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Bialer MG, Ferrero MC, Delpino MV, Ruiz-Ranwez V, Posadas DM, Baldi PC, Zorreguieta A. Adhesive Functions or Pseudogenization of Type Va Autotransporters in Brucella Species. Front Cell Infect Microbiol 2021; 11:607610. [PMID: 33987105 PMCID: PMC8111173 DOI: 10.3389/fcimb.2021.607610] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2020] [Accepted: 04/01/2021] [Indexed: 01/18/2023] Open
Abstract
Adhesion to host cells is a key step for successful infection of many bacterial pathogens and may define tropism to different host tissues. To do so, bacteria display adhesins on their surfaces. Brucella is an intracellular pathogen capable of proliferating in a wide variety of cell types. It has been described that BmaC, a large protein that belongs to the classical (type Va) autotransporter family, is required for efficient adhesion of Brucella suis strain 1330 to epithelial cells and fibronectin. Here we show that B. suis 1330 harbors two other type Va autotransporters (BmaA and BmaB), which, although much smaller, share significant sequence similarities with BmaC and contain the essential domains to mediate proper protein translocation to the bacterial surface. Gain and loss of function studies indicated that BmaA, BmaB, and BmaC contribute, to a greater or lesser degree, to adhesion of B. suis 1330 to different cells such as synovial fibroblasts, osteoblasts, trophoblasts, and polarized epithelial cells as well as to extracellular matrix components. It was previously shown that BmaC localizes to a single bacterial pole. Interestingly, we observed here that, similar to BmaC, the BmaB adhesin is localized mostly at a single cell pole, reinforcing the hypothesis that Brucella displays an adhesive pole. Although Brucella species have strikingly similar genomes, they clearly differ in their host preferences. Mainly, the differences identified between species appear to be at loci encoding surface proteins. A careful in silico analysis of the putative type Va autotransporter orthologues from several Brucella strains showed that the bmaB locus from Brucella abortus and both, the bmaA and bmaC loci from Brucella melitensis are pseudogenes in all strains analyzed. Results reported here evidence that all three autotransporters play a role in the adhesion properties of B. suis 1330. However, Brucella spp. exhibit extensive variations in the repertoire of functional adhesins of the classical autotransporter family that can be displayed on the bacterial surface, making them an interesting target for future studies on host preference and tropism.
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Affiliation(s)
- Magalí G Bialer
- Fundación Instituto Leloir (FIL), IIBBA (CONICET-FIL), Buenos Aires, Argentina
| | - Mariana C Ferrero
- Facultad de Farmacia y Bioquímica, Cátedra de Inmunología, Universidad de Buenos Aires, Buenos Aires, Argentina.,Instituto de Estudios de la Inmunidad Humoral (IDEHU), CONICET-Universidad de Buenos Aires, Buenos Aires, Argentina
| | - M Victoria Delpino
- Instituto de Inmunología, Genética y Metabolismo (INIGEM), CONICET-Universidad de Buenos Aires, Buenos Aires, Argentina
| | | | - Diana M Posadas
- Fundación Instituto Leloir (FIL), IIBBA (CONICET-FIL), Buenos Aires, Argentina
| | - Pablo C Baldi
- Facultad de Farmacia y Bioquímica, Cátedra de Inmunología, Universidad de Buenos Aires, Buenos Aires, Argentina.,Instituto de Estudios de la Inmunidad Humoral (IDEHU), CONICET-Universidad de Buenos Aires, Buenos Aires, Argentina
| | - Angeles Zorreguieta
- Fundación Instituto Leloir (FIL), IIBBA (CONICET-FIL), Buenos Aires, Argentina.,Departamento de Química Biológica, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Buenos Aires, Argentina
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2
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Characterization of innate immune response to Brucella melitensis infection in goats with permissive or restrictive phenotype for Brucella intramacrophagic growth. Vet Immunol Immunopathol 2021; 234:110223. [PMID: 33711712 DOI: 10.1016/j.vetimm.2021.110223] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2019] [Revised: 03/02/2021] [Accepted: 03/04/2021] [Indexed: 11/22/2022]
Abstract
Caprine brucellosis is a chronic, world-wide distributed disease which causes reproductive failure in goats and Brucella melitensis, its causative agent, bears a great zoonotic potential. There is evidence suggesting that some cattle and pigs have an innate ability to resist Brucella infection, but this has not yet been investigated in goats. In this study, we compared caprine macrophages that exhibit extreme restriction and permissiveness to B. melitensis' intracellular growth in vitro. Monocyte derived macrophages (MDMs) from 110 female goats were cultured and challenged in vitro with B. melitensis 16 M. After initial screening, 18 donor goats were selected based on their macrophages ability to restrict or allow bacterial intracellular growth and some elements of humoral and cellular immunity were studied in depth. MDMs that were able to restrict the pathogen's intracellular growth showed enhanced bacterial internalization, although there were no differences between groups in the production of reactive oxygen and nitrogen intermediates following 48 h treatment with heat-killed B. melitensis. Moreover, there were no differences between groups in the level of antibodies reacting with keyhole limpet hemocyanin (natural antibodies, NAbs) or with Brucella LPS antigens (cross-reacting antibodies, CrAbs), although a strong positive correlation between individual levels of IgM NAbs and IgM CrAbs was detected. Altogether, these results represent an initial step in understanding innate primary host response to B. melitensis, and deciphering which mechanisms may determine a successful outcome of the infection in goats.
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Abstract
Brucellosis is a bacterial disease of domestic animals and humans. The pathogenic ability of Brucella organisms relies on their stealthy strategy and their capacity to replicate within host cells and to induce long-lasting infections. Brucella organisms barely induce neutrophil activation and survive within these leukocytes by resisting microbicidal mechanisms. Very few Brucella-infected neutrophils are found in the target organs, except for the bone marrow, early in infection. Still, Brucella induces a mild reactive oxygen species formation and, through its lipopolysaccharide, promotes the premature death of neutrophils, which release chemokines and express "eat me" signals. This effect drives the phagocytosis of infected neutrophils by mononuclear cells that become thoroughly susceptible to Brucella replication and vehicles for bacterial dispersion. The premature death of the infected neutrophils proceeds without NETosis, necrosis/oncosis, or classical apoptosis morphology. In the absence of neutrophils, the Th1 response exacerbates and promotes bacterial removal, indicating that Brucella-infected neutrophils dampen adaptive immunity. This modulatory effect opens a window for bacterial dispersion in host tissues before adaptive immunity becomes fully activated. However, the hyperactivation of immunity is not without a price, since neutropenic Brucella-infected animals develop cachexia in the early phases of the disease. The delay in the immunological response seems a sine qua non requirement for the development of long-lasting brucellosis. This property may be shared with other pathogenic alphaproteobacteria closely related to Brucella We propose a model in which Brucella-infected polymorphonuclear neutrophils (PMNs) function as "Trojan horse" vehicles for bacterial dispersal and as modulators of the Th1 adaptive immunity in infection.
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Amjadi O, Rafiei A, Mardani M, Zafari P, Zarifian A. A review of the immunopathogenesis of Brucellosis. Infect Dis (Lond) 2019; 51:321-333. [PMID: 30773082 DOI: 10.1080/23744235.2019.1568545] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/21/2023] Open
Abstract
Brucellosis, caused by the intracellular pathogens Brucella, is one of the major zoonotic infections. Considering the economic burden, its prevalence has been a health concern especially in endemic regions. Brucella is able to survive and replicate within host cells by expressing different virulence factors and using various strategies to avoid the host's immune response. This leads to progression of the disease from an acute phase to chronic brucellosis. Exploration of genetic variations has confirmed the expected influence of gene polymorphisms on susceptibility and resistance to brucellosis of humans. Since there is no approved human vaccine and treatment is uncertain with risk of relapse, it is important to increase knowledge about pathogenesis, diagnosis and treatment of brucellosis in order to manage and control this infection, especially in endemic regions.
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Affiliation(s)
- Omolbanin Amjadi
- a Student Research Committee, Department of Immunology, School of Medicine , Mazandaran University of Medical Sciences , Sari , Iran
| | - Alireza Rafiei
- b Department of Immunology, School of Medicine , Mazandaran University of Medical Sciences , Sari , Iran
| | - Masoud Mardani
- c Infectious Diseases and Tropical Medicine Research Center , Shahid Beheshti University of Medical Sciences , Tehran , Iran
| | - Parisa Zafari
- a Student Research Committee, Department of Immunology, School of Medicine , Mazandaran University of Medical Sciences , Sari , Iran.,b Department of Immunology, School of Medicine , Mazandaran University of Medical Sciences , Sari , Iran
| | - Ahmadreza Zarifian
- d Infectious Disease Research Group, Student Research Committee, Medical School , Mashhad University of Medical Sciences , Mashhad , Iran
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5
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Lee JJ, Simborio HL, Reyes AWB, Hop HT, Arayan LT, Lee HJ, Min W, Her M, Rhee MH, Watarai M, Chang HH, Kim S. Influence of platelet-activating factor receptor (PAFR) on Brucella abortus infection: implications for manipulating the phagocytic strategy of B. abortus. BMC Microbiol 2016; 16:70. [PMID: 27098179 PMCID: PMC4839150 DOI: 10.1186/s12866-016-0685-8] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2015] [Accepted: 04/07/2016] [Indexed: 01/25/2023] Open
Abstract
BACKGROUND Brucella abortus is an intracellular pathogen which can infect and persist in host cells through multiple interactions. Above all, its interaction to host cell receptor is important to understand the pathogenic mechanisms of B. abortus. Accordingly, we demonstrated that platelet-activating factor receptor (PAFR) affects host cell response against B. abortus infection. RESULTS First of all, B. abortus infection to macrophage induces secretion of platelet-activating factor (PAF), which is a PAFR agonist. The stimulation of PAFR by PAF remarkably increases B. abortus uptake into macrophages. It induces Janus kinase 2 (JAK2) and p38α phosphorylation, indicating that PAFR-mediated activation of JAK2 signaling leads to enhanced uptake of B. abortus. Moreover, the dynamics of F-actin polymerization revealed that PAFR-mediated B. abortus uptake is related with the reorganization of F-actin and JAK2. Upon B. abortus phagocytosis, reduced PAFR in the membrane and subsequently increased levels of PAFR colocalization with endosomes were observed which indicate that B. abortus uptake into macrophages allowed PAFR trafficking to endosomes. CONCLUSIONS This study demonstrated that PAFR has a compelling involvement in B. abortus uptake as a promoter of phagocytosis, which is associated with JAK2 activation. Thus, our findings establish a novel insight into a receptor-related phagocytic mechanism of B. abortus.
