51
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Lavigne JP, Patey G, Sangari FJ, Bourg G, Ramuz M, O'Callaghan D, Michaux-Charachon S. Identification of a new virulence factor, BvfA, in Brucella suis. Infect Immun 2005; 73:5524-9. [PMID: 16113268 PMCID: PMC1231096 DOI: 10.1128/iai.73.9.5524-5529.2005] [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: 12/27/2022] Open
Abstract
We report the identification of BvfA (for Brucella virulence factor A), a small periplasmic protein unique to the genus Brucella, which is essential for the virulence of Brucella suis. A BvfA knockout mutant was highly attenuated both in in vitro macrophage infection assays and in vivo in the murine model of brucellosis. Fluorescence-activated cell sorting analysis with green fluorescent protein fusions showed that the expression of bvfA is induced within macrophages by phagosome acidification and coregulated with the B. suis virB operon, suggesting that it too may play a role in the establishment of the intracellular replication niche.
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Affiliation(s)
- Jean-Philippe Lavigne
- Institut National de la Santé et de la Recherche Médicale, U431, Faculté de Médecine, Avenue Kennedy, 30900 Nimes, France
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52
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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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53
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Jimenez de Bagues MP, Maria-Pilar JDB, Dudal S, Dornand J, Gross A. Cellular bioterrorism: how Brucella corrupts macrophage physiology to promote invasion and proliferation. Clin Immunol 2005; 114:227-38. [PMID: 15721833 DOI: 10.1016/j.clim.2004.07.010] [Citation(s) in RCA: 55] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2004] [Accepted: 07/22/2004] [Indexed: 01/18/2023]
Abstract
Brucellosis is a worldwide human zoonosis caused by intracellular bacteria of the genus Brucella. Virulence factors play an important role in allowing Brucella infection and proliferation within macrophages. Brucella enters macrophages through lipid raft microdomains, avoids phagolysosome fusion, and inhibits TNF-alpha secretion and apoptosis. Furthermore, Brucella can perturb bactericidal activity in macrophages by influencing the host cell response to its advantage through its LPS or by activating the cAMP/PKA pathway. To date, small steps have been taken in defining and understanding the virulence factors of Brucella used in macrophage subversion, but further investigation is required to fully explain virulence and persistence.
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Affiliation(s)
- Maria-Pilar Jimenez de Bagues
- Unidad de Sanidad Animal, Servicio de Investigación Agroalimentaria, Diputación General de Aragón, Ap. 727. 50080 Zaragoza, Spain
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54
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Hwang BY, Lee HJ, Yang YH, Joo HS, Kim BG. Characterization and investigation of substrate specificity of the sugar aminotransferase WecE from E. coli K12. ACTA ACUST UNITED AC 2005; 11:915-25. [PMID: 15271350 DOI: 10.1016/j.chembiol.2004.04.015] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2004] [Revised: 03/26/2004] [Accepted: 04/07/2004] [Indexed: 11/30/2022]
Abstract
WecE gene, encoding a sugar aminotransferase (SAT), has been cloned from E. coli K12 and expressed in E. coli BL21 (DE3). The enzyme was purified and characterized. WecE used TDP-4-keto-6-deoxy-D-glucose (TDP-D-Glc4O) and L-glutamate as a good amino acceptor and donor, respectively, leading to the production of TDP-4-amino-4,6-dideoxy-D-galactose (TDP-Fuc4N), which was identified by NMR studies. WecE also showed a similar activity for TDP-4-keto 6-deoxy-D-mannose (TDP-D-Man4O), but no activity for GDP-4-keto-6-deoxy-D-mannose (GDP-D-Man4O), suggesting that the nucleotide moiety would become a key determinant to the substrate specificity of amine acceptor for the activity of the SAT. Multiple alignments showed that SATs have four highly conserved motifs located around the active site and could be divided into three subgroups (VIalpha, VIbeta, and VIgamma) that might be closely related with their substrate specificities.
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Affiliation(s)
- Bum-Yeol Hwang
- School of Chemical Engineering and Institute for Molecular Biology and Genetics, Seoul National University, Seoul 151-742, Korea
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55
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Fretin D, Fauconnier A, Köhler S, Halling S, Léonard S, Nijskens C, Ferooz J, Lestrate P, Delrue RM, Danese I, Vandenhaute J, Tibor A, DeBolle X, Letesson JJ. The sheathed flagellum of Brucella melitensis is involved in persistence in a murine model of infection. Cell Microbiol 2005; 7:687-98. [PMID: 15839898 DOI: 10.1111/j.1462-5822.2005.00502.x] [Citation(s) in RCA: 122] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
Persistence infection is the keystone of the ruminant and human diseases called brucellosis and Malta fever, respectively, and is linked to the intracellular tropism of Brucella spp. While described as non-motile, Brucella spp. have all the genes except the chemotactic system, necessary to assemble a functional flagellum. We undertook to determine whether these genes are expressed and are playing a role in some step of the disease process. We demonstrated that in the early log phase of a growth curve in 2YT nutrient broth, Brucella melitensis expresses genes corresponding to the basal (MS ring) and the distal (hook and filament) parts of the flagellar apparatus. Under these conditions, a polar and sheathed flagellar structure is visible by transmission electron microscopy (TEM). We evaluated the effect of mutations in flagellar genes of B. melitensis encoding various parts of the structure, MS ring, P ring, motor protein, secretion apparatus, hook and filament. None of these mutants gave a discernible phenotype as compared with the wild-type strain in cellular models of infection. In contrast, all these mutants were unable to establish a chronic infection in mice infected via the intraperitoneal route, raising the question of the biological role(s) of this flagellar appendage.
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Affiliation(s)
- D Fretin
- Unité de Recherche en Biologie Moléculaire, University of Namur, Belgium
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56
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The use of liposomes for detection of the surface lipopolysaccharide antigen, Vibrio cholerae cells, and antibodies against them. APPL BIOCHEM MICRO+ 2005. [DOI: 10.1007/s10438-005-0035-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
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57
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Canavessi AMO, Harms J, de Leon Gatti N, Splitter GA. The role of integrase/recombinase xerD and monofunctional biosynthesis peptidoglycan transglycosylase genes in the pathogenicity of Brucella abortus infection in vitro and in vivo. Microb Pathog 2004; 37:241-51. [PMID: 15519045 DOI: 10.1016/j.micpath.2004.07.004] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2004] [Revised: 07/15/2004] [Accepted: 07/22/2004] [Indexed: 11/28/2022]
Abstract
Brucella abortus clones identified previously using a green fluorescence protein reporter system after 4h macrophage infection provided insight regarding possible genes involved in early host-pathogen interaction. Among identified genes were an integrase/recombinase (xerD) gene involved in cell division, and a monofunctional biosynthesis peptidoglycan transglycosylase (mtgA) gene that catalyzes the final stages of the peptidoglycan membrane synthesis. Here, we evaluate the in vitro and in vivo survival of B. abortus xerD and mtgA insertional mutants. B. abortus xerD::kan and B. abortus mtgA::kan demonstrated no significant growth defects in broth culture when compared to the parental strain, S2308. Also, neither gene was required for B. abortus S2308 replication in RAW 264.7 macrophages. However, experimental evidence using interferon regulatory factor 1 knockout mice, a mouse strain highly susceptible to virulent Brucella, revealed that mice infected with B. abortus xerD::kan or B. abortus mtgA::kan survived longer than mice infected with S2308. Additionally, in immunocompetent BALB/c mice, B. abortus xerD::kan had a significantly lower level of bacterial survival when compared to S2308. Together, these results suggest that B. abortus xerD and mtgA genes play a role during the initial phase of infection in mice.
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Affiliation(s)
- Aurea M O Canavessi
- Department of Animal Health and Biomedical Sciences, University of Wisconsin-Madison, 1656 Linden Drive, Madison, WI 53706, USA
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58
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Danese I, Haine V, Delrue RM, Tibor A, Lestrate P, Stevaux O, Mertens P, Paquet JY, Godfroid J, De Bolle X, Letesson JJ. The Ton system, an ABC transporter, and a universally conserved GTPase are involved in iron utilization by Brucella melitensis 16M. Infect Immun 2004; 72:5783-90. [PMID: 15385478 PMCID: PMC517599 DOI: 10.1128/iai.72.10.5783-5790.2004] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Brucella spp. are gram-negative intracellular facultative pathogens that are known to produce 2,3-dihydroxybenzoic acid (DHBA), a catechol siderophore that is essential for full virulence in the natural host. The mechanism of DHBA entry into Brucella and other gram-negative bacteria is poorly understood. Using mini-Tn5Kmcat mutagenesis, we created a transposon library of Brucella melitensis 16M and isolated 32 mutants with a defect in iron acquisition or assimilation. Three of these transposon mutants are deficient in utilization of DHBA. Analysis of these three mutants indicated that the ExbB, DstC, and DugA proteins are required for optimal assimilation of DHBA and/or citrate. ExbB is part of the Ton complex, and DstC is a permease homologue of an iron(III) ABC transporter; in gram-negative bacteria these two complexes are involved in the uptake of iron through the outer and inner membranes, respectively. DugA is a new partner in iron utilization that exhibits homology with the bacterial conserved GTPase YchF. Based on this homology, DugA could have a putative regulatory function in iron assimilation in Brucella. None of the three mutants was attenuated in cellular models or in the mouse model of infection, which is consistent with the previous suggestion that DHBA utilization is not required in these models.
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Affiliation(s)
- Isabelle Danese
- Unité de Recherche en Biologie Moléculaire, University of Namur, Belgium.
