In vitro identification of two adherence factors required for in vivo virulence of Pseudomonas fluorescens

Pimenta, Aparecida Linhares; Martino, Patrick Di; Bouder, Emmanuel Le; Hulen, Christian; Blight, Mark A.

doi:10.1016/j.micinf.2003.09.002

Cited by 39 publications

(36 citation statements)

References 65 publications

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“…S4 in the supplemental material at http://www.uni-wuerzburg.de/infektionsbiologie/imistart.htm and at http://www.pasteur.fr/recherche/unites/Ggb/supmat.html). In previous reports workers described LPS as a molecule that is important for adhesion of different pathogenic bacteria, such as Pseudomonas fluorescens, Serratia marcescens, and Klebsiella pneumoniae (23,45), to abiotic surfaces. The absence of biofilm formation by strain 536waaG is consistent with these reports and suggests that LPS, especially the LPS core, is critical for adhesion of E. coli strain 536 to abiotic surfaces (Fig.…”

Section: Discussionmentioning

confidence: 99%

The Transcriptional Antiterminator RfaH Represses Biofilm Formation inEscherichia coli

et al. 2006

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We investigated the influence of regulatory and pathogenicity island-associated factors (Hha, RpoS, LuxS, EvgA, RfaH, and tRNA 5 Leu ) on biofilm formation by uropathogenic Escherichia coli (UPEC) strain 536. Only inactivation of rfaH, which encodes a transcriptional antiterminator, resulted in increased initial adhesion and biofilm formation by E. coli 536. rfaH inactivation in nonpathogenic E. coli K-12 isolate MG1655 resulted in the same phenotype. Transcriptome analysis of wild-type strain 536 and an rfaH mutant of this strain revealed that deletion of rfaH correlated with increased expression of flu orthologs. flu encodes antigen 43 (Ag43), which mediates autoaggregation and biofilm formation. We confirmed that deletion of rfaH leads to increased levels of flu and flu-like transcripts in E. coli K-12 and UPEC. Supporting the hypothesis that RfaH represses biofilm formation through reduction of the Ag43 level, the increased-biofilm phenotype of E. coli MG1655rfaH was reversed upon inactivation of flu. Deletion of the two flu orthologs, however, did not modify the behavior of mutant 536rfaH. Our results demonstrate that the strong initial adhesion and biofilm formation capacities of strain MG1655rfaH are mediated by both increased steady-state production of Ag43 and likely increased Ag43 presentation due to null rfaH-dependent lipopolysaccharide depletion. Although the roles of rfaH in the biofilm phenotype are different in UPEC strain 536 and K-12 strain MG1655, this study shows that RfaH, in addition to affecting the expression of bacterial virulence factors, also negatively controls expression and surface presentation of Ag43 and possibly another Ag43-independent factor(s) that mediates cell-cell interactions and biofilm formation.

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Section: Discussionmentioning

confidence: 99%

The Transcriptional Antiterminator RfaH Represses Biofilm Formation inEscherichia coli

et al. 2006

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“…Accurate measurement of adhesion is therefore essential for monitoring the tendency of bacteria to attach to surfaces and to switch from a planktonic lifestyle to a biofilm lifestyle. Data accumulated in previous studies suggest that LPS is involved in bacterial cell adhesion to both abiotic (2,8,20,32,35,54,56) and biotic (17,38,49,56,57) surfaces. Moreover, environmental factors, such as growth temperature, pH, ionic strength, nutrient availability, and oxygen levels, may influence cell adhesion via modification of LPS expression and conformation (16,36,46,47,53).…”

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confidence: 99%

Differential Lipopolysaccharide Core Capping Leads to Quantitative and Correlated Modifications of Mechanical and Structural Properties in Pseudomonas aeruginosa Biofilms

Lau¹,

Lindhout²,

Beveridge³

et al. 2009

J Bacteriol

106

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Bacterial biofilms are responsible for the majority of all microbial infections and have profound impact on industrial and geochemical processes. While many studies documented phenotypic differentiation and gene regulation of biofilms, the importance of their structural and mechanical properties is poorly understood. Here we investigate how changes in lipopolysaccharide (LPS) core capping in Pseudomonas aeruginosa affect biofilm structure through modification of adhesive, cohesive, and viscoelastic properties at an early stage of biofilm development. Microbead force spectroscopy and atomic force microscopy were used to characterize P. aeruginosa biofilm interactions with either glass substrata or bacterial lawns. Using isogenic migA, wapR, and rmlC mutants with defined LPS characteristics, we observed significant changes in cell mechanical properties among these strains compared to wild-type strain PAO1. Specifically, truncation of core oligosaccharides enhanced both adhesive and cohesive forces by up to 10-fold, whereas changes in instantaneous elasticity were correlated with the presence of O antigen. Using confocal laser scanning microscopy to quantify biofilm structural changes with respect to differences in LPS core capping, we observed that textural parameters varied with adhesion or the inverse of cohesion, while areal and volumetric parameters were linked to adhesion, cohesion, or the balance between them. In conclusion, this report demonstrated for the first time that changes in LPS expression resulted in quantifiable cellular mechanical changes that were correlated with structural changes in bacterial biofilms. Thus, the interplay between architectural and functional properties may be an important contributor to bacterial community survival.Biofilms are sessile microbial communities growing on a surface or at an interface, often enmeshed in polymeric substances. Being the predominant mode of microbial growth in nature, bacterial biofilms are particularly problematic in the context of human health, accounting for up to 80% of all bacterial infections. In industrial processes, bacterial biofilms cause corrosion and biofouling, resulting in considerable loss of productivity. In the natural environment, biofilms play a role in modulating worldwide geochemical cycles. Given the impact of biofilms in these diverse areas, the need for developing effective strategies to control them is of paramount importance. Since bacterial cell surface structures are convenient targets for control agents, their roles in influencing biofilm function and architecture warrant in-depth investigations. To date, most studies of biofilms have focused on genetic regulation, phenotypic differentiation and their contribution to antibiotic resistance. In contrast, the mechanical and structural properties that link the genotypes to phenotypes of bacterial biofilms are not well understood and rarely studied in a quantitative and correlated manner.Pseudomonas aeruginosa is a gram-negative opportunistic pathogen implicated in serious infe...

