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Aragón-Aranda B, Palacios-Chaves L, Salvador-Bescós M, de Miguel MJ, Muñoz PM, Vences-Guzmán MÁ, Zúñiga-Ripa A, Lázaro-Antón L, Sohlenkamp C, Moriyón I, Iriarte M, Conde-Álvarez R. The Phospholipid N-Methyltransferase and Phosphatidylcholine Synthase Pathways and the ChoXWV Choline Uptake System Involved in Phosphatidylcholine Synthesis Are Widely Conserved in Most, but Not All Brucella Species. Front Microbiol 2021; 12:614243. [PMID: 34421831 PMCID: PMC8371380 DOI: 10.3389/fmicb.2021.614243] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2020] [Accepted: 07/09/2021] [Indexed: 11/13/2022] Open
Abstract
The brucellae are facultative intracellular bacteria with a cell envelope rich in phosphatidylcholine (PC). PC is abundant in eukaryotes but rare in prokaryotes, and it has been proposed that Brucella uses PC to mimic eukaryotic-like features and avoid innate immune responses in the host. Two PC synthesis pathways are known in prokaryotes: the PmtA-catalyzed trimethylation of phosphatidylethanolamine and the direct linkage of choline to CDP-diacylglycerol catalyzed by the PC synthase Pcs. Previous studies have reported that B. abortus and B. melitensis possess non-functional PmtAs and that PC is synthesized exclusively via Pcs in these strains. A putative choline transporter ChoXWV has also been linked to PC synthesis in B. abortus. Here, we report that Pcs and Pmt pathways are active in B. suis biovar 2 and that a bioinformatics analysis of Brucella genomes suggests that PmtA is only inactivated in B. abortus and B. melitensis strains. We also show that ChoXWV is active in B. suis biovar 2 and conserved in all brucellae except B. canis and B. inopinata. Unexpectedly, the experimentally verified ChoXWV dysfunction in B. canis did not abrogate PC synthesis in a PmtA-deficient mutant, which suggests the presence of an unknown mechanism for obtaining choline for the Pcs pathway in Brucella. We also found that ChoXWV dysfunction did not cause attenuation in B. suis biovar 2. The results of these studies are discussed with respect to the proposed role of PC in Brucella virulence and how differential use of the Pmt and Pcs pathways may influence the interactions of these bacteria with their mammalian hosts.
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Affiliation(s)
- Beatriz Aragón-Aranda
- Dpto. de Microbiología y Parasitología, Instituto de Salud Tropical (ISTUN), Instituto de Investigación Sanitaria de Navarra, Universidad de Navarra, Pamplona, Spain
| | - Leyre Palacios-Chaves
- Dpto. de Microbiología y Parasitología, Instituto de Salud Tropical (ISTUN), Instituto de Investigación Sanitaria de Navarra, Universidad de Navarra, Pamplona, Spain
| | - Miriam Salvador-Bescós
- Dpto. de Microbiología y Parasitología, Instituto de Salud Tropical (ISTUN), Instituto de Investigación Sanitaria de Navarra, Universidad de Navarra, Pamplona, Spain
| | - María Jesús de Miguel
- Unidad de Producción y Sanidad Animal, Centro de Investigación y Tecnología Agroalimentaria de Aragón, Zaragoza, Spain.,Instituto Agroalimentario de Aragón-IA2, CITA-Universidad de Zaragoza, Zaragoza, Spain
| | - Pilar M Muñoz
- Unidad de Producción y Sanidad Animal, Centro de Investigación y Tecnología Agroalimentaria de Aragón, Zaragoza, Spain.,Instituto Agroalimentario de Aragón-IA2, CITA-Universidad de Zaragoza, Zaragoza, Spain
| | | | - Amaia Zúñiga-Ripa
- Dpto. de Microbiología y Parasitología, Instituto de Salud Tropical (ISTUN), Instituto de Investigación Sanitaria de Navarra, Universidad de Navarra, Pamplona, Spain
| | - Leticia Lázaro-Antón
- Dpto. de Microbiología y Parasitología, Instituto de Salud Tropical (ISTUN), Instituto de Investigación Sanitaria de Navarra, Universidad de Navarra, Pamplona, Spain
| | - Christian Sohlenkamp
- Centro de Ciencias Genómicas, Universidad Nacional Autónoma de México, Cuernavaca, Mexico
| | - Ignacio Moriyón
- Dpto. de Microbiología y Parasitología, Instituto de Salud Tropical (ISTUN), Instituto de Investigación Sanitaria de Navarra, Universidad de Navarra, Pamplona, Spain
| | - Maite Iriarte
- Dpto. de Microbiología y Parasitología, Instituto de Salud Tropical (ISTUN), Instituto de Investigación Sanitaria de Navarra, Universidad de Navarra, Pamplona, Spain
| | - Raquel Conde-Álvarez
- Dpto. de Microbiología y Parasitología, Instituto de Salud Tropical (ISTUN), Instituto de Investigación Sanitaria de Navarra, Universidad de Navarra, Pamplona, Spain
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Roop RM, Barton IS, Hopersberger D, Martin DW. Uncovering the Hidden Credentials of Brucella Virulence. Microbiol Mol Biol Rev 2021; 85:e00021-19. [PMID: 33568459 PMCID: PMC8549849 DOI: 10.1128/mmbr.00021-19] [Citation(s) in RCA: 47] [Impact Index Per Article: 15.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023] Open
Abstract
Bacteria in the genus Brucella are important human and veterinary pathogens. The abortion and infertility they cause in food animals produce economic hardships in areas where the disease has not been controlled, and human brucellosis is one of the world's most common zoonoses. Brucella strains have also been isolated from wildlife, but we know much less about the pathobiology and epidemiology of these infections than we do about brucellosis in domestic animals. The brucellae maintain predominantly an intracellular lifestyle in their mammalian hosts, and their ability to subvert the host immune response and survive and replicate in macrophages and placental trophoblasts underlies their success as pathogens. We are just beginning to understand how these bacteria evolved from a progenitor alphaproteobacterium with an environmental niche and diverged to become highly host-adapted and host-specific pathogens. Two important virulence determinants played critical roles in this evolution: (i) a type IV secretion system that secretes effector molecules into the host cell cytoplasm that direct the intracellular trafficking of the brucellae and modulate host immune responses and (ii) a lipopolysaccharide moiety which poorly stimulates host inflammatory responses. This review highlights what we presently know about how these and other virulence determinants contribute to Brucella pathogenesis. Gaining a better understanding of how the brucellae produce disease will provide us with information that can be used to design better strategies for preventing brucellosis in animals and for preventing and treating this disease in humans.