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59
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Samuel G, Reeves P. Biosynthesis of O-antigens: genes and pathways involved in nucleotide sugar precursor synthesis and O-antigen assembly. Carbohydr Res 2004; 338:2503-19. [PMID: 14670712 DOI: 10.1016/j.carres.2003.07.009] [Citation(s) in RCA: 385] [Impact Index Per Article: 19.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
Abstract
The O-antigen is an important component of the outer membrane of Gram-negative bacteria. It is a repeat unit polysaccharide and consists of a number of repeats of an oligosaccharide, the O-unit, which generally has between two and six sugar residues. O-Antigens are extremely variable, the variation lying in the nature, order and linkage of the different sugars within the polysaccharide. The genes involved in O-antigen biosynthesis are generally found on the chromosome as an O-antigen gene cluster, and the structural variation of O-antigens is mirrored by genetic variation seen in these clusters. The genes within the cluster fall into three major groups. The first group is involved in nucleotide sugar biosynthesis. These genes are often found together in the cluster and have a high level of identity. The genes coding for a significant number of nucleotide sugar biosynthesis pathways have been identified and these pathways seem to be conserved in different O-antigen clusters and across a wide range of species. The second group, the glycosyl transferases, is involved in sugar transfer. They are often dispersed throughout the cluster and have low levels of similarity. The third group is the O-antigen processing genes. This review is a summary of the current knowledge on these three groups of genes that comprise the O-antigen gene clusters, focusing on the most extensively studied E. coli and S. enterica gene clusters.
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Affiliation(s)
- Gabrielle Samuel
- School of Molecular and Microbial Biosciences, University of Sydney, Sydney, NSW 2006, Australia
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60
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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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61
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Nascimento ALTO, Ko AI, Martins EAL, Monteiro-Vitorello CB, Ho PL, Haake DA, Verjovski-Almeida S, Hartskeerl RA, Marques MV, Oliveira MC, Menck CFM, Leite LCC, Carrer H, Coutinho LL, Degrave WM, Dellagostin OA, El-Dorry H, Ferro ES, Ferro MIT, Furlan LR, Gamberini M, Giglioti EA, Góes-Neto A, Goldman GH, Goldman MHS, Harakava R, Jerônimo SMB, Junqueira-de-Azevedo ILM, Kimura ET, Kuramae EE, Lemos EGM, Lemos MVF, Marino CL, Nunes LR, de Oliveira RC, Pereira GG, Reis MS, Schriefer A, Siqueira WJ, Sommer P, Tsai SM, Simpson AJG, Ferro JA, Camargo LEA, Kitajima JP, Setubal JC, Van Sluys MA. Comparative genomics of two Leptospira interrogans serovars reveals novel insights into physiology and pathogenesis. J Bacteriol 2004; 186:2164-72. [PMID: 15028702 PMCID: PMC374407 DOI: 10.1128/jb.186.7.2164-2172.2004] [Citation(s) in RCA: 312] [Impact Index Per Article: 15.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Leptospira species colonize a significant proportion of rodent populations worldwide and produce life-threatening infections in accidental hosts, including humans. Complete genome sequencing of Leptospira interrogans serovar Copenhageni and comparative analysis with the available Leptospira interrogans serovar Lai genome reveal that despite overall genetic similarity there are significant structural differences, including a large chromosomal inversion and extensive variation in the number and distribution of insertion sequence elements. Genome sequence analysis elucidates many of the novel aspects of leptospiral physiology relating to energy metabolism, oxygen tolerance, two-component signal transduction systems, and mechanisms of pathogenesis. A broad array of transcriptional regulation proteins and two new families of afimbrial adhesins which contribute to host tissue colonization in the early steps of infection were identified. Differences in genes involved in the biosynthesis of lipopolysaccharide O side chains between the Copenhageni and Lai serovars were identified, offering an important starting point for the elucidation of the organism's complex polysaccharide surface antigens. Differences in adhesins and in lipopolysaccharide might be associated with the adaptation of serovars Copenhageni and Lai to different animal hosts. Hundreds of genes encoding surface-exposed lipoproteins and transmembrane outer membrane proteins were identified as candidates for development of vaccines for the prevention of leptospirosis.
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Affiliation(s)
- A L T O Nascimento
- Centro de Biotecnologia, Instituto Butantan, Universidade de São Paulo, São Paulo, Brazil.
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62
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Marianelli C, La Rosa G, Ciuchini F, Muscillo M, Pasquali P, Adone R. Genetic diversity at alkB locus in Brucella abortus. ACTA ACUST UNITED AC 2004; 50:494-9. [PMID: 14720187 DOI: 10.1046/j.1439-0450.2003.00711.x] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
DNA polymorphism of the alkB gene, a DNA repair gene, was assessed by PCR on Brucella abortus biovars 1 (strains 99, S19, 45/20, RB51 and 2308), 3 (Tulya strain), 5 (B3196 strain) and 6 (870 strain). A DNA repetitive element, named IS711, was detected in all studied biovars 1 and its complete nucleotide sequence was determined. We found that the element in alkB gene, bounded by 14 bp imperfect inverted repeats (IRs), is 840 bp long and appears to duplicate a consensus target site, CTAG. Analysing its nucleotide sequence of both forward and reverse strands, more than 10 open reading frames (ORFs) were found. Two potential transposase coding regions were chosen comparing all possible ORFs with the database. Comparing IS711 elements isolated from Brucella species, including both those characterized in our work and the published ones, differences in length and in nucleotide composition were observed among Brucella species, members of the same species and within the same strain. Our results confirm the heterogeneity of IS711 elements in Brucella genus and suggest the possibility to use this element to assess gene and genome diversity and to identify new molecular markers for Brucella species.
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Affiliation(s)
- C Marianelli
- Dipartimento di Sanità Alimentare ed Animale, Istituto Superiore di Sanità, Viale Regina Elena, Rome, Italy.
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63
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Abstract
Rough mutants of Brucella spp. are attenuated for survival in animal models. However, conflicting in vitro evidence has been obtained concerning the intracellular survival of rough mutants. Transposon-derived rough mutants isolated in our laboratory were previously shown to exhibit small but significant reductions in intracellular survival in a 12-h in vitro assay. Several recent publications report that rough mutants exhibited increased macrophage uptake relative to their smooth parental strains, and a reduction in numbers at the end of the assay has been interpreted as intracellular killing. In an effort to explore the role of O antigen in the interaction between Brucella abortus and macrophages, we have monitored the uptake of rough mutants and survival in vitro by using the murine macrophage cell line J774.A1. The results confirm a 10- to 20-fold-increased uptake of rough mutants over that of smooth organisms under standard conditions. Recovery of the rough mutants persisted up to 8 h postinfection, but at the point when intracellular replication of the smooth organisms was observed, the number of rough organisms recovered declined. Fluorescence microscopy revealed the intracellular multiplication of both smooth and rough organisms, and assays performed in the absence of antibiotic confirmed the replication of the rough organisms. Examination by phase-contrast microscopy revealed the lytic death of macrophages infected with the rough mutants, which was confirmed by the release of lactate dehydrogenase (LDH) from the cell cytoplasm. Thus, the decline in the number of rough organisms was the result of the lysis of macrophages and not from intracellular killing. The cytopathic effect is characterized as necrotic rather than apoptotic cell death based on early LDH release, annexin V and propidium iodide staining, morphological changes of infected cells and nuclei, and glycine protection. The cytopathic effect was observed with macrophages at multiplicities of infection (MOIs) of as low as 20 and was not observed with epithelial cells at MOIs of as high as 2000. These findings suggest a role for O antigen during the early stages of host-agent interaction that is essential in establishing an intracellular niche that maintains and supports persistent intracellular infection resulting in disease.
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Affiliation(s)
- Jianwu Pei
- Veterinary Pathobiology, Texas A&M University and Texas Agricultural Experiment Station, College Station, Texas 77843-4467, USA
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64
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Delrue RM, Lestrate P, Tibor A, Letesson JJ, De Bolle X. Brucellapathogenesis, genes identified from random large-scale screens. FEMS Microbiol Lett 2004; 231:1-12. [PMID: 14979322 DOI: 10.1016/s0378-1097(03)00963-7] [Citation(s) in RCA: 72] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Pathogenicity islands, specialized secretion systems, virulence plasmids, fimbriae, pili, adhesins, and toxins are all classical bacterial virulence factors. However, many of these factors, though widespread among bacterial pathogens, are not necessarily found among bacteria that colonize eukaryotic cells in a pathogenic/symbiotic relationship. Bacteria that form these relationships have developed other strategies to infect and grow in their hosts. This is particularly true for Brucella and other members of the class Proteobacteria. Thus far the identification of virulence factors for Brucella has been largely dependent on large-scale screens and testing in model systems. The genomes of the facultative intracellular pathogens Brucella melitensis and Brucella suis were sequenced recently. This has identified several more potential virulence factors for Brucella that were not found in large screens. Here, we present an overall view of Brucella virulence by compiling virulence data from the study of 184 attenuated mutants.