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Affiliation(s)
- Jin Ju Lee
- Animal and Plant Quarantine Agency, Anyang, Gyeonggi-do, 430-757, Republic of Korea
| | - Hannah Leah Simborio
- Institute of Animal Medicine, College of Veterinary Medicine, Gyeongsang National University, Jinju, 660-701, Republic of Korea
| | | | - Huynh Tan Hop
- Institute of Animal Medicine, College of Veterinary Medicine, Gyeongsang National University, Jinju, 660-701, Republic of Korea
| | - Lauren Togonon Arayan
- Institute of Animal Medicine, College of Veterinary Medicine, Gyeongsang National University, Jinju, 660-701, Republic of Korea
| | - Hu Jang Lee
- Institute of Animal Medicine, College of Veterinary Medicine, Gyeongsang National University, Jinju, 660-701, Republic of Korea
| | - Wongi Min
- Institute of Animal Medicine, College of Veterinary Medicine, Gyeongsang National University, Jinju, 660-701, Republic of Korea
| | - Moon Her
- Animal and Plant Quarantine Agency, Anyang, Gyeonggi-do, 430-757, Republic of Korea
| | - Man Hee Rhee
- College of Veterinary Medicine, Kyungpook National University, Daegu, 702-701, Republic of Korea
| | - Masahisa Watarai
- Department of Veterinary Public Health, Faculty of Agriculture, Yamaguchi University, Yamaguchi, 753-8515, Japan
| | - Hong Hee Chang
- Institute of Agriculture and Life Science, Gyeongsang National University, Jinju, 660-701, Republic of Korea
| | - Suk Kim
- Institute of Animal Medicine, College of Veterinary Medicine, Gyeongsang National University, Jinju, 660-701, Republic of Korea. .,Institute of Agriculture and Life Science, Gyeongsang National University, Jinju, 660-701, Republic of Korea.
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Goolab S, Roth RL, van Heerden H, Crampton MC. Analyzing the molecular mechanism of lipoprotein localization in Brucella. Front Microbiol 2015; 6:1189. [PMID: 26579096 PMCID: PMC4623201 DOI: 10.3389/fmicb.2015.01189] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2015] [Accepted: 10/12/2015] [Indexed: 01/18/2023] Open
Abstract
Bacterial lipoproteins possess diverse structure and functionality, ranging from bacterial physiology to pathogenic processes. As such many lipoproteins, originating from Brucella are exploited as potential vaccines to countermeasure brucellosis infection in the host. These membrane proteins are translocated from the cytoplasm to the cell membrane where they are anchored peripherally by a multifaceted targeting mechanism. Although much research has focused on the identification and classification of Brucella lipoproteins and their potential use as vaccine candidates for the treatment of Brucellosis, the underlying route for the translocation of these lipoproteins to the outer surface of the Brucella (and other pathogens) outer membrane (OM) remains mostly unknown. This is partly due to the complexity of the organism and evasive tactics used to escape the host immune system, the variation in biological structure and activity of lipoproteins, combined with the complex nature of the translocation machinery. The biosynthetic pathway of Brucella lipoproteins involves a distinct secretion system aiding translocation from the cytoplasm, where they are modified by lipidation, sorted by the lipoprotein localization machinery pathway and thereafter equipped for export to the OM. Surface localized lipoproteins in Brucella may employ a lipoprotein flippase or the β-barrel assembly complex for translocation. This review provides an overview of the characterized Brucella OM proteins that form part of the OM, including a handful of other characterized bacterial lipoproteins and their mechanisms of translocation. Lipoprotein localization pathways in gram negative bacteria will be used as a model to identify gaps in Brucella lipoprotein localization and infer a potential pathway. Of particular interest are the dual topology lipoproteins identified in Escherichia coli and Haemophilus influenza. The localization and topology of these lipoproteins from other gram negative bacteria are well characterized and may be useful to infer a solution to better understand the translocation process in Brucella.
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Affiliation(s)
- Shivani Goolab
- Protein Technologies, Biosciences, Council for Scientific and Industrial ResearchPretoria, South Africa
- Department of Veterinary Tropical Diseases, Faculty of Veterinary Science, University of PretoriaPretoria, South Africa
| | - Robyn L. Roth
- Protein Technologies, Biosciences, Council for Scientific and Industrial ResearchPretoria, South Africa
| | - Henriette van Heerden
- Department of Veterinary Tropical Diseases, Faculty of Veterinary Science, University of PretoriaPretoria, South Africa
| | - Michael C. Crampton
- Protein Technologies, Biosciences, Council for Scientific and Industrial ResearchPretoria, South Africa
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Mol JPS, Costa EA, Carvalho AF, Sun YH, Tsolis RM, Paixão TA, Santos RL. Early transcriptional responses of bovine chorioallantoic membrane explants to wild type, ΔvirB2 or ΔbtpB Brucella abortus infection. PLoS One 2014; 9:e108606. [PMID: 25259715 PMCID: PMC4178178 DOI: 10.1371/journal.pone.0108606] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2014] [Accepted: 08/29/2014] [Indexed: 12/23/2022] Open
Abstract
The pathogenesis of the Brucella-induced inflammatory response in the bovine placenta is not completely understood. In this study we evaluated the role of the B. abortus Type IV secretion system and the anti-inflammatory factor BtpB in early interactions with bovine placental tissues. Transcription profiles of chorioallantoic membrane (CAM) explants inoculated with wild type (strain 2308), ΔvirB2 or ΔbtpB Brucella abortus were compared by microarray analysis at 4 hours post infection. Transcripts with significant variation (>2 fold change; P<0.05) were functionally classified, and transcripts related to defense and inflammation were assessed by quantitative real time RT-PCR. Infection with wild type B. abortus resulted in slightly more genes with decreased than increased transcription levels. Conversely, infection of trophoblastic cells with the ΔvirB2 or the ΔbtpB mutant strains, that lack a functional T4SS or that has impaired inhibition of TLR signaling, respectively, induced more upregulated than downregulated genes. Wild type Brucella abortus impaired transcription of host genes related to immune response when compared to ΔvirB and ΔbtpB mutants. Our findings suggest that proinflammatory genes are negatively modulated in bovine trophoblastic cells at early stages of infection. The virB operon and btpB are directly or indirectly related to modulation of these host genes. These results shed light on the early interactions between B. abortus and placental tissue that ultimately culminate in inflammatory pathology and abortion.
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Affiliation(s)
- Juliana P. S. Mol
- Departamento de Clínica e Cirurgia Veterinárias, Escola de Veterinária, Universidade Federal de Minas Gerais, Belo Horizonte, MG, Brazil
| | - Erica A. Costa
- Departamento de Clínica e Cirurgia Veterinárias, Escola de Veterinária, Universidade Federal de Minas Gerais, Belo Horizonte, MG, Brazil
| | - Alex F. Carvalho
- Departamento de Medicina Veterinária Preventiva, Escola de Veterinária, Universidade Federal de Minas Gerais, Belo Horizonte, MG, Brazil
| | - Yao-Hui Sun
- Department of Medical Microbiology and Immunology, School of Medicine, University of California Davis, Davis, California, United States of America
| | - Reneé M. Tsolis
- Department of Medical Microbiology and Immunology, School of Medicine, University of California Davis, Davis, California, United States of America
| | - Tatiane A. Paixão
- Departamento de Patologia Geral, Instituto de Ciências Biológicas, Universidade Federal de Minas Gerais, Belo Horizonte, MG, Brazil
| | - Renato L. Santos
- Departamento de Clínica e Cirurgia Veterinárias, Escola de Veterinária, Universidade Federal de Minas Gerais, Belo Horizonte, MG, Brazil
- * E-mail:
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8
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Rossetti CA, Drake KL, Siddavatam P, Lawhon SD, Nunes JES, Gull T, Khare S, Everts RE, Lewin HA, Adams LG. Systems biology analysis of Brucella infected Peyer's patch reveals rapid invasion with modest transient perturbations of the host transcriptome. PLoS One 2013; 8:e81719. [PMID: 24349118 PMCID: PMC3857238 DOI: 10.1371/journal.pone.0081719] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2013] [Accepted: 10/21/2013] [Indexed: 01/12/2023] Open
Abstract
Brucella melitensis causes the most severe and acute symptoms of all Brucella species in human beings and infects hosts primarily through the oral route. The epithelium covering domed villi of jejunal-ileal Peyer's patches is an important site of entry for several pathogens, including Brucella. Here, we use the calf ligated ileal loop model to study temporal in vivo Brucella-infected host molecular and morphological responses. Our results document Brucella bacteremia occurring within 30 min after intraluminal inoculation of the ileum without histopathologic traces of lesions. Based on a system biology Dynamic Bayesian Network modeling approach (DBN) of microarray data, a very early transient perturbation of the host enteric transcriptome was associated with the initial host response to Brucella contact that is rapidly averted allowing invasion and dissemination. A detailed analysis revealed active expression of Syndecan 2, Integrin alpha L and Integrin beta 2 genes, which may favor initial Brucella adhesion. Also, two intestinal barrier-related pathways (Tight Junction and Trefoil Factors Initiated Mucosal Healing) were significantly repressed in the early stage of infection, suggesting subversion of mucosal epithelial barrier function to facilitate Brucella transepithelial migration. Simultaneously, the strong activation of the innate immune response pathways would suggest that the host mounts an appropriate protective immune response; however, the expression of the two key genes that encode innate immunity anti-Brucella cytokines such as TNF-α and IL12p40 were not significantly changed throughout the study. Furthermore, the defective expression of Toll-Like Receptor Signaling pathways may partially explain the lack of proinflammatory cytokine production and consequently the absence of morphologically detectable inflammation at the site of infection. Cumulatively, our results indicate that the in vivo pathogenesis of the early infectious process of Brucella is primarily accomplished by compromising the mucosal immune barrier and subverting critical immune response mechanisms.
