pamplona, Spain
- Instituto de Bioquímica y Microbiología, Universidad Austral de Chile, Campus Isla Teja, casilla 567, Valdivia, Chile
| | - María-Jesús Grilló
- Grupo de Sanidad Animal, Instituto de Agrobiotecnología (CSIC-Universidad Pública de Navarra-Gobierno de Navarra), Campus de Arrosadía, 31006 Pamplona, Spain
| | - María-Jesús de Miguel
- Unidad de Sanidad Animal, Centro de Investigación y Tecnología Agroalimentaria de Aragón (CITA), Gobierno de Aragón. Av. Montañana, 930, 50059 Zaragoza, Spain
| | - Ignacio López-Goñi
- Departamento de Microbiología y Parasitología e Instituto de Salud Tropical, Universidad de Navarra, C/ Irunlarrea, 1, 31008 Pamplona, Spain
| | - Beatriz San-Román
- Grupo de Sanidad Animal, Instituto de Agrobiotecnología (CSIC-Universidad Pública de Navarra-Gobierno de Navarra), Campus de Arrosadía, 31006 Pamplona, Spain
| | - Ana Zabalza-Baranguá
- Grupo de Sanidad Animal, Instituto de Agrobiotecnología (CSIC-Universidad Pública de Navarra-Gobierno de Navarra), Campus de Arrosadía, 31006 Pamplona, Spain
| | - Ignacio Moriyón
- Departamento de Microbiología y Parasitología e Instituto de Salud Tropical, Universidad de Navarra, C/ Irunlarrea, 1, 31008 Pamplona, Spain
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Diverse genetic regulon of the virulence-associated transcriptional regulator MucR in Brucella abortus 2308. Infect Immun 2013; 81:1040-51. [PMID: 23319565 DOI: 10.1128/iai.01097-12] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023] Open
Abstract
The Ros-type regulator MucR is one of the few transcriptional regulators that have been linked to virulence in Brucella. Here, we show that a Brucella abortus in-frame mucR deletion strain exhibits a pronounced growth defect during in vitro cultivation and, more importantly, that the mucR mutant is attenuated in cultured macrophages and in mice. The genetic basis for the attenuation of Brucella mucR mutants has not been defined previously, but in the present study the genes regulated by MucR in B. abortus have been elucidated using microarray analysis and real-time reverse transcription-PCR (RT-PCR). In B. abortus 2308, MucR regulates a wide variety of genes whose products may function in establishing and maintaining cell envelope integrity, polysaccharide biosynthesis, iron homeostasis, genome plasticity, and transcriptional regulation. Particularly notable among the MucR-regulated genes identified is arsR6 (nolR), which encodes a transcriptional regulator previously linked to virulence in Brucella melitensis 16 M. Importantly, electrophoretic mobility shift assays (EMSAs) determined that a recombinant MucR protein binds directly to the promoter regions of several genes repressed by MucR (including arsR6 [nolR]), and in Brucella, as in other alphaproteobacteria, MucR binds to its own promoter to repress expression of the gene that encodes it. Overall, these studies have uncovered the diverse genetic regulon of MucR in Brucella, and in doing so this work has begun to define the MucR-controlled genetic circuitry whose misregulation contributes to the virulence defect of Brucella mucR mutants.
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Grilló MJ, Blasco JM, Gorvel JP, Moriyón I, Moreno E. What have we learned from brucellosis in the mouse model? Vet Res 2012; 43:29. [PMID: 22500859 PMCID: PMC3410789 DOI: 10.1186/1297-9716-43-29] [Citation(s) in RCA: 162] [Impact Index Per Article: 13.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2011] [Accepted: 04/13/2012] [Indexed: 01/18/2023] Open
Abstract
Brucellosis is a zoonosis caused by Brucella species. Brucellosis research in natural hosts is often precluded by practical, economical and ethical reasons and mice are widely used. However, mice are not natural Brucella hosts and the course of murine brucellosis depends on bacterial strain virulence, dose and inoculation route as well as breed, genetic background, age, sex and physiological statu of mice. Therefore, meaningful experiments require a definition of these variables. Brucella spleen replication profiles are highly reproducible and course in four phases: i), onset or spleen colonization (first 48 h); ii), acute phase, from the third day to the time when bacteria reach maximal numbers; iii), chronic steady phase, where bacterial numbers plateaus; and iv), chronic declining phase, during which brucellae are eliminated. This pattern displays clear physiopathological signs and is sensitive to small virulence variations, making possible to assess attenuation when fully virulent bacteria are used as controls. Similarly, immunity studies using mice with known defects are possible. Mutations affecting INF-γ, TLR9, Myd88, Tγδ and TNF-β favor Brucella replication; whereas IL-1β, IL-18, TLR4, TLR5, TLR2, NOD1, NOD2, GM-CSF, IL/17r, Rip2, TRIF, NK or Nramp1 deficiencies have no noticeable effects. Splenomegaly development is also useful: it correlates with IFN-γ and IL-12 levels and with Brucella strain virulence. The genetic background is also important: Brucella-resistant mice (C57BL) yield lower splenic bacterial replication and less splenomegaly than susceptible breeds. When inoculum is increased, a saturating dose above which bacterial numbers per organ do not augment, is reached. Unlike many gram-negative bacteria, lethal doses are large (≥ 108 bacteria/mouse) and normally higher than the saturating dose. Persistence is a useful virulence/attenuation index and is used in vaccine (Residual Virulence) quality control. Vaccine candidates are also often tested in mice by determining splenic Brucella numbers after challenging with appropriate virulent brucellae doses at precise post-vaccination times. Since most live or killed Brucella vaccines provide some protection in mice, controls immunized with reference vaccines (S19 or Rev1) are critical. Finally, mice have been successfully used to evaluate brucellosis therapies. It is concluded that, when used properly, the mouse is a valuable brucellosis model.