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Affiliation(s)
- Rose-May Delrue
- Unité de Recherche en Biologie Moléculaire (URBM), Laboratoire d'Immunologie et de Microbiologie, Université de Namur, Namur, Belgium
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65
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Lestrate P, Dricot A, Delrue RM, Lambert C, Martinelli V, De Bolle X, Letesson JJ, Tibor A. Attenuated signature-tagged mutagenesis mutants of Brucella melitensis identified during the acute phase of infection in mice. Infect Immun 2004; 71:7053-60. [PMID: 14638795 PMCID: PMC308902 DOI: 10.1128/iai.71.12.7053-7060.2003] [Citation(s) in RCA: 83] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
For this study, we screened 1,152 signature-tagged mutagenesis mutants of Brucella melitensis 16M in a mouse model of infection and found 36 of them to be attenuated in vivo. Molecular characterization of transposon insertion sites showed that for four mutants, the affected genes were only present in Rhizobiaceae. Another mutant contained a disruption in a gene homologous to mosA, which is involved in rhizopine biosynthesis in some strains of Rhizobium, suggesting that this sugar may be involved in Brucella pathogenicity. A mutant was disrupted in a gene homologous to fliF, a gene potentially coding for the MS ring, a basal component of the flagellar system. Surprisingly, a mutant was affected in the rpoA gene, coding for the essential alpha-subunit of the RNA polymerase. This disruption leaves a partially functional protein, impaired for the activation of virB transcription, as demonstrated by the absence of induction of the virB promoter in the Tn5::rpoA background. The results presented here highlight the fact that the ability of Brucella to induce pathogenesis shares similarities with the molecular mechanisms used by both Rhizobium and Agrobacterium to colonize their hosts.
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Affiliation(s)
- P Lestrate
- Unité de Recherche en Biologie Moléculaire (URBM), Laboratoire d'Immunologie et de Microbiologie, University of Namur, 5000 Namur, Belgium
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66
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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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67
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Lübeck PS, Hoorfar J, Ahrens P, Skurnik M. Cloning and characterization of the Yersinia enterocolitica serotype O:9 lipopolysaccharide O-antigen gene cluster. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2003; 529:207-9. [PMID: 12756758 DOI: 10.1007/0-306-48416-1_40] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 03/02/2023]
Affiliation(s)
- Peter S Lübeck
- Department of Bacteriology, Danish Veterinary Institute, Copenhagen, Denmark
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68
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Monreal D, Grilló MJ, González D, Marín CM, De Miguel MJ, López-Goñi I, Blasco JM, Cloeckaert A, Moriyón I. Characterization of Brucella abortus O-polysaccharide and core lipopolysaccharide mutants and demonstration that a complete core is required for rough vaccines to be efficient against Brucella abortus and Brucella ovis in the mouse model. Infect Immun 2003; 71:3261-71. [PMID: 12761107 PMCID: PMC155776 DOI: 10.1128/iai.71.6.3261-3271.2003] [Citation(s) in RCA: 84] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Brucella abortus rough lipopolysaccharide (LPS) mutants were obtained by transposon insertion into two wbk genes (wbkA [putative glycosyltransferase; formerly rfbU] and per [perosamine synthetase]), into manB (pmm [phosphomannomutase; formerly rfbK]), and into an unassigned gene. Consistent with gene-predicted roles, electrophoretic analysis, 2-keto-3-manno-D-octulosonate measurements, and immunoblots with monoclonal antibodies to O-polysaccharide, outer and inner core epitopes showed no O-polysaccharide expression and no LPS core defects in the wbk mutants. The rough LPS of manB mutant lacked the outer core epitope and the gene was designated manB(core) to distinguish it from the wbk manB(O-Ag). The fourth gene (provisionally designated wa**) coded for a putative glycosyltransferase involved in inner core synthesis, but the mutant kept the outer core epitope. Differences in phage and polymyxin sensitivity, exposure or expression of outer membrane protein, core and lipid A epitopes, and lipid A acylation demonstrated that small changes in LPS core caused significant differences in B. abortus outer membrane topology. In mice, the mutants showed different degrees of attenuation and induced antibodies to rough LPS and outer membrane proteins. Core-defective mutants and strain RB51 were ineffective vaccines against B. abortus in mice. The mutants per and wbkA induced protection but less than the standard smooth vaccine S19, and controls suggested that anti O-polysaccharide antibodies accounted largely for the difference. Whereas no core-defective mutant was effective against B. ovis, S19, RB51, and the wbkA and per mutants afforded similar levels of protection. These results suggest that rough Brucella vaccines should carry a complete core for maximal effectiveness.
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Affiliation(s)
- D. Monreal
- Departamento de Microbiología, Universidad de Navarra, Pamplona, Servicio de Investigación Agroalimentaria, Diputación General de Aragón, Zaragoza, Spain, Unité BioAgresseurs, Santé et Environnement, Institut National de la Recherche Agronomique, 37380 Nouzilly, France
| | - M. J. Grilló
- Departamento de Microbiología, Universidad de Navarra, Pamplona, Servicio de Investigación Agroalimentaria, Diputación General de Aragón, Zaragoza, Spain, Unité BioAgresseurs, Santé et Environnement, Institut National de la Recherche Agronomique, 37380 Nouzilly, France
| | - D. González
- Departamento de Microbiología, Universidad de Navarra, Pamplona, Servicio de Investigación Agroalimentaria, Diputación General de Aragón, Zaragoza, Spain, Unité BioAgresseurs, Santé et Environnement, Institut National de la Recherche Agronomique, 37380 Nouzilly, France
| | - C. M. Marín
- Departamento de Microbiología, Universidad de Navarra, Pamplona, Servicio de Investigación Agroalimentaria, Diputación General de Aragón, Zaragoza, Spain, Unité BioAgresseurs, Santé et Environnement, Institut National de la Recherche Agronomique, 37380 Nouzilly, France
| | - M. J. De Miguel
- Departamento de Microbiología, Universidad de Navarra, Pamplona, Servicio de Investigación Agroalimentaria, Diputación General de Aragón, Zaragoza, Spain, Unité BioAgresseurs, Santé et Environnement, Institut National de la Recherche Agronomique, 37380 Nouzilly, France
| | - I. López-Goñi
- Departamento de Microbiología, Universidad de Navarra, Pamplona, Servicio de Investigación Agroalimentaria, Diputación General de Aragón, Zaragoza, Spain, Unité BioAgresseurs, Santé et Environnement, Institut National de la Recherche Agronomique, 37380 Nouzilly, France
| | - J. M. Blasco
- Departamento de Microbiología, Universidad de Navarra, Pamplona, Servicio de Investigación Agroalimentaria, Diputación General de Aragón, Zaragoza, Spain, Unité BioAgresseurs, Santé et Environnement, Institut National de la Recherche Agronomique, 37380 Nouzilly, France
| | - A Cloeckaert
- Departamento de Microbiología, Universidad de Navarra, Pamplona, Servicio de Investigación Agroalimentaria, Diputación General de Aragón, Zaragoza, Spain, Unité BioAgresseurs, Santé et Environnement, Institut National de la Recherche Agronomique, 37380 Nouzilly, France
| | - I. Moriyón
- Departamento de Microbiología, Universidad de Navarra, Pamplona, Servicio de Investigación Agroalimentaria, Diputación General de Aragón, Zaragoza, Spain, Unité BioAgresseurs, Santé et Environnement, Institut National de la Recherche Agronomique, 37380 Nouzilly, France
- Corresponding author. Mailing address: Departamento de Microbiología, Universidad de Navarra, Aptdo. 177, 31080 Pamplona, Spain. Phone: 34-948-425600. Fax: 34-948-425649. E-mail:
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69
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Fernandez-Prada CM, Zelazowska EB, Nikolich M, Hadfield TL, Roop RM, Robertson GL, Hoover DL. Interactions between Brucella melitensis and human phagocytes: bacterial surface O-Polysaccharide inhibits phagocytosis, bacterial killing, and subsequent host cell apoptosis. Infect Immun 2003; 71:2110-9. [PMID: 12654833 PMCID: PMC152029 DOI: 10.1128/iai.71.4.2110-2119.2003] [Citation(s) in RCA: 91] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Brucellae are gram-negative intracellular pathogens that survive and multiply within host phagocytic cells. Smooth organisms present O-polysaccharides (OPS) on their surface. The wboA gene, which codes for the enzyme glycosyl transferase, is essential for the assembly of O-chain in Brucella. Deletion of wboA in smooth, virulent B. melitensis 16M results in a rough mutant designated WRR51. Unlike B. abortus, both smooth and rough strains of B. melitensis are resistant to complement-mediated killing. To determine the role of surface OPS in the interactions of B. melitensis with monocytes/macrophages (M/M), 16M and WRR51 were transformed with the plasmid pBBR1MCS-6y encoding green fluorescent protein, and the transformants were used to infect human mononuclear phagocytes with and without fresh human serum as a source of complement. Human monocytes were cultured in the presence of macrophage colony-stimulating factor to allow their differentiation into macrophages during the course of infection. Intracellular bacteria were easily visualized using fluorescence microscopy. Infection in M/M, identified by surface staining and fate of infected phagocytes, was quantitated by flow cytometry. Rough bacteria were internalized, with no requirement for opsonization by serum, at a higher rate than smooth organisms. Smooth B. melitensis survived and multiplied for at least 6 days inside M/M, but rough organisms were eliminated by death of the infected cells. In human monocytes cultured for 1 day without serum in order to trigger the apoptotic pathway, infection by rough brucellae accelerated phagocyte death; smooth brucellae inhibited apoptosis. This study suggests that the presence of surface OPS on live B. melitensis benefits the bacterium by preventing the death of macrophages, Brucella's preferred target for intracellular replication.
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Affiliation(s)
- Carmen M Fernandez-Prada
- Department of Bacterial Diseases, Walter Reed Army Institute of Research, Bldg. 503, Room 2N57, Washington, D.C. 20307-5100, USA.