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Affiliation(s)
- Carlos A. Rossetti
- Department of Veterinary Pathobiology, College of Veterinary Medicine and Biomedical Sciences, Texas A&M University, College Station, Texas, United States of America
| | - Kenneth L. Drake
- Seralogix, Limited Liability Corporation, Austin, Texas, United States of America
| | - Prasad Siddavatam
- Seralogix, Limited Liability Corporation, Austin, Texas, United States of America
| | - Sara D. Lawhon
- Department of Veterinary Pathobiology, College of Veterinary Medicine and Biomedical Sciences, Texas A&M University, College Station, Texas, United States of America
| | - Jairo E. S. Nunes
- Department of Veterinary Pathobiology, College of Veterinary Medicine and Biomedical Sciences, Texas A&M University, College Station, Texas, United States of America
| | - Tamara Gull
- Department of Veterinary Pathobiology, College of Veterinary Medicine and Biomedical Sciences, Texas A&M University, College Station, Texas, United States of America
| | - Sangeeta Khare
- Department of Veterinary Pathobiology, College of Veterinary Medicine and Biomedical Sciences, Texas A&M University, College Station, Texas, United States of America
| | - Robin E. Everts
- Department of Animal Sciences, University of Illinois, Urbana, Illinois, United States of America
| | - Harris A. Lewin
- Department of Animal Sciences, University of Illinois, Urbana, Illinois, United States of America
| | - Leslie Garry Adams
- Department of Veterinary Pathobiology, College of Veterinary Medicine and Biomedical Sciences, Texas A&M University, College Station, Texas, United States of America
- * E-mail:
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9
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Gomez G, Adams LG, Rice-Ficht A, Ficht TA. Host-Brucella interactions and the Brucella genome as tools for subunit antigen discovery and immunization against brucellosis. Front Cell Infect Microbiol 2013; 3:17. [PMID: 23720712 PMCID: PMC3655278 DOI: 10.3389/fcimb.2013.00017] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2012] [Accepted: 04/26/2013] [Indexed: 01/18/2023] Open
Abstract
Vaccination is the most important approach to counteract infectious diseases. Thus, the development of new and improved vaccines for existing, emerging, and re-emerging diseases is an area of great interest to the scientific community and general public. Traditional approaches to subunit antigen discovery and vaccine development lack consideration for the critical aspects of public safety and activation of relevant protective host immunity. The availability of genomic sequences for pathogenic Brucella spp. and their hosts have led to development of systems-wide analytical tools that have provided a better understanding of host and pathogen physiology while also beginning to unravel the intricacies at the host-pathogen interface. Advances in pathogen biology, host immunology, and host-agent interactions have the potential to serve as a platform for the design and implementation of better-targeted antigen discovery approaches. With emphasis on Brucella spp., we probe the biological aspects of host and pathogen that merit consideration in the targeted design of subunit antigen discovery and vaccine development.
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Affiliation(s)
- Gabriel Gomez
- Department of Veterinary Pathobiology, Texas A&M University College Station, TX 77843, USA.
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10
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Monocyte-derived macrophages from Zebu (Bos taurus indicus) are more efficient to control Brucella abortus intracellular survival than macrophages from European cattle (Bos taurus taurus). Vet Immunol Immunopathol 2013; 151:294-302. [DOI: 10.1016/j.vetimm.2012.12.001] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2012] [Revised: 12/01/2012] [Accepted: 12/03/2012] [Indexed: 11/24/2022]
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11
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Lee J, Kim D, Kim D, Lee H, Min W, Rhee M, Yun B, Kim S. Phellinus baumii
extract influences pathogenesis of Brucella abortus
in phagocyte by disrupting the phagocytic and intracellular trafficking pathway. J Appl Microbiol 2013; 114:329-38. [DOI: 10.1111/jam.12072] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2012] [Revised: 10/18/2012] [Accepted: 11/06/2012] [Indexed: 10/27/2022]
Affiliation(s)
- J.J. Lee
- Institute of Animal Medicine, College of Veterinary Medicine, Gyeongsang National University; Jinju Korea
| | - D.H. Kim
- Institute of Animal Medicine, College of Veterinary Medicine, Gyeongsang National University; Jinju Korea
| | - D.G. Kim
- Institute of Animal Medicine, College of Veterinary Medicine, Gyeongsang National University; Jinju Korea
| | - H.J. Lee
- Institute of Animal Medicine, College of Veterinary Medicine, Gyeongsang National University; Jinju Korea
| | - W. Min
- Institute of Animal Medicine, College of Veterinary Medicine, Gyeongsang National University; Jinju Korea
| | - M.H. Rhee
- Department of Physiology; College of Veterinary Medicine, Kyungpook National University; Daegu Korea
| | - B.S. Yun
- Division of Biotechnology; College of Environmental and Bioresource Sciences, Chonbuk National University; Iksan Korea
| | - S. Kim
- Institute of Animal Medicine, College of Veterinary Medicine, Gyeongsang National University; Jinju Korea
- Institute of Agriculture and Life Science, Gyeongsang National University; Jinju Korea
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12
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Posadas DM, Ruiz-Ranwez V, Bonomi HR, Martín FA, Zorreguieta A. BmaC, a novel autotransporter of Brucella suis, is involved in bacterial adhesion to host cells. Cell Microbiol 2012; 14:965-82. [PMID: 22321605 DOI: 10.1111/j.1462-5822.2012.01771.x] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Abstract
Brucella is an intracellular pathogen responsible of a zoonotic disease called brucellosis. Brucella survives and proliferates within several types of phagocytic and non-phagocytic cells. Like in other pathogens, adhesion of brucellae to host surfaces was proposed to be an important step in the infection process. Indeed, Brucella has the capacity to bind to culture human cells and key components of the extracellular matrix, such as fibronectin. However, little is known about the molecular bases of Brucella adherence. In an attempt to identify bacterial genes encoding adhesins, a phage display library of Brucella suis was panned against fibronectin. Three fibronectin-binding proteins of B. suis were identified using this approach. One of the candidates, designated BmaC was a very large protein of 340 kDa that is predicted to belong to the type I (monomeric) autotransporter family. Microscopy studies showed that BmaC is located at one pole on the bacterial surface. The phage displaying the fibronectin-binding peptide of BmaC inhibited the attachment of brucellae to both, HeLa cells and immobilized fibronectin in vitro. In addition, a bmaC deletion mutant was impaired in the ability of B. suis to attach to immobilized fibronectin and to the surface of HeLa and A549 cells and was out-competed by the wild-type strain in co-infection experiments. Finally, anti-fibronectin or anti-BmaC antibodies significantly inhibited the binding of wild-type bacteria to HeLa cells. Our results highlight the role of a novel monomeric autotransporter protein in the adhesion of B. suis to the extracellular matrix and non-phagocytic cells via fibronectin binding.
