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Zavala-Alvarado C, G. Huete S, Vincent AT, Sismeiro O, Legendre R, Varet H, Bussotti G, Lorioux C, Lechat P, Coppée JY, Veyrier FJ, Picardeau M, Benaroudj N. The oxidative stress response of pathogenic Leptospira is controlled by two peroxide stress regulators which putatively cooperate in controlling virulence. PLoS Pathog 2021; 17:e1009087. [PMID: 34855911 PMCID: PMC8638851 DOI: 10.1371/journal.ppat.1009087] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2020] [Accepted: 10/05/2021] [Indexed: 11/18/2022] Open
Abstract
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 impoverished 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, a double perRAperRB mutant was avirulent. Interestingly, this correlated with major changes in gene and non-coding RNA expression. Notably, several virulence-associated genes (clpB, ligA/B, and lvrAB) were repressed. By obtaining a double mutant in a pathogenic Leptospira strain, our study has uncovered an interplay of two PerRs in the adaptation of Leptospira to oxidative stress with a putative role in virulence and pathogenicity, most likely through the transcriptional control of a complex regulatory network.
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Affiliation(s)
- Crispin Zavala-Alvarado
- Institut Pasteur, Université de Paris, Biologie des Spirochètes, F-75015 Paris, France
- Université de Paris, Sorbonne Paris Cité, F-75015 Paris, France
| | - Samuel G. Huete
- Institut Pasteur, Université de Paris, Biologie des Spirochètes, F-75015 Paris, France
- Université de Paris, Sorbonne Paris Cité, F-75015 Paris, France
| | - Antony T. Vincent
- INRS-Centre Armand-Frappier, Bacterial Symbionts Evolution, Laval, Québec, Canada
| | - Odile Sismeiro
- Institut Pasteur, Université de Paris, Biomics Transcriptome et Epigenome, F-75015 Paris, France
| | - Rachel Legendre
- Institut Pasteur, Université de Paris, Biomics Transcriptome et Epigenome, F-75015 Paris, France
- Institut Pasteur, Université de Paris, Hub Bioinformatique et Biostatistique, F-75015 Paris, France
| | - Hugo Varet
- Institut Pasteur, Université de Paris, Biomics Transcriptome et Epigenome, F-75015 Paris, France
- Institut Pasteur, Université de Paris, Hub Bioinformatique et Biostatistique, F-75015 Paris, France
| | - Giovanni Bussotti
- Institut Pasteur, Université de Paris, Hub Bioinformatique et Biostatistique, F-75015 Paris, France
| | - Céline Lorioux
- Institut Pasteur, Université de Paris, Biologie des Spirochètes, F-75015 Paris, France
| | - Pierre Lechat
- Institut Pasteur, Université de Paris, Hub Bioinformatique et Biostatistique, F-75015 Paris, France
| | - Jean-Yves Coppée
- Institut Pasteur, Université de Paris, Biomics Transcriptome et Epigenome, F-75015 Paris, France
| | - Frédéric J. Veyrier
- INRS-Centre Armand-Frappier, Bacterial Symbionts Evolution, Laval, Québec, Canada
| | - Mathieu Picardeau
- Institut Pasteur, Université de Paris, Biologie des Spirochètes, F-75015 Paris, France
| | - Nadia Benaroudj
- Institut Pasteur, Université de Paris, Biologie des Spirochètes, F-75015 Paris, France
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Abstract
This chapter covers the progress made in the Leptospira field since the application of mutagenesis techniques and how they have allowed the study of virulence factors and, more generally, the biology of Leptospira. The last decade has seen advances in our ability to perform molecular genetic analysis of Leptospira. Major achievements include the generation of large collections of mutant strains and the construction of replicative plasmids, enabling complementation of mutations. However, there are still no practical tools for routine genetic manipulation of pathogenic Leptospira strains, slowing down advances in pathogenesis research. This review summarizes the status of the molecular genetic toolbox for Leptospira species and highlights new challenges in the nascent field of Leptospira genetics.
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Affiliation(s)
- Mathieu Picardeau
- Biology of Spirochetes Unit, Institut Pasteur, 28 Rue Du Docteur Roux, 75724, Paris Cedex 15, France.
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3
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Characterization of LE3 and LE4, the only lytic phages known to infect the spirochete Leptospira. Sci Rep 2018; 8:11781. [PMID: 30082683 PMCID: PMC6078989 DOI: 10.1038/s41598-018-29983-6] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2018] [Accepted: 07/17/2018] [Indexed: 12/19/2022] Open
Abstract
Leptospira is a phylogenetically unique group of bacteria, and includes the causative agents of leptospirosis, the most globally prevalent zoonosis. Bacteriophages in Leptospira are largely unexplored. To date, a genomic sequence is available for only one temperate leptophage called LE1. Here, we sequenced and analysed the first genomes of the lytic phages LE3 and LE4 that can infect the saprophyte Leptospira biflexa using the lipopolysaccharide O-antigen as receptor. Bioinformatics analysis showed that the 48-kb LE3 and LE4 genomes are similar and contain 62% genes whose function cannot be predicted. Mass spectrometry led to the identification of 21 and 23 phage proteins in LE3 and LE4, respectively. However we did not identify significant similarities with other phage genomes. A search for prophages close to LE4 in the Leptospira genomes allowed for the identification of a related plasmid in L. interrogans and a prophage-like region in the draft genome of a clinical isolate of L. mayottensis. Long-read whole genome sequencing of the L. mayottensis revealed that the genome contained a LE4 phage-like circular plasmid. Further isolation and genomic comparison of leptophages should reveal their role in the genetic evolution of Leptospira.
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Llanes A, Restrepo CM, Riesgo-Ferreiro P, Rajeev S. Genomic Variability among Field Isolates and Laboratory-Adapted Strains of Leptospira borgpetersenii Serovar Hardjo. Int J Microbiol 2018; 2018:2137036. [PMID: 29951097 PMCID: PMC5987247 DOI: 10.1155/2018/2137036] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2018] [Revised: 03/12/2018] [Accepted: 03/20/2018] [Indexed: 11/17/2022] Open
Abstract
Leptospira borgpetersenii serovar Hardjo colonizes cattle kidneys and may occasionally infect humans and other mammals. Strains belonging to two clonal subtypes (types A and B) with marked differences in their pathogenicity in the hamster experimental model have been described for this serovar. Such differences have been attributed to point mutations in individual genes, although those genes have not yet been characterized. In order to better understand genetic variability among L. borgpetersenii serovar Hardjo isolates, we sequenced and compared the genomes of two laboratory-adapted strains and three abattoir-derived field isolates of L. borgpetersenii serovar Hardjo. Relatively low genetic variability was observed within isolates of the same subtype, with most of the mutations of moderate or high impact found in the laboratory-adapted isolates. In contrast, several differences regarding gene content and genetic variants were observed between the two subtypes. Putative type-specific genes appear to encode proteins associated with functions that are critical for infection. Some of these genes seem to be involved in transcriptional regulation, possibly leading to a distinct regulatory pattern in each type. These results show that changes in regulatory mechanisms, previously suggested to be critical during Leptospira speciation, may occur in L. borgpetersenii. In addition, the bioinformatics methodology used in this study for variant calling can be useful to other groups working with nonmodel prokaryotic organisms such as Leptospira species.