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70
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Porte F, Naroeni A, Ouahrani-Bettache S, Liautard JP. Role of the Brucella suis lipopolysaccharide O antigen in phagosomal genesis and in inhibition of phagosome-lysosome fusion in murine macrophages. Infect Immun 2003; 71:1481-90. [PMID: 12595466 PMCID: PMC148865 DOI: 10.1128/iai.71.3.1481-1490.2003] [Citation(s) in RCA: 117] [Impact Index Per Article: 5.6] [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 cell types. However, the molecular mechanisms and the microbial factors involved are poorly understood. Smooth lipopolysaccharide (LPS) of Brucella has been reported to be an important virulence factor, although its precise role in pathogenesis is not yet clear. In this study, we show that the LPS O side chain is involved in inhibition of the early fusion between Brucella suis-containing phagosomes and lysosomes in murine macrophages. In contrast, the phagosomes containing rough mutants, which fail to express the O antigen, rapidly fuse with lysosomes. In addition, we show that rough mutants do not enter host cells by using lipid rafts, contrary to smooth strains. Thus, we propose that the LPS O chain might be a major factor that governs the early behavior of bacteria inside macrophages.
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Affiliation(s)
- Françoise Porte
- Institut National de la Santé et de la Recherche Médicale U-431, Montpellier, France.
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71
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Ko J, Splitter GA. Molecular host-pathogen interaction in brucellosis: current understanding and future approaches to vaccine development for mice and humans. Clin Microbiol Rev 2003; 16:65-78. [PMID: 12525425 PMCID: PMC145300 DOI: 10.1128/cmr.16.1.65-78.2003] [Citation(s) in RCA: 210] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Brucellosis caused by Brucella spp. is a major zoonotic disease. Control of brucellosis in agricultural animals is a prerequisite for the prevention of this disease in human beings. Recently, Brucella melitensis was declared by the Centers for Disease Control and Prevention to be one of three major bioterrorist agents due to the expense required for the treatment of human brucellosis patients. Also, the economic agricultural loss due to bovine brucellosis emphasizes the financial impact of brucellosis in society. Thus, vaccination might efficiently solve this disease. Currently, B. abortus RB51 and B. melitensis REV.1 are used to immunize cattle and to immunize goats and sheep, respectively, in many countries. However, these genetically undefined strains still induce abortion and persistent infection, raising questions of safety and efficiency. In fact, the REV.1 vaccine is quite virulent and apparently unstable, creating the need for improved vaccines for B. melitensis. In addition, Brucella spp. may or may not provide cross-protection against infection by heterologous Brucella species, hampering the acceleration of vaccine development. This review provides our current understanding of Brucella pathogenesis and host immunity for the development of genetically defined efficient vaccine strains. Additionally, conditions required for an effective Brucella vaccine strain as well as the future research direction needed to investigate Brucella pathogenesis and host immunity are postulated.
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Affiliation(s)
- Jinkyung Ko
- Laboratory of Cellular and Molecular Immunology, Department of Animal Health and Biomedical Sciences, University of Wisconsin, Madison, Wisconsin 53706, USA
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72
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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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73
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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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74
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Letesson JJ, Lestrate P, Delrue RM, Danese I, Bellefontaine F, Fretin D, Taminiau B, Tibor A, Dricot A, Deschamps C, Haine V, Leonard S, Laurent T, Mertens P, Vandenhaute J, De Bolle X. Fun stories about Brucella: the "furtive nasty bug". Vet Microbiol 2002; 90:317-28. [PMID: 12414152 DOI: 10.1016/s0378-1135(02)00208-0] [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: 11/18/2022]
Abstract
Although Brucella is responsible for one of the major worldwide zoonosis, our understanding of its pathogenesis remains in its infancy. In this paper, we summarize some of the research in progress in our laboratory that we think could contribute to a better understanding of the Brucella molecular virulence mechanisms and their regulation.
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Affiliation(s)
- J-J Letesson
- Laboratoire d'Immunologie et de Microbiologie, Unité de Recherche en Biologie Moleculaire, Facultés Universitaires Notre-Dame de la Paix, rue de Bruxelles 61, B-5000 Namur, Belgium.
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75
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Abstract
The metabolic capabilities of the species of Brucella were originally of interest as a means of distinguishing them from each other and from other genera. Certain unusual characteristics, especially erythritol utilization, were studied in the hopes they would shed light on the pathogenicity. With the advent of modern genetic methods and genomic sequencing, it is now possible to get a good idea of the total capabilities of the organism and to do tests to confirm these deductions. Brucella appears to be a fairly normal member of the alpha-proteobacteria, but with some differences. A few questions remain, such as whether Brucella uses the Entner-Doudoroff pathway. Some of the genes in carbohydrate utilization have been shown to be important in virulence.
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Affiliation(s)
- Richard C Essenberg
- Department of Biochemistry and Molecular Biology, 246 Noble Research Center, Oklahoma State University, Stillwater, OK 74078, USA.
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76
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Abstract
The first effective Brucella vaccine was based on live Brucella abortus strain 19, a laboratory-derived strain attenuated by an unknown process during subculture. This induces reasonable protection against B. abortus, but at the expense of persistent serological responses. A similar problem occurs with the B. melitensis Rev.1 strain that is still the most effective vaccine against caprine and ovine brucellosis. Vaccines based on killed cells of virulent strains administered with adjuvant induced significant protection but also unacceptable levels of antibodies interfering with diagnostic tests. Attempts were made to circumvent this problem by using a live rough strain B. abortus 45/20, but this reverted to virulence in vivo. Use of killed cells of this strain in adjuvant met with moderate success but batch to batch variation in reactogenicity and agglutinogenicity limited application. This problem has been overcome by the development of the rifampicin-resistant mutant B. abortus RB51 strain. This strain has proved safe and effective in the field against bovine brucellosis and exhibits negligible interference with diagnostic serology. Attempts are being made to develop defined rough mutant vaccine strains that would be more effective against B. melitensis and B. suis. Various studies have examined cell-free native and recombinant proteins as candidate protective antigens, with or without adjuvants. Limited success has been obtained with these or with DNA vaccines encoding known protective antigens in experimental models and further work is indicated.
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Affiliation(s)
- Gerhardt G Schurig
- Center for Molecular Medicine and Infectious Diseases, Virginia-Maryland Regional College of Veterinary Medicine, Virginia Tech, Blacksburg, VA 24061, USA
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77
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Kohler S, Foulongne V, Ouahrani-Bettache S, Bourg G, Teyssier J, Ramuz M, Liautard JP. The analysis of the intramacrophagic virulome of Brucella suis deciphers the environment encountered by the pathogen inside the macrophage host cell. Proc Natl Acad Sci U S A 2002; 99:15711-6. [PMID: 12438693 PMCID: PMC137781 DOI: 10.1073/pnas.232454299] [Citation(s) in RCA: 198] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The pathogen Brucella suis resides and multiplies within a phagocytic vacuole of its host cell, the macrophage. The resulting complex relationship has been investigated by the analysis of the set of genes required for virulence, which we call intramacrophagic virulome. Ten thousand two hundred and seventy-two miniTn5 mutants of B. suis constitutively expressing gfp were screened by fluorescence microscopy for lack of intracellular multiplication in human macrophages. One hundred thirty-one such mutants affected in 59 different genes could be isolated, and a function was ascribed to 53 of them. We identified genes involved in (i) global adaptation to the intracellular environment, (ii) amino acid, and (iii) nucleotide synthesis, (iv) sugar metabolism, (v) oxidoreduction, (vi) nitrogen metabolism, (vii) regulation, (viii) disulphide bond formation, and (ix) lipopolysaccharide biosynthesis. Results led to the conclusion that the replicative compartment of B. suis is poor in nutrients and characterized by low oxygen tension, and that nitrate may be used for anaerobic respiration. Intramacrophagic virulome analysis hence allowed the description of the nature of the replicative vacuole of the pathogen in the macrophage and extended our understanding of the niche in which B. suis resides. We propose calling this specific compartment "brucellosome."
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Affiliation(s)
- Stephan Kohler
- Institut National de la Santé et de la Recherche Médicale U-431 (INSERM U-431), Université Montpellier II, France.
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78
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Paulsen IT, Seshadri R, Nelson KE, Eisen JA, Heidelberg JF, Read TD, Dodson RJ, Umayam L, Brinkac LM, Beanan MJ, Daugherty SC, Deboy RT, Durkin AS, Kolonay JF, Madupu R, Nelson WC, Ayodeji B, Kraul M, Shetty J, Malek J, Van Aken SE, Riedmuller S, Tettelin H, Gill SR, White O, Salzberg SL, Hoover DL, Lindler LE, Halling SM, Boyle SM, Fraser CM. The Brucella suis genome reveals fundamental similarities between animal and plant pathogens and symbionts. Proc Natl Acad Sci U S A 2002; 99:13148-53. [PMID: 12271122 PMCID: PMC130601 DOI: 10.1073/pnas.192319099] [Citation(s) in RCA: 330] [Impact Index Per Article: 15.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2002] [Indexed: 11/18/2022] Open
Abstract
The 3.31-Mb genome sequence of the intracellular pathogen and potential bioterrorism agent, Brucella suis, was determined. Comparison of B. suis with Brucella melitensis has defined a finite set of differences that could be responsible for the differences in virulence and host preference between these organisms, and indicates that phage have played a significant role in their divergence. Analysis of the B. suis genome reveals transport and metabolic capabilities akin to soil/plant-associated bacteria. Extensive gene synteny between B. suis chromosome 1 and the genome of the plant symbiont Mesorhizobium loti emphasizes the similarity between this animal pathogen and plant pathogens and symbionts. A limited repertoire of genes homologous to known bacterial virulence factors were identified.
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Affiliation(s)
- Ian T Paulsen
- The Institute for Genomic Research, 9712 Medical Center Drive, Rockville, MD 20850, USA.