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Affiliation(s)
- Diana M Posadas
- Fundación Instituto Leloir, IIBBA CONICET and FCEyN, Universidad de Buenos Aires, Patricias Argentinas 435, (C1405BWE) Buenos Aires, Argentina
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13
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Cha SB, Rayamajhi N, Lee WJ, Shin MK, Jung MH, Shin SW, Kim JW, Yoo HS. Generation and envelope protein analysis of internalization defective Brucella abortus mutants in professional phagocytes, RAW 264.7. ACTA ACUST UNITED AC 2011; 64:244-54. [DOI: 10.1111/j.1574-695x.2011.00896.x] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Affiliation(s)
- Seung Bin Cha
- Department of Infectious Diseases; College of Veterinary Medicine; KRF Zoonotic Disease Priority Research Institute; Brain Korea 21 for Veterinary Science; Seoul National University; Seoul; South Korea
| | - Nabin Rayamajhi
- Department of Infectious Diseases; College of Veterinary Medicine; KRF Zoonotic Disease Priority Research Institute; Brain Korea 21 for Veterinary Science; Seoul National University; Seoul; South Korea
| | - Won Jung Lee
- Department of Infectious Diseases; College of Veterinary Medicine; KRF Zoonotic Disease Priority Research Institute; Brain Korea 21 for Veterinary Science; Seoul National University; Seoul; South Korea
| | - Min Kyung Shin
- Department of Infectious Diseases; College of Veterinary Medicine; KRF Zoonotic Disease Priority Research Institute; Brain Korea 21 for Veterinary Science; Seoul National University; Seoul; South Korea
| | - Myung Hwan Jung
- Department of Infectious Diseases; College of Veterinary Medicine; KRF Zoonotic Disease Priority Research Institute; Brain Korea 21 for Veterinary Science; Seoul National University; Seoul; South Korea
| | - Seung Won Shin
- Department of Infectious Diseases; College of Veterinary Medicine; KRF Zoonotic Disease Priority Research Institute; Brain Korea 21 for Veterinary Science; Seoul National University; Seoul; South Korea
| | - Jong Wan Kim
- Department of Animal and Plant and Fisheries Quarantine and Inspection Agency; Anyang 430-757; South Korea
| | - Han Sang Yoo
- Department of Infectious Diseases; College of Veterinary Medicine; KRF Zoonotic Disease Priority Research Institute; Brain Korea 21 for Veterinary Science; Seoul National University; Seoul; South Korea
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14
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Lee JJ, Bae JH, Kim DH, Lim JJ, Kim DG, Lee HJ, Min W, Rhee MH, Chang HH, Park H, Kim S. Intracellular replication inhibitory effects of Galla Rhois ethanol extract for Brucella abortus infection. JOURNAL OF ETHNOPHARMACOLOGY 2011; 138:602-609. [PMID: 22008879 DOI: 10.1016/j.jep.2011.10.007] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/07/2011] [Revised: 09/23/2011] [Accepted: 10/03/2011] [Indexed: 05/31/2023]
Abstract
ETHNOPHARMACOLOGICAL RELEVANCE Galla Rhois (GR) has long been applied in traditional Korean and Oriental medicine. Although GR has an anti-bacterial effect, the anti-bacterial mechanism and therapeutic efficiency of GR for intracellular parasitic Brucella infection are still unclear. AIM OF THE STUDY The objective of this study was to investigate the antibacterial and therapeutic effects of GR ethanol extract (GRE), which is a natural antibacterial component for the treatment of Brucella abortus infection. MATERIALS AND METHODS The antibacterial activity of GRE towards Brucella abortus was evaluated by incubating Brucella abortus with GRE. Following treatment with GRE, Brucella abortus adherence, uptake, intracellular growth, and intracellular trafficking in macrophages were monitored. Mice were infected intraperitoneally with Brucella abortus and treated orally with GRE for 14 days, and then the weight and CFUs from each spleen were monitored. RESULTS The viability of Brucella abortus was markedly decreased in a dose-dependent manner. Moreover, Brucella abortus internalization and intracellular growth within macrophages were reduced in GRE-treated cells. The number of bacteria that adhered to GRE-pretreated cells was significantly lower than that of untreated cells. With regards to intracellular trafficking, treatment with GRE augmented the colocalization of Brucella abortus-containing phagosomes with LAMP-1. GRE-treated mice showed considerably decreased weight and bacterial burdens in the spleen compared to untreated mice. CONCLUSION GRE exhibits antibacterial and protective effects on Brucella abortus in vitro and in vivo. These results highlight the beneficial effects of GRE in the prevention and treatment of brucellosis.
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Affiliation(s)
- Jin Ju Lee
- Institute of Animal Medicine, College of Veterinary Medicine, Gyeongsang National University, Jinju 660-701, Republic of Korea
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15
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Abstract
The aim of this study was to evaluate the influence of macrophage alternative activation in the intracellular pathogen natural disease resistance phenotype of the host. Macrophage monolayers from resistant (R) (3) or susceptible (S) (3) cattle donors were treated with 10 ng/ml of bovine recombinant IL-4 (rbIL-4), and infected with virulent and avirulent Mycobacterium bovis (MOI 10:1). Bactericidal assays were performed to assess the bacterial phagocytic index and intracellular survival. Total RNA was reverse transcribed and used to analyze the relative changes in gene expression of IL-10, IL-12, IL-18 IL-1β, TNF-α, MCP-1, MCP-2, IL-6, MIP-1, MIP-3, iNOS, ARGII and SLAM by real time PCR. Cell supernatants were collected and nitric oxide and arginase production was assessed. Apoptosis induction was measured by TUNEL. IL-4 treatment increased the phagocytic index in both R and S macrophages; however intracellular survival was augmented mainly in S macrophages. Alternative activation decreased gene expression of pro-inflammatory cytokines, nitric oxide production and DNA fragmentation mainly in R macrophages. On the other hand, arginase production was not different between R and S macrophages. Alternative activation modifies the macrophage response against M. bovis. IL-4 treatment minimized the functional differences that exist between R and S macrophages.
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16
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Comparative analysis of the early transcriptome of Brucella abortus--infected monocyte-derived macrophages from cattle naturally resistant or susceptible to brucellosis. Res Vet Sci 2010; 91:40-51. [PMID: 20932540 DOI: 10.1016/j.rvsc.2010.09.002] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2010] [Revised: 06/30/2010] [Accepted: 09/04/2010] [Indexed: 11/27/2022]
Abstract
Brucellosis is a worldwide zoonotic infectious disease that has a significant economic impact on animal production and human public health. We characterized the gene expression profile of B. abortus-infected monocyte-derived macrophages (MDMs) from naïve cattle naturally resistant (R) or susceptible (S) to brucellosis using a cDNA microarray technology. Our data indicate that (1) B. abortus induced a slightly increased genome activation in R MDMs and a down-regulated transcriptome in S MDMs, during the onset of infection, (2) R MDMs had the ability to mount a type 1 immune response against B. abortus infection which was impaired in S cells, and (3) the host cell activity was not altered after 12 h post-B. abortus infection in R MDMs while the cell cycle was largely arrested in infected S MDMs at 12 h p.i. These results contribute to an improved understanding of how host responses may be manipulated to prevent infection by brucellae.
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17
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Neta AVC, Mol JP, Xavier MN, Paixão TA, Lage AP, Santos RL. Pathogenesis of bovine brucellosis. Vet J 2010; 184:146-55. [DOI: 10.1016/j.tvjl.2009.04.010] [Citation(s) in RCA: 111] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2008] [Revised: 02/05/2009] [Accepted: 04/13/2009] [Indexed: 12/14/2022]
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18
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Martinez R, Toro R, Montoya F, Burbano M, Tobn J, Gallego J, Dunner S, Can J. BovineSLC11A13 UTR SSCP genotype evaluated by a macrophagein vitrokilling assay employing aBrucella abortusstrain. J Anim Breed Genet 2008; 125:271-9. [DOI: 10.1111/j.1439-0388.2008.00727.x] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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19
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Westhusin ME, Shin T, Templeton JW, Burghardt RC, Adams LG. Rescuing valuable genomes by animal cloning: a case for natural disease resistance in cattle. J Anim Sci 2007; 85:138-42. [PMID: 17179549 DOI: 10.2527/jas.2006-258] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Tissue banking and animal cloning represent a powerful tool for conserving and regenerating valuable animal genomes. Here we report an example involving cattle and the rescue of a genome affording natural disease resistance. During the course of a 2-decade study involving the phenotypic and genotypic analysis for the functional and genetic basis of natural disease resistance against bovine brucellosis, a foundation sire was identified and confirmed to be genetically resistant to Brucella abortus. This unique animal was utilized extensively in numerous animal breeding studies to further characterize the genetic basis for natural disease resistance. The bull died in 1996 of natural causes, and no semen was available for AI, resulting in the loss of this valuable genome. Fibroblast cell lines had been established in 1985, cryopreserved, and stored in liquid nitrogen for future genetic analysis. Therefore, we decided to utilize these cells for somatic cell nuclear transfer to attempt the production of a cloned bull and salvage this valuable genotype. Embryos were produced by somatic cell nuclear transfer and transferred to 20 recipient cows, 10 of which became pregnant as determined by ultrasound at d 40 of gestation. One calf survived to term. At present, the cloned bull is 4.5 yr old and appears completely normal as determined by physical examination and blood chemistry. Furthermore, in vitro assays performed to date indicate this bull is naturally resistant to B. abortus, Mycobacterium bovis, and Salmonella typhimurium, as was the original genetic donor.
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Affiliation(s)
- M E Westhusin
- Texas A&M University, College of Veterinary Medicine & Biomedical Sciences, College Station, TX, USA.
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20
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Fontes P, Alvarez-Martinez MT, Gross A, Carnaud C, Köhler S, Liautard JP. Absence of evidence for the participation of the macrophage cellular prion protein in infection with Brucella suis. Infect Immun 2005; 73:6229-36. [PMID: 16177294 PMCID: PMC1230949 DOI: 10.1128/iai.73.10.6229-6236.2005] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Brucella spp. are stealthy bacteria that enter host cells without major perturbation. The molecular mechanism involved is still poorly understood, although numerous studies have been published on this subject. Recently, it was reported that Brucella abortus utilizes cellular prion protein (PrP(C)) to enter the cells and to reach its replicative niche. The molecular mechanisms involved were not clearly defined, prompting us to analyze this process using blocking antibodies against PrP(C). However, the behavior of Brucella during cellular infection under these conditions was not modified. In a next step, the behavior of Brucella in macrophages lacking the prion gene and the infection of mice knocked out for the prion gene were studied. We observed no difference from results obtained with the wild-type control. Although some contacts between PrP(C) and Brucella were observed on the surface of the cells by using confocal microscopy, we could not show that Brucella specifically bound recombinant PrP(C). Therefore, we concluded from our results that prion protein (PrP(C)) was not involved in Brucella infection.