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Affiliation(s)
- Alejandro Llanes
- Centro de Biología Celular y Molecular de Enfermedades, Instituto de Investigaciones Científicas y Servicios de Alta Tecnología (INDICASAT AIP), Ciudad del Saber, Panama, Panama
| | - Carlos Mario Restrepo
- Centro de Biología Celular y Molecular de Enfermedades, Instituto de Investigaciones Científicas y Servicios de Alta Tecnología (INDICASAT AIP), Ciudad del Saber, Panama, Panama
| | | | - Sreekumari Rajeev
- School of Veterinary Medicine, Ross University, Basseterre, Saint Kitts and Nevis
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Zeng L, Wang D, Hu N, Zhu Q, Chen K, Dong K, Zhang Y, Yao Y, Guo X, Chang YF, Zhu Y. A Novel Pan-Genome Reverse Vaccinology Approach Employing a Negative-Selection Strategy for Screening Surface-Exposed Antigens against leptospirosis. Front Microbiol 2017; 8:396. [PMID: 28352257 PMCID: PMC5348505 DOI: 10.3389/fmicb.2017.00396] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2016] [Accepted: 02/27/2017] [Indexed: 01/18/2023] Open
Abstract
Reverse vaccinology (RV) has been widely used for screening of surface-exposed proteins (PSEs) of important pathogens, including outer membrane proteins (OMPs), and extracellular proteins (ECPs) as potential vaccine candidates. In this study, we applied a novel RV negative strategy and a pan-genome analysis for screening of PSEs from 17 L. interrogans strains covering 11 predominately epidemic serovars and 17 multilocus typing (MLST) sequence types (STs) worldwide. Our results showed, for instance, out of a total of 633 predicted PSEs in strain 56601, 92.8% were OMPs or ECPs (588/633). Among the 17 strains, 190 core PSEs, 913 dispensable PSEs and 861 unique PSEs were identified. Of the 190 PSEs, 121 were further predicted to be highly antigenic and thus may serve as potential vaccine candidates against leptospirosis. With the exception of LipL45, OmpL1, and LigB, the majority of the 121 PSEs were newly identified antigens. For example, hypothetical proteins BatC, LipL71, and the OmpA family proteins sharing many common features, such as surface-exposed localization, universal conservation, and eliciting strong antibody responses in patients, are regarded as the most promising vaccine antigens. Additionally, a wide array of potential virulence factors among the predicted PSEs including TonB-dependent receptor, sphingomyelinase 2, leucine-rich repeat protein, and 4 neighboring hypothetical proteins were identified as potential antigenicity, and deserve further investigation. Our results can contribute to the prediction of suitable antigens as potential vaccine candidates against leptospirosis and also provide further insights into mechanisms of leptospiral pathogenicity. In addition, our novel negative-screening strategy combined with pan-genome analysis can be a routine RV method applied to numerous other pathogens.
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Affiliation(s)
- LingBing Zeng
- Department of Laboratory Medicine, the First Affiliated Hospital of NanChang UniversityNanchang, China; Department of Medical Microbiology and Immunology, Shanghai Jiao Tong University School of MedicineShanghai, China
| | - Dongliang Wang
- CAS Key Laboratory for Biological Effects of Nanomaterials and Nanosafety, National Center for Nanoscience and Technology Beijing, China
| | - NiYa Hu
- Department of Laboratory Medicine, the First Affiliated Hospital of NanChang University Nanchang, China
| | - Qing Zhu
- Department of Laboratory Medicine, the First Affiliated Hospital of NanChang University Nanchang, China
| | - Kaishen Chen
- Department of Laboratory Medicine, the First Affiliated Hospital of NanChang University Nanchang, China
| | - Ke Dong
- Department of Medical Microbiology and Immunology, Shanghai Jiao Tong University School of Medicine Shanghai, China
| | - Yan Zhang
- Department of Medical Microbiology and Immunology, Shanghai Jiao Tong University School of Medicine Shanghai, China
| | - YuFeng Yao
- Deparment of Molecular Immunology, Institute of Medical Biology, Chinese Academy of Medical Sciences, Peking Union Medical College Kunming, China
| | - XiaoKui Guo
- Department of Medical Microbiology and Immunology, Shanghai Jiao Tong University School of Medicine Shanghai, China
| | - Yung-Fu Chang
- Department of Population Medicine and Diagnostic Sciences, College of Veterinary Medicine, Cornell University Ithaca, NY, USA
| | - YongZhang Zhu
- Department of Medical Microbiology and Immunology, Shanghai Jiao Tong University School of Medicine Shanghai, China
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Llanes A, Restrepo CM, Rajeev S. Whole Genome Sequencing Allows Better Understanding of the Evolutionary History of Leptospira interrogans Serovar Hardjo. PLoS One 2016; 11:e0159387. [PMID: 27442015 PMCID: PMC4956267 DOI: 10.1371/journal.pone.0159387] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2016] [Accepted: 07/02/2016] [Indexed: 11/19/2022] Open
Abstract
The genome of a laboratory-adapted strain of Leptospira interrogans serovar Hardjo was sequenced and analyzed. Comparison of the sequenced genome with that recently published for a field isolate of the same serovar revealed relatively high sequence conservation at the nucleotide level, despite the different biological background of both samples. Conversely, comparison of both serovar Hardjo genomes with those of L. borgpetersenii serovar Hardjo showed extensive differences between the corresponding chromosomes, except for the region occupied by their rfb loci. Additionally, comparison of the serovar Hardjo genomes with those of different L. interrogans serovars allowed us to detect several genomic features that may confer an adaptive advantage to L. interrogans serovar Hardjo, including a possible integrated plasmid and an additional copy of a cluster encoding a membrane transport system known to be involved in drug resistance. A phylogenomic strategy was used to better understand the evolutionary position of the Hardjo serovar among L. interrogans serovars and other Leptospira species. The proposed phylogeny supports the hypothesis that the presence of similar rfb loci in two different species may be the result of a lateral gene transfer event.
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Affiliation(s)
- Alejandro Llanes
- Centro de Biología Celular y Molecular de Enfermedades, Instituto de Investigaciones Científicas y Servicios de Alta Tecnología (INDICASAT AIP), Ciudad del Saber, Panamá, Panamá
- * E-mail:
| | - Carlos Mario Restrepo
- Centro de Biología Celular y Molecular de Enfermedades, Instituto de Investigaciones Científicas y Servicios de Alta Tecnología (INDICASAT AIP), Ciudad del Saber, Panamá, Panamá
| | - Sreekumari Rajeev
- Ross University School of Veterinary Medicine, Basseterre, St. Kitts & Nevis
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7
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Fouts DE, Matthias MA, Adhikarla H, Adler B, Amorim-Santos L, Berg DE, Bulach D, Buschiazzo A, Chang YF, Galloway RL, Haake DA, Haft DH, Hartskeerl R, Ko AI, Levett PN, Matsunaga J, Mechaly AE, Monk JM, Nascimento ALT, Nelson KE, Palsson B, Peacock SJ, Picardeau M, Ricaldi JN, Thaipandungpanit J, Wunder EA, Yang XF, Zhang JJ, Vinetz JM. What Makes a Bacterial Species Pathogenic?:Comparative Genomic Analysis of the Genus Leptospira. PLoS Negl Trop Dis 2016; 10:e0004403. [PMID: 26890609 PMCID: PMC4758666 DOI: 10.1371/journal.pntd.0004403] [Citation(s) in RCA: 194] [Impact Index Per Article: 24.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2015] [Accepted: 01/03/2016] [Indexed: 12/20/2022] Open
Abstract
Leptospirosis, caused by spirochetes of the genus Leptospira, is a globally widespread, neglected and emerging zoonotic disease. While whole genome analysis of individual pathogenic, intermediately pathogenic and saprophytic Leptospira species has been reported, comprehensive cross-species genomic comparison of all known species of infectious and non-infectious Leptospira, with the goal of identifying genes related to pathogenesis and mammalian host adaptation, remains a key gap in the field. Infectious Leptospira, comprised of pathogenic and intermediately pathogenic Leptospira, evolutionarily diverged from non-infectious, saprophytic Leptospira, as demonstrated by the following computational biology analyses: 1) the definitive taxonomy and evolutionary relatedness among all known Leptospira species; 2) genomically-predicted metabolic reconstructions that indicate novel adaptation of infectious Leptospira to mammals, including sialic acid biosynthesis, pathogen-specific porphyrin metabolism and the first-time demonstration of cobalamin (B12) autotrophy as a bacterial virulence factor; 3) CRISPR/Cas systems demonstrated only to be present in pathogenic Leptospira, suggesting a potential mechanism for this clade's refractoriness to gene targeting; 4) finding Leptospira pathogen-specific specialized protein secretion systems; 5) novel virulence-related genes/gene families such as the Virulence Modifying (VM) (PF07598 paralogs) proteins and pathogen-specific adhesins; 6) discovery of novel, pathogen-specific protein modification and secretion mechanisms including unique lipoprotein signal peptide motifs, Sec-independent twin arginine protein secretion motifs, and the absence of certain canonical signal recognition particle proteins from all Leptospira; and 7) and demonstration of infectious Leptospira-specific signal-responsive gene expression, motility and chemotaxis systems. By identifying large scale changes in infectious (pathogenic and intermediately pathogenic) vs. non-infectious Leptospira, this work provides new insights into the evolution of a genus of bacterial pathogens. This work will be a comprehensive roadmap for understanding leptospirosis pathogenesis. More generally, it provides new insights into mechanisms by which bacterial pathogens adapt to mammalian hosts.
