Project description:The life-threatening pathogen Leptospira interrogans navigates a dual existence: surviving in environmental reservoirs and infecting mammalian hosts. Leptospira biofilm formation is thought to be an important survival strategy in environmental contexts and may also contribute to the persistence of leptospirosis in maintenance hosts. Examining the correlation between biofilm formation and the virulence of pathogenic strains might improve our comprehension of the epidemiology of leptospirosis. To further explore Leptospira’s survival strategy, our study focused on elucidating the biological state of pathogenic Leptospira within biofilms, particularly aiming to uncover the adaptations and regulatory mechanisms that are involved in such complex microenvironments. To determine the transcriptional profile of pathogenic Leptospira in biofilm, we compared the genome-wide transcriptomic profiles in late biofilms (21 days old) with those in exponential planktonic cultures (5 days old), revealing a pronounced transcriptomic shift. While genes linked to motility, energy production, and metabolism were downregulated, those governing the general stress response, defense against metal stress, and redox homeostasis showed a significant upsurge, hinting at a tailored defensive strategy against stress in late biofilms. A standout finding was the increased expression of the csoR, copZ, and copA locus, integral to copper ion stress response in other bacterial genera, suggesting a unique adaptation to metal-induced stress. Further, despite a reduced metabolic state in biofilms, their disruption swiftly restored metabolic activity. Crucially, bacteria either in late biofilms or resulting from biofilm disruption retained virulence in a hamster infection model, defying the notion that biofilm maturation abolishes pathogenicity. In summary, our study highlights Leptospira's adaptive equilibrium in biofilms: minimizing cellular energy expenditure to conserve resources, potentially aiding in withstanding stresses while maintaining its pathogenicity. These insights are important for explaining the survival strategies of Leptospira, revealing that a biofilm lifestyle may confer an advantage in maintaining virulence. This understanding is essential for managing leptospirosis across both environmental reservoirs and mammalian hosts.
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:Our data demonstrate the suitability of target capture technology for purifying very low quantities of Leptospira DNA from biological samples where the human genome is in vast excess. This enables deep sequencing of partial Leptospira genomes directly from clinical samples using next generation technologies and genotyping.
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:Mandatory potency testing of Leptospira vaccine batches relies partially on in vivo procedures, requiring large numbers of laboratory animals. Cell-based assays could replace in vivo tests if biomarkers indicative of Leptospira vaccine potency are identified. We investigated innate immune responsiveness induced by inactivated L. interrogans serogroups Canicola and Icterohaemorrhagiae, and two bivalent, non-adjuvanted canine Leptospira vaccines containing the same serogroups. First, the transcriptome and proteome analysis of canine 030-D cells stimulated with Leptospira strains, and the corresponding vaccine revealed more than 900 DEGs and 23 DEPs in common to these three stimuli. Second, comparison of responses induced by this Leptospira vaccine and a vaccine from another manufacturer revealed a large overlap in DEGs and DEPs as well, suggesting potential to identify biomarkers of Leptospira vaccine activity. Because not many common DEPs were identified, we selected seven molecules from the identified DEGs, associated with pathways related to innate immunity, of which CXCL-10, IL-1β, SAA, and complement C3 showed increased secretion upon stimulation with both Leptospira vaccines. These molecules could be interesting targets for development of biomarker-based assays in the future. Additionally, this study contributes to the understanding of the mechanisms by which Leptospira vaccines induce innate immune responses in the dog.
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:We used RNAseq to investigate innate immune responsiveness in canine 030-D cell line induced by inactivated L. interrogans serogroups Canicola and Icterohaemorrhagiae, and two bivalent, non-adjuvanted canine Leptospira vaccines containing the same serogroups. We identified more than 900 DEGs associated with pathways related to innate immune responses in common to these three stimuli. Several molecules including CXCL-10, SAA, and complement factor C3 were identified that could serve as targets for development of a biomarker-based in vitro assay to assess Leptospira vaccine quality. In vitro assay could replace the current animal vaccine-challenge potency assay and contribute to reduction of animal use in vaccine manufacturing.
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.