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21
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Jiménez de Bagüés MP, Gross A, Terraza A, Dornand J. Regulation of the mitogen-activated protein kinases by Brucella spp. expressing a smooth and rough phenotype: relationship to pathogen invasiveness. Infect Immun 2005; 73:3178-83. [PMID: 15845529 PMCID: PMC1087367 DOI: 10.1128/iai.73.5.3178-3183.2005] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
By comparing smooth wild-type Brucella spp. to their rough mutants, we show that the LPS O chain restricted the activation of the ERK1/2 and p38 mitogen-activated protein kinase (MAPK) pathways, thus preventing the synthesis of immune mediators that regulate host defense. We conclude that the MAPKs are a target for immune intervention by virulent smooth Brucella.
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Affiliation(s)
- María P Jiménez de Bagüés
- Centro de Investigación y Tecnología Agroalimentaria de Aragón (CITA), Gobierno de Aragón, Ap. 727, 50080 Zaragoza, Spain.
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22
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Lapaque N, Moriyon I, Moreno E, Gorvel JP. Brucella lipopolysaccharide acts as a virulence factor. Curr Opin Microbiol 2005; 8:60-6. [PMID: 15694858 DOI: 10.1016/j.mib.2004.12.003] [Citation(s) in RCA: 178] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
Brucella is a facultative intracellular bacterium responsible for brucellosis. Virulence factors involved in Brucella replication and Brucella's strategies to circumvent the immune response are under investigation. VirB proteins that form the type IV secretion system and that are involved in intracellular replication are considered as one of Brucella's virulence factors. In addition to this secretion system, bacterial outer membrane components have also been described as being implicated in Brucella survival in the host. For example, this bacterium possesses an unconventional non-endotoxic lipopolysaccharide that confers resistance to anti-microbial attacks and modulates the host immune response. These properties make lipopolysaccharide an important virulence factor for Brucella survival and replication in the host.
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Affiliation(s)
- Nicolas Lapaque
- Centre d'Immunologie INSERM-CNRS-Université de la Méditerranée, Parc Scientifique de Luminy, Case 906, 13288 Marseille Cedex 9, France
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23
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Jiménez de Bagüés MP, Terraza A, Gross A, Dornand J. Different responses of macrophages to smooth and rough Brucella spp.: relationship to virulence. Infect Immun 2004; 72:2429-33. [PMID: 15039375 PMCID: PMC375206 DOI: 10.1128/iai.72.4.2429-2433.2004] [Citation(s) in RCA: 68] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
By comparing smooth wild-type Brucella strains to their rough mutants, we show that the lipopolysaccharide (LPS) O side chain of pathogenic Brucella has a dramatic impact on macrophage activation. It favors the development of virulent Brucella by preventing the synthesis of immune mediators, important for host defense. We conclude that this O chain property is firmly linked to Brucella virulence.
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Affiliation(s)
- María P Jiménez de Bagüés
- Unidad de Sanidad Animal, Servicio de Investigación Agroalimentaria, Diputación General de Aragón, 50080 Zaragoza, Spain.
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24
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Rittig MG, Kaufmann A, Robins A, Shaw B, Sprenger H, Gemsa D, Foulongne V, Rouot B, Dornand J. Smooth and rough lipopolysaccharide phenotypes of Brucella induce different intracellular trafficking and cytokine/chemokine release in human monocytes. J Leukoc Biol 2003; 74:1045-55. [PMID: 12960272 DOI: 10.1189/jlb.0103015] [Citation(s) in RCA: 111] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
Virulence of the intracellular pathogen Brucella for humans is mainly associated with its lipopolysaccharide (LPS) phenotype, with smooth LPS phenotypes generally being virulent and rough ones not. The reason for this association is not quite understood. We now demonstrate by flow cytometry, electron microscopy, and ELISA that human peripheral blood monocytes interact both quantitatively and qualitatively different with smooth and rough Brucella organisms in vitro. We confirm that considerably higher numbers of rough than smooth brucellae attach to and enter the monocytes in nonopsonic conditions; but only smooth brucellae replicate in the host cells. We show for the first time that rough brucellae induce higher amounts than smooth brucellae of several CXC (GRO-alpha, IL-8) and CC (MIP-1alpha, MIP-1beta, MCP-1, RANTES) chemokines, as well as pro- (IL-6, TNF-alpha) and anti-inflammatory (IL-10) cytokines released by challenged monocytes. Upon uptake, phagosomes containing rough brucellae develop selective fusion competence to form spacious communal compartments, whereas phagosomes containing smooth brucellae are nonfusiogenic. Collectively, our data suggest that rough brucellae attract and infect monocytes more effectively than smooth brucellae, but only smooth LPS phenotypes establish a specific host cell compartment permitting successful parasitism. These novel findings link the LPS phenotype of Brucella and its virulence for humans at the level of the infected host cells. Whether this is due to a direct effect of the LPS molecules or to upstream bacterial mechanisms remains to be established.
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Affiliation(s)
- Michael G Rittig
- School of Biomedical Sciences, University of Nottingham Medical School, Nottingham NG7 2UH, UK.
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25
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Gross A, Bouaboula M, Casellas P, Liautard JP, Dornand J. Subversion and utilization of the host cell cyclic adenosine 5'-monophosphate/protein kinase A pathway by Brucella during macrophage infection. JOURNAL OF IMMUNOLOGY (BALTIMORE, MD. : 1950) 2003; 170:5607-14. [PMID: 12759440 DOI: 10.4049/jimmunol.170.11.5607] [Citation(s) in RCA: 40] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Brucella spp. are intramacrophage pathogens that induce chronic infections in a wide range of mammals, including domestic animals and humans. Therefore, the macrophage response to infection has important consequences for both the survival of phagocytosed bacteria and the further development of host immunity. However, very little is known about the macrophage cell signaling pathways initiated upon infection and the virulence strategy that Brucella use to counteract these responses and secure their survival. In a previous study, we have shown that macrophages activated by SR141716A, a ligand of the cannabinoid receptor CB1, acquired the capacity to control Brucella and observed that the CB1 receptor-triggering engages the microbicidal activity of phagocytes. To analyze the perturbation of cell signaling pathway during macrophage infection by Brucella, we hypothesized that SR141716A provides cell signaling that interferes with the bacterial message leading to inhibition of macrophage functions. As CB1 receptor belongs to the family of G protein-linked receptors, we explored the cAMP signaling pathway. In this study, we show that the CB1 ligand inhibited the bacteria-induced cell signaling. Taking advantage of this result, we then demonstrated that Brucella infection elicited a rapid activation of the cAMP/protein kinase A pathway. This activation resulted in a prolonged phosphorylation of the transcription factor CREB. We finally demonstrate that the activation of the cAMP/protein kinase A pathway is crucial for the survival and establishment of Brucella within macrophages. For the first time in phagocytes, we thus characterized a primordial virulence strategy of Brucella involving the host signaling pathway, a novel point of immune intervention of this virulent pathogen.
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Affiliation(s)
- Antoine Gross
- Institut National de la Santé et de la Recherche Médicale Unité 431, IFR 56, University of Montpellier II, Montpellier, France.
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26
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Abstract
Brucella organisms are pathogens that ultimate goal is to propagate in their preferred niche, the cell. Upon cell contact the bacteria is internalized via receptor molecules by activating small GTPases of the Rho subfamily and by a moderate recruitment of actin filaments. Once inside cells, Brucella localizes in early phagosomes, where it avoids fusion with late endosomes and lysosomes. These early events require the control of Rab small GTPases, and cytokines such as the G-CSF. Then, the bacterium redirects its trafficking to autophagosomes and finally reaches the endoplasmic reticulum, where it extensively replicates. Some of the bacterial molecular determinants involved in the internalization and early events after ingestion are controlled by the BvrS/BvrR two component regulatory system, whereas the intracellular trafficking beyond this early compartments are controlled by the VirB type IV secretion system. Once inside the endoplasmic reticulum, Brucella extensively replicates without restricting basic cellular functions or inducing obvious damage to cells. The integrity of Brucella LPS on the bacterial surface is one of the required factors for Brucella intracellular survival, and therefore for virulence.
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Affiliation(s)
- Jean Pierre Gorvel
- Centre d'Immunologie INSERM-CNRS de Marseille-Luminy, 13288 Marseille Cedex 9, France.
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27
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Cloeckaert A, Vizcaíno N, Paquet JY, Bowden RA, Elzer PH. Major outer membrane proteins of Brucella spp.: past, present and future. Vet Microbiol 2002; 90:229-47. [PMID: 12414146 DOI: 10.1016/s0378-1135(02)00211-0] [Citation(s) in RCA: 113] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
The major outer membrane proteins (OMPs) of Brucella spp. were initially identified in the early 1980s and characterised as potential immunogenic and protective antigens. They were classified according to their apparent molecular mass as 36-38 kDa OMPs or group 2 porin proteins and 31-34 and 25-27 kDa OMPs which belong to the group 3 proteins. The genes encoding the group 2 porin proteins were identified in the late 1980s and consist of two genes, omp2a and omp2b, which are closely linked in the Brucella genome, and which share a great degree of identity (>85%). In the 1990s, two genes were identified coding for the group 3 proteins and were named omp25 and omp31. The predicted amino acid sequences of omp25 and omp31 share 34% identity. The recent release of the genome sequence of B. melitensis 16 M has revealed the presence of five additional gene products homologous to Omp25 and Omp31. The use of recombinant protein technology and monoclonal antibodies (MAbs) has shown that the major OMPs appear to be of little relevance as antigens in smooth (S) B. abortus or B. melitensis infections i.e. low or no protective activity in the mouse model of infection and low or no immunogenicity during host infection. However, group 3 proteins, in particular Omp31, appear as immunodominant antigen in the course of rough (R) B. ovis infection in rams and as important protective antigen in the B. ovis mouse model of infection. The major OMP genes display diversity and specific markers have been identified for Brucella species, biovars, and strains, including the recent marine mammal Brucella isolates for which new species names have been proposed. Recently, Omp25 has been shown to be involved in virulence of B. melitensis, B. abortus and B. ovis. Mutants lacking Omp25 are indeed attenuated in animal models of infection, and moreover provide levels of protection similar or better than currently used attenuated vaccine strain B. melitensis Rev.1. Therefore, these mutant strains appear interesting vaccine candidates for the future. The other group 3 proteins identified in the genome merit also further investigation related to the development of new vaccines.