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Affiliation(s)
- María-Jesús Grilló
- Instituto de Agrobiotecnología, CSIC-UPNA-Gobierno de Navarra, Pamplona, Spain
| | - José María Blasco
- Centro de Investigación y Tecnología Agroalimentaria (CITA) de Aragón, Zaragoza, Spain
| | - Jean Pierre Gorvel
- Centre d'Immunologie de Marseille-Luminy, Aix Marseille Université, Faculté de Sciences de Luminy, Luminy, France
- Institut National de la Santé et de la Recherche Médicale U631, Marseille, France
- Centre National de la Recherche Scientifique UMR6102, Marseille, France
| | - Ignacio Moriyón
- Departamento de Microbiología y Parasitología, Universidad de Navarra, Pamplona, Spain
- Instituto de Salud Tropical, Universidad de Navarra, Pamplona, Spain
| | - Edgardo Moreno
- Programa de Investigación en Enfermedades Tropicales, Escuela de Medicina Veterinaria, Universidad Nacional, Heredia, Costa Rica
- Instituto Clodomiro Picado, Facultad de Microbiología, Universidad de Costa Rica, San José, Costa Rica
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Mancilla M, Marín CM, Blasco JM, Zárraga AM, López-Goñi I, Moriyón I. Spontaneous excision of the O-polysaccharide wbkA glycosyltranferase gene is a cause of dissociation of smooth to rough Brucella colonies. J Bacteriol 2012; 194:1860-7. [PMID: 22328663 PMCID: PMC3318470 DOI: 10.1128/jb.06561-11] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2011] [Accepted: 01/27/2012] [Indexed: 01/07/2023] Open
Abstract
The brucellae are Gram-negative pathogens that cause brucellosis, a zoonosis of worldwide importance. The genus Brucella includes smooth and rough species that differ in that they carry smooth and rough lipopolysaccharides, respectively. Brucella abortus, B. melitensis, and B. suis are typical smooth species. However, these smooth brucellae dissociate into rough mutants devoid of the lipopolysaccharide O-polysaccharide, a major antigen and a virulence determinant encoded in regions wbo (included in genomic island-2) and wbk. We demonstrate here the occurrence of spontaneous recombination events in those three Brucella species leading to the deletion of a 5.5-kb fragment carrying the wbkA glycosyltranferase gene and to the appearance of rough mutants. Analysis of the recombination intermediates suggested homologous recombination between the ISBm1 insertion sequences flanking wbkA as the mechanism generating the deletion. Excision of wbkA was reduced but not abrogated in a recA-deficient mutant, showing the existence of both RecA-dependent and -independent processes. Although the involvement of the ISBm1 copies flanking wbkA suggested a transpositional event, the predicted transpositional joint could not be detected. This absence of detectable transposition was consistent with the presence of polymorphism in the inverted repeats of one of the ISBm1 copies. The spontaneous excision of wbkA represents a novel dissociation mechanism of smooth brucellae that adds to the previously described excision of genomic island-2. This ISBm1-mediated wbkA excision and the different %GC levels of the excised fragment and of other wbk genes suggest that the Brucella wbk locus is the result of at least two horizontal acquisition events.