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Affiliation(s)
- Derrick E. Fouts
- J. Craig Venter Institute, Rockville, Maryland, United States of America
| | - Michael A. Matthias
- Division of Infectious Diseases, Department of Medicine, University of California San Diego School of Medicine, La Jolla, California, United States of America
| | - Haritha Adhikarla
- Department of Epidemiology of Microbial Diseases, Yale School of Public Health, New Haven, Connecticut, United States of America
| | - Ben Adler
- Australian Research Council Centre of Excellence in Structural and Functional Microbial Genomics, Department of Microbiology, Monash University, Clayton, Australia
| | - Luciane Amorim-Santos
- Department of Epidemiology of Microbial Diseases, Yale School of Public Health, New Haven, Connecticut, United States of America
- Centro de Pesquisas Gonçalo Moniz, Fundação Oswaldo Cruz/MS, Salvador, Bahia, Brazil
| | - Douglas E. Berg
- Division of Infectious Diseases, Department of Medicine, University of California San Diego School of Medicine, La Jolla, California, United States of America
| | - Dieter Bulach
- Victorian Bioinformatics Consortium, Monash University, Clayton, Victoria, Australia
| | - Alejandro Buschiazzo
- Institut Pasteur de Montevideo, Laboratory of Molecular and Structural Microbiology, Montevideo, Uruguay
- Institut Pasteur, Department of Structural Biology and Chemistry, Paris, France
| | - Yung-Fu Chang
- Department of Population Medicine & Diagnostic Sciences, College of Veterinary Medicine, Cornell University, Ithaca, New York, United States of America
| | - Renee L. Galloway
- Centers for Disease Control and Prevention (DHHS, CDC, OID, NCEZID, DHCPP, BSPB), Atlanta, Georgia, United States of America
| | - David A. Haake
- VA Greater Los Angeles Healthcare System, Los Angeles, California, United States of America
- David Geffen School of Medicine at UCLA, Los Angeles, California, United States of America
| | - Daniel H. Haft
- J. Craig Venter Institute, Rockville, Maryland, United States of America
| | - Rudy Hartskeerl
- WHO/FAO/OIE and National Collaborating Centre for Reference and Research on Leptospirosis, KIT Biomedical Research, Royal Tropical Institute (KIT), Amsterdam, The Netherlands
| | - Albert I. Ko
- Department of Epidemiology of Microbial Diseases, Yale School of Public Health, New Haven, Connecticut, United States of America
- Centro de Pesquisas Gonçalo Moniz, Fundação Oswaldo Cruz/MS, Salvador, Bahia, Brazil
| | - Paul N. Levett
- Government of Saskatchewan, Disease Control Laboratory Regina, Canada
| | - James Matsunaga
- VA Greater Los Angeles Healthcare System, Los Angeles, California, United States of America
- David Geffen School of Medicine at UCLA, Los Angeles, California, United States of America
| | - Ariel E. Mechaly
- Institut Pasteur de Montevideo, Laboratory of Molecular and Structural Microbiology, Montevideo, Uruguay
| | - Jonathan M. Monk
- Department of Bioengineering, University of California, San Diego, La Jolla, California, United States of America
| | - Ana L. T. Nascimento
- Centro de Biotecnologia, Instituto Butantan, São Paulo, SP, Brazil
- Programa Interunidades em Biotecnologia, Instituto de Ciências Biomédicas, USP, São Paulo, SP, Brazil
| | - Karen E. Nelson
- J. Craig Venter Institute, Rockville, Maryland, United States of America
| | - Bernhard Palsson
- Department of Bioengineering, University of California, San Diego, La Jolla, California, United States of America
| | - Sharon J. Peacock
- Department of Medicine, University of Cambridge, Cambridge, United Kingdom
| | - Mathieu Picardeau
- Institut Pasteur, Biology of Spirochetes Unit, National Reference Centre and WHO Collaborating Center for Leptospirosis, Paris, France
| | - Jessica N. Ricaldi
- Instituto de Medicina Tropical Alexander von Humboldt; Facultad de Medicina Alberto Hurtado, Universidd Peruana Cayetano Heredia, Lima, Peru
| | | | - Elsio A. Wunder
- Department of Epidemiology of Microbial Diseases, Yale School of Public Health, New Haven, Connecticut, United States of America
- Centro de Pesquisas Gonçalo Moniz, Fundação Oswaldo Cruz/MS, Salvador, Bahia, Brazil
| | - X. Frank Yang
- Department of Microbiology and Immunology, Indiana University School of Medicine, Indianapolis, Indiana, United States of America
| | - Jun-Jie Zhang
- Department of Microbiology and Immunology, Indiana University School of Medicine, Indianapolis, Indiana, United States of America
| | - Joseph M. Vinetz
- Division of Infectious Diseases, Department of Medicine, University of California San Diego School of Medicine, La Jolla, California, United States of America
- Instituto de Medicina Tropical Alexander von Humboldt; Facultad de Medicina Alberto Hurtado, Universidd Peruana Cayetano Heredia, Lima, Peru
- Instituto de Medicina “Alexander von Humboldt,” Universidad Peruana Cayetano Heredia, Lima, Peru
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8
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Wang Y, Zhuang X, Zhong Y, Zhang C, Zhang Y, Zeng L, Zhu Y, He P, Dong K, Pal U, Guo X, Qin J. Distribution of Plasmids in Distinct Leptospira Pathogenic Species. PLoS Negl Trop Dis 2015; 9:e0004220. [PMID: 26555137 PMCID: PMC4640553 DOI: 10.1371/journal.pntd.0004220] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2015] [Accepted: 10/19/2015] [Indexed: 11/18/2022] Open
Abstract
Leptospirosis, caused by pathogenic Leptospira, is a worldwide zoonotic infection. The genus Leptospira includes at least 21 species clustered into three groups--pathogens, non-pathogens, and intermediates--based on 16S rRNA phylogeny. Research on Leptospira is difficult due to slow growth and poor transformability of the pathogens. Recent identification of extrachromosomal elements besides the two chromosomes in L. interrogans has provided new insight into genome complexity of the genus Leptospira. The large size, low copy number, and high similarity of the sequence of these extrachromosomal elements with the chromosomes present challenges in isolating and detecting them without careful genome assembly. In this study, two extrachromosomal elements were identified in L. borgpetersenii serovar Ballum strain 56604 through whole genome assembly combined with S1 nuclease digestion following pulsed-field gel electrophoresis (S1-PFGE) analysis. Further, extrachromosomal elements in additional 15 Chinese epidemic strains of Leptospira, comprising L. borgpetersenii, L. weilii, and L. interrogans, were successfully separated and identified, independent of genome sequence data. Southern blot hybridization with extrachromosomal element-specific probes, designated as lcp1, lcp2 and lcp3-rep, further confirmed their occurrences as extrachromosomal elements. In total, 24 plasmids were detected in 13 out of 15 tested strains, among which 11 can hybridize with the lcp1-rep probe and 11 with the lcp2-rep probe, whereas two can hybridize with the lcp3-rep probe. None of them are likely to be species-specific. Blastp search of the lcp1, lcp2, and lcp3-rep genes with a nonredundant protein database of Leptospira species genomes showed that their homologous sequences are widely distributed among clades of pathogens but not non-pathogens or intermediates. These results suggest that the plasmids are widely distributed in Leptospira species, and further elucidation of their biological significance might contribute to our understanding of biology and infectivity of pathogenic spirochetes.