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Affiliation(s)
- Axel Cloeckaert
- Unité de Pathologie Aviaire et Parasitologie, Institut National de la Recherche Agronomique, 37380 Nouzilly, France.
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28
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Adams LG. The pathology of brucellosis reflects the outcome of the battle between the host genome and the Brucella genome. Vet Microbiol 2002; 90:553-61. [PMID: 12414171 DOI: 10.1016/s0378-1135(02)00235-3] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
The successful co-existence of each Brucella spp. with its preferred host is the outcome of ancient co-evolutionary relationships and selection pressures that often result in a stalemate where the pathogen has evolved to survive within the biological systems of the host, and the host has evolved innate and acquired immune systems which allow controlled survival of infection by the pathogen, ultimately supporting the survival of the host-pathogen system. In general, Brucella spp. have evolved a similar fundamental pathogenesis of facultative intracellular parasitism though the predominant route of natural exposure varies from oropharynx to genital tract, as does the preferred tissue and cellular tropism, e.g. non-professional placental trophoblasts, fetal lung, professional macrophages of reticulendothelial system, and the male and female reproductive tracts. The morphogenesis of the pyogranulomatous lesions stimulated by Brucella reflects the nature of the persistent parasitism, i.e. genome versus genome. The question is, how can this perplexing array of survival mechanisms be unraveled? Fortunately, the integration of real-time image analysis, cell biology, genome-wide analysis, proteomics and bioinformatics holds the most promise ever for the global analysis of the Brucella infectious process and the host:pathogen interface leading to a clearer understanding of the interactions of these biological systems. These discoveries will be expected to provide a frameshift in rationales for interrupting and/or controlling brucellosis at host and/or pathogen levels.
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Affiliation(s)
- L Garry Adams
- Department of Veterinary Pathobiology, College of Veterinary Medicine, Texas A&M University, College Station, TX 77843-4467, USA.
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29
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Gutiérrez-Pabello JA, McMurray DN, Adams LG. Upregulation of thymosin beta-10 by Mycobacterium bovis infection of bovine macrophages is associated with apoptosis. Infect Immun 2002; 70:2121-7. [PMID: 11895978 PMCID: PMC127845 DOI: 10.1128/iai.70.4.2121-2127.2002] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Bovine macrophages underwent apoptosis as a result of infection with a Mycobacterium bovis field strain. Macrophages infected with a multiplicity of infection (MOI) of 25:1 developed chromatin condensation and DNA fragmentation at 4 h and 8 h, respectively, whereas changes in chromatin condensation induced by MOIs of 10:1 and 1:1 required more time and had a reduced number of apoptotic cells. Not only infected macrophages underwent apoptosis, but also uninfected bystander macrophages became apoptotic. Increased differential expression of thymosin beta-10 was identified in M. bovis-infected bovine macrophages by differential display reverse transcriptase PCR. Phagocytosis of latex beads had no effect on the expression of thymosin beta-10, whereas bacterial suspensions upregulated thymosin beta-10 expression, suggesting that M. bovis or mycobacterial products are essential in the process. Heat-inactivated M. bovis induced a slight increase in thymosin beta-10 mRNA, whereas live virulent and attenuated M. bovis organisms increased the gene expression almost twofold. A mouse macrophage cell line (RAW 264.7) overexpressing the bovine thymosin beta-10 transgene had spontaneous apoptosis at a higher rate (66.5%) than parental cells (4.7%) or RAW cells harboring the empty vector (22.8%). The apoptotic rates of the overexpressing cells were significantly higher when compared with both the empty vector transfected (P < 0.01) and parental cells (P < 0.001). Our evidence suggests that upregulation of thymosin beta-10 in M. bovis-infected macrophages is linked with increased cell death due to apoptosis.
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Affiliation(s)
- José A Gutiérrez-Pabello
- Department of Veterinary Pathobiology, College of Veterinary Medicine, Texas A&M University, College Station, Texas 77843, USA
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30
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Naroeni A, Porte F. Role of cholesterol and the ganglioside GM(1) in entry and short-term survival of Brucella suis in murine macrophages. Infect Immun 2002; 70:1640-4. [PMID: 11854258 PMCID: PMC127813 DOI: 10.1128/iai.70.3.1640-1644.2002] [Citation(s) in RCA: 128] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Brucella species are gram-negative, facultative intracellular bacteria that infect humans and animals. These organisms can survive and replicate within a membrane-bound compartment inside professional and nonprofessional phagocytic cells. Inhibition of phagosome-lysosome fusion has been proposed as a mechanism for intracellular survival in both types of cells. We have previously shown that the maturation inhibition of the Brucella-containing phagosome appears to be restricted at the phagosomal membrane, but the precise molecular mechanisms and factors involved in this inhibition have yet to be identified. Interestingly, recent studies have revealed that caveolae or lipid rafts are implicated in the entry of some microorganisms into host cells and mediate an endocytic pathway avoiding fusion with lysosomes. In this study, we investigated the role of cholesterol and the ganglioside GM(1), two components of lipid rafts, in entry and short-term survival of Brucella suis in murine macrophages, by using cholesterol-sequestering (filipin and beta-methyl cyclodextrin) and GM(1)-binding (cholera toxin B) molecules. Our results suggest that lipid rafts may provide a portal for entry of Brucella into murine macrophages under nonopsonic conditions, thus allowing phagosome-lysosome fusion inhibition, and provide further evidence to support the idea that the phagosome maturation inhibition is restricted at the phagosomal membrane.
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Affiliation(s)
- Aroem Naroeni
- Institut National de la Santé et de la Recherche Médicale U-431, Montpellier, France
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31
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Guzmán-Verri C, Chaves-Olarte E, von Eichel-Streiber C, López-Goñi I, Thelestam M, Arvidson S, Gorvel JP, Moreno E. GTPases of the Rho subfamily are required for Brucella abortus internalization in nonprofessional phagocytes: direct activation of Cdc42. J Biol Chem 2001; 276:44435-43. [PMID: 11579087 DOI: 10.1074/jbc.m105606200] [Citation(s) in RCA: 74] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Members of the genus Brucella are intracellular alpha-Proteobacteria responsible for brucellosis, a chronic disease of humans and animals. Little is known about Brucella virulence mechanisms, but the abilities of these bacteria to invade and to survive within cells are decisive factors for causing disease. Transmission electron and fluorescence microscopy of infected nonprofessional phagocytic HeLa cells revealed minor membrane changes accompanied by discrete recruitment of F-actin at the site of Brucella abortus entry. Cell uptake of B. abortus was negatively affected to various degrees by actin, actin-myosin, and microtubule chemical inhibitors. Modulators of MAPKs and protein-tyrosine kinases hampered Brucella cell internalization. Inactivation of Rho small GTPases using clostridial toxins TcdB-10463, TcdB-1470, TcsL-1522, and TcdA significantly reduced the uptake of B. abortus by HeLa cells. In contrast, cytotoxic necrotizing factor from Escherichia coli, known to activate Rho, Rac, and Cdc42 small GTPases, increased the internalization of both virulent and non-virulent B. abortus. Expression of dominant-positive Rho, Rac, and Cdc42 forms in HeLa cells promoted the uptake of B. abortus, whereas expression of dominant-negative forms of these GTPases in HeLa cells hampered Brucella uptake. Cdc42 was activated upon cell contact by virulent B. abortus, but not by a noninvasive isogenic strain, as proven by affinity precipitation of active Rho, Rac, and Cdc42. The polyphasic approach used to discern the molecular events leading to Brucella internalization provides new alternatives for exploring the complexity of the signals required by intracellular pathogens for cell invasion.
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Affiliation(s)
- C Guzmán-Verri
- Programa de Investigación en Enfermedades Tropicales, Escuela de Medicina Veterinaria, Universidad Nacional, P. O. Box 304, 3000 Heredia, Costa Rica
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Paquet JY, Diaz MA, Genevrois S, Grayon M, Verger JM, de Bolle X, Lakey JH, Letesson JJ, Cloeckaert A. Molecular, antigenic, and functional analyses of Omp2b porin size variants of Brucella spp. J Bacteriol 2001; 183:4839-47. [PMID: 11466287 PMCID: PMC99538 DOI: 10.1128/jb.183.16.4839-4847.2001] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Omp2a and Omp2b are highly homologous porins present in the outer membrane of the bacteria from the genus Brucella, a facultative intracellular pathogen. The genes coding for these proteins are closely linked in the Brucella genome and oriented in opposite directions. In this work, we present the cloning, purification, and characterization of four Omp2b size variants found in various Brucella species, and we compare their antigenic and functional properties to the Omp2a and Omp2b porins of Brucella melitensis reference strain 16M. The variation of the Omp2a and Omp2b porin sequences among the various strains of the genus Brucella seems to result mostly from multiple gene conversions between the two highly homologous genes. As shown in this study, this phenomenon has led to the creation of natural Omp2a and Omp2b chimeric proteins in Omp2b porin size variants. The comparison by liposome swelling assay of the porins sugar permeability suggested a possible functional differences between Omp2a and Omp2b, with Omp2a showing a more efficient pore in sugar diffusion. The sequence variability in the Omp2b size variants was located in the predicted external loops of the porin. Several epitopes recognized by anti-Omp2b monoclonal antibodies were mapped by comparison of the Omp2b size variants antigenicity, and two of them were located in the most exposed surface loops. However, since variations are mostly driven by simple exchanges of conserved motifs between the two genes (except for an Omp2b version from an atypical strain of Brucella suis biovar 3), the porin variability does not result in major antigenic variability of the Brucella surface that could help the bacteria during the reinfection of a host. Porin variation in Brucella seems to result mainly in porin conductivity modifications.