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79
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Tibor A, Wansard V, Bielartz V, Delrue RM, Danese I, Michel P, Walravens K, Godfroid J, Letesson JJ. Effect of omp10 or omp19 deletion on Brucella abortus outer membrane properties and virulence in mice. Infect Immun 2002; 70:5540-6. [PMID: 12228280 PMCID: PMC128365 DOI: 10.1128/iai.70.10.5540-5546.2002] [Citation(s) in RCA: 40] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The distinctive properties of Brucella outer membrane have been considered to be critical for Brucella sp. virulence. Among the outer membrane molecules possibly related to these properties, Omp10 and Omp19 are immunoreactive outer membrane lipoproteins. Moreover, these proteins of Brucella could constitute a new family of outer membrane proteins specifically encountered in the family RHIZOBIACEAE: We evaluated the impact of omp10 or omp19 deletion on Brucella abortus outer membrane properties and virulence in mice. The omp10 mutant was dramatically attenuated for survival in mice and was defective for growth in minimal medium but was not impaired in intracellular growth in vitro, nor does it display clear modification of the outer membrane properties. Significantly fewer brucellae were recovered from the spleens of mice infected with the omp19 mutant than from those of mice infected with the parent strain at 4 and 8 weeks postinfection. The omp19 mutant exhibited an increase in sensitivity to the polycation polymyxin B and to sodium deoxycholate. These results indicate that inactivation of the omp19 gene alters the outer membrane properties of B. abortus.
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Affiliation(s)
- Anne Tibor
- Unité de Recherche en Biologie Moléculaire, Facultés Universitaires Notre-Dame de la Paix, B-5000 Namur, Belgium.
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80
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Taminiau B, Daykin M, Swift S, Boschiroli ML, Tibor A, Lestrate P, De Bolle X, O'Callaghan D, Williams P, Letesson JJ. Identification of a quorum-sensing signal molecule in the facultative intracellular pathogen Brucella melitensis. Infect Immun 2002; 70:3004-11. [PMID: 12010991 PMCID: PMC128001 DOI: 10.1128/iai.70.6.3004-3011.2002] [Citation(s) in RCA: 72] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2001] [Revised: 01/15/2002] [Accepted: 03/21/2002] [Indexed: 11/20/2022] Open
Abstract
Brucella melitensis is a gram-negative alpha2-proteobacterium responsible for abortion in goats and for Malta fever in humans. This facultative intracellular pathogen invades and survives within both professional and nonprofessional phagocytes. A dichloromethane extract of spent culture supernatant from B. melitensis induces bioluminescence in an Escherichia coli acyl-homoserine lactone (acyl-HSL) biosensor strain based upon the activity of the LasR protein of Pseudomonas aeruginosa. HPLC fractionation of the extract, followed by mass spectrometry, identified the major active molecule as N-dodecanoylhomoserine lactone (C12-HSL). This is the first report of the production of an acyl-HSL by an intracellular pathogen. The addition of synthetic C12-HSL to an early log phase culture of either B. melitensis or Brucella suis 1330 reduces the transcription of the virB operon, which contains virulence genes known to be required for intracellular survival. This mimics events seen during the stationary phase of growth and suggests that quorum sensing may play a role in the control of virulence in Brucella.
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Affiliation(s)
- Bernard Taminiau
- Unité de Recherche en Biologie Moléculaire (URBM), Laboratoire d'Immunologie et Microbiologie, Facultés Universitaires Notre-Dame de la Paix, 5000 Namur, Belgium.
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81
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Mertens P, Walgraffe D, Laurent T, Deschrevel N, Letesson JJ, De Bolle X. Selection of phage-displayed peptides recognised by monoclonal antibodies directed against the lipopolysaccharide of Brucella. Int Rev Immunol 2002; 20:181-99. [PMID: 11878764 DOI: 10.3109/08830180109043033] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
Panning and screening of various phage display libraries with monoclonal antibodies (mAbs) directed against the O-chain of the lipopolysaccharide (LPS) of Brucella sp. allowed the identification of peptidic mimotopes of some O-chain epitopes. Four mAbs were tested. The A76-12G12 mAb, which is specific for LPS of all strains of Brucella, either A- or M-dominant, did not yield any peptidic mimotope, despite a specific yield enrichment during the rounds of panning. The B66-4F9 mAb, that recognises an epitope common to both Brucella sp. and Yersinia enterocilitca O:9 strains, allowed the selection of only one phage clone that was shown to be an antigenic but not immunogenic mimotope. The B66-2C8 and A15-6B3 mAbs, respectively, specific for the LPS of A-dominant and M-dominant Brucella sp., yielded several sequences, which allowed the determination of consensus sequences. These consensus will be of high interest for the construction of second generation libraries. For the best binding peptides, competition with LPS for the binding to the mAb is detected, which suggests that the peptides bind to the paratope of the mAb. The phages selected from the libraries were used to immunise mice, and a weak antibody response directed against LPS has been observed for some peptides. These data suggest that a subset of the selected peptides are immunogenic mimotopes of the LPS epitopes.
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Affiliation(s)
- P Mertens
- Immunology and Microbiology laboratory, Research Unit in Molecular Biology (URBM), University of Namur (FUNDP), Belgium.
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82
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Cloeckaert A, Zygmunt MS, Guilloteau LA. Brucella abortus vaccine strain RB51 produces low levels of M-like O-antigen. Vaccine 2002; 20:1820-2. [PMID: 11906770 DOI: 10.1016/s0264-410x(02)00035-x] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
Brucella abortus RB51 is a rough (R) stable vaccine strain used in cattle and is believed to be devoid of O-side chain. We analyzed by use of a panel of monoclonal antibodies (MAbs) directed against seven previously defined O-polysaccharide (O-PS) epitopes the O-chain expression in strain RB51. Two MAbs specific for the C/Y (A=M) and C (M>A) epitopes showed low bindings in ELISA to strain RB51. O-chain expression was further confirmed by Western blot after SDS-PAGE of strain RB51. In particular, the MAb of C (M>A) specificity, showing preferential binding to M-dominant smooth (S) Brucella strains, revealed in strain RB51 a typical smooth-lipopolysaccharide (S-LPS) pattern which resembled that of M-dominant S-LPS. Thus, the results clearly show that strain RB51 produces low levels of M-like O-antigen.
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Affiliation(s)
- Axel Cloeckaert
- Laboratoire de Pathologie Infectieuse et Immunologie, Institut National de la Recherche Agronomique, 37380 Nouzilly, France.
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83
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Kariminia A, Kavoossy G, Khatami S, Zowghi E, Ardestani SK. Study of interleukin-10 and interleukin-12 productions in response to lipopolysaccharides extracted from two different Brucella strains. Comp Immunol Microbiol Infect Dis 2002; 25:85-93. [PMID: 11848132 DOI: 10.1016/s0147-9571(01)00029-7] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
The aim of the present study is to investigate the cytokines induction by smooth lipopolysaccharides (S-LPS) extracted from Brucella melitensis (Rev1 vaccine strain) and Brucella abortus (a field isolate). These lipopolysaccharides were used to induce inflammatory cytokines production in peripheral blood cell culture of healthy individuals. Secretion of IL-10 and IL-12 (p70) were measured by means of specific Elisa. In addition, intracellular expression of IL-12 was assessed in CD14+ cells by flow cytometry. It was shown that Brucella LPS is a potent inducer of IL-10. However interferon gamma (IFN-gamma) priming was able to significantly decrease the production of IL-10. Flow cytometry studies showed that LPS alone was not able to induce intracellular IL-12 expression in CD14+ cells. Nevertheless, IFN-gamma priming significantly increased the percentage of CD14+ IL-12+ cells. In conclusion, it was demonstrated that the Brucella LPS could be a potent inducer of IL-10 and induction of IL-12 production needs the most favorable conditions.
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84
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Köhler S, Ekaza E, Paquet JY, Walravens K, Teyssier J, Godfroid J, Liautard JP. Induction of dnaK through its native heat shock promoter is necessary for intramacrophagic replication of Brucella suis. Infect Immun 2002; 70:1631-4. [PMID: 11854256 PMCID: PMC127800 DOI: 10.1128/iai.70.3.1631-1634.2002] [Citation(s) in RCA: 29] [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
The heat shock protein DnaK is essential for intramacrophagic replication of Brucella suis. The replacement of the stress-inducible, native dnaK promoter of B. suis by the promoter of the constitutively expressed bla gene resulted in temperature-independent synthesis of DnaK. In contrast to a dnaK null mutant, this strain grew at 37 degrees C, with a thermal cutoff at 39 degrees C. However, the constitutive dnaK mutant, which showed high sensitivity to H(2)O(2)-mediated stress, failed to multiply in murine macrophage-like cells and was rapidly eliminated in a mouse model of infection, adding strong arguments to our hypothesis that stress-mediated and heat shock promoter-dependent induction of dnaK is a crucial event in the intracellular replication of B. suis.
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Affiliation(s)
- Stephan Köhler
- Institut National de la Santé et de la Recherche Médicale U-431, Université Montpellier II, F-34095 Montpellier, France.