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Affiliation(s)
- Yanzhuo Wang
- Department of Microbiology and Immunology, Institutes of Medical Science, Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Xuran Zhuang
- Department of Microbiology and Immunology, Institutes of Medical Science, Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Yi Zhong
- Computational Biology Department, Memorial Sloan Kettering Cancer Center, New York, New York, United States of America
| | - Cuicai Zhang
- National Institute for Communicable Disease Control and Prevention, Chinese Center for Disease Control and Prevention (ICDC, CCDC), Beijing, China
| | - Yan Zhang
- Department of Microbiology and Immunology, Institutes of Medical Science, Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Lingbing Zeng
- The First Affiliated Hospital of Nanchang University, Nanchang, China
| | - Yongzhang Zhu
- Department of Microbiology and Immunology, Institutes of Medical Science, Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Ping He
- Department of Microbiology and Immunology, Institutes of Medical Science, Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Ke Dong
- Department of Microbiology and Immunology, Institutes of Medical Science, Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Utpal Pal
- Department of Veterinary Medicine, University of Maryland, College Park and Virginia-Maryland Regional College of Veterinary Medicine, College Park, Maryland, United States of America
- * E-mail: (UP); (XG); (JQ)
| | - Xiaokui Guo
- Department of Microbiology and Immunology, Institutes of Medical Science, Shanghai Jiao Tong University School of Medicine, Shanghai, China
- * E-mail: (UP); (XG); (JQ)
| | - Jinhong Qin
- Department of Microbiology and Immunology, Institutes of Medical Science, Shanghai Jiao Tong University School of Medicine, Shanghai, China
- * E-mail: (UP); (XG); (JQ)
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9
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Pappas CJ, Benaroudj N, Picardeau M. A replicative plasmid vector allows efficient complementation of pathogenic Leptospira strains. Appl Environ Microbiol 2015; 81:3176-81. [PMID: 25724960 PMCID: PMC4393447 DOI: 10.1128/aem.00173-15] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2015] [Accepted: 02/23/2015] [Indexed: 11/20/2022] Open
Abstract
Leptospirosis, an emerging zoonotic disease, remains poorly understood because of a lack of genetic manipulation tools available for pathogenic leptospires. Current genetic manipulation techniques include insertion of DNA by random transposon mutagenesis and homologous recombination via suicide vectors. This study describes the construction of a shuttle vector, pMaORI, that replicates within saprophytic, intermediate, and pathogenic leptospires. The shuttle vector was constructed by the insertion of a 2.9-kb DNA segment including the parA, parB, and rep genes into pMAT, a plasmid that cannot replicate in Leptospira spp. and contains a backbone consisting of an aadA cassette, ori R6K, and oriT RK2/RP4. The inserted DNA segment was isolated from a 52-kb region within Leptospira mayottensis strain 200901116 that is not found in the closely related strain L. mayottensis 200901122. Because of the size of this region and the presence of bacteriophage-like proteins, it is possible that this region is a result of a phage-related genomic island. The stability of the pMaORI plasmid within pathogenic strains was tested by passaging cultures 10 times without selection and confirming the presence of pMaORI. Concordantly, we report the use of trans complementation in the pathogen Leptospira interrogans. Transformation of a pMaORI vector carrying a functional copy of the perR gene in a null mutant background restores the expression of PerR and susceptibility to hydrogen peroxide comparable to that of wild-type cells. In conclusion, we demonstrate the replication of a stable plasmid vector in a large panel of Leptospira strains, including pathogens. The shuttle vector described will expand our ability to perform genetic manipulation of Leptospira spp.
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Affiliation(s)
- Christopher J Pappas
- Institut Pasteur, Unité Biologie des Spirochètes, Paris, France Manhattanville College, Department of Biology, Purchase, New York, USA
| | - Nadia Benaroudj
- Institut Pasteur, Unité Biologie des Spirochètes, Paris, France
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Zhu W, Wang J, Zhu Y, Tang B, Zhang Y, He P, Zhang Y, Liu B, Guo X, Zhao G, Qin J. Identification of three extra-chromosomal replicons in Leptospira pathogenic strain and development of new shuttle vectors. BMC Genomics 2015; 16:90. [PMID: 25887950 PMCID: PMC4338851 DOI: 10.1186/s12864-015-1321-y] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2014] [Accepted: 02/04/2015] [Indexed: 12/20/2022] Open
Abstract
Background The genome of pathogenic Leptospira interrogans contains two chromosomes. Plasmids and prophages are known to play specific roles in gene transfer in bacteria and can potentially serve as efficient genetic tools in these organisms. Although plasmids and prophage remnants have recently been reported in Leptospira species, their characteristics and potential applications in leptospiral genetic transformation systems have not been fully evaluated. Results Three extrachromosomal replicons designated lcp1 (65,732 bp), lcp2 (56,757 bp), and lcp3 (54,986 bp) in the L. interrogans serovar Linhai strain 56609 were identified through whole genome sequencing. All three replicons were stable outside of the bacterial chromosomes. Phage particles were observed in the culture supernatant of 56609 after mitomycin C induction, and lcp3, which contained phage-related genes, was considered to be an inducible prophage. L. interrogans–Escherichia coli shuttle vectors, constructed with the predicted replication elements of single rep or rep combined with parAB loci from the three plasmids were shown to successfully transform into both saprophytic and pathogenic Leptospira species, suggesting an essential function for rep genes in supporting auto-replication of the plasmids. Additionally, a wide distribution of homologs of the three rep genes was identified in L. interrogans isolates, and correlation tests showed that the transformability of the shuttle vectors in L. interrogans isolates depended, to certain extent, on genetic compatibility between the rep sequences of both plasmid and host. Conclusions Three extrachromosomal replicons co-exist in L. interrogans, one of which we consider to be an inducible prophage. The vectors constructed with the rep genes of the three replicons successfully transformed into saprophytic and pathogenic Leptospira species alike, but this was partly dependent on genetic compatibility between the rep sequences of both plasmid and host. Electronic supplementary material The online version of this article (doi:10.1186/s12864-015-1321-y) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Weinan Zhu
- Department of Microbiology and Immunology, Institutes of Medical Science, Shanghai Jiao Tong University School of Medicine, 280 South Chongqing Road, Shanghai, 200025, China.
| | - Jin Wang
- CAS Key Laboratory of Synthetic Biology, Institute of Plant Physiology and Ecology, Shanghai Institute for Biological Sciences, Chinese Academy of Sciences, Shanghai, China.
| | - Yongzhang Zhu
- Department of Microbiology and Immunology, Institutes of Medical Science, Shanghai Jiao Tong University School of Medicine, 280 South Chongqing Road, Shanghai, 200025, China.
| | - Biao Tang
- State Key Laboratory of Genetic Engineering, Department of Microbiology, School of Life Sciences, Fudan University, 220 Handan Road, Shanghai, 200433, China.
| | - Yunyi Zhang
- CAS Key Laboratory of Synthetic Biology, Institute of Plant Physiology and Ecology, Shanghai Institute for Biological Sciences, Chinese Academy of Sciences, Shanghai, China.
| | - Ping He
- Department of Microbiology and Immunology, Institutes of Medical Science, Shanghai Jiao Tong University School of Medicine, 280 South Chongqing Road, Shanghai, 200025, China.
| | - Yan Zhang
- Department of Microbiology and Immunology, Institutes of Medical Science, Shanghai Jiao Tong University School of Medicine, 280 South Chongqing Road, Shanghai, 200025, China.
| | - Boyu Liu
- Department of Microbiology and Immunology, Institutes of Medical Science, Shanghai Jiao Tong University School of Medicine, 280 South Chongqing Road, Shanghai, 200025, China.
| | - Xiaokui Guo
- Department of Microbiology and Immunology, Institutes of Medical Science, Shanghai Jiao Tong University School of Medicine, 280 South Chongqing Road, Shanghai, 200025, China.
| | - Guoping Zhao
- CAS Key Laboratory of Synthetic Biology, Institute of Plant Physiology and Ecology, Shanghai Institute for Biological Sciences, Chinese Academy of Sciences, Shanghai, China. .,State Key Laboratory of Genetic Engineering, Department of Microbiology, School of Life Sciences, Fudan University, 220 Handan Road, Shanghai, 200433, China.
| | - Jinhong Qin
- Department of Microbiology and Immunology, Institutes of Medical Science, Shanghai Jiao Tong University School of Medicine, 280 South Chongqing Road, Shanghai, 200025, China.
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Abstract
Recent advances in molecular genetics, such as the ability to construct defined mutants, have allowed the study of virulence factors and more generally the biology in Leptospira. However, pathogenic leptospires remain much less easily transformable than the saprophyte L. biflexa and further development and improvement of genetic tools are required. Here, we review tools that have been used to genetically manipulate Leptospira. We also describe the major advances achieved in both genomics and postgenomics technologies, including transcriptomics and proteomics.
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Youn JH, Hayashida K, Koizumi N, Ohnishi M, Sugimoto C. Comparative genomic analysis of eight Leptospira strains from Japan and the Philippines revealing the existence of four putative novel genomic islands/islets in L. interrogans serovar Lai strain 56601. Comp Immunol Microbiol Infect Dis 2014; 37:289-97. [PMID: 25449997 DOI: 10.1016/j.cimid.2014.09.001] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2013] [Revised: 07/22/2014] [Accepted: 09/25/2014] [Indexed: 11/15/2022]
Abstract
Leptospirosis is one of the most widespread zoonotic diseases worldwide and can be considered an emerging health problem to both human and animal. Despite the importance of the disease, complete genome sequences are currently available for only three Leptospira interrogans strains: 56601, Fiocruz L1-130, and IPAV. Therefore, intra- and inter-species comparative genomic analyses of Leptospira are limited. Here, to advance current knowledge of the genomic differences within Leptospira species, next-generation sequencing technology was used to examine the genomes of eight L. interrogans strains belonging to six different serogroups isolated from humans and dogs in Japan and the Philippines. The genomic sequences were mapped to that of the reference strain, L. interrogans serovar Lai strain 56601. The results revealed the presence of four novel genomic islands/islets (GIs) in strain 56601. This study provides a deeper insight into the molecular basis and evolutionary perspective of the virulence of leptospires.
