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Wan W, Li D, Li D, Jiao J. Advances in genetic manipulation of Chlamydia trachomatis. Front Immunol 2023; 14:1209879. [PMID: 37449211 PMCID: PMC10337758 DOI: 10.3389/fimmu.2023.1209879] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2023] [Accepted: 06/14/2023] [Indexed: 07/18/2023] Open
Abstract
Chlamydia trachomatis, one species of Chlamydia spp., has the greatest impact on human health and is the main cause of bacterial sexually transmitted diseases and preventable blindness among all Chamydia spp. species. The obligate intracellular parasitism and unique biphasic developmental cycle of C. trachomatis are the main barriers for the development of tools of genetic manipulation. The past decade has witnessed significant gains in genetic manipulation of C. trachomatis, including chemical mutagenesis, group II intron-based targeted gene knockout, fluorescence-reported allelic exchange mutagenesis (FRAEM), CRISPR interference (CRISPRi) and the recently developed transposon mutagenesis. In this review, we discuss the current status of genetic manipulations of C. trachomatis and highlights new challenges in the nascent field of Chlamydia genetics.
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Affiliation(s)
- Weiqiang Wan
- State Key Laboratory of Pathogen and Biosecurity, Beijing Institute of Microbiology and Epidemiology, Beijing, China
| | - Danni Li
- State Key Laboratory of Pathogen and Biosecurity, Beijing Institute of Microbiology and Epidemiology, Beijing, China
| | - Dan Li
- Department of Respiratory Medicine, Center for Pathogen Biology and Infectious Diseases, Key Laboratory of Organ Regeneration and Transplantation of the Ministry of Education, The First Hospital of Jilin University, Changchun, China
| | - Jun Jiao
- State Key Laboratory of Pathogen and Biosecurity, Beijing Institute of Microbiology and Epidemiology, Beijing, China
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Marti H, Suchland RJ, Rockey DD. The Impact of Lateral Gene Transfer in Chlamydia. Front Cell Infect Microbiol 2022; 12:861899. [PMID: 35321311 PMCID: PMC8936141 DOI: 10.3389/fcimb.2022.861899] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2022] [Accepted: 02/07/2022] [Indexed: 11/24/2022] Open
Abstract
Lateral gene transfer (LGT) facilitates many processes in bacterial ecology and pathogenesis, especially regarding pathogen evolution and the spread of antibiotic resistance across species. The obligate intracellular chlamydiae, which cause a range of diseases in humans and animals, were historically thought to be highly deficient in this process. However, research over the past few decades has demonstrated that this was not the case. The first reports of homologous recombination in the Chlamydiaceae family were published in the early 1990s. Later, the advent of whole-genome sequencing uncovered clear evidence for LGT in the evolution of the Chlamydiaceae, although the acquisition of tetracycline resistance in Chlamydia (C.) suis is the only recent instance of interphylum LGT. In contrast, genome and in vitro studies have shown that intraspecies DNA exchange occurs frequently and can even cross species barriers between closely related chlamydiae, such as between C. trachomatis, C. muridarum, and C. suis. Additionally, whole-genome analysis led to the identification of various DNA repair and recombination systems in C. trachomatis, but the exact machinery of DNA uptake and homologous recombination in the chlamydiae has yet to be fully elucidated. Here, we reviewed the current state of knowledge concerning LGT in Chlamydia by focusing on the effect of homologous recombination on the chlamydial genome, the recombination machinery, and its potential as a genetic tool for Chlamydia.
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Affiliation(s)
- Hanna Marti
- Institute of Veterinary Pathology, Vetsuisse-Faculty, University of Zurich, Zurich, Switzerland
- *Correspondence: Hanna Marti,
| | - Robert J. Suchland
- Division of Allergy and Infectious Diseases, Department of Medicine, University of Washington, Seattle, WA, United States
| | - Daniel D. Rockey
- Department of Biomedical Sciences, Carlson College of Veterinary Medicine, Oregon State University, Corvallis, OR, United States
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Transposon Mutagenesis in Chlamydia trachomatis Identifies CT339 as a ComEC Homolog Important for DNA Uptake and Lateral Gene Transfer. mBio 2019; 10:mBio.01343-19. [PMID: 31387908 PMCID: PMC6686042 DOI: 10.1128/mbio.01343-19] [Citation(s) in RCA: 33] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
Transposon mutagenesis is a widely applied and powerful genetic tool for the discovery of genes associated with selected phenotypes. Chlamydia trachomatis is a clinically significant, obligate intracellular bacterium for which many conventional genetic tools and capabilities have been developed only recently. This report describes the successful development and application of a Himar transposon mutagenesis system for generating single-insertion mutant clones of C. trachomatis This system was used to generate a pool of 105 transposon mutant clones that included insertions in genes encoding flavin adenine dinucleotide (FAD)-dependent monooxygenase (C. trachomatis 148 [ct148]), deubiquitinase (ct868), and competence-associated (ct339) proteins. A subset of Tn mutant clones was evaluated for growth differences under cell culture conditions, revealing that most phenocopied the parental strain; however, some strains displayed subtle and yet significant differences in infectious progeny production and inclusion sizes. Bacterial burden studies in mice also supported the idea that a FAD-dependent monooxygenase (ct148) and a deubiquitinase (ct868) were important for these infections. The ct339 gene encodes a hypothetical protein with limited sequence similarity to the DNA-uptake protein ComEC. A transposon insertion in ct339 rendered the mutant incapable of DNA acquisition during recombination experiments. This observation, along with in situ structural analysis, supports the idea that this protein is playing a role in the fundamental process of lateral gene transfer similar to that of ComEC. In all, the development of the Himar transposon system for Chlamydia provides an effective genetic tool for further discovery of genes that are important for basic biology and pathogenesis aspects.IMPORTANCE Chlamydia trachomatis infections have an immense impact on public health; however, understanding the basic biology and pathogenesis of this organism has been stalled by the limited repertoire of genetic tools. This report describes the successful adaptation of an important tool that has been lacking in Chlamydia studies: transposon mutagenesis. This advance enabled the generation of 105 insertional mutants, demonstrating that numerous gene products are not essential for in vitro growth. Mammalian infections using these mutants revealed that several gene products are important for infections in vivo Moreover, this tool enabled the investigation and discovery of a gene critical for lateral gene transfer; a process fundamental to the evolution of bacteria and likely for Chlamydia as well. The development of transposon mutagenesis for Chlamydia has broad impact for the field and for the discovery of genes associated with selected phenotypes, providing an additional avenue for the discovery of molecular mechanisms used for pathogenesis and for a more thorough understanding of this important pathogen.