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85
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Halling SM, Zuerner RL. Evidence for lateral transfer to Brucellae: characterization of a locus with a Tn-like element (Tn2020). BIOCHIMICA ET BIOPHYSICA ACTA 2002; 1574:109-16. [PMID: 11955619 DOI: 10.1016/s0167-4781(01)00352-9] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
A genomic locus was discovered within Brucella abortus that contains a novel transposon-like element designated Tn2020. Tn2020 is bounded by a copy of an insertion sequence designated IS2020 and a truncated imperfect copy of IS2020 (tIS2020A). The truncated copy is immediately adjacent to a second copy of IS2020. These data are consistent with the locus having evolved by a complex rearrangement following the transposition of a second copy of Tn2020. Analysis of the organization, orientation, and open reading frames (ORFs) of IS2020 places it within the IS6 family. Four ORFs from Tn2020 were translated in vitro producing a potential transposase with an apparent molecular mass of 27.5 kDa, and three polypeptides with apparent molecular masses of 71 kDa, 22 kDa, and 14 kDa. The central region of Tn2020 encodes the 71 kDa and 14 kDa proteins, while the 22 kDa protein is likely an internal translation initiation product of the IS2020 transposase. The 71 kDa protein shares sequence similarity with several bacterial transcriptional regulatory proteins and may form a helix-turn-helix structure capable of binding DNA. No homologous protein sequences to the 14 kDa peptide were detected in available databases. The 27.5 kDa transposase and its 22 kDa internal translation product shared significant similarity to several transposases from diverse bacterial hosts. Immediately 5' of Tn2020 are genes encoding ribosomal proteins RplU and RpmA. This region also contains a 90 bp sequence that shares significant homology to a repetitive element with inverted repeats from the Sinorhizobium genome. Downstream from Tn2020 is an ORF encoding a protein having significant similarity to a hypothetical protein from Caulobacter. The locus is lower in G+C content from that of the genome. These data suggest that lateral transfer of genetic material has occurred.
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Affiliation(s)
- Shirley M Halling
- Bacterial Diseases of Livestock Unit, National Animal Disease Center, Agricultural Research Service, United States Department of Agriculture, P.O. Box 70, Ames, IA 50010, USA.
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86
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Albermann C, Piepersberg W. Expression and identification of the RfbE protein from Vibrio cholerae O1 and its use for the enzymatic synthesis of GDP-D-perosamine. Glycobiology 2001; 11:655-61. [PMID: 11479276 DOI: 10.1093/glycob/11.8.655] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
The 4-amino-6-deoxy-monosaccharide D-perosamine is an important element in the glycosylation of interesting cell products, such as antibiotics and lipopolysaccharides (LPS) of Gram-positive and Gram-negative bacteria. The biosynthetic pathway of the precursor molecule, GDP-D-perosamine, in Vibrio cholerae O1 starts with an isomerisation of fructose-6-phosphate catalyzed by the bifunctional enzyme phosphomannose isomerase-guanosine diphosphomannose pyrophosphorylase (RfbA; E.C. 2.7.7.22) creating the intermediate mannose-6-phosphate, which is subsequently converted by the phosphomanno-mutase (RfbB; E.C. 5.4.2.8) and further by RfbA to GDP-D-mannose, to GDP-4 keto-6-deoxymannose by a 4,6-dehydratase (RfbD; E.C. 4.2.1.47) and finally to GDP-D-perosamine by an aminotransferase (RfbE; E.C. not yet classified). We cloned the rfbD and the rfbE genes of V. cholerae O1 in Escherichia coli expression vectors. Both biosynthetic enzymes were overproduced in E. coli BL21 (DE3) and their activities were analyzed. The enzymatic conversion from GDP-D-mannose to GDP-D-perosamine was optimized and the final product, GDP-D-perosamine, was purified and identified by nuclear magnetic resonance, mass spectrometry, and chromatography. The catalytically active form of the GDP-4-keto-6-deoxy-D-mannose-4-aminotransferase seems to be a tetramer of 170 kDa. The His-tag RfbE fusion protein has a Km of 0.06 mM and a Vmax value of 38 nkat/mg protein for the substrate GDP-4-keto-6-deoxy-D-mannose. The Km and Vmax values for the cosubstrate L-glutamate were 0.1 mM and 42 nkat/mg protein, respectively. The intention of this work is to establish a basis for both the in vitro production of GDP-D-perosamine and for an in vivo perosaminylation system in a suitable bacterial host, preferably E. coli.
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Affiliation(s)
- C Albermann
- Chemische Mikrobiologie, Bergische Universität GH Wuppertal, Gauss-Str. 20, D-42097, Germany
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87
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Fernandez-Prada CM, Nikolich M, Vemulapalli R, Sriranganathan N, Boyle SM, Schurig GG, Hadfield TL, Hoover DL. Deletion of wboA enhances activation of the lectin pathway of complement in Brucella abortus and Brucella melitensis. Infect Immun 2001; 69:4407-16. [PMID: 11401980 PMCID: PMC98513 DOI: 10.1128/iai.69.7.4407-4416.2001] [Citation(s) in RCA: 41] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Brucella spp. are gram-negative intracellular pathogens that survive and multiply within phagocytic cells of their hosts. Smooth organisms present O polysaccharides (OPS) on their surface. These OPS help the bacteria avoid the bactericidal action of serum. The wboA gene, coding for the enzyme glycosyltransferase, is essential for the synthesis of O chain in Brucella. In this study, the sensitivity to serum of smooth, virulent Brucella melitensis 16M and B. abortus 2308, rough wboA mutants VTRM1, RA1, and WRR51 derived from these two Brucella species, and the B. abortus vaccine strain RB51 was assayed using normal nonimmune human serum (NHS). The deposition of complement components and mannose-binding lectin (MBL) on the bacterial surface was detected by flow cytometry. Rough B. abortus mutants were more sensitive to the bactericidal action of NHS than were rough B. melitensis mutants. Complement components were deposited on smooth strains at a slower rate compared to rough strains. Deposition of iC3b and C5b-9 and bacterial killing occurred when bacteria were treated with C1q-depleted, but not with C2-depleted serum or NHS in the presence of Mg-EGTA. These results indicate that (i) OPS-deficient strains derived from B. melitensis 16M are more resistant to the bactericidal action of NHS than OPS-deficient strains derived from B. abortus 2308, (ii) both the classical and the MBL-mediated pathways are involved in complement deposition and complement-mediated killing of Brucella, and (iii) the alternative pathway is not activated by smooth or rough brucellae.
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Affiliation(s)
- C M Fernandez-Prada
- Department of Bacterial Diseases, Walter Reed Army Institute of Research, Washington, DC, 20307, USA.
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88
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Suzuki N, Nakano Y, Yoshida Y, Nakao H, Yamashita Y, Koga T. Genetic analysis of the gene cluster for the synthesis of serotype a-specific polysaccharide antigen in Aactinobacillus actinomycetemcomitans. BIOCHIMICA ET BIOPHYSICA ACTA 2000; 1517:135-8. [PMID: 11118626 DOI: 10.1016/s0167-4781(00)00229-3] [Citation(s) in RCA: 22] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The serotype a-specific polysaccharide antigen (SPA) of Actinobacillus actinomycetemcomitans consists of 6-deoxy-D-talose. A gene cluster associated with the biosynthesis of SPA was cloned and sequenced from the chromosomal DNA of A. actinomycetemcomitans SUNYaB 75 (serotype a). This cluster consisted of 14 open reading frames. Insertional inactivation of eight genes in this cluster resulted in loss of the ability of A. actinomycetemcomitans SUNYaB 75 cells to produce the polysaccharide. A protein database search revealed that the 11 sequential genes containing these eight genes were not found in SPA-associated gene clusters of the other serotypes of A. actinomycetemcomitans. These results suggest that the gene cluster is unique to serotype a and is essential to the synthesis of the SPA.
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Affiliation(s)
- N Suzuki
- Department of Preventive Dentistry, Kyushu University Faculty of Dental Science, Fukuoka 812-8582, Japan
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89
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Lestrate P, Delrue RM, Danese I, Didembourg C, Taminiau B, Mertens P, De Bolle X, Tibor A, Tang CM, Letesson JJ. Identification and characterization of in vivo attenuated mutants of Brucella melitensis. Mol Microbiol 2000; 38:543-51. [PMID: 11069678 DOI: 10.1046/j.1365-2958.2000.02150.x] [Citation(s) in RCA: 121] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Abstract
Brucella melitensis 16M is a Gram-negative alpha2-proteobacterium responsible for abortion in goats and for Malta fever in humans. This facultative intracellular pathogen invades into and survives within both professional and non-professional phagocytes. Signature-tagged mutagenesis (STM) was used to identify genes required for the in vivo pathogenesis of Brucella. A library of transposon mutants was screened in a murine infection model. Out of 672 mutants screened, 20 were not recovered after a 5 day passage in BALB/c mice. The attenuation of 18 mutants was confirmed using an in vivo competition assay against the wild-type strain. The 18 mutants were characterized further for their ability to replicate in murine macrophages and in HeLa cells. The sequences disrupted by the transposon in the mutants have homology to genes coding for proteins of different functional classes: transport, amino acid and DNA metabolism, transcriptional regulation, peptidoglycan synthesis, a chaperone-like protein and proteins of unknown function. The mutants selected in this study provide new insights into the molecular basis of Brucella virulence.
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Affiliation(s)
- P Lestrate
- Unité de Recherche en Biologie Moléculaire (URBM), Laboratoire d'Immunologie et de Microbiologie, University of Namur, rue de Bruxelles 61, 5000 Namur, Belgium.
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90
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Godfroid F, Cloeckaert A, Taminiau B, Danese I, Tibor A, de Bolle X, Mertens P, Letesson JJ. Genetic organisation of the lipopolysaccharide O-antigen biosynthesis region of brucella melitensis 16M (wbk). Res Microbiol 2000; 151:655-68. [PMID: 11081580 DOI: 10.1016/s0923-2508(00)90130-x] [Citation(s) in RCA: 73] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Brucella spp. are Gram-negative, facultative intracellular bacteria that cause a zoonotic world-wide disease. As in other Gram-negative bacteria, its S-LPS (smooth lipopolysaccharide) is a major determinant of virulence. The Brucella melitensis 16M LPS O-antigen is a homopolymer of 4-formamido-4,6, dideoxymannose. In this study, the previously cloned 14-kb wbk gene cluster was sequenced, and seven open reading frames (ORFs) as well as four insertion sequences were identified. Six of the seven ORFs are homologous to LPS biosynthesis genes from other organisms. The gmd, per and wbkC gene products are predicted to be involved in 4-formamido-4,6,dideoxymannose synthesis. By deletion experiments, we demonstrated that the putative formyltransferase WbkC is absolutely required for the O-side-chain production. The wbkA gene product is similar to several mannosyltransferases and is probably involved in the polymerisation of the B. melitensis O-side-chain. We also identified two genes (wzm and wzt) encoding proteins with high similarity to several two-component ABC (ATP-binding cassette) transporters. Their implication in O-antigen translocation across the inner membrane was confirmed by gene replacement. Finally, no function has been assigned to the wbkB gene either by homology search or functionally, because deletion of wbkB did not interfere with the O-antigen structure. The seven ORFs have a low G + C content, indicating that they might have been acquired by lateral transfer from a progenitor with more A + T rich DNA.