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Affiliation(s)
- R Martin Roop
- Department of Microbiology and Immunology, Brody School of Medicine, East Carolina University, Greenville, North Carolina, USA
| | - Ian S Barton
- Department of Microbiology and Immunology, Brody School of Medicine, East Carolina University, Greenville, North Carolina, USA
| | - Dariel Hopersberger
- Department of Microbiology and Immunology, Brody School of Medicine, East Carolina University, Greenville, North Carolina, USA
| | - Daniel W Martin
- Department of Microbiology and Immunology, Brody School of Medicine, East Carolina University, Greenville, North Carolina, USA
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Kirthika P, Senevirathne A, Jawalagatti V, Park S, Lee JH. Deletion of the lon gene augments expression of Salmonella Pathogenicity Island (SPI)-1 and metal ion uptake genes leading to the accumulation of bactericidal hydroxyl radicals and host pro-inflammatory cytokine-mediated rapid intracellular clearance. Gut Microbes 2020; 11:1695-1712. [PMID: 32567462 PMCID: PMC7524146 DOI: 10.1080/19490976.2020.1777923] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/15/2020] [Revised: 05/21/2020] [Accepted: 05/26/2020] [Indexed: 02/03/2023] Open
Abstract
In the present study, we characterized the involvement of Lon protease in bacterial virulence and intracellular survival in Salmonella under abiotic stress conditions resembling the conditions of a natural infection. Wild type (JOL401) and the lon mutant (JOL909) Salmonella Typhimurium were exposed to low temperature, pH, osmotic, and oxidative stress conditions and changes in gene expression profiles related to virulence and metal ion uptake were investigated. Expression of candidate genes invF and hilC of Salmonella Pathogenicity Island (SPI)-1 and sifA and sseJ of SPI-2 revealed that Lon protease controls SPI-1 genes and not SPI-2 genes under all stress conditions tested. The lon mutant exhibited increased accumulation of hydroxyl (OH·) ions that lead to cell damage due to oxidative stress. This oxidative damage can also be linked to an unregulated influx of iron due to the upregulation of ion channel genes such as fepA in the lon mutant. The deletion of lon from the Salmonella genome causes oxidative damage and increased expression of virulence genes. It also prompts the secretion of host pro-inflammatory cytokines leading to early clearance of the bacteria from host cells. We conclude that poor bacterial recovery from mice infected with the lon mutant is a result of disrupted bacterial intracellular equilibrium and rapid activation of cytokine expression leading to bacterial lysis.
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Affiliation(s)
- Perumalraja Kirthika
- College of Veterinary Medicine, Jeonbuk National University, Iksan, Republic of Korea
| | - Amal Senevirathne
- College of Veterinary Medicine, Jeonbuk National University, Iksan, Republic of Korea
| | | | - SungWoo Park
- College of Veterinary Medicine, Jeonbuk National University, Iksan, Republic of Korea
| | - John Hwa Lee
- College of Veterinary Medicine, Jeonbuk National University, Iksan, Republic of Korea
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Masjedian Jezi F, Razavi S, Mirnejad R, Zamani K. Immunogenic and protective antigens of Brucella as vaccine candidates. Comp Immunol Microbiol Infect Dis 2019; 65:29-36. [PMID: 31300122 DOI: 10.1016/j.cimid.2019.03.015] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2018] [Revised: 03/20/2019] [Accepted: 03/26/2019] [Indexed: 01/18/2023]
Abstract
Brucella is an intracellular pathogen that causes abortion in domestic animals and undulant fever in humans. Due to the lack of a human vaccine against brucellosis, animal vaccines play an important role in the management of animal and human brucellosis for decades. Strain 19, RB51 and Rev1 are the approved Brucella spp. vaccine strains that are most commonly used to protect livestock against infection and abortion. However, due to some disadvantages of these vaccines, numerous studies have been conducted for the development of effective vaccines that could also be used in other susceptible animals. In this review, we compare different aspects of immunogenic antigens that have been a candidate for the brucellosis vaccine.
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Affiliation(s)
- Faramarz Masjedian Jezi
- Department of Microbiology, School of Medicine, Iran University of Medical Sciences, Tehran, I
| | - Shabnam Razavi
- Department of Microbiology, School of Medicine, Iran University of Medical Sciences, Tehran, I
| | - Reza Mirnejad
- Molecular Biology Research Center, Baqiyatallah University of Medical Sciences, Tehran, Iran
| | - Khosrow Zamani
- Department of Microbiology, School of Medicine, Iran University of Medical Sciences, Tehran, I; Student Research Committee, Iran University of Medical Sciences, Tehran, Iran.
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5
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Alsayed Hasanain AF, El-Masry MA, Zayed AAAH, Nafee AMA, Attia RAMH, Abdel-Aal SM. Predictors of therapeutic failure among patients with acute brucellosis treated by dual therapy with doxycycline-rifampin. Trop Med Int Health 2018; 24:185-191. [PMID: 30411836 DOI: 10.1111/tmi.13179] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
OBJECTIVE To determine the frequency of therapeutic failure among patients with acute and subacute brucellosis and to explore the predictors of failure. METHODS The study included 213 consecutive, naïve patients with acute and subacute brucellosis. All participants underwent clinical evaluation, chest radiography, stool microscopic examination and interferon-gamma release assay. Patients received the WHO-recommended therapy of doxycycline 200 mg/day and rifampin 900 mg/day, for 6 weeks. RESULTS Mean age of the study population was 39.8 ± 12.2 years; 64.8% of them were males. The therapeutic failure rate was 16.4%. Adverse effects were reported by 13.1%. Multivariate analysis of factors associated with therapeutic failure revealed latent tuberculosis infection (LTBI) (OR 3.1, 95% CI, 1.9-24.6, P: 0.009), ascariasis (OR 2.6, 95% CI 1.5-17.9, P: 0.012), and the use of acid suppressive therapy (OR 2.1, 95% CI 1.2-19.5, P: 0.037) as the predictors of therapeutic failure. CONCLUSIONS The prevalence of therapeutic failure among the Egyptian patients with acute/subacute brucellosis is increasing. Predictors of therapeutic failure are LTBI, ascariasis, and the use of acid suppressive therapy.