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Zhong G. Chlamydial Plasmid-Dependent Pathogenicity. Trends Microbiol 2016; 25:141-152. [PMID: 27712952 DOI: 10.1016/j.tim.2016.09.006] [Citation(s) in RCA: 77] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2016] [Revised: 09/11/2016] [Accepted: 09/19/2016] [Indexed: 10/20/2022]
Abstract
Most Chlamydia species carry a 7.5kb plasmid encoding eight open reading frames conventionally called plasmid glycoproteins 1-8 or pGP1-8. Although the plasmid is not critical for chlamydial growth in vitro, its role in chlamydial pathogenesis is clearly demonstrated in the genital tracts of mice infected with Chlamydia muridarum, a model for investigating the human pathogen Chlamydia trachomatis. Plasmid-free C. trachomatis is also attenuated in both the mouse genital tract and nonhuman primate ocular tissue. Deficiency in pGP3 alone, which is regulated by pGP4, largely reproduced the in vivo but not in vitro phenotypes of the plasmid-free organisms, suggesting that pGP3 is a key in vivo virulence factor. The positive and negative regulations of some chromosomal genes by pGP4 and pGP5, respectively, may allow the plasmid to promote chlamydial adaptation to varied animal tissue environments. The focus of this review is to summarize the progress on the pathogenic functions of the plasmid-encoded open reading frames, which may motivate further investigation of the molecular mechanisms of chlamydial pathogenicity and development of medical utility of the chlamydial plasmid system.
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Affiliation(s)
- Guangming Zhong
- Department of Microbiology and Immunology, University of Texas Health Science Center at San Antonio, 7703 Floyd Curl Drive, San Antonio, TX 78229, USA.
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Yang Z, Tang L, Shao L, Zhang Y, Zhang T, Schenken R, Valdivia R, Zhong G. The Chlamydia-Secreted Protease CPAF Promotes Chlamydial Survival in the Mouse Lower Genital Tract. Infect Immun 2016; 84:2697-702. [PMID: 27382018 PMCID: PMC4995919 DOI: 10.1128/iai.00280-16] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2016] [Accepted: 06/30/2016] [Indexed: 12/16/2022] Open
Abstract
Despite the extensive in vitro characterization of CPAF (chlamydial protease/proteasome-like activity factor), its role in chlamydial infection and pathogenesis remains unclear. We now report that a Chlamydia trachomatis strain deficient in expression of CPAF (L2-17) is no longer able to establish a successful infection in the mouse lower genital tract following an intravaginal inoculation. The L2-17 organisms were cleared from the mouse lower genital tract within a few days, while a CPAF-sufficient C. trachomatis strain (L2-5) survived in the lower genital tract for more than 3 weeks. However, both the L2-17 and L2-5 organisms maintained robust infection courses that lasted up to 4 weeks when they were directly delivered into the mouse upper genital tract. The CPAF-dependent chlamydial survival in the lower genital tract was confirmed in multiple strains of mice. Thus, we have demonstrated a critical role of CPAF in promoting C. trachomatis survival in the mouse lower genital tracts. It will be interesting to further investigate the mechanisms of the CPAF-dependent chlamydial pathogenicity.
