Project description:Pathogenic Leptospira spp. are the causative agents of the zoonotic disease leptospirosis. During infection, Leptospira are confronted with deadly reactive oxygen species (ROS). Withstanding ROS produced by the host innate immunity is an important strategy evolved by pathogenic Leptospira for persisting in and colonizing hosts. The peroxide stress regulator, PerR, represses genes involved in ROS defenses in L. interrogans. We have performed RNA sequencing in WT and perR mutant strains to characterize the L. interrogans adaptive response to hydrogen peroxide. We showed that Leptospira solicit three main peroxidase machineries (catalase, cytochrome C peroxidase and peroxiredoxin) and heme to adapt to peroxide stress as well as canonical chaperones of the heat shock response, and DNA repair. Determining the PerR regulon allowed to identify the PerR-dependent mechanisms of the peroxide adaptive response and has revealed a regulatory network involving other transcriptional regulators, two-component systems and sigma factors as well as non-coding RNAs that putatively orchestrate, in concert with PerR, this adaptive response. Our findings provide comprehensive insight into the mechanisms required by pathogenic Leptospira to overcome infection-related oxidants. This will participate in framing future hypothesis-driven studies to identify and decipher novel virulence mechanisms.
Project description:Pathogenic Leptospira spp. are the causative agents of the zoonotic disease leptospirosis. During infection, Leptospira are confronted with deadly reactive oxygen species (ROS). Withstanding ROS produced by the host innate immunity is an important strategy evolved by pathogenic Leptospira for persisting in and colonizing hosts. The peroxide stress regulator, PerRA, represses genes involved in ROS defenses in L. interrogans. We have identified an ORF encoding a putative second PerR in pathogenic Leptospira that we named PerRB. We have determined the transcriptomic profil of a single perRB and a double perRAperRB mutants. The concomitant inactivation of perRA and perRB has a pleiotropic effect on the transcriptomic profil of L. interrogans. The lack of both PerRA and PerRB regulators led to the differential expression of several virulence-associated genes and a loss of virulence. Our findings provide new insights into a new regulatory network that controls virulence and host colonization.
Project description:The overall goal of these experiments was to determine how human endothelial cells respond to pathogenic Leptospira interrogans. Leptospira interrogans causes leptospirosis, the most widespread zoonotic infection in the world. A hallmark of leptospirosis is widespread endothelial damage, which in severe cases leads to hemorrhage. In these experiments, we infected two endothelial cell lines with pathogenic Leptospira interrogans serovar Canicola strain Ca12-005, and as controls, with the non-pathogenic Leptospira biflexa serovar Patoc strain Pfra. As additional controls, uninfected cells were also included in the analyses.
Project description:The overall goal of these experiments was to determine how human endothelial cells respond to pathogenic Leptospira interrogans. Leptospira interrogans causes leptospirosis, the most widespread zoonotic infection in the world. A hallmark of leptospirosis is widespread endothelial damage, which in severe cases leads to hemorrhage. In these experiments, we infected two endothelial cell lines with pathogenic Leptospira interrogans serovar Canicola strain Ca12-005, and as controls, with the non-pathogenic Leptospira biflexa serovar Patoc strain Pfra. As additional controls, uninfected cells were also included in the analyses.