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Affiliation(s)
- F Godfroid
- Unité de recherche en biologie moléculaire (URBM), Laboratoire d'immunologie et de microbiologie, Facultés universitaires Notre Dame de la Paix, Belgium
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91
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Ugalde JE, Czibener C, Feldman MF, Ugalde RA. Identification and characterization of the Brucella abortus phosphoglucomutase gene: role of lipopolysaccharide in virulence and intracellular multiplication. Infect Immun 2000; 68:5716-23. [PMID: 10992476 PMCID: PMC101528 DOI: 10.1128/iai.68.10.5716-5723.2000] [Citation(s) in RCA: 91] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2000] [Accepted: 07/04/2000] [Indexed: 11/20/2022] Open
Abstract
Smooth lipopolysaccharide (LPS) of Brucella abortus has been reported to be an important virulence factor, although its precise role in pathogenesis is not yet clear. While the protective properties of LPS against complement are well accepted, there is still some controversy about the capacity of rough mutants to replicate intracellularly. The B. abortus phosphoglucomutase gene (pgm) was cloned, sequenced, and disrupted. The gene has a high index of identity to Agrobacterium tumefaciens pgm but is not part of the glycogen operon. A B. abortus null mutant lacks LPS O antigen but has an LPS core with an electrophoretic profile undistinguishable from that of the wild-type core, suggesting that glucose, galactose, or a derivative of these sugars may be part of the linkage between the core and the O antigen. This mutant is unable to survive in mice but replicates in HeLa cells, indicating that the complete LPS is not essential either for invasion or for intracellular multiplication. This behavior suggests that the LPS may play a role in extracellular survival in the animal, probably protecting the cell against complement-mediated lysis, but is not involved in intracellular survival.
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Affiliation(s)
- J E Ugalde
- Instituto de Investigaciones Biotecnológicas-Instituto Tecnológico de Chascomús, Universidad Nacional de General San Martín, Buenos Aires, Argentina
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92
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Ekaza E, Guilloteau L, Teyssier J, Liautard JP, Köhler S. Functional analysis of the ClpATPase ClpA of Brucella suis, and persistence of a knockout mutant in BALB/c mice. MICROBIOLOGY (READING, ENGLAND) 2000; 146 ( Pt 7):1605-1616. [PMID: 10878125 DOI: 10.1099/00221287-146-7-1605] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
The protein ClpA belongs to a diverse group of polypeptides named ClpATPases, which are highly conserved, and which include several molecular chaperones. In this study the gene encoding the 91 kDa protein b-ClpA of the facultative intracellular pathogen Brucella suis, which showed 70% identity to ClpA of Rhodobacter blasticus, was identified and sequenced. Following heterologous expression in Escherichia coli strains SG1126 (DeltaclpA) and SG1127 (Deltalon DeltaclpA), b-ClpA replaced the function of E. coli ClpA, participating in the degradation of abnormal proteins. A b-clpA null mutant of B. suis was constructed, and growth experiments at 37 and 42 degrees C showed reduced growth rates for the null mutant, especially at the elevated temperature. The mutant complemented by b-clpA and overexpressing the gene was even more impaired at 37 and 42 degrees C. In intracellular infection of human THP-1 or murine J774 macrophage-like cells, the clpA null mutant and, to a lesser extent, the strain of B. suis overexpressing b-clpA behaved similarly to the wild-type strain. In a murine model of infection, however, the absence of ClpA significantly increased persistence of B. suis. These results showed that in B. suis the highly conserved protein ClpA by itself was dispensable for intramacrophagic growth, but was involved in temperature-dependent growth regulation, and in bacterial clearance from infected BALB/c mice.
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Affiliation(s)
- Euloge Ekaza
- Institut National de la Santé et de la Recherche Médicale U-431, Université Montpellier II, CC 100, Pl. E. Bataillon, 34095 Montpellier, France1
| | - Laurence Guilloteau
- Laboratoire de Pathologie Infectieuse et d'Immunologie, Institut National de la Recherche Agronomique, 37380 Nouzilly, France2
| | - Jacques Teyssier
- Institut National de la Santé et de la Recherche Médicale U-431, Université Montpellier II, CC 100, Pl. E. Bataillon, 34095 Montpellier, France1
| | - Jean-Pierre Liautard
- Institut National de la Santé et de la Recherche Médicale U-431, Université Montpellier II, CC 100, Pl. E. Bataillon, 34095 Montpellier, France1
| | - Stephan Köhler
- Institut National de la Santé et de la Recherche Médicale U-431, Université Montpellier II, CC 100, Pl. E. Bataillon, 34095 Montpellier, France1
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93
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Vemulapalli R, He Y, Buccolo LS, Boyle SM, Sriranganathan N, Schurig GG. Complementation of Brucella abortus RB51 with a functional wboA gene results in O-antigen synthesis and enhanced vaccine efficacy but no change in rough phenotype and attenuation. Infect Immun 2000; 68:3927-32. [PMID: 10858205 PMCID: PMC101669 DOI: 10.1128/iai.68.7.3927-3932.2000] [Citation(s) in RCA: 58] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Brucella abortus RB51 is a stable rough, attenuated mutant vaccine strain derived from the virulent strain 2308. Recently, we demonstrated that the wboA gene in RB51 is disrupted by an IS711 element (R. Vemulapalli, J. R. McQuiston, G. G. Schurig, N. Srirauganathan, S. M. Halling, and S. M. Boyle, Clin. Diagn. Lab. Immunol. 6:760-764, 1999). Disruption of the wboA gene in smooth, virulent B. abortus, Brucella melitensis, and Brucella suis results in rough, attenuated mutants which fail to produce the O polysaccharide (O antigen). In this study, we explored whether the wboA gene disruption is responsible for the rough phenotype of RB51. We complemented RB51 with a functional wboA gene, and the resulting strain was designated RB51WboA. Colony and Western blot analyses indicated that RB51WboA expressed the O antigen; immunoelectron microscopy revealed that the O antigen was present in the cytoplasm. Crystal violet staining, acryflavin agglutination, and polymyxin B sensitivity studies indicated that RB51WboA had rough phenotypic characteristics similar to those of RB51. Bacterial clearance studies of BALB/c mice indicated no increase in the survival ability of RB51WboA in vivo compared to that of RB51. Vaccination of mice with live RB51WboA induced antibodies to the O antigen which were predominantly of the immunoglobulin G2a (IgG2a) and IgG3 isotypes. After in vitro stimulation of splenocytes with killed bacterial cells, quantitation of gamma interferon in the culture supernatants indicated that RB51WboA immunization induced higher levels of gamma interferon than immunization with RB51. Mice vaccinated with RB51WboA were better protected against a challenge infection with the virulent strain 2308 than those vaccinated with RB51. These studies indicate that in addition to the disruption of the wboA gene there is at least one other mutation in RB51 responsible for its rough phenotype. These studies also suggest that the expressed O antigen in RB51WboA is responsible either directly or indirectly for the observed enhancement in the T-cell response.
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Affiliation(s)
- R Vemulapalli
- Department of Biomedical Sciences and Pathobiology, Virginia-Maryland Regional College of Veterinary Medicine, Virginia Polytechnic Institute and State University, Blacksburg, Virginia 24061-0342, USA.
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94
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Hong PC, Tsolis RM, Ficht TA. Identification of genes required for chronic persistence of Brucella abortus in mice. Infect Immun 2000; 68:4102-7. [PMID: 10858227 PMCID: PMC101704 DOI: 10.1128/iai.68.7.4102-4107.2000] [Citation(s) in RCA: 196] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/1999] [Accepted: 04/19/2000] [Indexed: 11/20/2022] Open
Abstract
The genetic basis for chronic persistence of Brucella abortus in lymphoid organs of mice, cows, and humans is currently unknown. We identified B. abortus genes involved in chronic infection, by assessing the ability of 178 signature-tagged mutants to establish and maintain persistent infection in mice. Each mutant was screened for its ability to colonize the spleens of mice at 2 and 8 weeks after inoculation. Comparison of the results from both time points identified two groups of mutants attenuated for chronic infection in mice. The first group was not recovered at either 2 or 8 weeks postinfection and was therefore defective in establishing infection. Mutants in this group carried transposon insertions in genes involved in lipopolysaccharide biosynthesis (wbkA), in aromatic amino acid biosynthesis, and in type IV secretion (virB1 and virB10). The second group, which was recovered at wild-type levels 2 weeks postinfection but not 8 weeks postinfection was able to establish infection but was unable to maintain chronic infection. One mutant in this group carried a transposon insertion in a gene with homology to gcvB of Mycobacterium tuberculosis, encoding glycine dehydrogenase, an enzyme whose activity is increased during the state of nonreplicating persistence. These results suggest that some mechanisms for long-term persistence may be shared among chronic intracellular pathogens. Furthermore, identification of two groups of genes, those required for initiating infection and those required only for long-term persistence, suggests that B. abortus uses distinct sets of virulence determinants to establish and maintain chronic infection in mice.