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Affiliation(s)
- J Y Paquet
- Unité de Recherche en Biologie Moléculaire (URBM), Laboratoire d'Immunologie-Microbiologie, Facultés Universitaires Notre-Dame de la Paix, 5000 Namur, Belgium
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Rittig MG, Alvarez-Martinez MT, Porte F, Liautard JP, Rouot B. Intracellular survival of Brucella spp. in human monocytes involves conventional uptake but special phagosomes. Infect Immun 2001; 69:3995-4006. [PMID: 11349069 PMCID: PMC98462 DOI: 10.1128/iai.69.6.3995-4006.2001] [Citation(s) in RCA: 53] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Brucella spp. are facultative intracellular parasites of various mammals, including humans, typically infecting lymphoid as well as reproductive organs. We have investigated how B. suis and B. melitensis enter human monocytes and in which compartment they survive. Peripheral blood monocytes readily internalized nonopsonized brucellae and killed most of them within 12 to 18 h. The presence of Brucella-specific antibodies (but not complement) increased the uptake of bacteria without increasing their intracellular survival, whereas adherence of the monocytes or incubation in Ca(2+)- and Mg(2+)-free medium reduced the uptake. Engulfment of all Brucella organisms (regardless of bacterial viability or virulence) initially resulted in phagosomes with tightly apposed walls (TP). Most TP were fully fusiogenic and matured to spacious phagolysosomes containing degraded bacteria, whereas some TP (more in monocyte-derived macrophages, HeLa cells, and CHO cells than in monocytes) remained tightly apposed to intact bacteria. Immediate treatment of infected host cells with the lysosomotropic base ammonium chloride caused a swelling of all phagosomes and a rise in the intraphagosomal pH, abolishing the intracellular survival of Brucella. These results indicate that (i) human monocytes readily internalize Brucella in a conventional way using various phagocytosis-promoting receptors, (ii) the maturation of some Brucella phagosomes is passively arrested between the steps of acidification and phagosome-lysosome fusion, (iii) brucellae are killed in maturing but not in arrested phagosomes, and (iv) survival of internalized Brucella depends on an acidic intraphagosomal pH and/or close contact with the phagosomal wall.
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Affiliation(s)
- M G Rittig
- INSERM U-431, Université de Montpellier II, Montpellier, France.
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Barthel R, Feng J, Piedrahita JA, McMurray DN, Templeton JW, Adams LG. Stable transfection of the bovine NRAMP1 gene into murine RAW264.7 cells: effect on Brucella abortus survival. Infect Immun 2001; 69:3110-9. [PMID: 11292730 PMCID: PMC98266 DOI: 10.1128/iai.69.5.3110-3119.2001] [Citation(s) in RCA: 72] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Genetically based natural resistance to brucellosis in cattle provides for novel strategies to control zoonotic diseases. Bovine NRAMP1, the homologue of a murine gene (Bcg), has been identified as a major candidate for controlling the in vivo resistant phenotype. We developed an in vitro model for expression of resistance- and susceptibility-associated alleles of bovine NRAMP1 as stable transgenes under the regulatory control of the bovine NRAMP1 promoter in the murine RAW264.7 macrophage cell line (Bcg(s)) to analyze the regulation of the NRAMP1 gene and its role in macrophage function. We demonstrated that the 5'-flanking region of bovine NRAMP1, despite the lack of TATA and CAAT boxes, has a functional promoter capable of driving the expression of a transgene in murine macrophages. A polymorphism within a microsatellite in the 3' untranslated region critically affects the expression of bovine NRAMP1 and the control of in vitro replication of Brucella abortus but not Salmonella enterica serovar Dublin. We did not observe any differences in the production of NO by resting or gamma interferon (IFN-gamma)- and IFN-gamma-lipopolysaccharide (LPS)-treated transfected cell lines, yet the resistant transfected cell lines produced significantly less NO than other cell lines, following stimulation with LPS at 24 and 48 h.
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Affiliation(s)
- R Barthel
- Department of Veterinary Pathobiology, College of Veterinary Medicine, Texas A&M University, College Station, Texas 77843, USA
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Burgess AW, Paquet JY, Letesson JJ, Anderson BE. Isolation, sequencing and expression of Bartonella henselae omp43 and predicted membrane topology of the deduced protein. Microb Pathog 2000; 29:73-80. [PMID: 10906262 DOI: 10.1006/mpat.2000.0366] [Citation(s) in RCA: 22] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The infection of and interaction of human endothelial cells with Bartonella henselae is one of the most interesting aspects of Bartonella -associated disease. The gene encoding the 43 kDa B. henselae outer membrane protein (Omp43) that binds endothelial cells was cloned and sequenced. Sequence analysis revealed an open reading frame of 1206 nucleotides coding for a protein of 402 amino acids. Analysis of the deduced amino acid sequence shows 38% identity over the entire sequence to the Brucella spp. In addition to this Omp2b porin also shows a signal sequence and peptidase cleavage site. Cleavage of the signal peptide results in a mature 380 amino acid polypeptide with a predicted molecular weight of 42 kDa. Omp43 was expressed in Escherichia coli as a fusion protein. Purified recombinant Omp43 at concentrations of 11 and 2.75 microg/ml bound to intact human umbilical vein endothelial cells. Membrane topology analysis predicts that Omp43 exists as a 16 stranded beta barrel protein, similar to that predicted for the Omp2b Brucella abortus porin. Characterization and expression of the gene encoding Omp43 should provide a tool for further investigation of the role of adherence to endothelial cells in the pathogenesis of B. henselae.
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Affiliation(s)
- A W Burgess
- University of South Florida College of Medicine, Department of Medical Microbiology and Immunology, Tampa 33612, USA.
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Paquet JY, Vinals C, Wouters J, Letesson JJ, Depiereux E. Topology prediction of Brucella abortus Omp2b and Omp2a porins after critical assessment of transmembrane beta strands prediction by several secondary structure prediction methods. J Biomol Struct Dyn 2000; 17:747-57. [PMID: 10698111 DOI: 10.1080/07391102.2000.10506564] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/28/2022]
Abstract
In order to propose a reliable model for Brucella porin topology, several structure prediction methods were evaluated in their ability to predict porin topology. Four porins of known structure were selected as test-cases and their secondary structure delineated. The specificity and sensitivity of 11 methods were separately evaluated. Our critical assessment shows that some secondary structure prediction methods (PHD, Dsc, Sopma) originally designed to predict globular protein structure are useful on porin topology prediction. The overall best prediction is obtained by combining these three "generalist" methods with a transmembrane beta strand prediction technique. This "consensus" method was applied to Brucella porins Omp2b and Omp2a, sharing no sequence homology with any other porin. The predicted topology is a 16-stranded antiparallel beta barrel with Omp2a showing a higher number of negatively charged residue in the exposed loops than Omp2b. Experiments are in progress to validate the proposed topology and the functional hypotheses. The ability of the proposed consensus method to predict topology of complex outer membrane protein is briefly discussed.
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Affiliation(s)
- J Y Paquet
- Unité de Recherche en Biologie Moléculaire, Facultés Universitaires Notre-Dame-de-la-Paix, Namur, Belgium.
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Gross A, Terraza A, Ouahrani-Bettache S, Liautard JP, Dornand J. In vitro Brucella suis infection prevents the programmed cell death of human monocytic cells. Infect Immun 2000; 68:342-51. [PMID: 10603407 PMCID: PMC97140 DOI: 10.1128/iai.68.1.342-351.2000] [Citation(s) in RCA: 174] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
During the complex interaction between an infectious agent and a host organism, the pathogen can interfere with the host cell's programmed death to its own benefit. Induction or prevention of host cell apoptosis appears to be a critical step for determining the infection outcome. Members of the gram-negative bacterial genus Brucella are intracellular pathogens which preferentially invade monocytic cells and develop within these cells. We investigated the effect of Brucella suis infection on apoptosis of human monocytic phagocytes. The present study provides evidence that Brucella infection inhibited spontaneously occurring apoptosis in human monocytes. Prevention of monocyte apoptosis was not mediated by Brucella lipopolysaccharide and required bacterial survival within infected cells. Both invaded and noninvaded cells were protected, indicating that soluble mediators released during infection were involved in the phenomenon. Analysis of Brucella-infected monocytes revealed specific overexpression of the A1 gene, a member of the bcl-2 family implicated in the survival of hematopoietic cells. Brucella infection also rendered macrophage-like cells resistant to Fas ligand- or gamma interferon-induced apoptosis, suggesting that Brucella infection protected host cells from several cytotoxic processes occurring at different steps of the immune response. The present data clearly show that Brucella suis modulated the monocyte/macrophage's apoptotic response to the advantage of the pathogen, thus preventing host cell elimination. This might represent a strategy for Brucella development in infected hosts.