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Affiliation(s)
- Jung-Ho Youn
- Division of Collaboration and Education, Research Center for Zoonosis Control, Hokkaido University, Kita-20, Nishi-10, Kita-ku, Sapporo 001-0020, Hokkaido, Japan.
| | - Kyoko Hayashida
- National Research Center for Protozoan Diseases, Obihiro University, Nishi-2-13, Inada-cho, Obihiro 080-8555, Hokkaido, Japan
| | - Nobuo Koizumi
- Department of Bacteriology, National Institute of Infectious Disease, 1-23-1 Toyama, Shinju-ku 162-8640, Tokyo, Japan
| | - Makoto Ohnishi
- Department of Bacteriology, National Institute of Infectious Disease, 1-23-1 Toyama, Shinju-ku 162-8640, Tokyo, Japan
| | - Chihiro Sugimoto
- Division of Collaboration and Education, Research Center for Zoonosis Control, Hokkaido University, Kita-20, Nishi-10, Kita-ku, Sapporo 001-0020, Hokkaido, Japan.
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Zhu WN, Huang LL, Zeng LB, Zhuang XR, Chen CY, Wang YZ, Qin JH, Zhu YZ, Guo XK. Isolation and characterization of two novel plasmids from pathogenic Leptospira interrogans serogroup Canicola Serovar Canicola strain Gui44. PLoS Negl Trop Dis 2014; 8:e3103. [PMID: 25144555 PMCID: PMC4140679 DOI: 10.1371/journal.pntd.0003103] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2014] [Accepted: 07/01/2014] [Indexed: 12/01/2022] Open
Abstract
Background Previous genomic analysis of pathogenic Leptospira has identified two circular chromosomes but no plasmid. This study aims to investigate potential extrachromosomal elements of L.interrogans serovar Canicola strain Gui44. Methodology Two novel plasmids, pGui1 and pGui2, were isolated from the pathogenic strain Gui44, using a modified alkaline lysis method. Southern blotting was performed to determine the presence and size of them. Then, 454 and Hiseq sequencing were applied to obtain and analyze the complete sequences of the two plasmids. Furthermore, real-time quantitative PCR and next-generation sequencing were used to compare relative copy numbers of the two plasmids with that of the chromosomes. Finally, after serial passages in vitro for more than 2 years, the strain Gui44 was subsequently re-sequenced to estimate stability of the two plasmids. Principal Findings The larger plasmid, pGui1, 74,981 base pairs (bp) in length with GC content of 34.63%, possesses 62 open reading frames (ORFs). The smaller plasmid, pGui2, is 66,851 bp in length with GC content of 33.33%, and contains 63 ORFs. The replication initiation proteins encoded by pGui1 and pGui2 demonstrate significant sequence similarity with LA1839 (86% and 88%), a well-known replication protein in another pathogenic L.interrogans serovar Lai strain Lai, suggesting the ability for autonomous plasmid replication. Quantitative PCR and next-generation sequencing confirms a single copy of both plasmids and their stable presence in the strain Gui44 with in vitro serial passages after more than 2 years. Interestingly, the two plasmids both contain a significant number of novel genes (35 in pGui1 and 52 in pGui2). Conclusions This report confirms the presence of two separate circular plasmids in serovar Canicola strain Gui44 and provides a new understanding of genomic organization, adaptation, evolution and pathogenesis of Leptospira, which will aid in the development of in vivo genetic manipulation systems in pathogenic Leptospira species. Leptospira species are the causative agent of leptospirosis, one of the most common animal to human transmitted diseases. Previous genomic analysis of L.interrogans serovar Lai and Copenhageni has identified the presence of large (4.33 mega base) and small (350 kilo base) circular chromosomes without evidence of any plasmids. Detailed understanding of Leptospira and its pathogenicity was delayed by the lack of available genetic tools. In this study we confirm the existence of two novel plasmids in L.interrogans serovar Canicola strain Gui44, an epidemic strain in China. Some novel genes identified in the two plasmids may play important roles in the characterization of the strain. The two plasmids will provide useful information in understanding the diversity of Leptospira genome and markedly improve our understanding of the evolution and pathogenesis of L.interrogans. In particular, it will contribute to the development of genetic manipulation systems in pathogenic Leptospira species.
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Affiliation(s)
- Wei-Nan Zhu
- Department of Immunology and Microbiology, Institutes of Medical Sciences, Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Li-Li Huang
- Department of Immunology and Microbiology, Institutes of Medical Sciences, Shanghai Jiao Tong University School of Medicine, Shanghai, China
- Soochow University Affiliated Children's Hospital, Soochow, China
| | - Ling-Bing Zeng
- Department of Immunology and Microbiology, Institutes of Medical Sciences, Shanghai Jiao Tong University School of Medicine, Shanghai, China
- The First Affiliated Hospital of Nanchang University, Nanchang, China
| | - Xu-Ran Zhuang
- Department of Immunology and Microbiology, Institutes of Medical Sciences, Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Chun-Yan Chen
- Department of Immunology and Microbiology, Institutes of Medical Sciences, Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Yan-Zhuo Wang
- Department of Immunology and Microbiology, Institutes of Medical Sciences, Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Jin-Hong Qin
- Department of Immunology and Microbiology, Institutes of Medical Sciences, Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Yong-Zhang Zhu
- Department of Immunology and Microbiology, Institutes of Medical Sciences, Shanghai Jiao Tong University School of Medicine, Shanghai, China
- * E-mail: (YZZ); (XKG)
| | - Xiao-Kui Guo
- Department of Immunology and Microbiology, Institutes of Medical Sciences, Shanghai Jiao Tong University School of Medicine, Shanghai, China
- * E-mail: (YZZ); (XKG)
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14
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Huang L, Zhu W, He P, Zhang Y, Zhuang X, Zhao G, Guo X, Qin J, Zhu Y. Re-characterization of an extrachromosomal circular plasmid in the pathogenic Leptospira interrogans serovar Lai strain 56601. Acta Biochim Biophys Sin (Shanghai) 2014; 46:605-11. [PMID: 24874103 DOI: 10.1093/abbs/gmu033] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023] Open
Abstract
In China, Leptospira interrogans serovar Lai strain 56601 (str.56601) is one of main pathogenic strains that cause severe leptospirosis in both human and animals. The genome of this organism was completely sequenced in 2003. However, in 2011, we identified and corrected some assembly errors in the str.56601 genome due to the repeat sequences widely distributed in the Leptospira genome. In this study, we re-analyzed the previously reported mobile, phage-related genomic island in the chromosome and rectified detailed sequence information in both the plasmid and chromosome using various experimental methods. The presence of a separate circular extrachromosomal plasmid was also confirmed, and its location in the genomic region was determined relative to the genomic island reported in L. interrogans serovar Lai by a combination of pulsed-field gel electrophoresis -based and plasmid extraction-based Southern blot analysis. This report confirmed that the separate extrachromosomal circular plasmid is not integrated into the chromosome of L. interrogans str.56601 and markedly improved our understanding of the genomic organization, evolution, and pathogenesis of L. interrogans. In particular, characterization of this extrachromosomal circular plasmid will contribute to the development of genetic manipulation systems in pathogenic Leptospira species.