Project description:The overall goal of these experiments was to determine how human endothelial cells respond to pathogenic Leptospira interrogans. Leptospira interrogans causes leptospirosis, the most widespread zoonotic infection in the world. A hallmark of leptospirosis is widespread endothelial damage, which in severe cases leads to hemorrhage. In these experiments, we infected two endothelial cell lines with pathogenic Leptospira interrogans serovar Canicola strain Ca12-005, and as controls, with the non-pathogenic Leptospira biflexa serovar Patoc strain Pfra. As additional controls, uninfected cells were also included in the analyses. The cell line used fhere was a microvascular endothelial line, HMEC (Ades et al, 1992. HMEC-1: establishment of an immortalized human microvascular endothelial cell line. J Invest Dermatol. 99:683-690); due to loss of the original analysis files, only raw data files are provided. Infection times were performed at a multiplicity of infection (# bacteria/endothelial cell) of 10 for either 1 hour or 3 hours, after which RNA was harvested and reverse transcribed. Labeled cDNAs were used to probe HEEBO arrays purchased from Microarrays Inc. (Nashville, TN). In each of three biological replicate experiments, for each time point, three comparisons were made. First, the L. interrogans-infected cells were compared to the L. biflexa-infected cells. Second, the L. Interrogans-infected cells were compared to the uninfected cells. Third, the L. biflexa-infected cells were compared to the uninfected cells. A second endothelial cell line,
Project description:The overall goal of these experiments was to determine how human endothelial cells respond to pathogenic Leptospira interrogans. Leptospira interrogans causes leptospirosis, the most widespread zoonotic infection in the world. A hallmark of leptospirosis is widespread endothelial damage, which in severe cases leads to hemorrhage. In these experiments, we infected two endothelial cell lines with pathogenic Leptospira interrogans serovar Canicola strain Ca12-005, and as controls, with the non-pathogenic Leptospira biflexa serovar Patoc strain Pfra. As additional controls, uninfected cells were also included in the analyses. The cell line used was Ea.hy926, a macrovascular line (Edgell, C. J.,et al. 1990. In vitro Cell. & Dev. Biol. 26:1167-1172, and Edgell, C. J., et al. 1983. Proc. Natl. Acad. Sci. 80:3734-3737). Infection times were performed at a multiplicity of infection (# bacteria/endothelial cell) of 10 for either 1 hour or 3 hours, after which RNA was harvested and reverse transcribed. Labeled cDNAs were used to probe HEEBO arrays purchased from Microarrays Inc. (Nashville, TN). In each of three biological replicate experiments, for each time point, three comparisons were made. First, the L. interrogans-infected cells were compared to the L. biflexa-infected cells. Second, the L. Interrogans-infected cells were compared to the uninfected cells. Third, the L. biflexa-infected cells were compared to the uninfected cells. A second endothelial cell line, HMEC (Ades et al, 1992. HMEC-1: establishment of an immortalized human microvascular endothelial cell line. J Invest Dermatol. 99:683-690), which is of microvascular origin, was also used; raw data files are provided separately.
Project description:Transmission of leptospirosis requires that the spirochete pathogen adapts rapidly to the mammalian host milieu during infection and the external environment upon shedding from the renal tubules of animal reservoirs. The pathogenic Leptospira genomes encode a notably large number (≥76) of putative two-component system (TCS) proteins, which presumably play a key role in switching the ecological niches. Yet to date, the regulatory networks that govern virulence and environmental adaptation have not been elucidated in Leptospira. We identified seven ORFs encoding putative TCS proteins that are exclusively conserved in all the pathogenic Leptospira species. Two of these ORFs (LMANv2_670020, LMANv2_670019), juxtaposed in an operon, are predicted to encode a cytoplasmic hybrid histidine kinase and response regulator. Corresponding transposon mutants ΔlvrA/B and ΔlvrB demonstrated a loss-of-virulence in a hamster model of leptospirosis and aberrant motility phenotype. RNA sequencing revealed the differential expression of transcripts on a global scale in ΔlvrA/B (8.13%), ΔlvrB (5.06%) and ΔlvrA/B∩ΔlvrB (8.24%). In vitro transcriptomes provided insights into the role of Lvr dyad in regulating virulence, motility, signal transduction and metabolism related genes. Phosphotransfer assays indicated that LvrA interacts with LvrB in a branched signaling pathway. Phylogenetic analyses indicated that Our findings suggest that a novel, hybrid two-component system Lvr plays a key role in governing virulence and mediating global regulation in pathogenic Leptospira.