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Affiliation(s)
- A Gross
- INSERM U431, IFR Eugène Bataillon, Université de Montpellier II, 34095 Montpellier Cedex 5, France
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Porte F, Liautard JP, Köhler S. Early acidification of phagosomes containing Brucella suis is essential for intracellular survival in murine macrophages. Infect Immun 1999; 67:4041-7. [PMID: 10417172 PMCID: PMC96697 DOI: 10.1128/iai.67.8.4041-4047.1999] [Citation(s) in RCA: 181] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Brucella suis is a facultative intracellular pathogen of mammals, residing in macrophage vacuoles. In this work, we studied the phagosomal environment of these bacteria in order to better understand the mechanisms allowing survival and multiplication of B. suis. Intraphagosomal pH in murine J774 cells was determined by measuring the fluorescence intensity of opsonized, carboxyfluorescein-rhodamine- and Oregon Green 488-rhodamine-labeled bacteria. Compartments containing live B. suis acidified to a pH of about 4.0 to 4.5 within 60 min. Acidification of B. suis-containing phagosomes in the early phase of infection was abolished by treatment of host cells with 100 nM bafilomycin A(1), a specific inhibitor of vacuolar proton-ATPases. This neutralization at 1 h postinfection resulted in a 2- to 34-fold reduction of opsonized and nonopsonized viable intracellular bacteria at 4 and 6 h postinfection, respectively. Ammonium chloride and monensin, other pH-neutralizing reagents, led to comparable loss of intracellular viability. Addition of ammonium chloride at 7 h after the beginning of infection, however, did not affect intracellular multiplication of B. suis, in contrast to treatment at 1 h postinfection, where bacteria were completely eradicated within 48 h. Thus, we conclude that phagosomes with B. suis acidify rapidly after infection, and that this early acidification is essential for replication of the bacteria within the macrophage.
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Affiliation(s)
- F Porte
- Institut National de la Santé et de la Recherche Médicale U-431, Montpellier, France.
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Gross A, Spiesser S, Terraza A, Rouot B, Caron E, Dornand J. Expression and bactericidal activity of nitric oxide synthase in Brucella suis-infected murine macrophages. Infect Immun 1998; 66:1309-16. [PMID: 9529047 PMCID: PMC108054 DOI: 10.1128/iai.66.4.1309-1316.1998] [Citation(s) in RCA: 86] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
We examined the expression and activity of inducible nitric oxide synthase (iNOS) in both gamma interferon (IFN-gamma)-treated and untreated murine macrophages infected with the gram-negative bacterium Brucella suis. The bacteria were opsonized with a mouse serum containing specific antibrucella antibodies (ops-Brucella) or with a control nonimmune serum (c-Brucella). The involvement of the produced NO in the killing of intracellular B. suis was evaluated. B. suis survived and replicated within J774A.1 cells. Opsonization with specific antibodies increased the number of phagocytized bacteria but lowered their intramacrophage development. IFN-gamma enhanced the antibrucella activity of phagocytes, with this effect being greater in ops-Brucella infection. Expression of iNOS, interleukin-6, and tumor necrosis factor alpha (TNF-alpha) mRNAs was induced in both c-Brucella- and ops-Brucella-infected cells and was strongly potentiated by IFN-gamma. In contrast to that of cytokine mRNAs, iNOS mRNA expression was independent of opsonization. Similar levels of iNOS mRNAs were expressed in IFN-gamma-treated cells infected with c-Brucella or ops-Brucella; however, expression of iNOS protein and production of NO were detected only in IFN-gamma-treated cells infected with ops-Brucella. These discrepancies between iNOS mRNA and protein levels were not due to differences in TNF-alpha production. The iNOS inhibitor N omega-nitro-L-arginine methyl ester increased B. suis multiplication specifically in IFN-gamma-treated cells infected with ops-Brucella, demonstrating a microbicidal effect of the NO produced. This observation was in agreement with in vitro experiments showing that B. suis was sensitive to NO killing. Together our data indicate that in B. suis-infected murine macrophages, the posttranscriptional regulation of iNOS necessitates an additive signal triggered by macrophage Fcgamma receptors. They also support the possibility that in mice, NO favors the elimination of Brucella, providing that IFN-gamma and antibrucella antibodies are present, i.e., following expression of acquired immunity.
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Affiliation(s)
- A Gross
- INSERM U431, IFR Eugène Bataillon, Université de Montpellier-II, France
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Shoemaker CA, Klesius PH, Plumb JA. Killing of Edwardsiella ictaluri by macrophages from channel catfish immune and susceptible to enteric septicemia of catfish. Vet Immunol Immunopathol 1997; 58:181-90. [PMID: 9336886 DOI: 10.1016/s0165-2427(97)00026-3] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
The role of peritoneal macrophages in immunity to enteric septicemia of catfish (ESC) after infection with live Edwardsiella ictaluri was investigated. Channel catfish macrophage-mediated bacteriocidal activity was dependent on the macrophage:bacteria ratio. Ratios of 1:1 to 1:12 exhibited significant differences (P < or = 0.05) in killing between macrophages from immune fish when compared to killing by macrophages from susceptible fish at 2.5 h. At 5 h, macrophages from immune fish were capable of effective killing (83.3%) at a 1:24 effector:target ratio, whereas macrophages from susceptible fish killed significantly (P < or = 0.05) less (56.9%). Macrophage bacteriocidal activity was significantly greater (P < or = 0.05) in macrophages from individual immune fish (93.4%) compared to macrophages from individual susceptible fish (85.4%). The kinetics of macrophage killing showed a linear increase in bacteriocidal activity from 1 to 3 h. Opsonization with immune serum enabled macrophages from immune fish to kill bacteria more effectively (93.8 vs. 75.9%) at 2.5 h. Opsonization of E. ictaluri with immune serum significantly suppressed the killing ability of macrophages from susceptible fish (46.2%) at 2.5 h. The results suggest that macrophages from fish immune to ESC had a greater capacity to kill E. ictaluri than macrophages from susceptible fish especially when E. ictaluri were opsonized with anti-E. ictaluri antibody.
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Affiliation(s)
- C A Shoemaker
- United States Department of Agriculture, Fish Disease and Parasite Research Laboratory, Auburn, AL 36830, USA
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Libby SJ, Adams LG, Ficht TA, Allen C, Whitford HA, Buchmeier NA, Bossie S, Guiney DG. The spv genes on the Salmonella dublin virulence plasmid are required for severe enteritis and systemic infection in the natural host. Infect Immun 1997; 65:1786-92. [PMID: 9125562 PMCID: PMC175217 DOI: 10.1128/iai.65.5.1786-1792.1997] [Citation(s) in RCA: 101] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023] Open
Abstract
The pathogenic role of the spv (Salmonella plasmid virulence) genes of Salmonella dublin was determined in the natural, bovine host. Since the lack of overt signs of enteritis or enterocolitis due to Salmonella infections in mice has limited the development of a convenient experimental system to study enteric disease, we used calves to study the contribution of the spv genes to S. dublin-induced salmonellosis. Since the SpvR transcriptional regulator is required for expression of the spvABCD operon, we constructed an spvR knockout mutation in a calf-virulent strain of S. dublin. Calves were infected with the wild-type strain, an spvR mutant, and an spvR mutant containing a complementing plasmid. Calves that were infected with the wild type or the complemented spvR mutant rapidly developed severe diarrhea and became moribund. Calves that were infected with the spvR mutant showed little or no clinical signs of systemic salmonellosis and developed only mild diarrhea. The survival and growth of the wild-type strain and the spvR mutant were determined by using blood-derived bovine monocytes. Wild-type S. dublin survived and grew inside cells, while the spvR mutant did not proliferate. These results suggest that the spv genes of S. dublin promote enhanced intracellular proliferation in intestinal tissues and at extraintestinal sites in the natural host.
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Affiliation(s)
- S J Libby
- Department of Medicine, University of California, San Diego, La Jolla 92093-0640, USA.
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Abstract
Brucella abortus is a facultative, intracellular, pathogenic bacterium that replicates within macrophages and resists macrophage microbicidal mechanisms. To study gene expression and to elucidate the defense mechanisms used by B. abortus to resist destruction within macrophages, protein synthesis by B. abortus was examined by pulse-labeling techniques during intracellular growth within J774A.1, a macrophage-like cell line. Prominent changes observed include increased synthesis of Brucella proteins with estimated molecular masses of 62, 28, 24, and 17 kDa. The 62-kDa protein was identified by immunoprecipitation analysis as Hsp62, a GroEL homolog. A protein of 60 kDa was expressed during acid shock and may represent a modified form of Hsp62. The 28- and 17-kDa proteins have not been observed under any in vitro stress condition and presumably represent macrophage-specific induction. The 24-kDa protein comigrates with an unidentified protein induced by acid shock, designated Asp24. Expression of Asp24 is optimal at pH values below 4.0 and within the first 3 h following a shift from pH 7.3 to 3.8. This corresponds directly with a period of optimal bacterial survival at a reduced pH and suggests an active role for this protein in resistance to such environments. The identification of these gene products and the mechanisms controlling their expression is an important step in understanding the resistance of Brucella spp. to intracellular destruction within macrophages.
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Affiliation(s)
- J Lin
- Department of Veterinary Pathobiology, College of Veterinary Medicine, Texas A&M University, College Station
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