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Affiliation(s)
- Lili Huang
- Department of Microbiology and Immunology, Institute of Medical Science, Shanghai Jiao Tong University School of Medicine, 280 South Chongqing Road, Shanghai 200025, China
| | - Weinan Zhu
- Department of Microbiology and Immunology, Institute of Medical Science, Shanghai Jiao Tong University School of Medicine, 280 South Chongqing Road, Shanghai 200025, China
| | - Ping He
- Department of Microbiology and Immunology, Institute of Medical Science, Shanghai Jiao Tong University School of Medicine, 280 South Chongqing Road, Shanghai 200025, China
| | - Yan Zhang
- Department of Microbiology and Immunology, Institute of Medical Science, Shanghai Jiao Tong University School of Medicine, 280 South Chongqing Road, Shanghai 200025, China
| | - Xuran Zhuang
- Department of Microbiology and Immunology, Institute of Medical Science, Shanghai Jiao Tong University School of Medicine, 280 South Chongqing Road, Shanghai 200025, China
| | - Guoping Zhao
- CAS-Key Laboratory of Synthetic Biology, Institute of Plant Physiology and Ecology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai 200032, China
| | - Xiaokui Guo
- Department of Microbiology and Immunology, Institute of Medical Science, Shanghai Jiao Tong University School of Medicine, 280 South Chongqing Road, Shanghai 200025, China
| | - Jinhong Qin
- Department of Microbiology and Immunology, Institute of Medical Science, Shanghai Jiao Tong University School of Medicine, 280 South Chongqing Road, Shanghai 200025, China
| | - Yongzhang Zhu
- Department of Microbiology and Immunology, Institute of Medical Science, Shanghai Jiao Tong University School of Medicine, 280 South Chongqing Road, Shanghai 200025, China
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15
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Lehmann JS, Matthias MA, Vinetz JM, Fouts DE. Leptospiral pathogenomics. Pathogens 2014; 3:280-308. [PMID: 25437801 PMCID: PMC4243447 DOI: 10.3390/pathogens3020280] [Citation(s) in RCA: 60] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2014] [Revised: 03/22/2014] [Accepted: 03/28/2014] [Indexed: 11/30/2022] Open
Abstract
Leptospirosis, caused by pathogenic spirochetes belonging to the genus Leptospira, is a zoonosis with important impacts on human and animal health worldwide. Research on the mechanisms of Leptospira pathogenesis has been hindered due to slow growth of infectious strains, poor transformability, and a paucity of genetic tools. As a result of second generation sequencing technologies, there has been an acceleration of leptospiral genome sequencing efforts in the past decade, which has enabled a concomitant increase in functional genomics analyses of Leptospira pathogenesis. A pathogenomics approach, by coupling of pan-genomic analysis of multiple isolates with sequencing of experimentally attenuated highly pathogenic Leptospira, has resulted in the functional inference of virulence factors. The global Leptospira Genome Project supported by the U.S. National Institute of Allergy and Infectious Diseases to which key scientific contributions have been made from the international leptospirosis research community has provided a new roadmap for comprehensive studies of Leptospira and leptospirosis well into the future. This review describes functional genomics approaches to apply the data generated by the Leptospira Genome Project towards deepening our knowledge of virulence factors of Leptospira using the emerging discipline of pathogenomics.
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Affiliation(s)
- Jason S Lehmann
- Division of Infectious Diseases, Department of Medicine, University of California San Diego, School of Medicine, La Jolla, CA 92093-0741, USA.
| | - Michael A Matthias
- Division of Infectious Diseases, Department of Medicine, University of California San Diego, School of Medicine, La Jolla, CA 92093-0741, USA.
| | - Joseph M Vinetz
- Division of Infectious Diseases, Department of Medicine, University of California San Diego, School of Medicine, La Jolla, CA 92093-0741, USA.
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16
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Gyles C, Boerlin P. Horizontally Transferred Genetic Elements and Their Role in Pathogenesis of Bacterial Disease. Vet Pathol 2013; 51:328-40. [DOI: 10.1177/0300985813511131] [Citation(s) in RCA: 128] [Impact Index Per Article: 11.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
This article reviews the roles that laterally transferred genes (LTG) play in the virulence of bacterial pathogens. The features of LTG that allow them to be recognized in bacterial genomes are described, and the mechanisms by which LTG are transferred between and within bacteria are reviewed. Genes on plasmids, integrative and conjugative elements, prophages, and pathogenicity islands are highlighted. Virulence genes that are frequently laterally transferred include genes for bacterial adherence to host cells, type 3 secretion systems, toxins, iron acquisition, and antimicrobial resistance. The specific roles of LTG in pathogenesis are illustrated by specific reference to Escherichia coli, Salmonella, pyogenic streptococci, and Clostridium perfringens.
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Affiliation(s)
- C. Gyles
- Department of Pathobiology, Ontario Veterinary College, University of Guelph, Guelph, Ontario, Canada
| | - P. Boerlin
- Department of Pathobiology, Ontario Veterinary College, University of Guelph, Guelph, Ontario, Canada
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Pradhan D, Priyadarshini V, Munikumar M, Swargam S, Umamaheswari A, Bitla A. Para-(benzoyl)-phenylalanine as a potential inhibitor against LpxC of Leptospira spp.: homology modeling, docking, and molecular dynamics study. J Biomol Struct Dyn 2013; 32:171-85. [PMID: 23383626 DOI: 10.1080/07391102.2012.758056] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Leptospira interrogans, a Gram-negative bacterial pathogen is the main cause of human leptospirosis. Lipid A is a highly immunoreactive endotoxic center of lipopolysaccharide (LPS) that anchors LPS into the outer membrane of Leptospira. Discovery of compounds inhibiting lipid-A biosynthetic pathway would be promising for dissolving the structural integrity of membrane leading to cell lysis and death of Leptospira. LpxC, a unique enzyme of lipid-A biosynthetic pathway was identified as common drug target of Leptospira. Herein, homology modeling, docking, and molecular dynamics (MD) simulations were employed to discover potential inhibitors of LpxC. A reliable tertiary structure of LpxC in complex with inhibitor BB-78485 was constructed in Modeller 9v8. A data-set of BB-78485 structural analogs were docked with LpxC in Maestro v9.2 virtual screening workflow, which implements three stage Glide docking protocol. Twelve lead molecules with better XP Gscore compared to BB-78485 were proposed as potential inhibitors of LpxC. Para-(benzoyl)-phenylalanine - that showed lowest XP Gscore (-10.35 kcal/mol) - was predicted to have best binding affinity towards LpxC. MD simulations were performed for LpxC and para-(benzoyl)-phenylalanine docking complex in Desmond v3.0. Trajectory analysis showed the docking complex and inter-molecular interactions was stable throughout the entire production part of MD simulations. The results indicate para-(benzoyl)-phenylalanine as a potent drug molecule against leptospirosis. An animated Interactive 3D Complement (I3DC) is available in Proteopedia at http://proteopedia.org/w/Journal:JBSD:10.
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Affiliation(s)
- Dibyabhaba Pradhan
- a Department of Bioinformatics , SVIMS Bioinformatics Centre, SVIMS University , Tirupati , 517507 , AP , India
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Umamaheswari A, Pradhan D, Hemanthkumar M. Identification of potential Leptospira phosphoheptose isomerase inhibitors through virtual high-throughput screening. GENOMICS PROTEOMICS & BIOINFORMATICS 2011; 8:246-55. [PMID: 21382593 PMCID: PMC5054147 DOI: 10.1016/s1672-0229(10)60026-5] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The life-threatening infections caused by Leptospira serovars demand the need for designing anti-leptospirosis drugs. The present study encompasses exploring inhibitors against phosphoheptose isomerase (GmhA) of Leptospira, which is vital for lipopolysaccharide (LPS) biosynthesis and is identified as a common drug target through the subtractive genomic approach. GmhA model was built in Modeller 9v7. Structural refinement and energy minimization of the predicted model was carried out using Maestro 9.0. The refined model reliability was assessed through Procheck, ProSA, ProQ and Profile 3D. The substrate-based virtual high-throughput screening (VHTS) in Ligand.Info Meta-Database tool generated an in-house library of 354 substrate structural analogs. Furthermore, structure-based VHTS from the in-house library with different conformations of each ligand provided 14 novel competitive inhibitors. The model together with insight gained from the VHTS would be a promising starting point for developing anti-leptospirosis competitive inhibitors targeting LPS biosynthesis pathway.
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Comparative proteogenomic analysis of the Leptospira interrogans virulence-attenuated strain IPAV against the pathogenic strain 56601. Cell Res 2011; 21:1210-29. [PMID: 21423275 DOI: 10.1038/cr.2011.46] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
Abstract
The virulence-attenuated Leptospira interrogans serovar Lai strain IPAV was derived by prolonged laboratory passage from a highly virulent ancestral strain isolated in China. We studied the genetic variations of IPAV that render it avirulent via comparative analysis against the pathogenic L. interrogans serovar Lai strain 56601. The complete genome sequence of the IPAV strain was determined and used to compare with, and then rectify and reannotate the genome sequence of strain 56601. Aside from their highly similar genomic structure and gene order, a total of 33 insertions, 53 deletions and 301 single-nucleotide variations (SNVs) were detected throughout the genome of IPAV directly affecting 101 genes, either in their 5' upstream region or within their coding region. Among them, the majority of the 44 functional genes are involved in signal transduction, stress response, transmembrane transport and nitrogen metabolism. Comparative proteomic analysis based on quantitative liquid chromatography (LC)-MS/MS data revealed that among 1 627 selected pairs of orthologs, 174 genes in the IPAV strain were upregulated, with enrichment mainly in classes of energy production and lipid metabolism. In contrast, 228 genes in strain 56601 were upregulated, with the majority enriched in the categories of protein translation and DNA replication/repair. The combination of genomic and proteomic approaches illustrated that altered expression or mutations in critical genes, such as those encoding a Ser/Thr kinase, carbon-starvation protein CstA, glutamine synthetase, GTP-binding protein BipA, ribonucleotide-diphosphate reductase and phosphate transporter, and alterations in the translational profile of lipoproteins or outer membrane proteins are likely to account for the virulence attenuation in strain IPAV.