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Sidhu-Muñoz RS, Sancho P, Cloeckaert A, Zygmunt MS, de Miguel MJ, Tejedor C, Vizcaíno N. Characterization of Cell Envelope Multiple Mutants of Brucella ovis and Assessment in Mice of Their Vaccine Potential. Front Microbiol 2018; 9:2230. [PMID: 30294312 PMCID: PMC6158377 DOI: 10.3389/fmicb.2018.02230] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2018] [Accepted: 08/31/2018] [Indexed: 01/22/2023] Open
Abstract
Brucella ovis is a non-zoonotic Brucella species lacking specific vaccine. It presents a narrow host range, a unique biology relative to other Brucella species, and important distinct surface properties. To increase our knowledge on its peculiar surface and virulence features, and seeking to develop a specific vaccine, multiple mutants for nine relevant cell-envelope-related genes were investigated. Mutants lacking Omp10 plus Omp19 could not be obtained, suggesting that at least one of these lipoproteins is required for viability. A similar result was obtained for the double deletion of omp31 and omp25 that encode two major surface proteins. Conversely, the absence of major Omp25c (proved essential for internalization in HeLa cells) together with Omp25 or Omp31 was tolerated by the bacterium. Although showing important in vitro and in vivo defects, the Δomp10Δomp31Δomp25c mutant was obtained, demonstrating that B. ovis PA survives to the simultaneous absence of Omp10 and four out seven proteins of the Omp25/Omp31 family (i.e., Omp31, Omp25c, Omp25b, and Omp31b, the two latter naturally absent in B. ovis). Three multiple mutants were selected for a detailed analysis of virulence in the mouse model. The Δomp31Δcgs and Δomp10Δomp31Δomp25c mutants were highly attenuated when inoculated at 106 colony forming units/mouse but they established a persistent infection when the infection dose was increased 100-fold. The Δomp10ΔugpBΔomp31 mutant showed a similar behavior until week 3 post-infection but was then totally cleared from spleen. Accordingly, it was retained as vaccine candidate for mice protection assays. When compared to classical B. melitensis Rev1 heterologous vaccine, the triple mutant induced limited splenomegaly, a significantly higher antibody response against whole B. ovis PA cells, an equivalent memory cellular response and, according to spleen colonization measurements, better protection against a challenge with virulent B. ovis PA. Therefore, it would be a good candidate to be evaluated in the natural host as a specific vaccine against B. ovis that would avoid the drawbacks of B. melitensis Rev1. In addition, the lack in this attenuated strain of Omp31, recognized as a highly immunogenic protein during B. ovis infection, would favor the differentiation between infected and vaccinated animals using Omp31 as diagnostic target.
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Affiliation(s)
- Rebeca Singh Sidhu-Muñoz
- Departamento de Microbiología y Genética, Universidad de Salamanca, Salamanca, Spain.,Instituto de Investigación Biomédica de Salamanca, Salamanca, Spain
| | - Pilar Sancho
- Departamento de Microbiología y Genética, Universidad de Salamanca, Salamanca, Spain
| | - Axel Cloeckaert
- Plasticité Génomique, Biodiversité, Antibiorésistance (PGBA), UR1282 - Infectiologie Animale, Santé Publique (IASP-311), Institut National de la Recherche Agronomique Centre Val de Loire, Nouzilly, France
| | - Michel Stanislas Zygmunt
- Plasticité Génomique, Biodiversité, Antibiorésistance (PGBA), UR1282 - Infectiologie Animale, Santé Publique (IASP-311), Institut National de la Recherche Agronomique Centre Val de Loire, Nouzilly, France
| | - María Jesús de Miguel
- Unidad de Producción y Sanidad Animal, Centro de Investigación y Tecnología Agroalimentaria de Aragón, Instituto Agroalimentario de Aragón - IA2, Zaragoza, Spain
| | - Carmen Tejedor
- Departamento de Microbiología y Genética, Universidad de Salamanca, Salamanca, Spain
| | - Nieves Vizcaíno
- Departamento de Microbiología y Genética, Universidad de Salamanca, Salamanca, Spain.,Instituto de Investigación Biomédica de Salamanca, Salamanca, Spain
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7
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Wang Y, Li Y, Li H, Song H, Zhai N, Lou L, Wang F, Zhang K, Bao W, Jin X, Su L, Tu Z. Brucella Dysregulates Monocytes and Inhibits Macrophage Polarization through LC3-Dependent Autophagy. Front Immunol 2017; 8:691. [PMID: 28659924 PMCID: PMC5467008 DOI: 10.3389/fimmu.2017.00691] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2017] [Accepted: 05/29/2017] [Indexed: 01/18/2023] Open
Abstract
Brucellosis is caused by infection with Brucella species and exhibits diverse clinical manifestations in infected humans. Monocytes and macrophages are not only the first line of defense against Brucella infection but also a main reservoir for Brucella. In the present study, we examined the effects of Brucella infection on human peripheral monocytes and monocyte-derived polarized macrophages. We showed that Brucella infection led to an increase in the proportion of CD14++CD16− monocytes and the expression of the autophagy-related protein LC3B, and the effects of Brucella-induced monocytes are inhibited after 6 weeks of antibiotic treatment. Additionally, the production of IL-1β, IL-6, IL-10, and TNF-α from monocytes in patients with brucellosis was suppressed through the LC3-dependent autophagy pathway during Brucella infection. Moreover, Brucella infection inhibited macrophage polarization. Consistently, the addition of 3-MA, an inhibitor of LC3-related autophagy, partially restored macrophage polarization. Intriguingly, we also found that the upregulation of LC3B expression by rapamycin and heat-killed Brucella in vitro inhibits M2 macrophage polarization, which can be reversed partially by 3-MA. Taken together, these findings reveal that Brucella dysregulates monocyte and macrophage polarization through LC3-dependent autophagy. Thus, targeting this pathway may lead to the development of new therapeutics against Brucellosis.