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“…The Drosophila genome has been sequenced, which has facilitated the development of microarray, proteomic, and RNA interference (RNAi) technologies for genome-wide analysis of Drosophila processes (14,23,65,66). Additionally, the relative affordability, short generation time (10 to 14 days), and ease of use allow sample sizes that are large enough to permit statistical analysis of the data and make Drosophila an attractive complement to mammalian models.The Drosophila killing model has been successfully used to characterize host-microbe interactions of bacterial (9,13,15,17,22,52,55), fungal (1, 3), and parasitic (62) pathogens, and the results of these studies suggest that there is good correlation between pathogenesis in mammals and in nonmammalian animals such as Drosophila. In these studies the microbe of interest is either fed to Drosophila or introduced directly into the hemocoel (body cavity) through the thorax by using a needle, and the survival of the infected animals is monitored over time.…”

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confidence: 99%

Porphyromonas gingivalis Virulence in a Drosophila melanogaster Model

et al. 2011

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Porphyromonas gingivalis has been implicated in the etiology of adult periodontitis. In this study, we examined the viability of Drosophila melanogaster as a new model for examining P. gingivalis-host interactions. P. gingivalis (W83) infection of Drosophila resulted in a systemic infection that killed in a dose-dependent manner. Differences in the virulence of several clinically prevalent P. gingivalis strains were observed in the Drosophila killing model, and the results correlated well with studies in mammalian infection models and human epidemiologic studies. P. gingivalis pathobiology in Drosophila did not result from uncontrolled growth of the bacterium in the Drosophila hemolymph (blood) or overt damage to Drosophila tissues. P. gingivalis killing of Drosophila was multifactorial, involving several bacterial factors that are also involved in virulence in mammals. The results from this study suggest that many aspects of P. gingivalis pathogenesis in mammals are conserved in Drosophila, and thus the Drosophila killing model should be useful for characterizing P. gingivalis-host interactions and, potentially, polymicrobe-host interactions.Porphyromonas gingivalis is a Gram-negative, obligate anaerobe that has been strongly implicated in the etiology of adult (chronic) periodontitis (21, 29), a destructive disease that affects the gums and supporting structures of the teeth. P. gingivalis-host interactions have previously been studied using several animal models, the most common of which are murine models (5,7,18,20,28), including an abscess model (39), a subcutaneous chamber model (24), and a periodontal bone loss model (41). Studies performed using murine models have demonstrated that P. gingivalis strains vary in their ability to cause periodontal bone loss (20, 40) and soft tissue destruction and death (28,43,56) and that strain W83 is highly virulent relative to many other strains of P. gingivalis (28,43,56). Murine models have also been used to identify P. gingivalis components that are important for pathogenesis (25,43,51,59) and to characterize the host response to P. gingivalis infection (6,11,31,35).The fruit fly, Drosophila melanogaster, has been well established as a nonmammalian model for studying host-pathogen interactions (1,17,52,55,63). Drosophila relies solely on an innate immune response to combat invading microbes, and this immune response strongly parallels the mammalian innate immune response (47,48). Like the mammalian innate immune response, Drosophila uses pattern recognition receptors to detect conserved microbial motifs on invading microbes, and the flies activate an immune response that is specific for the type of invading microbe. The absence of an adaptive immune response makes Drosophila useful for studying the interactions between microbes and the host innate immune response, in isolation. Numerous tools exist for the genetic manipulation of Drosophila, and these have been used to generate thousands of transgenic and mutant lines, including lines useful for identifying host fac...

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In vitro identification of two adherence factors required for in vivo virulence of Pseudomonas fluorescens

Cited by 39 publications

References 65 publications

The Transcriptional Antiterminator RfaH Represses Biofilm Formation inEscherichia coli

The Transcriptional Antiterminator RfaH Represses Biofilm Formation inEscherichia coli

Differential Lipopolysaccharide Core Capping Leads to Quantitative and Correlated Modifications of Mechanical and Structural Properties in Pseudomonas aeruginosa Biofilms

Porphyromonas gingivalis Virulence in a Drosophila melanogaster Model

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