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Spontaneous excision of the Salmonella enterica serovar Enteritidis-specific defective prophage-like element phiSE14. J Bacteriol 2010; 192:2246-54. [PMID: 20172996 DOI: 10.1128/jb.00270-09] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Salmonella enterica serovar Enteritidis has emerged as a major health problem worldwide in the last few decades. DNA loci unique to S. Enteritidis can provide markers for detection of this pathogen and may reveal pathogenic mechanisms restricted to this serovar. An in silico comparison of 16 Salmonella genomic sequences revealed the presence of an approximately 12.5-kb genomic island (GEI) specific to the sequenced S. Enteritidis strain NCTC13349. The GEI is inserted at the 5' end of gene ydaO (SEN1377), is flanked by 308-bp imperfect direct repeats (attL and attR), and includes 21 open reading frames (SEN1378 to SEN1398), encoding primarily phage-related proteins. Accordingly, this GEI has been annotated as the defective prophage SE14 in the genome of strain NCTC13349. The genetic structure and location of phiSE14 are conserved in 99 of 103 wild-type strains of S. Enteritidis studied here, including reference strains NCTC13349 and LK5. Notably, an extrachromosomal circular form of phiSE14 was detected in every strain carrying this island. The presence of attP sites in the circular forms detected in NCTC13349 and LK5 was confirmed. In addition, we observed spontaneous loss of a tetRA-tagged version of phiSE14, leaving an empty attB site in the genome of strain NCTC13349. Collectively, these results demonstrate that phiSE14 is an unstable genetic element that undergoes spontaneous excision under standard growth conditions. An internal fragment of phiSE14 designated Sdf I has been used as a serovar-specific genetic marker in PCR-based detection systems and as a tool to determine S. Enteritidis levels in experimental infections. The instability of this region may require a reassessment of its suitability for such applications.
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Ko AI, Goarant C, Picardeau M. Leptospira: the dawn of the molecular genetics era for an emerging zoonotic pathogen. Nat Rev Microbiol 2009; 7:736-47. [PMID: 19756012 PMCID: PMC3384523 DOI: 10.1038/nrmicro2208] [Citation(s) in RCA: 475] [Impact Index Per Article: 31.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Leptospirosis is a zoonotic disease that has emerged as an important cause of morbidity and mortality among impoverished populations. One hundred years after the discovery of the causative spirochaetal agent, little is understood about Leptospira spp. pathogenesis, which in turn has hampered the development of new intervention strategies to address this neglected disease. However, the recent availability of complete genome sequences for Leptospira spp. and the discovery of genetic tools for their transformation have led to important insights into the biology of these pathogens and their pathogenesis. We discuss the life cycle of the bacterium, the recent advances in our understanding and the implications for the future prevention of leptospirosis.
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Affiliation(s)
- Albert I. Ko
- Division of Infectious Disease, Weill Medical College of Cornell University, New York, USA
- Gonçalo Moniz Research Centre, Oswaldo Cruz Foundation, Brazilian Ministry of Health, Salvador, Brazil
| | - Cyrille Goarant
- Institut Pasteur de Nouvelle-Calédonie, Laboratoire de Recherche en Bactériologie, Nouméa, New-Caledonia
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Dorman CJ, Kane KA. DNA bridging and antibridging: a role for bacterial nucleoid-associated proteins in regulating the expression of laterally acquired genes. FEMS Microbiol Rev 2009; 33:587-92. [DOI: 10.1111/j.1574-6976.2008.00155.x] [Citation(s) in RCA: 59] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022] Open
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Identification of a novel prophage-like gene cluster actively expressed in both virulent and avirulent strains of Leptospira interrogans serovar Lai. Infect Immun 2008; 76:2411-9. [PMID: 18362131 DOI: 10.1128/iai.01730-07] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
DNA microarray analysis was used to compare the differential gene expression profiles between Leptospira interrogans serovar Lai type strain 56601 and its corresponding attenuated strain IPAV. A 22-kb genomic island covering a cluster of 34 genes (i.e., genes LA0186 to LA0219) was actively expressed in both strains but concomitantly upregulated in strain 56601 in contrast to that of IPAV. Reverse transcription-PCR assays proved that the gene cluster comprised five transcripts. Gene annotation of this cluster revealed characteristics of a putative prophage-like remnant with at least 8 of 34 sequences encoding prophage-like proteins, of which the LA0195 protein is probably a putative prophage CI-like regulator. The transcription initiation activities of putative promoter-regulatory sequences of transcripts I, II, and III, all proximal to the LA0195 gene, were further analyzed in the Escherichia coli promoter probe vector pKK232-8 by assaying the reporter chloramphenicol acetyltransferase (CAT) activities. The strong promoter activities of both transcripts I and II indicated by the E. coli CAT assay were well correlated with the in vitro sequence-specific binding of the recombinant LA0195 protein to the corresponding promoter probes detected by the electrophoresis mobility shift assay. On the other hand, the promoter activity of transcript III was very low in E. coli and failed to show active binding to the LA0195 protein in vitro. These results suggested that the LA0195 protein is likely involved in the transcription of transcripts I and II. However, the identical complete DNA sequences of this prophage remnant from these two strains strongly suggests that possible regulatory factors or signal transduction systems residing outside of this region within the genome may be responsible for the differential expression profiling in these two strains.
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Picardeau M, Bulach DM, Bouchier C, Zuerner RL, Zidane N, Wilson PJ, Creno S, Kuczek ES, Bommezzadri S, Davis JC, McGrath A, Johnson MJ, Boursaux-Eude C, Seemann T, Rouy Z, Coppel RL, Rood JI, Lajus A, Davies JK, Médigue C, Adler B. Genome sequence of the saprophyte Leptospira biflexa provides insights into the evolution of Leptospira and the pathogenesis of leptospirosis. PLoS One 2008; 3:e1607. [PMID: 18270594 PMCID: PMC2229662 DOI: 10.1371/journal.pone.0001607] [Citation(s) in RCA: 233] [Impact Index Per Article: 14.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2007] [Accepted: 01/17/2008] [Indexed: 11/19/2022] Open
Abstract
Leptospira biflexa is a free-living saprophytic spirochete present in aquatic environments. We determined the genome sequence of L. biflexa, making it the first saprophytic Leptospira to be sequenced. The L. biflexa genome has 3,590 protein-coding genes distributed across three circular replicons: the major 3,604 chromosome, a smaller 278-kb replicon that also carries essential genes, and a third 74-kb replicon. Comparative sequence analysis provides evidence that L. biflexa is an excellent model for the study of Leptospira evolution; we conclude that 2052 genes (61%) represent a progenitor genome that existed before divergence of pathogenic and saprophytic Leptospira species. Comparisons of the L. biflexa genome with two pathogenic Leptospira species reveal several major findings. Nearly one-third of the L. biflexa genes are absent in pathogenic Leptospira. We suggest that once incorporated into the L. biflexa genome, laterally transferred DNA undergoes minimal rearrangement due to physical restrictions imposed by high gene density and limited presence of transposable elements. In contrast, the genomes of pathogenic Leptospira species undergo frequent rearrangements, often involving recombination between insertion sequences. Identification of genes common to the two pathogenic species, L. borgpetersenii and L. interrogans, but absent in L. biflexa, is consistent with a role for these genes in pathogenesis. Differences in environmental sensing capacities of L. biflexa, L. borgpetersenii, and L. interrogans suggest a model which postulates that loss of signal transduction functions in L. borgpetersenii has impaired its survival outside a mammalian host, whereas L. interrogans has retained environmental sensory functions that facilitate disease transmission through water.