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Affiliation(s)
- Yang Wang
- Institute of Translational Medicine, The First Hospital of Jilin University, Changchun, China.,Department of Infectious Diseases, The First Hospital of Jilin University, Changchun, China
| | - Yuxiang Li
- Department of Infectious Diseases, The First Hospital of Jilin University, Changchun, China
| | - Haijun Li
- Institute of Translational Medicine, The First Hospital of Jilin University, Changchun, China
| | - Hongxiao Song
- Institute of Translational Medicine, The First Hospital of Jilin University, Changchun, China
| | - Naicui Zhai
- Institute of Translational Medicine, The First Hospital of Jilin University, Changchun, China
| | - Lixin Lou
- Department of Infectious Diseases, The First Hospital of Jilin University, Changchun, China
| | - Feng Wang
- Department of Infectious Diseases, The First Hospital of Jilin University, Changchun, China
| | - Kaiyu Zhang
- Department of Infectious Diseases, The First Hospital of Jilin University, Changchun, China
| | - Wanguo Bao
- Department of Infectious Diseases, The First Hospital of Jilin University, Changchun, China
| | - Xia Jin
- CAS Key Laboratory of Molecular Virology and Immunology, Institute Pasteur of Shanghai, Chinese Academy of Sciences, Shanghai, China
| | - Lishan Su
- Institute of Translational Medicine, The First Hospital of Jilin University, Changchun, China.,Lineberger Comprehensive Cancer Center, School of Medicine, University of North Carolina at Chapel Hill, Chapel Hill, NC, United States
| | - Zhengkun Tu
- Institute of Translational Medicine, The First Hospital of Jilin University, Changchun, China.,Department of Infectious Diseases, The First Hospital of Jilin University, Changchun, China
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Ahmed W, Zheng K, Liu ZF. Establishment of Chronic Infection: Brucella's Stealth Strategy. Front Cell Infect Microbiol 2016; 6:30. [PMID: 27014640 PMCID: PMC4791395 DOI: 10.3389/fcimb.2016.00030] [Citation(s) in RCA: 81] [Impact Index Per Article: 10.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2015] [Accepted: 02/29/2016] [Indexed: 01/18/2023] Open
Abstract
Brucella is a facultative intracellular pathogen that causes zoonotic infection known as brucellosis which results in abortion and infertility in natural host. Humans, especially in low income countries, can acquire infection by direct contact with infected animal or by consumption of animal products and show high morbidity, severe economic losses and public health problems. However for survival, host cells develop complex immune mechanisms to defeat and battle against attacking pathogens and maintain a balance between host resistance and Brucella virulence. On the other hand as a successful intracellular pathogen, Brucella has evolved multiple strategies to evade immune response mechanisms to establish persistent infection and replication within host. In this review, we mainly summarize the "Stealth" strategies employed by Brucella to modulate innate and the adaptive immune systems, autophagy, apoptosis and possible role of small noncoding RNA in the establishment of chronic infection. The purpose of this review is to give an overview for recent understanding how this pathogen evades immune response mechanisms of host, which will facilitate to understanding the pathogenesis of brucellosis and the development of novel, more effective therapeutic approaches to treat brucellosis.
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Affiliation(s)
- Waqas Ahmed
- State Key Laboratory of Agricultural Microbiology, College of Veterinary Medicine, Huazhong Agricultural University Wuhan, China
| | - Ke Zheng
- State Key Laboratory of Agricultural Microbiology, College of Veterinary Medicine, Huazhong Agricultural University Wuhan, China
| | - Zheng-Fei Liu
- State Key Laboratory of Agricultural Microbiology, College of Veterinary Medicine, Huazhong Agricultural University Wuhan, China
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Jacob J, Makou P, Finke A, Mielke M. Inflammatory response of TLR4 deficient spleen macrophages (CRL 2471) to Brucella abortus S19 and an isogenic ΔmglA deletion mutant. Int J Med Microbiol 2016; 306:141-51. [PMID: 26946956 DOI: 10.1016/j.ijmm.2016.02.006] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2015] [Revised: 01/29/2016] [Accepted: 02/16/2016] [Indexed: 01/21/2023] Open
Abstract
UNLABELLED Brucellosis is a worldwide distributed zoonosis caused by members of the genus Brucella. One of them, Brucella abortus, is the etiological agent of bovine brucellosis. With the attenuated strain B. abortus S19 a vaccine is available. However, both, virulence (safety) and the ability to induce a protective B and T cell response (efficacy) have to be tested in suitable assays before successful use in the field. For this purpose, several macrophage cell lines of various origins have been used while splenic macrophages are the preferred host cells in vivo. We here characterized the in vitro response of the murine splenic macrophage cell line CRL 2471(I-13.35) to B. abortus. This cell line still depends on the presence of colony-stimulating factor 1 (CSF1) and is derived from LPS resistant (TLR4 deficient) C3H/HeJ mice. For infection the vaccine strain B. abortus S19A as well as the formerly described isogenic deletion mutant B. abortus S19A ΔmglA 3.14 were used. While numbers of viable bacteria did not differ significantly between the vaccine strain and the deletion mutant at 6h post infection, a higher bacterial load was measured in case of the mutant at 24h and 48h after infection. This was also true, when IFNγ was used for macrophage activation. A comprehensive gene expression profile of macrophages was analysed 6 and 24h after infection by means of an RT-PCR based gene expression array. The mutant strain B. abortus S19A ΔmglA 3.14 elicited a stronger cellular response of the splenic macrophages as compared to the parental vaccine strain. This was most prominent for the pro-inflammatory cytokines IL-1α, IL-1β, TNF-α and IL6 as well as for the chemokine ligands CXCL1, CXCL2, CXCL10, CCL2, CCL5, CCL7, CCL17 and the co-stimulatory molecules CD40 and ICAM1. While these differences were also present in IFNγ-stimulated macrophages, an addition of IFNγ after infection not only resulted in a dramatic increase of the translation of the afore mentioned genes but also resulted in the translation of IFNß1, IL12ß, MIP1α and β (CCL3, CCL4), NOS2 (and SOD2) and FAS. CONCLUSION The TLR4 deficient murine splenic macrophage cell line CRL 2471 was used for the first time for the characterization of macrophage-Brucella interaction to investigate the pre-immune phase of brucellosis in vitro. Typical pro-inflammatory cytokines and certain surface receptors were differentially induced by B. abortus S19 A and an isogenic ΔmglA deletion mutant in vitro. This model may be useful for further studies to characterize the inflammatory response of splenic macrophages to intracellular gram-negative bacteria avoiding cell responses to soluble LPS.
