Survival Tests for Leptospira spp.

Mouville, Clémence; Benaroudj, Nadia

doi:10.1007/978-1-0716-0459-5_20

Cited by 9 publications

(7 citation statements)

References 21 publications

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“…Survival of leptospires upon treatments with antimicrobial peptides was assessed by Alamar Blue viability assay ( 28 ). After 2 h incubation with LL-37 or Bmap28 in PBS, 2.5 × 10 6 leptospires in 100 μL in 96-well plates were mixed with 80 μL of EMJH and 20 μL of 10× Alamar Blue dye.…”

Section: Methodsmentioning

confidence: 99%

Escape of TLR5 Recognition by Leptospira spp.: A Rationale for Atypical Endoflagella

et al. 2020

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Holzapfel et al. TLR5 Evasion by Leptospires the FlaB, but not the FlaA subunits. Altogether, in contrast to different bacteria that modify their flagellin sequences to escape TLR5 recognition, our study suggests that the peculiar central localization and stability of the FlaB monomers in the periplasmic endoflagellae, associated with the downregulation of FlaB subunits in hosts, constitute an efficient strategy of leptospires to escape the TLR5 recognition and the induced immune response.

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Section: Methodsmentioning

confidence: 99%

Escape of TLR5 Recognition by Leptospira spp.: A Rationale for Atypical Endoflagella

et al. 2020

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“…Rezasurin (Alamar Blue Assay, ThermoFisher Scientific) was added and cells were further incubated for 24h. Viability is assessed by the reduction of blue resazurin into pink resorufin [ 55 ]. Plating experiments were performed by diluting treated and non-treated cells in EMJH in the absence of H 2 O 2 and plating the samples on EMJH agar medium [ 55 ].…”

Section: Methodsmentioning

confidence: 99%

The transcriptional response of pathogenic Leptospira to peroxide reveals new defenses against infection-related oxidative stress

et al. 2020

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Pathogenic Leptospira spp. are the causative agents of the waterborne zoonotic disease leptospirosis. Leptospira are challenged by numerous adverse conditions, including deadly reactive oxygen species (ROS), when infecting their hosts. Withstanding ROS produced by the host innate immunity is an important strategy evolved by pathogenic Leptospira for persisting in and colonizing hosts. In L. interrogans, genes encoding defenses against ROS are repressed by the peroxide stress regulator, PerR. In this study, RNA sequencing was performed to characterize both the L. interrogans response to low and high concentrations of hydrogen peroxide and the PerR regulon. We showed that Leptospira solicit three main peroxidase machineries (catalase, cytochrome C peroxidase and peroxiredoxin) and heme to detoxify oxidants produced during peroxide stress. In addition, canonical molecular chaperones of the heat shock response and DNA repair proteins from the SOS response were required for Leptospira recovering from oxidative damage. Identification of the PerR regulon upon exposure to H 2 O 2 allowed to define the contribution of this regulator in the oxidative stress response. This study has revealed a PerR-independent regulatory network involving other transcriptional regulators, two-component systems and sigma factors as well as noncoding RNAs that putatively orchestrate, in concert with PerR, the oxidative stress response. We have shown that PerR-regulated genes encoding a TonB-dependent transporter and a two-component system (VicKR) are involved in Leptospira tolerance to superoxide. This could represent the first defense mechanism against superoxide in L. interrogans, a bacterium lacking canonical superoxide dismutase. Our findings provide an insight into the mechanisms required by pathogenic Leptospira to overcome oxidative damage during infectionrelated conditions. This will participate in framing future hypothesis-driven studies to identify and decipher novel virulence mechanisms in this life-threatening pathogen.

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“…For the colorimetric assay, 100 µl of leptospires were incubated with resazurin (Alamar Blue reagent, ThermoScientific) for 48h. Leptospires viability was assessed by their capacity to reduce blue resazurin into pink resorufin as described previously [54].…”

Section: Determination Of Bacteria Viabilitymentioning

confidence: 99%

The oxidative stress response of pathogenic Leptospira is controlled by two peroxide stress regulators which putatively cooperate in controlling virulence

Zavala-Alvarado

Huete

Vincent³

et al. 2020

Preprint

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Pathogenic Leptospira are the causative agents of leptospirosis, the most widespread zoonotic infectious disease. Leptospirosis is a potentially severe and life-threatening emerging disease with highest burden in sub-tropical areas and impoverish populations. Mechanisms allowing pathogenic Leptospira to survive inside a host and induce acute leptospirosis are not fully understood. The ability to resist deadly oxidants produced by the host during infection is pivotal for Leptospira virulence. We have previously shown that genes encoding defenses against oxidants in L. interrogans are repressed by PerRA (encoded by LIMLP_10155), a peroxide stress regulator of the Fur family. In this study, we describe the identification and characterization of another putative PerR-like regulator (LIMLP_05620) in L. interrogans. Protein sequence and phylogenetic analyses indicated that LIMLP_05620 displayed all the canonical PerR amino acid residues and is restricted to pathogenic Leptospira clades. We therefore named this PerR-like regulator PerRB. In L. interrogans, the PerRB regulon is distinct from that of PerRA. While a perRA mutant had a greater tolerance to peroxide, inactivating perRB led to a higher tolerance to superoxide, suggesting that these two regulators have a distinct function in the adaptation of L. interrogans to oxidative stress. The concomitant inactivation of perRA and perRB resulted in a higher tolerance to both peroxide and superoxide and, unlike the single mutants, to the loss of Leptospira virulence. Interestingly, this correlated with major changes in gene and non-coding RNA expression, only observed in the double perRAperRB mutant. Notably, several virulence-associated genes (clpB, ligA/B, and lvrAB) were repressed. By obtaining the first double mutant in a pathogenic Leptospira strain, our study has uncovered for the first time the interplay of two PerRs, not only in the adaptation of Leptospira to oxidative stress, but also in their virulence and pathogenicity, most likely through the transcriptional control of a complex regulatory network.

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Survival Tests for Leptospira spp.

Cited by 9 publications

References 21 publications

Escape of TLR5 Recognition by Leptospira spp.: A Rationale for Atypical Endoflagella

Escape of TLR5 Recognition by Leptospira spp.: A Rationale for Atypical Endoflagella

The transcriptional response of pathogenic Leptospira to peroxide reveals new defenses against infection-related oxidative stress

The oxidative stress response of pathogenic Leptospira is controlled by two peroxide stress regulators which putatively cooperate in controlling virulence

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