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Affiliation(s)
| | - Dieter M. Bulach
- Victorian Bioinformatics Consortium, Monash University, Clayton, Victoria, Australia
- Australian Research Council Centre of Excellence in Structural and Functional Microbial Genomics, Department of Microbiology, Monash University, Clayton, Victoria, Australia
- Australian Bacterial Pathogenesis Program, Department of Microbiology, Monash University, Clayton, Victoria, Australia
| | | | - Richard L. Zuerner
- Bacterial Diseases of Livestock Research Unit, National Animal Disease Center (NADC), Agricultural Research Service (ARS), United States Department of Agriculture (USDA), Ames, Iowa, United States of America
| | - Nora Zidane
- Plate-forme Génomique, Institut Pasteur, Paris, France
| | - Peter J. Wilson
- Australian Genome Research Facility, Gehrmann Laboratories, University of Queensland, St. Lucia, Queensland, Australia
| | - Sophie Creno
- Plate-forme Génomique, Institut Pasteur, Paris, France
| | - Elizabeth S. Kuczek
- Australian Genome Research Facility, Gehrmann Laboratories, University of Queensland, St. Lucia, Queensland, Australia
| | | | - John C. Davis
- Australian Genome Research Facility, Gehrmann Laboratories, University of Queensland, St. Lucia, Queensland, Australia
| | - Annette McGrath
- Australian Genome Research Facility, Gehrmann Laboratories, University of Queensland, St. Lucia, Queensland, Australia
| | - Matthew J. Johnson
- Australian Genome Research Facility, Gehrmann Laboratories, University of Queensland, St. Lucia, Queensland, Australia
| | | | - Torsten Seemann
- Victorian Bioinformatics Consortium, Monash University, Clayton, Victoria, Australia
| | - Zoé Rouy
- Commissariat à l'Energie Atomique (CEA), Direction des Sciences du Vivant, Laboratoire de Génomique Comparative, Institut de Génomique, Genoscope, Evry, France
| | - Ross L. Coppel
- Victorian Bioinformatics Consortium, Monash University, Clayton, Victoria, Australia
- Australian Research Council Centre of Excellence in Structural and Functional Microbial Genomics, Department of Microbiology, Monash University, Clayton, Victoria, Australia
| | - Julian I. Rood
- Victorian Bioinformatics Consortium, Monash University, Clayton, Victoria, Australia
- Australian Research Council Centre of Excellence in Structural and Functional Microbial Genomics, Department of Microbiology, Monash University, Clayton, Victoria, Australia
- Australian Bacterial Pathogenesis Program, Department of Microbiology, Monash University, Clayton, Victoria, Australia
| | - Aurélie Lajus
- Commissariat à l'Energie Atomique (CEA), Direction des Sciences du Vivant, Laboratoire de Génomique Comparative, Institut de Génomique, Genoscope, Evry, France
| | - John K. Davies
- Victorian Bioinformatics Consortium, Monash University, Clayton, Victoria, Australia
- Australian Research Council Centre of Excellence in Structural and Functional Microbial Genomics, Department of Microbiology, Monash University, Clayton, Victoria, Australia
- Australian Bacterial Pathogenesis Program, Department of Microbiology, Monash University, Clayton, Victoria, Australia
| | - Claudine Médigue
- Commissariat à l'Energie Atomique (CEA), Direction des Sciences du Vivant, Laboratoire de Génomique Comparative, Institut de Génomique, Genoscope, Evry, France
- Centre National de la Recherche Scientifique (CNRS) UMR8030, Génomique Métabolique, Evry, France
| | - Ben Adler
- Victorian Bioinformatics Consortium, Monash University, Clayton, Victoria, Australia
- Australian Research Council Centre of Excellence in Structural and Functional Microbial Genomics, Department of Microbiology, Monash University, Clayton, Victoria, Australia
- Australian Bacterial Pathogenesis Program, Department of Microbiology, Monash University, Clayton, Victoria, Australia
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He P, Sheng YY, Shi YZ, Jiang XG, Qin JH, Zhang ZM, Zhao GP, Guo XK. Genetic diversity among major endemic strains of Leptospira interrogans in China. BMC Genomics 2007; 8:204. [PMID: 17603913 PMCID: PMC1936430 DOI: 10.1186/1471-2164-8-204] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2007] [Accepted: 07/01/2007] [Indexed: 12/19/2022] Open
Abstract
BACKGROUND Leptospirosis is a world-widely distributed zoonosis. Humans become infected via exposure to pathogenic Leptospira spp. from contaminated water or soil. The availability of genomic sequences of Leptospira interrogans serovar Lai and serovar Copenhageni opened up opportunities to identify genetic diversity among different pathogenic strains of L. interrogans representing various kinds of serotypes (serogroups and serovars). RESULTS Comparative genomic hybridization (CGH) analysis was used to compare the gene content of L. interrogans serovar Lai strain Lai with that of other 10 L. interrogans strains prevailed in China and one identified from Brazil using a microarray spotted with 3,528 protein coding sequences (CDSs) of strain Lai. The cutoff ratio of sample/reference (S/R) hybridization for detecting the absence of genes from one tested strain was set by comparing the ratio of S/R hybridization and the in silico sequence similarities of strain Lai and serovar Copenhageni strain Fiocruz L1-130. Among the 11 strains tested, 275 CDSs were found absent from at least one strain. The common backbone of the L. interrogans genome was estimated to contain about 2,917 CDSs. The genes encoding fundamental cellular functions such as translation, energy production and conversion were conserved. While strain-specific genes include those that encode proteins related to either cell surface structures or carbohydrate transport and metabolism. We also found two genomic islands (GIs) in strain Lai containing genes divergently absent in other strains. Because genes encoding proteins with potential pathogenic functions are located within GIs, these elements might contribute to the variations in disease manifestation. Differences in genes involved in O-antigen biosynthesis were also identified for strains belonging to different serogroups, which offers an opportunity for future development of genomic typing tools for serological classification. CONCLUSION CGH analyses for pathogenic leptospiral strains prevailed in China against the L. interrogans serovar Lai strain Lai CDS-spotted microarrays revealed 2,917 common backbone CDSs and strain specific genes encoding proteins mainly related to cell surface structures and carbohydrated transport/metabolism. Of the 275 CDSs considered absent from at least one of the L. interrogans strains tested, most of them were clustered in the rfb gene cluster and two putative genomic islands (GI A and B) in strain Lai. The strain-specific genes detected via this work will provide a knowledge base for further investigating the pathogenesis of L interrogans and/or for the development of effective vaccines and/or diagnostic tools.
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Affiliation(s)
- Ping He
- Department of Microbiology and Parasitology, Shanghai Jiao Tong University School of Medicine, Shanghai 200025, China
| | - Yue-Ying Sheng
- Department of Microbiology and Parasitology, Shanghai Jiao Tong University School of Medicine, Shanghai 200025, China
| | - Yao-Zhou Shi
- National Engineering Center for Biochip at Shanghai, Zhangjiang High Tech Park, Shanghai 201203, China
| | - Xiu-Gao Jiang
- National Institute for Communicable Disease Control and Prevention, Chinese Center for Disease Control and Prevention (ICDC, CCDC), Beijing 102206, China
| | - Jin-Hong Qin
- Department of Microbiology and Parasitology, Shanghai Jiao Tong University School of Medicine, Shanghai 200025, China
| | - Zhi-Ming Zhang
- National Engineering Center for Biochip at Shanghai, Zhangjiang High Tech Park, Shanghai 201203, China
| | - Guo-Ping Zhao
- National Engineering Center for Biochip at Shanghai, Zhangjiang High Tech Park, Shanghai 201203, China
- State Key Laboratory for Disease and Health Genomics, Chinese National Human Genome Center at Shanghai, Zhangjiang High Tech Park, Shanghai 201203, China
| | - Xiao-Kui Guo
- Department of Microbiology and Parasitology, Shanghai Jiao Tong University School of Medicine, Shanghai 200025, China
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Abstract
PURPOSE OF REVIEW Leptospirosis is among the most important zoonotic diseases worldwide. Completion of the genomic sequences of leptospires has facilitated advances in diagnosis and prevention of the disease, and yielded insight into its pathogenesis. This article reviews this research, emphasizing recent progress. RECENT FINDINGS Leptospirosis is caused by a group of highly invasive spiral bacteria (spirochetes) that can infect both people and animals. Spirochetes can survive in the environment and host, and therefore outer membrane and secretory proteins that interact with the host are of considerable interest in leptospire research. The genetic approach to studying pathogenesis is hindered by fastidious growth of pathogenic leptospires. Integrated genomic and proteomic approaches, however, have yielded enhanced understanding of the pathogenesis of leptospirosis. Furthermore, studies of innate immune response to the organism have enhanced our understanding of host susceptibility and resistance to infection. In-silico analysis and high-throughput cloning and expression have had major impacts on efforts to develop vaccine candidates and diagnostic reagents. SUMMARY In the future, we must effectively utilize the wealth of genetic information to combat the disease. More studies into genetics, immune mechanisms that may be exploited to prevent leptospirosis, and pathogenesis of the disease are necessary.
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Affiliation(s)
- Raghavan U M Palaniappan
- Department of Population Medicine and Diagnostic Sciences, College of Veterinary Medicine, Cornell University, Ithaca, New York 14853, USA.
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