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Affiliation(s)
- Jens Jacob
- Robert Koch-Institute, Nordufer 20, 13353 Berlin, Germany.
| | - Patricia Makou
- Robert Koch-Institute, Nordufer 20, 13353 Berlin, Germany
| | - Antje Finke
- Robert Koch-Institute, Nordufer 20, 13353 Berlin, Germany
| | - Martin Mielke
- Robert Koch-Institute, Nordufer 20, 13353 Berlin, Germany
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10
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Park S, Choi YS, Park SH, Kim YR, Chu H, Hwang KJ, Park MY. Lon Mutant of Brucella abortus Induces Tumor Necrosis Factor-Alpha in Murine J774.A1 Macrophage. Osong Public Health Res Perspect 2013; 4:301-7. [PMID: 24524018 PMCID: PMC3922098 DOI: 10.1016/j.phrp.2013.10.002] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2013] [Revised: 09/30/2013] [Accepted: 10/02/2013] [Indexed: 11/29/2022] Open
Abstract
Objectives The objective of this study was to isolate a Brucella lon mutant and to analyze the cytokine response of B. lon mutant during macrophage infection. Methods A wild-type Brucella abortus strain was mutagenized by Tn5 transposition. From the mouse macrophage J774.A1 cells, total RNA was isolated at 0 hours, 6 hours, 12 hours, and 24 hours after infection with Brucella. Using mouse cytokine microarrays, we measured transcriptional levels of the cytokine response, and validated our results with a reverse transcriptase-polymerase chain reaction (RT-PCR) assay to confirm the induction of cytokine messenger RNA (mRNA). Results In host J774.A1 macrophages, mRNA levels of T helper 1 (Th1)-type cytokines, including tumor necrosis factor-alpha (TNF-α), interferon-gamma (IFN-γ), interleukin-2 (IL-2), and IL-3, were significantly higher in the lon mutant compared to wild-type Brucella and the negative control. TNF-α levels in cell culture media were induced as high as 2 μg/mL after infection with the lon mutant, a greater than sixfold change. Conclusion In order to understand the role of the lon protein in virulence, we identified and characterized a novel B. lon mutant. We compared the immune response it generates to the wild-type Brucella response in a mouse macrophage cell line. We demonstrated that the B. lon mutants induce TNF-α expression from the host J774.A1 macrophage.
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Affiliation(s)
- Sungdo Park
- Division of Zoonoses, Korea National Institute of Health, Osong, Korea
| | - Young-Sill Choi
- Division of Zoonoses, Korea National Institute of Health, Osong, Korea
| | - Sang-Hee Park
- Division of Zoonoses, Korea National Institute of Health, Osong, Korea
| | - Young-Rok Kim
- Division of Zoonoses, Korea National Institute of Health, Osong, Korea
| | - Hyuk Chu
- Division of Zoonoses, Korea National Institute of Health, Osong, Korea
| | - Kyu-Jam Hwang
- Division of Zoonoses, Korea National Institute of Health, Osong, Korea
| | - Mi-Yeoun Park
- Division of Zoonoses, Korea National Institute of Health, Osong, Korea
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Gomes MTR, Campos PC, de Almeida LA, Oliveira FS, Costa MMS, Marim FM, Pereira GSM, Oliveira SC. The role of innate immune signals in immunity to Brucella abortus. Front Cell Infect Microbiol 2012; 2:130. [PMID: 23112959 PMCID: PMC3480720 DOI: 10.3389/fcimb.2012.00130] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2012] [Accepted: 10/04/2012] [Indexed: 01/18/2023] Open
Abstract
Innate immunity serves as the first line of defense against infectious agents such as intracellular bacteria. The innate immune platform includes Toll-like receptors (TLRs), retinoid acid-inducible gene-I-like receptors and other cytosolic nucleic acid sensors, nucleotide-binding and oligomerization domain-like receptors, adaptors, kinases and other signaling molecules that are required to elicit effective responses against different pathogens. Our research group has been using the Gram-negative bacteria Brucella abortus as a model of pathogen. We have demonstrated that B. abortus triggers MAPK and NF-κB signaling pathways in macrophages in a MyD88 and IRAK-4-dependent manner. Furthermore, we claimed that so far TLR9 is the most important single TLR during Brucella infection. The identification of host receptors that recognize pathogen-derived nucleic acids has revealed an essential role for nucleic acid sensing in the triggering of immunity to intracellular pathogens. Besides TLRs, herein we describe recent advances in NOD1, NOD2, and type I IFN receptors in innate immune pathways during B. abortus infection.
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Affiliation(s)
| | | | | | | | | | | | | | - Sergio C. Oliveira
- Department of Biochemistry and Immunology, Institute of Biological Sciences, Federal University of Minas GeraisBelo Horizonte, MG, Brazil
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12
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Goenka R, Guirnalda PD, Black SJ, Baldwin CL. B Lymphocytes provide an infection niche for intracellular bacterium Brucella abortus. J Infect Dis 2012; 206:91-8. [PMID: 22561364 DOI: 10.1093/infdis/jis310] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
BACKGROUND Brucella spp. are intracellular bacteria that establish lifelong infections whose mechanisms of chronicity are poorly understood. Notably, B cells facilitate the establishment of the high infection plateau that persists for months. METHODS We evaluated the contribution of murine B cells toward providing infection niches for Brucella by using flow cytometry and microscopy and by determining live bacterial counts associated with B cells both in vivo and in vitro. RESULTS Herein we demonstrate that immunoglobulin M and complement-opsonized Brucella abortus infects and survives inside primary murine B cells protected from bactericidal effects of gentamicin. The entry was dependent on microfilaments for internalization and subsequently brucellae reside in a late endosomal/lysosomal compartment. Throughout the infection, 10% of colony-forming units from infected mice was associated with B cells, and these cells transferred disease to naive hosts. Furthermore, Brucella-positive cells were positive for transforming growth factor (TGF) β1, and about 10% of such cells were B cells, similar to rates found for other intracellular pathogens that induce their hosts cells to produce TGF-β1. CONCLUSIONS To conclude, infected B cells contribute to chronic bacterial infections by providing an intracellular niche that may exert an immunoregulatory role. Although professional phagocytic cells harbor intracellular bacteria including Brucella, infection of lymphocytes by bacteria has not been previously appreciated.