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Affiliation(s)
- Marcos Mancilla
- Instituto de Salud Tropical y Departamento de Microbiología y Parasitología, Universidad de Navarra, Pamplona, Spain
| | - Clara M. Marín
- Centro de Investigación y Tecnología Agroalimentaria, Unidad de Sanidad Animal, Gobierno de Aragón, Zaragoza, Spain
| | - José M. Blasco
- Centro de Investigación y Tecnología Agroalimentaria, Unidad de Sanidad Animal, Gobierno de Aragón, Zaragoza, Spain
| | - Ana María Zárraga
- Instituto de Bioquímica y Microbiología, Facultad de Ciencias, Universidad Austral de Chile, Valdivia, Chile
| | - Ignacio López-Goñi
- Instituto de Salud Tropical y Departamento de Microbiología y Parasitología, Universidad de Navarra, Pamplona, Spain
| | - Ignacio Moriyón
- Instituto de Salud Tropical y Departamento de Microbiología y Parasitología, Universidad de Navarra, Pamplona, Spain
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von Bargen K, Gorvel JP, Salcedo SP. Internal affairs: investigating the Brucella intracellular lifestyle. FEMS Microbiol Rev 2012; 36:533-62. [PMID: 22373010 DOI: 10.1111/j.1574-6976.2012.00334.x] [Citation(s) in RCA: 153] [Impact Index Per Article: 12.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2011] [Revised: 01/10/2012] [Accepted: 02/16/2012] [Indexed: 01/18/2023] Open
Abstract
Bacteria of the genus Brucella are Gram-negative pathogens of several animal species that cause a zoonotic disease in humans known as brucellosis or Malta fever. Within their hosts, brucellae reside within different cell types where they establish a replicative niche and remain protected from the immune response. The aim of this article is to discuss recent advances in the field in the specific context of the Brucella intracellular 'lifestyle'. We initially discuss the different host cell targets and their relevance during infection. As it represents the key to intracellular replication, the focus is then set on the maturation of the Brucella phagosome, with particular emphasis on the Brucella factors that are directly implicated in intracellular trafficking and modulation of host cell signalling pathways. Recent data on the role of the type IV secretion system are discussed, novel effector molecules identified and how some of them impact on trafficking events. Current knowledge on Brucella gene regulation and control of host cell death are summarized, as they directly affect intracellular persistence. Understanding how Brucella molecules interplay with their host cell targets to modulate cellular functions and establish the intracellular niche will help unravel how this pathogen causes disease.
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Affiliation(s)
- Kristine von Bargen
- Faculté de Sciences de Luminy, Centre d'Immunologie de Marseille-Luminy, Aix Marseille Université, UM 2, Marseille Cedex, France
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O'Callaghan D, Whatmore AM. Brucella genomics as we enter the multi-genome era. Brief Funct Genomics 2011; 10:334-41. [PMID: 21930657 DOI: 10.1093/bfgp/elr026] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
The genus Brucella includes species considered among the worlds most important zoonotic pathogens, with brucellosis remaining a significant problem in large parts of the world. Over the last decade a number of Brucella genomes have been fully sequenced providing new insights into this relatively poorly understood group of organisms. In the forthcoming months and years, the availability of many additional genomes should help in further understanding of the evolution, host specificity and pathogenicity of this group as well as providing a resource to further improve epidemiological typing tools. This article describes progress to date and looks forward to the opportunities that should be afforded as we enter an era of multiple, freely available, Brucella genome sequences.
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Turse JE, Pei J, Ficht TA. Lipopolysaccharide-Deficient Brucella Variants Arise Spontaneously during Infection. Front Microbiol 2011; 2:54. [PMID: 21833310 PMCID: PMC3153030 DOI: 10.3389/fmicb.2011.00054] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2010] [Accepted: 02/10/2011] [Indexed: 12/22/2022] Open
Abstract
Lipopolysaccharide-deficient mutants of smooth Brucella species (rough mutants) have been shown to arise spontaneously in culture. However, in situ analysis of Brucella infected macrophages using antibody directed against O-polysaccharide suggested a loss of reactivity of Brucella consistent with the appearance of rough organisms, and a potential contribution to infection. The experiments reported describe the direct recovery of Brucella from macrophages infected in vitro and from the spleens of infected mice at a frequency similar to that described in vitro, suggesting that Brucella dissociation is not simply an in vitro artifact. The frequency of appearance of spontaneous rough organisms deficient in O-polysaccharide expression measured in vitro is approximately 2–3 logs higher than the appearance of mutation to antibiotic resistance, purine auxotrophy, or reversion of erythritol sensitive ΔeryC mutants to tolerance. Genetic trans-complementation using a plasmid-based expression of Brucella manBA successfully restored O-polysaccharide expression in only one-third of O-polysaccharide deficient spontaneous mutants. Suggesting that the appearance of rough mutants is caused by mutation at more than one locus. In addition, Sanger sequencing of the manBA structural genes detected multiple sequence changes that may explain the observed phenotypic differences. The presence of O-polysaccharide resulted in macrophage and neutrophil infiltration into the peritoneal cavity and systemic distribution of the organism. In contrast, rough organisms are controlled by resident macrophages or by extracellular killing mechanisms and rapidly cleared from this compartment consistent with the inability to cause disease. Loss of O-polysaccharide expression appears to be stochastic giving rise to organisms with biological properties distinct from the parental smooth organism during the course of infection.
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Affiliation(s)
- Joshua E Turse
- Veterinary Pathobiology and Faculty of Genetics, Texas A&M University and Texas AgriLife Research College Station, TX, USA
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