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Khalid A, Asim-Ur-Rehman, Ahmed N, Chaudhery I, Al-Jafary MA, Al-Suhaimi EA, Tarhini M, Lebaz N, Elaissari A. Polysaccharide Chemistry in Drug Delivery, Endocrinology, and Vaccines. Chemistry 2021; 27:8437-8451. [PMID: 33856737 DOI: 10.1002/chem.202100204] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2021] [Indexed: 12/26/2022]
Abstract
Polysaccharides, due to their outstanding properties, have attracted the attention of researchers, working in the biomedical field and especially of those working in drug delivery. Modified/functionalized polysaccharides further increase the importance for various applications. Delivery of therapeutics for diverse ailments in different endocrine glands and hormones safely, is a focal point of researchers working in the field. Among the routes followed, the transdermal route is preferred due to non-exposure of active moieties to the harsh gastric environment and first-pass metabolism. This review starts with the overview of polysaccharides used for the delivery of various therapeutic agents. Advantages of polysaccharides used in the transdermal route are addressed in detail. Types of polysaccharides will be elaborated through examples, and in this context, special emphasis will be on the polysaccharides being used for synthesis of the membranes/films. Techniques employed for their modification to design novel carriers for therapeutics delivery will also be discussed. The review will end with a brief discussion on recent developments and future perspectives for delivery of therapeutic agents, and vaccine development.
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Affiliation(s)
- Aimen Khalid
- Department of Pharmacy, Faculty of Biological Sciences, Quaid-i-Azam University, 45320, Islamabad, Pakistan
| | - Asim-Ur-Rehman
- Department of Pharmacy, Faculty of Biological Sciences, Quaid-i-Azam University, 45320, Islamabad, Pakistan
| | - Naveed Ahmed
- Department of Pharmacy, Faculty of Biological Sciences, Quaid-i-Azam University, 45320, Islamabad, Pakistan
| | - Iqra Chaudhery
- Department of Pharmacy, Faculty of Biological Sciences, Quaid-i-Azam University, 45320, Islamabad, Pakistan
| | - Meneerah A Al-Jafary
- Biology Department, College of Science, Institute for Research and Medical Consultations (IRMC), Imam Abdulrahman Bin Faisal University, 31441, Dammam, Saudi Arabia
| | - Ebtesam Abdullah Al-Suhaimi
- Biology Department, College of Science, Institute for Research and Medical Consultations (IRMC), Imam Abdulrahman Bin Faisal University, 31441, Dammam, Saudi Arabia
| | - Mohamad Tarhini
- Univ Lyon, University Claude Bernard Lyon-1, CNRS, ISA-UMR 5280, 69622, Villeurbanne, France
| | - Noureddine Lebaz
- Univ Lyon, University Claude Bernard Lyon-1, CNRS, LAGEPP-UMR 5007, 69100, Villeurbanne, France
| | - Abdelhamid Elaissari
- Univ Lyon, University Claude Bernard Lyon-1, CNRS, ISA-UMR 5280, 69622, Villeurbanne, France
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Salmonella Paratyphi A Outer Membrane Vesicles Displaying Vi Polysaccharide as a Multivalent Vaccine against Enteric Fever. Infect Immun 2021; 89:IAI.00699-20. [PMID: 33318138 DOI: 10.1128/iai.00699-20] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2020] [Accepted: 12/07/2020] [Indexed: 12/23/2022] Open
Abstract
Typhoid and paratyphoid fevers have a high incidence worldwide and coexist in many geographical areas, especially in low-middle-income countries (LMIC) in South and Southeast Asia. There is extensive consensus on the urgent need for better and affordable vaccines against systemic Salmonella infections. Generalized modules for membrane antigens (GMMA), outer membrane exosomes shed by Salmonella bacteria genetically manipulated to increase blebbing, resemble the bacterial surface where protective antigens are displayed in their native environment. Here, we engineered S Paratyphi A using the pDC5-viaB plasmid to generate GMMA displaying the heterologous S Typhi Vi antigen together with the homologous O:2 O antigen. The presence of both Vi and O:2 was confirmed by flow cytometry on bacterial cells, and their amount was quantified on the resulting vesicles through a panel of analytical methods. When tested in mice, such GMMA induced a strong antibody response against both Vi and O:2, and these antibodies were functional in a serum bactericidal assay. Our approach yielded a bivalent vaccine candidate able to induce immune responses against different Salmonella serovars, which could benefit LMIC residents and travelers.