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Affiliation(s)
- Radhika Goenka
- Department of Veterinary and Animal Sciences, University of Massachusetts, Amherst, Massachusetts 01003, USA
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13
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Abstract
Brucellosis is a global disease of domestic and wild mammals that is caused by intracellular bacteria of the genus Brucella. Although humans are not a natural reservoir for Brucella, infection in the human population is common in many countries, and brucellosis is one of the most common zoonotic infections. Brucella species have evolved to avoid the host's immune system and infection is usually characterized by long-term persistence of the bacteria. One important Brucella virulence factor for intracellular survival and persistence in the host is the type IV secretion system. This review will discuss the Brucella type IV secretion system in detail, including current knowledge of architecture and regulation, as well as the newly identified effector substrates that this system transports into host cells.
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Affiliation(s)
- Maarten F de Jong
- Department of Medical Microbiology & Immunology, University of California, Davis, CA, USA
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14
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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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15
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Extended safety and efficacy studies of the attenuated Brucella vaccine candidates 16 M(Delta)vjbR and S19(Delta)vjbR in the immunocompromised IRF-1-/- mouse model. CLINICAL AND VACCINE IMMUNOLOGY : CVI 2011; 19:249-60. [PMID: 22169089 DOI: 10.1128/cvi.05321-11] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
The global distribution of brucellosis and high incidence in certain areas of the world warrant the development of a safer and efficacious vaccine. For the past 10 years, we have focused our attention on the development of a safer, but still highly protective, live attenuated vaccine for human and animal use. We have demonstrated the safety and protective efficacy of the vaccine candidates 16 MΔvjbR and S19ΔvjbR against homologous and heterologous challenge in multiple immunocompetent animal models, including mice and deer. In the present study, we conducted a series of experiments to determine the safety of the vaccine candidates in interferon regulatory factor-1-knockout (IRF-1(-/-)) mice. IRF-1(-/-) mice infected with either wild-type Brucella melitensis 16 M or the vaccine strain Brucella abortus S19 succumb to the disease within the first 3 weeks of infection, which is characterized by a marked granulomatous and neutrophilic inflammatory response that principally targets the spleen and liver. In contrast, IRF-1(-/-) mice inoculated with either the 16 MΔvjbR or S19ΔvjbR vaccine do not show any clinical or major pathological changes associated with vaccination. Additionally, when 16 MΔvjbR- or S19ΔvjbR-vaccinated mice are challenged with wild-type Brucella melitensis 16M, the degree of colonization in multiple organs, along with associated pathological changes, is significantly reduced. These findings not only demonstrate the safety and protective efficacy of the vjbR mutant in an immunocompromised mouse model but also suggest the participation of lesser-known mechanisms in protective immunity against brucellosis.
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16
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da Silva PEA, Von Groll A, Martin A, Palomino JC. Efflux as a mechanism for drug resistance in Mycobacterium tuberculosis. ACTA ACUST UNITED AC 2011; 63:1-9. [PMID: 21668514 DOI: 10.1111/j.1574-695x.2011.00831.x] [Citation(s) in RCA: 132] [Impact Index Per Article: 10.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
Tuberculosis remains an important global public health problem, with an estimated prevalence of 14 million individuals with tuberculosis worldwide in 2007. Because antibiotic treatment is one of the main tools for tuberculosis control, knowledge of Mycobacterium tuberculosis drug resistance is an important component for the disease control strategy. Although several gene mutations in specific loci of the M. tuberculosis genome have been reported as the basis for drug resistance, additional resistance mechanisms are now believed to exist. Efflux is a ubiquitous mechanism responsible for intrinsic and acquired drug resistance in prokaryotic and eukaryotic cells. Mycobacterium tuberculosis presents one of the largest numbers of putative drug efflux pumps compared with its genome size. Bioinformatics as well as direct and indirect evidence have established relationships among drug efflux with intrinsic or acquired resistance in M. tuberculosis. This minireview describes the current knowledge on drug efflux in M. tuberculosis.
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Affiliation(s)
- Pedro Eduardo Almeida da Silva
- Universidade Federal do Rio Grande, Rio Grande, BrazilMycobacteriology Unit, Institute of Tropical Medicine Antwerp, Belgium
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17
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Martirosyan A, Moreno E, Gorvel JP. An evolutionary strategy for a stealthy intracellular Brucella pathogen. Immunol Rev 2011; 240:211-34. [PMID: 21349096 DOI: 10.1111/j.1600-065x.2010.00982.x] [Citation(s) in RCA: 162] [Impact Index Per Article: 12.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Abstract
Brucella is an intracellular bacterial pathogen that causes abortion and infertility in mammals and leads to a debilitating febrile illness that can progress into a long lasting disease with severe complications in humans. Its virulence depends on survival and replication properties in host cells. In this review, we describe the stealthy strategy used by Brucella to escape recognition of the innate immunity and the means by which this bacterium evades intracellular destruction. We also discuss the development of adaptive immunity and its modulation during brucellosis that in course leads to chronic infections. Brucella has developed specific strategies to influence antigen presentation mediated by cells. There is increasing evidence that Brucella also modulates signaling events during host adaptive immune responses.