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Affiliation(s)
- Zhangsheng Yang
- Department of Microbiology & Immunology, University of Texas Health Science Center at San Antonio, San Antonio, Texas, USA
| | - Lingli Tang
- Department of Clinic Diagnosis, Second Xiangya Hospital, Central South University, Changsha, Hunan, China
| | - Lili Shao
- Department of Microbiology & Immunology, University of Texas Health Science Center at San Antonio, San Antonio, Texas, USA
| | - Yuyang Zhang
- Department of Microbiology & Immunology, University of Texas Health Science Center at San Antonio, San Antonio, Texas, USA
| | - Tianyuan Zhang
- Department of Microbiology & Immunology, University of Texas Health Science Center at San Antonio, San Antonio, Texas, USA
| | - Robert Schenken
- Department of Obstetrics and Gynecology, University of Texas Health Science Center at San Antonio, San Antonio, Texas, USA
| | - Raphael Valdivia
- Duke Molecular Genetics and Microbiology, Duke University School of Medicine, Durham, North Carolina, USA
| | - Guangming Zhong
- Department of Microbiology & Immunology, University of Texas Health Science Center at San Antonio, San Antonio, Texas, USA
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Gottlieb SL, Deal CD, Giersing B, Rees H, Bolan G, Johnston C, Timms P, Gray-Owen SD, Jerse AE, Cameron CE, Moorthy VS, Kiarie J, Broutet N. The global roadmap for advancing development of vaccines against sexually transmitted infections: Update and next steps. Vaccine 2016; 34:2939-2947. [PMID: 27105564 PMCID: PMC6759054 DOI: 10.1016/j.vaccine.2016.03.111] [Citation(s) in RCA: 97] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2016] [Accepted: 03/31/2016] [Indexed: 11/09/2022]
Abstract
In 2014, the World Health Organization, the US National Institutes of Health, and global technical partners published a comprehensive roadmap for development of new vaccines against sexually transmitted infections (STIs). Since its publication, progress has been made in several roadmap activities: obtaining better epidemiologic data to establish the public health rationale for STI vaccines, modeling the theoretical impact of future vaccines, advancing basic science research, defining preferred product characteristics for first-generation vaccines, and encouraging investment in STI vaccine development. This article reviews these overarching roadmap activities, provides updates on research and development of individual vaccines against herpes simplex virus, Chlamydia trachomatis, Neisseria gonorrhoeae, and Treponema pallidum, and discusses important next steps to advance the global roadmap for STI vaccine development.
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Affiliation(s)
| | - Carolyn D Deal
- National Institute of Allergy and Infectious Diseases, Bethesda, MD, USA
| | | | - Helen Rees
- Wits Reproductive Health and HIV Institute, University of the Witswatersrand, Johannesburg, South Africa
| | - Gail Bolan
- Centers for Disease Control and Prevention, Atlanta, GA, USA
| | | | - Peter Timms
- University of Sunshine Coast, Queensland Australia and Institute of Health and Biomedical Innovation, Queensland University of Technology, Brisbane, Australia
| | | | - Ann E Jerse
- Uniformed Services University, Bethesda, MD, USA
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Abstract
Although progress in Chlamydia genetics has been rapid, genomic modification has previously been limited to point mutations and group II intron insertions which truncate protein products. The bacterium has thus far been intractable to gene deletion or more-complex genomic integrations such as allelic exchange. Herein, we present a novel suicide vector dependent on inducible expression of a chlamydial gene that renders Chlamydia trachomatis fully genetically tractable and permits rapid reverse genetics by fluorescence-reported allelic exchange mutagenesis (FRAEM). We describe the first available system of targeting chlamydial genes for deletion or allelic exchange as well as curing plasmids from C. trachomatis serovar L2. Furthermore, this approach permits the monitoring of mutagenesis by fluorescence microscopy without disturbing bacterial growth, a significant asset when manipulating obligate intracellular organisms. As proof of principle, trpA was successfully deleted and replaced with a sequence encoding both green fluorescent protein (GFP) and β-lactamase. The trpA-deficient strain was unable to grow in indole-containing medium, and this phenotype was reversed by complementation with trpA expressed in trans. To assess reproducibility at alternate sites, FRAEM was repeated for genes encoding type III secretion effectors CTL0063, CTL0064, and CTL0065. In all four cases, stable mutants were recovered one passage after the observation of transformants, and allelic exchange was limited to the specific target gene, as confirmed by whole-genome sequencing. Deleted sequences were not detected by quantitative real-time PCR (qPCR) from isogenic mutant populations. We demonstrate that utilization of the chlamydial suicide vector with FRAEM renders C. trachomatis highly amenable to versatile and efficient genetic manipulation. The obligate intracellular nature of a variety of infectious bacteria presents a significant obstacle to the development of molecular genetic tools for dissecting pathogenicity. Although progress in chlamydial genetics has been rapid, genomic modification has previously been limited to point mutations and group II intron insertions which truncate protein products. The bacterium has thus far been intractable to gene deletion or more-complex genomic integrations such as allelic exchange. Here, we present a novel suicide vector dependent on inducible expression of a chlamydial gene that renders Chlamydia trachomatis fully genetically tractable and permits rapid reverse genetics by fluorescence-reported allelic exchange mutagenesis (FRAEM). We describe the first available system of targeting chlamydial genes for deletion or allelic exchange as well as curing plasmids from C. trachomatis L2. Furthermore, this approach permits monitoring of mutagenesis by fluorescence microscopy without disturbing bacterial growth, a significant asset when manipulating obligate intracellular organisms.
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