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Sousa BF, Silva AFBD, Lima-Filho JV, Agostinho AG, Oliveira DN, de Alencar NMN, de Freitas CDT, Ramos MV. Latex proteins downregulate inflammation and restores blood-coagulation homeostasis in acute Salmonella infection. Mem Inst Oswaldo Cruz 2020; 115:e200458. [PMID: 33237133 PMCID: PMC7682140 DOI: 10.1590/0074-02760200458] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2020] [Accepted: 11/09/2020] [Indexed: 01/15/2023] Open
Abstract
BACKGROUND Calotropis procera latex protein fraction (LP) was previously shown to protect animals from septic shock. Further investigations showed that LP modulate nitric oxide and cytokines levels. OBJECTIVES To evaluate whether the protective effects of LP, against lethal bacterial infection, is observed in its subfractions (LPPII and LPPIII). METHODS Subfractions (5 and 10 mg/kg) were tested by i.p. administration, 24 h before challenging with lethal injection (i.p.) of Salmonella Typhimurium. LPPIII (5 mg/kg) which showed higher survival rate was assayed to evaluate bacterial clearance, histopathology, leukocyte recruitment, plasma coagulation time, cytokines and NO levels. FINDINGS LPPIII protected 70% of animals of death. The animals given LPPIII exhibited reduced bacterial load in blood and peritoneal fluid after 24 h compared to the control. LPPIII promoted macrophage infiltration in spleen and liver. LPPIII restored the coagulation time of infected animals, increased IL-10 and reduced NO in blood. MAIN CONCLUSIONS LPPIII recruited macrophages to the target organs of bacterial infection. This addressed inflammatory stimulus seems to reduce bacterial colonisation in spleen and liver, down regulate bacterial spread and contribute to avoid septic shock.
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Affiliation(s)
- Brandon Ferraz Sousa
- Universidade Federal do Ceará, Departamento de Bioquímica e Biologia Molecular, Fortaleza, CE, Brasil
| | | | - José Vitor Lima-Filho
- Universidade Federal Rural de Pernambuco, Departamento de Biologia, Recife, PE, Brasil
| | - Anderson Gomes Agostinho
- Universidade Federal do Ceará, Departamento de Bioquímica e Biologia Molecular, Fortaleza, CE, Brasil
| | | | | | | | - Márcio Viana Ramos
- Universidade Federal do Ceará, Departamento de Bioquímica e Biologia Molecular, Fortaleza, CE, Brasil
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Xie Z, Zhang Y, Huang X. Evidence and speculation: the response of Salmonella confronted by autophagy in macrophages. Future Microbiol 2020; 15:1277-1286. [PMID: 33026883 DOI: 10.2217/fmb-2020-0125] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
Bacteria of the Salmonella genus cause diseases ranging from self-limited gastroenteritis to typhoid fever. Macrophages are immune cells that engulf and restrict Salmonella. These cells will carry Salmonella into the circulatory system and provoke a systemic infection. Therefore, the interaction between macrophages and intracellular Salmonella is vital for its pathogenicity. As one of the immune responses of macrophages, autophagy, along with the fusion of autophagosomes with lysosomes, occupies an important position in eliminating Salmonella. However, Salmonella that can overcome cellular defensive responses and infect neighboring cells must derive strategies to escape autophagy. This review introduces novel findings on Salmonella and macrophage autophagy as a mechanism against infection and explores the strategies used by Salmonella to escape autophagy.
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Affiliation(s)
- Zhongyi Xie
- Department of Biochemistry & Molecular Biology, Jiangsu University School of Medicine, Zhenjiang, Jiangsu 212013, China.,International Genome Center, Jiangsu University, Zhenjiang, Jiangsu 212013, China
| | - Ying Zhang
- Department of Biochemistry & Molecular Biology, Jiangsu University School of Medicine, Zhenjiang, Jiangsu 212013, China
| | - Xinxiang Huang
- Department of Biochemistry & Molecular Biology, Jiangsu University School of Medicine, Zhenjiang, Jiangsu 212013, China
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5
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Antibodies and Protection in Systemic Salmonella Infections: Do We Still Have More Questions than Answers? Infect Immun 2020; 88:IAI.00219-20. [PMID: 32601109 DOI: 10.1128/iai.00219-20] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023] Open
Abstract
Salmonella causes grave systemic infections in humans and other animals and provides a paradigm for other diseases in which the bacteria have both intracellular and extracellular lifestyles. New generations of vaccines rely on the essential contribution of the antibody responses for their protection. The quality, antigen specificity, and functions associated with antibody responses to this pathogen have been elusive for a long time. Recent approaches that combine studies in humans and genetically manipulated experimental models and that exploit awareness of the location and within-host life cycle of the pathogen are shedding light on how humoral immunity to Salmonella operates. However, this area of research remains full of controversy and discrepancies. The overall scenario indicates that antibodies are essential for resistance against systemic Salmonella infections and can express the highest protective function when operating in conjunction with cell-mediated immunity. Antigen specificity, isotype profile, Fc-gamma receptor usage, and complement activation are all intertwined factors that still arcanely influence antibody-mediated protection to Salmonella.