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Affiliation(s)
- Anna Martirosyan
- Faculté de Sciences de Luminy, Centre d'Immunologie de Marseille-Luminy, Aix Marseille Université, Marseille, France
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18
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de Jong MF, Rolán HG, Tsolis RM. Innate immune encounters of the (Type) 4th kind: Brucella. Cell Microbiol 2010; 12:1195-202. [PMID: 20670294 DOI: 10.1111/j.1462-5822.2010.01498.x] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Abstract
In humans, pathogenic Brucella species cause a febrile illness known as brucellosis. A key pathogenic trait of this group of organisms is their ability to survive in immune cells and persist in tissues of the reticuloendothelial system, a process that requires the function of a Type IV secretion system. In contrast to other well-studied Gram-negative bacteria, Brucella spp. do not cause inflammation at the site of invasion, but have a latency period of 2-4 weeks before the onset of symptoms. This review discusses several mechanisms that allow Brucella spp. both to evade detection by pattern recognition receptors of the innate immune system and suppress their signalling. In contrast to these stealth features, the VirB Type IV secretion system, which mediates survival within phagocytic cells, stimulates innate immune responses in vivo. The responses stimulated by this virulence factor are sufficient to check bacterial growth, but not to elicit sterilizing immunity. The result is a stand-off between host and pathogen that results in persistent infection.
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Affiliation(s)
- Maarten F de Jong
- Department of Medical Microbiology & Immunology, University of California at Davis, Davis, CA, USA
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19
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Survival of the fittest: how Brucella strains adapt to their intracellular niche in the host. Med Microbiol Immunol 2009; 198:221-38. [PMID: 19830453 DOI: 10.1007/s00430-009-0123-8] [Citation(s) in RCA: 134] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2009] [Indexed: 02/06/2023]
Abstract
Brucella strains produce abortion and infertility in their natural hosts and a zoonotic disease in humans known as undulant fever. These bacteria do not produce classical virulence factors, and their capacity to successfully survive and replicate within a variety of host cells underlies their pathogenicity. Extensive replication of the brucellae in placental trophoblasts is associated with reproductive tract pathology in natural hosts, and prolonged persistence in macrophages leads to the chronic infections that are a hallmark of brucellosis in both natural hosts and humans. This review describes how Brucella strains have efficiently adapted to their intracellular lifestyle in the host.
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20
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Domenech P, Kobayashi H, LeVier K, Walker GC, Barry CE. BacA, an ABC transporter involved in maintenance of chronic murine infections with Mycobacterium tuberculosis. J Bacteriol 2009; 191:477-85. [PMID: 18996991 PMCID: PMC2620812 DOI: 10.1128/jb.01132-08] [Citation(s) in RCA: 68] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2008] [Accepted: 10/31/2008] [Indexed: 11/20/2022] Open
Abstract
BacA is an inner membrane protein associated with maintenance of chronic infections in several diverse host-pathogen interactions. To understand the function of the bacA gene in Mycobacterium tuberculosis (Rv1819c), we insertionally inactivated this gene and analyzed the resulting mutant for a variety of phenotypes. BacA deficiency in M. tuberculosis did not affect sensitivity to detergents, acidic pH, and zinc, indicating that there was no global compromise in membrane integrity, and a comprehensive evaluation of the major lipid constituents of the cell envelope failed to reveal any significant differences. Infection of mice with this mutant revealed no impact on establishment of infection but a profound effect on maintenance of extended chronic infection and ultimate outcome. As in alphaproteobacteria, deletion of BacA in M. tuberculosis led to increased bleomycin resistance, and heterologous expression of the M. tuberculosis BacA homolog in Escherichia coli conferred sensitivity to antimicrobial peptides. These results suggest a striking conservation of function for BacA-related proteins in transport of a critical molecule that determines the outcome of the host-pathogen interaction.
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Affiliation(s)
- Pilar Domenech
- Tuberculosis Research Section, Laboratory of Clinical Infectious Diseases, National Institute of Allergy and Infectious Disease, 33 North Drive, Bethesda, Maryland 20892, USA
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21
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Essential role for the BacA protein in the uptake of a truncated eukaryotic peptide in Sinorhizobium meliloti. J Bacteriol 2008; 191:1519-27. [PMID: 19074376 DOI: 10.1128/jb.01661-08] [Citation(s) in RCA: 54] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
The inner membrane BacA protein is essential for the establishment of chronic intracellular infections by Sinorhizobium meliloti and Brucella abortus within plant and mammalian hosts, respectively. In their free-living state, S. meliloti and B. abortus mutants lacking BacA have reductions in their outer membrane lipid A very-long-chain fatty acid (VLCFA) contents and exhibit low-level resistance to the glycopeptide bleomycin in comparison to their respective parent strains. In this paper we investigate the hypothesis that BacA is involved in peptide uptake in S. meliloti. We determined that an S. meliloti DeltabacA mutant is completely resistant to a truncated form of the eukaryotic peptide Bac7, Bac7(1-16), and this phenotype appears to be independent of its lipid A alteration. Subsequently, we discovered that BacA and/or Escherichia coli SbmA is essential for fluorescently labeled Bac7(1-16) uptake in S. meliloti. Given that there are hundreds of root nodule-specific peptides within the legume host, our data suggest that BacA-mediated peptide uptake could play a central role in the chronic infection process of S. meliloti. However, since we determined that two symbiotically defective S. meliloti bacA site-directed mutants (with the Q193G and R389G mutations, respectively) with known reductions in their lipid A VLCFA contents are still capable of peptide uptake, these findings suggest that BacA-dependent peptide uptake cannot fully account for the essential role of BacA in the legume symbiosis. Further, they provide evidence that the BacA function that leads to the S. meliloti lipid A VLCFA modification plays a key role in the chronic infection of legumes.