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Affiliation(s)
- P C Hong
- Department of Veterinary Pathobiology, College of Veterinary Medicine, Texas A&M University, College Station, Texas 77843-4467, USA
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95
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Cloeckaert A, Grayon M, Verger JM, Letesson JJ, Godfroid F. Conservation of seven genes involved in the biosynthesis of the lipopolysaccharide O-side chain in Brucella spp. Res Microbiol 2000; 151:209-16. [PMID: 10865948 DOI: 10.1016/s0923-2508(00)00141-8] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
Seven genes of the wb locus of Brucella melitensis 16M involved in the biosynthesis of the lipopolysaccharide O-side chain have been recently identified, i.e. wbkA, gmd, per, wzm, wzt, wbkB, and wbkC, coding, respectively, for proteins homologous to mannosyltransferase, GDP-mannose 4,6 dehydratase, perosamine synthetase, ABC-type transporter (integral membrane protein), ABC-type transporter (ATPase domain), a hypothetical protein of unknown function, and a putative formyl transferase. The seven genes have a G + C content lower (around 48%) than that typical of Brucella spp. (58%) and thus may have been acquired from a species other than Brucella. In the present study, we analyzed by polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) the seven O-chain biosynthetic genes for polymorphism among Brucella spp. PCR-RFLP showed that the seven genes are highly conserved and occur even in the naturally rough species B. ovis and B. canis and also in rough strains of B. abortus and B. melitensis. Nevertheless, the few polymorphisms that were observed consisted of absence of additional restriction sites sometimes allowing differentiation at the species level (e.g. B. ovis) or at the biovar or strain level. There were no apparent deletions or insertions in the PCR-amplified genes in any of the Brucella strains studied. In conclusion, the seven O-chain biosynthetic genes studied appear to be highly conserved among Brucella spp. and thus may have been acquired before species differentiation. Some of the species- or biovar-specific markers detected could be used for molecular typing of brucellae in addition to those previously described.
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Affiliation(s)
- A Cloeckaert
- Laboratoire de pathologie infectieuse et immunologie, Institut national de la recherche agronomique, Nouzilly, France.
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Foulongne V, Bourg G, Cazevieille C, Michaux-Charachon S, O'Callaghan D. Identification of Brucella suis genes affecting intracellular survival in an in vitro human macrophage infection model by signature-tagged transposon mutagenesis. Infect Immun 2000; 68:1297-303. [PMID: 10678941 PMCID: PMC97282 DOI: 10.1128/iai.68.3.1297-1303.2000] [Citation(s) in RCA: 149] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/1999] [Accepted: 12/06/1999] [Indexed: 11/20/2022] Open
Abstract
Bacteria of the genus Brucella are facultative intracellular pathogens which have developed the capacity to survive and multiply in professional and nonprofessional phagocytes. The genetic basis of this aspect of Brucella virulence is still poorly understood. To identify new virulence factors, we have adapted signature-tagged transposon mutagenesis, which has been used essentially in animal models, to an in vitro human macrophage infection model. A library of 1,152 Brucella suis 1330 tagged mini-Tn5 Km2 mutants, in 12 pools, was screened for intracellular survival and multiplication in vitamin D(3)-differentiated THP1 cells. Eighteen mutants were identified, and their attenuation was confirmed in THP1 macrophages and HeLa cells. For each avirulent mutant, a genomic fragment containing the transposon was cloned. The genomic DNA sequence flanking the transposon allowed us to assign functions to all of the inactivated genes. Transposon integration had occurred in 14 different genes, some of which were known virulence genes involved in intracellular survival or biosynthesis of smooth lipopolysaccharide (the virB operon and manB), thus validating the model. Other genes identified encoded factors involved in the regulation of gene expression and enzymes involved in biosynthetic or metabolic pathways. Possible roles in the virulence of Brucella for the different factors identified are discussed.
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Affiliation(s)
- V Foulongne
- INSERM U431, Faculté de Médecine, 30900 Nîmes, France
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97
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De Bolle X, Laurent T, Tibor A, Godfroid F, Weynants V, Letesson JJ, Mertens P. Antigenic properties of peptidic mimics for epitopes of the lipopolysaccharide from Brucella. J Mol Biol 1999; 294:181-91. [PMID: 10556037 DOI: 10.1006/jmbi.1999.3248] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The lipopolysaccharide (LPS) is up to now the only identified major virulence determinant of Brucella. This bacterium is responsible for brucellosis in animals and for Malta fever in humans. Several monoclonal antibodies (mAbs) directed against various LPS epitopes have been characterized. Two mAbs, named A15-6B3 and B66-2C8, directed against distinct LPS epitopes have been used to select peptides from 11 phage display libraries. The sequences of the selected peptides contain an overrepresentation of either proline or tryptophan residues when selected with either A15-6B3 or B66-2C8 mAbs, respectively. For the best binding peptides, competition with LPS for the binding to the mAb is detected, which suggests that the peptides bind to the paratope of the mAb. The phages selected from the libraries were used to immunise mice, and a weak antibody response directed against LPS has been observed. These data suggest that a subset of the selected peptides are mimotopes of the LPS epitopes.
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Affiliation(s)
- X De Bolle
- Immunology and Microbiology Laboratory, Research Unit in Molecular Biology (URBM), University of Namur (FUNDP), 61 rue de Bruxelles, Namur, B5000, Belgium.
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98
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O'Callaghan D, Cazevieille C, Allardet-Servent A, Boschiroli ML, Bourg G, Foulongne V, Frutos P, Kulakov Y, Ramuz M. A homologue of the Agrobacterium tumefaciens VirB and Bordetella pertussis Ptl type IV secretion systems is essential for intracellular survival of Brucella suis. Mol Microbiol 1999; 33:1210-20. [PMID: 10510235 DOI: 10.1046/j.1365-2958.1999.01569.x] [Citation(s) in RCA: 336] [Impact Index Per Article: 13.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Analysis of a TnblaM mutant of Brucella suis 1330, identified as being unable to multiply in Hela cells, allowed us to identify a 11 860 bp region of the B. suis genome encoding a type IV secretion system, homologous to the VirB system of Agrobacterium tumefaciens and the Ptl system of Bordetella pertussis. DNA sequence revealed 12 open reading frames (ORFs) encoding homologues of the 11 VirB proteins present in the pTi plasmid of Agrobacterium with a similar genetic organization, and a twelfth ORF encoding a putative lipoprotein, homologous to a protein involved in mating pair formation during bacterial conjugation and to adhesins used by Pseudomonas species to bind to plant roots. Phylogenetic trees based on the sequences of VirB4 and VirB9 protein homologues suggest that evolution of the systems from DNA transfer towards protein secretion did not stem from a single event but that the protein secretion systems have evolved independently. Four independent mutants in virB5, virB9 or virB10 were highly attenuated in an in vitro infection model with human macrophages. The virulence was restored by complementation with a plasmid containing the full virB region. The virB region appears to be essential for the intracellular survival and multiplication of B. suis.
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Affiliation(s)
- D O'Callaghan
- INSERM U431, Faculté de Médecine, Avenue Kennedy, 30900 Nîmes, France.
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99
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McQuiston JR, Vemulapalli R, Inzana TJ, Schurig GG, Sriranganathan N, Fritzinger D, Hadfield TL, Warren RA, Lindler LE, Snellings N, Hoover D, Halling SM, Boyle SM. Genetic characterization of a Tn5-disrupted glycosyltransferase gene homolog in Brucella abortus and its effect on lipopolysaccharide composition and virulence. Infect Immun 1999; 67:3830-5. [PMID: 10417145 PMCID: PMC96661 DOI: 10.1128/iai.67.8.3830-3835.1999] [Citation(s) in RCA: 63] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/1998] [Accepted: 05/04/1999] [Indexed: 11/20/2022] Open
Abstract
We constructed a rough mutant of Brucella abortus 2308 by transposon (Tn5) mutagenesis. Neither whole cells nor extracted lipopolysaccharide (LPS) from this mutant, designated RA1, reacted with a Brucella O-side-chain-specific monoclonal antibody (MAb), Bru-38, indicating the absence of O-side-chain synthesis. Compositional analyses of LPS from strain RA1 showed reduced levels of quinovosamine and mannose relative to the levels in the parental, wild-type strain, 2308. We isolated DNA flanking the Tn5 insertion in strain RA1 by cloning a 25-kb XbaI genomic fragment into pGEM-3Z to create plasmid pJM6. Allelic exchange of genomic DNA in B. abortus 2308 mediated by electroporation of pJM6 produced kanamycin-resistant clones that were not reactive with MAb Bru-38. Southern blot analysis of genomic DNA from these rough clones revealed Tn5 in a 25-kb XbaI genomic fragment. A homology search with the deduced amino acid sequence of the open reading frame disrupted by Tn5 revealed limited homology with various glycosyltransferases. This B. abortus gene has been named wboA. Transformation of strain RA1 with a broad-host-range plasmid bearing the wild-type B. abortus wboA gene resulted in the restoration of O-side-chain synthesis and the smooth phenotype. B. abortus RA1 was attenuated for survival in mice. However, strain RA1 persisted in mice spleens for a longer time than the B. abortus vaccine strain RB51, but as expected, neither strain induced antibodies specific for the O side chain.
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Affiliation(s)
- J R McQuiston
- Department of Biomedical Sciences and Pathobiology, Center for Molecular Medicine and Infectious Diseases, Virginia-Maryland Regional College of Veterinary Medicine, Virginia Polytechnic Institute and State University, Blacksburg, VA, USA
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