VBNC Legionella pneumophila cells are still able to produce virulence proteins

Alleron, Laëtitia; Khemiri, Arbia; Koubar, Mohamad; Lacombe, Christian; Coquet, Laurent; Cosette, Pascal; Jouenne, Thierry; Frère, Jacques

doi:10.1016/j.watres.2013.08.032

Cited by 80 publications

(44 citation statements)

References 72 publications

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“…These results corroborate the work of Alleron et al (2013) who demonstrated an accumulation of some virulence proteins in VBNC forms after using monochloramine treatment. This suggests either a possible overexpression of the epitopes or slight conformational changes unmasking the epitopes targeted by the MAb following an exposure to heat treatment of L. pneumophila cells.…”

Section: Electrode Activity Testingsupporting

confidence: 92%

Characterisation of electrochemical immunosensor for detection of viable not-culturable forms of Legionellla pneumophila in water samples

et al. 2015

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Legionella pneumophila may cause a fatal pneumonia in humans known as Legionnaires' disease (LD). The strategies of L. pneumophila to adapt to and resist stressful environmental conditions include the ability to enter into a VBNC (viable but not culturable) state. The detection of L. pneumophila in environmental samples benefits from the use of standardised methods: for detection and enumeration following membrane filtration (AFNOR T90-431, ISO 11731) and detection and quantification by polymerase chain reaction PCR (AFNOR T90-471, ISO 12869). Culture is hampered by its inability to detect VBNC forms and PCR is unable to discriminate between live and dead bacteria. The present immunosensor was obtained by the immobilisation of a monoclonal anti-L. pneumophila antibody (MAb) on an indium-tin oxide (ITO) electrode by the self-assembled monolayers (SAMs) method using an aminosilane. The immunosensor was characterised by wettability (contact angle measurement), atomic force microscopy (AFM), confocal laser scanning microscopy (CLSM), and electrochemical impedance spectroscopy (EIS). A limit of detection of 10 bacteria per mL was observed on artificial samples.

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Section: Electrode Activity Testingsupporting

confidence: 92%

Characterisation of electrochemical immunosensor for detection of viable not-culturable forms of Legionellla pneumophila in water samples

et al. 2015

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“…However, those induced by monochloramine treatment could not be resuscitated using the same method (Alleron et al 2013). Since we were unable to resuscitate the VBNC cells in our samples and they remained non-infectious (data not shown), we consider the cells to be dying, indicating required for Lp to survive in water.…”

Section: Discussionmentioning

confidence: 99%

Role of the LuxR family transcriptional regulator Lpg2524 in the survival ofLegionella pneumophilain water

Faucher

2017

Can. J. Microbiol.

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The water-borne Gram-negative bacterium Legionella pneumophila (Lp) is the causative agent of Legionnaires’ disease. Lp is typically transmitted to humans from water systems, where it grows inside amoebae. Survival of Lp in water is central to its transmission to humans. A transcriptomic study previously identified many genes induced by Lp in water. One such gene, lpg2524, encodes a putative LuxR family transcriptional regulator. It was hypothesized that this gene could be involved in the survival of Lp in water. Deletion of lpg2524 does not affect the growth of Lp in rich medium, in the amoeba Acanthamoeba castellanii, or in human macrophage-like THP-1 cells, showing that Lpg2524 is not required for growth in vitro and in vivo. Nevertheless, deletion of lpg2524 results in a faster colony-forming unit (CFU) reduction in an artificial freshwater medium, Fraquil, indicating that Lpg2524 is important for Lp to survive in water. Overexpression of Lpg2524 also results in a survival defect, suggesting that a precise level of this transcriptional regulator is essential for its function. However, our result shows that Lpg2524 is dispensable for survival in water when Lp is at a high cell density (109 CFU/mL), suggesting that its regulon is regulated by another regulator activated at high cell density.

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“…Alleron et al showed by means of an 35 S-labeling approach coupled to subsequent 2D gel electrophoresis-based proteomics, that unculturable L. pneumophila obtained after disinfection with monochloramine actively synthetized proteins and they identified nine proteins which were accumulating in higher quantities in the unculturable bacteria compared with the culturable control (32). Three of those proteins, Mip, DsbA2/Com1, and L1/RplA were quantified in UNC of our study although we used long-term starvation in tap water for generation of UNC.…”

Section: Overview Of L Pneumophila E and Pe Soluble Whole Cellmentioning

confidence: 99%

“…It has been shown that unculturable L. pneumophila may resuscitate to a fully virulent form by passage through an amoebal host (30,33,34,36) and therefore provide a largely undetected source of infections. Unculturable Legionellae have been observed for example after prolonged incubation in laboratory tap water microcosms at different temperatures, including elevated temperature at 42°C (36), heat shock (50 -70°C) (37), following disinfection (31)(32)(33), and after treatment with heavy metals (38).…”

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confidence: 99%

Life Stage-specific Proteomes of Legionella pneumophila Reveal a Highly Differential Abundance of Virulence-associated Dot/Icm effectors

Auraß

Gerlach

Becher

et al. 2016

Molecular & Cellular Proteomics

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Major differences in the transcriptional program underlying the phenotypic switch between exponential and post-exponential growth of Legionella pneumophila were formerly described characterizing important alterations in infection capacity. Additionally, a third state is known where the bacteria transform in a viable but nonculturable state under stress, such as starvation. We here describe phase-related proteomic changes in exponential phase (E), postexponential phase (PE) bacteria, and unculturable microcosms (UNC) containing viable but nonculturable state cells, and identify phasespecific proteins. We present data on different bacterial subproteomes of E and PE, such as soluble whole cell proteins, outer membrane-associated proteins, and extracellular proteins. In total, 1368 different proteins were identified, 922 were quantified and 397 showed differential abundance in E/PE. The quantified subproteomes of soluble whole cell proteins, outer membrane-associated proteins, and extracellular proteins; 841, 55, and 77 proteins, respectively, were visualized in Voronoi treemaps. 95 proteins were quantified exclusively in E, such as cell division proteins MreC, FtsN, FtsA, and ZipA; 33 exclusively in PE, such as motility-related proteins of flagellum biogenesis FlgE, FlgK, and FliA; and 9 exclusively in unculturable microcosms soluble whole cell proteins, such as hypothetical, as well as transport/binding-, and metabolism-related proteins. A high frequency of differentially abundant or phase-exclusive proteins was observed among the 91 quantified effectors of the major virulence-associated protein secretion system Dot/Icm (> 60%). 24 were E-exclusive, such as LepA/B, YlfA, MavG, Lpg2271, and 13 were PE-exclusive, such as RalF, VipD, Lem10. The growth phase-related specific abundance of a subset of Dot/Icm virulence effectors was confirmed by means of Western blotting. We therefore conclude that many effectors are predominantly abundant at either E or PE which suggests their phase specific function. The distinct temporal or spatial presence of such proteins might have important implications for functional assignments in the future or for use as lifestage specific markers for pathogen analysis. Molecular

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VBNC Legionella pneumophila cells are still able to produce virulence proteins

Cited by 80 publications

References 72 publications

Characterisation of electrochemical immunosensor for detection of viable not-culturable forms of Legionellla pneumophila in water samples

Characterisation of electrochemical immunosensor for detection of viable not-culturable forms of Legionellla pneumophila in water samples

Role of the LuxR family transcriptional regulator Lpg2524 in the survival ofLegionella pneumophilain water

Life Stage-specific Proteomes of Legionella pneumophila Reveal a Highly Differential Abundance of Virulence-associated Dot/Icm effectors

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