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22
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Lescot M, Audic S, Robert C, Nguyen TT, Blanc G, Cutler SJ, Wincker P, Couloux A, Claverie JM, Raoult D, Drancourt M. The genome of Borrelia recurrentis, the agent of deadly louse-borne relapsing fever, is a degraded subset of tick-borne Borrelia duttonii. PLoS Genet 2008; 4:e1000185. [PMID: 18787695 PMCID: PMC2525819 DOI: 10.1371/journal.pgen.1000185] [Citation(s) in RCA: 122] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2008] [Accepted: 07/31/2008] [Indexed: 01/22/2023] Open
Abstract
In an effort to understand how a tick-borne pathogen adapts to the body louse, we sequenced and compared the genomes of the recurrent fever agents Borrelia recurrentis and B. duttonii. The 1,242,163–1,574,910-bp fragmented genomes of B. recurrentis and B. duttonii contain a unique 23-kb linear plasmid. This linear plasmid exhibits a large polyT track within the promoter region of an intact variable large protein gene and a telomere resolvase that is unique to Borrelia. The genome content is characterized by several repeat families, including antigenic lipoproteins. B. recurrentis exhibited a 20.4% genome size reduction and appeared to be a strain of B. duttonii, with a decaying genome, possibly due to the accumulation of genomic errors induced by the loss of recA and mutS. Accompanying this were increases in the number of impaired genes and a reduction in coding capacity, including surface-exposed lipoproteins and putative virulence factors. Analysis of the reconstructed ancestral sequence compared to B. duttonii and B. recurrentis was consistent with the accelerated evolution observed in B. recurrentis. Vector specialization of louse-borne pathogens responsible for major epidemics was associated with rapid genome reduction. The correlation between gene loss and increased virulence of B. recurrentis parallels that of Rickettsia prowazekii, with both species being genomic subsets of less-virulent strains. Borreliae are vector-borne spirochetes that are responsible for Lyme disease and recurrent fevers. We completed the genome sequences of the tick-borne Borrelia duttonii and the louse-borne B. recurrentis. The former of these is responsible for emerging infections that mimic malaria in Africa and in travellers, and the latter is responsible for severe recurrent fever in poor African populations. Diagnostic tools for these pathogens remain poor with regard to sensitivity and specificity due, in part, to the lack of genomic sequences. In this study, we show that the genomic content of B. recurrentis is a subset of that of B. duttonii, the genes of which are undergoing a decay process. These phenomena are common to all louse-borne pathogens compared to their tick-borne counterparts. In B. recurrentis, this process may be due to the inactivation of genes encoding DNA repair mechanisms, implying the accumulation of errors in the genome. The increased virulence of B. recurrentis could not be traced back to specific virulence factors, illustrating the lack of correlation between the virulence of a pathogen and so-called virulence genes. Knowledge of these genomes will allow for the development of new molecular tools that provide a more-accurate, sensitive, and specific diagnosis of these emerging infections.
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Affiliation(s)
- Magali Lescot
- Structural and Genomic Information Laboratory, CNRS UPR2589, IFR88, Parc Scientifique de Luminy, Marseille, France
| | - Stéphane Audic
- Structural and Genomic Information Laboratory, CNRS UPR2589, IFR88, Parc Scientifique de Luminy, Marseille, France
| | - Catherine Robert
- Unité des Rickettsies, UMR CNRS-IRD 6236, IFR48, Faculté de Médecine, Université de la Méditerranée, Marseille, France
| | - Thi Tien Nguyen
- Unité des Rickettsies, UMR CNRS-IRD 6236, IFR48, Faculté de Médecine, Université de la Méditerranée, Marseille, France
| | - Guillaume Blanc
- Structural and Genomic Information Laboratory, CNRS UPR2589, IFR88, Parc Scientifique de Luminy, Marseille, France
| | - Sally J. Cutler
- School of Health and Bioscience, University of East London, Stratford, London, United Kingdom
| | | | | | - Jean-Michel Claverie
- Structural and Genomic Information Laboratory, CNRS UPR2589, IFR88, Parc Scientifique de Luminy, Marseille, France
| | - Didier Raoult
- Unité des Rickettsies, UMR CNRS-IRD 6236, IFR48, Faculté de Médecine, Université de la Méditerranée, Marseille, France
| | - Michel Drancourt
- Unité des Rickettsies, UMR CNRS-IRD 6236, IFR48, Faculté de Médecine, Université de la Méditerranée, Marseille, France
- * E-mail:
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23
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Beck S, Marlow VL, Woodall K, Doerrler WT, James EK, Ferguson GP. The Sinorhizobium meliloti MsbA2 protein is essential for the legume symbiosis. MICROBIOLOGY-SGM 2008; 154:1258-1270. [PMID: 18375818 DOI: 10.1099/mic.0.2007/014894-0] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
Sinorhizobium meliloti is a beneficial legume symbiont, closely related to Brucella species, which are chronic mammalian pathogens. We discovered that the S. meliloti MsbA2 protein is essential to ensure the symbiotic interaction with the host plant, alfalfa. S. meliloti invades plant cells via plant-derived structures known as infection threads. However, in the absence of MsbA2, S. meliloti remains trapped within abnormally thickened infection threads and induces a heightened plant defence response, characterized by a substantial thickening of the nodule endodermis layer and the accumulation of polyphenolic compounds. The S. meliloti MsbA2 protein is homologous to the Escherichia coli lipopolysaccharide/phospholipid trafficking protein MsbA. However, MsbA2 was not essential for the membrane transport of either lipopolysaccharide or phospholipids in S. meliloti. We determined that the msbA2 gene is transcribed in free-living S. meliloti and that in the absence of MsbA2 the polysaccharide content of S. meliloti is altered. Consequently, we propose a model whereby the altered polysaccharide content of the S. meliloti msbA2 mutant could be responsible for its symbiotic defect by inducing an inappropriate host response.
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Affiliation(s)
- Sebastian Beck
- Institute of Cell Biology and Centre for Science at Extreme Conditions, School of Biological Sciences, King's Buildings, University of Edinburgh, Edinburgh EH9 3JR, UK
| | - Victoria L Marlow
- School of Medicine, Department of Medicine and Therapeutics, Institute of Medical Sciences, University of Aberdeen, Foresterhill, Aberdeen AB25 2ZD, UK.,Institute of Cell Biology and Centre for Science at Extreme Conditions, School of Biological Sciences, King's Buildings, University of Edinburgh, Edinburgh EH9 3JR, UK
| | - Katy Woodall
- Institute of Cell Biology and Centre for Science at Extreme Conditions, School of Biological Sciences, King's Buildings, University of Edinburgh, Edinburgh EH9 3JR, UK
| | - William T Doerrler
- Department of Biological Sciences, Louisiana State University, 202 Life Sciences Building, Baton Rouge, LA 70803, USA
| | - Euan K James
- College of Life Sciences, University of Dundee, Dundee DD1 5EH, UK
| | - Gail P Ferguson
- School of Medicine, Department of Medicine and Therapeutics, Institute of Medical Sciences, University of Aberdeen, Foresterhill, Aberdeen AB25 2ZD, UK.,Institute of Cell Biology and Centre for Science at Extreme Conditions, School of Biological Sciences, King's Buildings, University of Edinburgh, Edinburgh EH9 3JR, UK
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