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Kingsley RA, Langridge G, Smith SE, Makendi C, Fookes M, Wileman TM, El Ghany MA, Keith Turner A, Dyson ZA, Sridhar S, Pickard D, Kay S, Feasey N, Wong V, Barquist L, Dougan G. Functional analysis of Salmonella Typhi adaptation to survival in water. Environ Microbiol 2019; 20:4079-4090. [PMID: 30450829 PMCID: PMC6282856 DOI: 10.1111/1462-2920.14458] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2018] [Revised: 10/16/2018] [Accepted: 10/21/2018] [Indexed: 11/28/2022]
Abstract
Contaminated water is a major risk factor associated with the transmission of Salmonella enterica serovar Typhi (S. Typhi), the aetiological agent of human typhoid. However, little is known about how this pathogen adapts to living in the aqueous environment. We used transcriptome analysis (RNA‐seq) and transposon mutagenesis (TraDIS) to characterize these adaptive changes and identify multiple genes that contribute to survival. Over half of the genes in the S. Typhi genome altered expression level within the first 24 h following transfer from broth culture to water, although relatively few did so in the first 30 min. Genes linked to central metabolism, stress associated with arrested proton motive force and respiratory chain factors changed expression levels. Additionally, motility and chemotaxis genes increased expression, consistent with a scavenging lifestyle. The viaB‐associated gene tviC encoding a glcNAc epimerase that is required for Vi polysaccharide biosynthesis was, along with several other genes, shown to contribute to survival in water. Thus, we define regulatory adaptation operating in S. Typhi that facilitates survival in water.
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Affiliation(s)
| | - Gemma Langridge
- Quadram Institute Bioscience, Norwich Research Park, Norwich, UK
| | - Sarah E Smith
- The Wellcome Trust Sanger Institute, Wellcome Trust Genome Campus, Hinxton, Cambridge, UK
| | - Carine Makendi
- The Wellcome Trust Sanger Institute, Wellcome Trust Genome Campus, Hinxton, Cambridge, UK
| | - Maria Fookes
- The Wellcome Trust Sanger Institute, Wellcome Trust Genome Campus, Hinxton, Cambridge, UK
| | - Tom M Wileman
- The Wellcome Trust Sanger Institute, Wellcome Trust Genome Campus, Hinxton, Cambridge, UK
| | - Moataz Abd El Ghany
- The Westmead Institute for Medical Research, The University of Sydney, Sydney, Australia and Marie Bashir Institute for Infectious Diseases and Biosecurity, The University of Sydney, Sydney, Australia
| | - A Keith Turner
- Quadram Institute Bioscience, Norwich Research Park, Norwich, UK
| | - Zoe A Dyson
- Department of Medicine, University of Cambridge, Addenbrooke's Hospital, Hills Road, Cambridge, UK
| | - Sushmita Sridhar
- The Wellcome Trust Sanger Institute, Wellcome Trust Genome Campus, Hinxton, Cambridge, UK.,Department of Medicine, University of Cambridge, Addenbrooke's Hospital, Hills Road, Cambridge, UK
| | - Derek Pickard
- The Wellcome Trust Sanger Institute, Wellcome Trust Genome Campus, Hinxton, Cambridge, UK
| | - Sally Kay
- The Wellcome Trust Sanger Institute, Wellcome Trust Genome Campus, Hinxton, Cambridge, UK
| | | | - Vanessa Wong
- Department of Medicine, University of Cambridge, Addenbrooke's Hospital, Hills Road, Cambridge, UK
| | - Lars Barquist
- Helmholtz Institute for RNA-based Infection Research, Würzburg, Germany.,Faculty of Medicine, University of Würzburg, Würzburg, Germany
| | - Gordon Dougan
- The Wellcome Trust Sanger Institute, Wellcome Trust Genome Campus, Hinxton, Cambridge, UK.,Department of Medicine, University of Cambridge, Addenbrooke's Hospital, Hills Road, Cambridge, UK
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Liaquat S, Sarwar Y, Ali A, Haque A, Farooq M, Martinez-Ballesteros I, Laorden L, Garaizar J, Bikandi J. Virulotyping of Salmonella enterica serovar Typhi isolates from Pakistan: Absence of complete SPI-10 in Vi negative isolates. PLoS Negl Trop Dis 2018; 12:e0006839. [PMID: 30500817 PMCID: PMC6267989 DOI: 10.1371/journal.pntd.0006839] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2018] [Accepted: 09/13/2018] [Indexed: 12/30/2022] Open
Abstract
The pathogenesis of Salmonella enterica serovar Typhi (S. Typhi), the cause of typhoid fever in humans, is mainly attributed to the acquisition of horizontally acquired DNA elements. Salmonella pathogenicity islands (SPIs) are indubitably the most important form of horizontally acquired DNA with respect to pathogenesis of this bacterium. The insertion or deletion of any of these transferrable SPIs may have impact on the virulence potential of S. Typhi. In this study, the virulence potential and genetic relatedness of 35 S. Typhi isolates, collected from 2004 to 2013 was determined by identification of SPI and non-SPI virulence factors through a combination of techniques including virulotyping, Whole Genome Sequencing (WGS), and Variable Number of Tandem Repeats (VNTR) profiling. In order to determine the virulence potential of local S. Typhi isolates, 56 virulence related genes were studied by PCR. These genes are located in the core as well as accessory genome (SPIs and plasmid). Major variations among studied virulence determinants were found in case of SPI-7 and SPI-10 associated genes. On the basis of presence of virulence related genes, the studied S. Typhi isolates from Pakistan were clustered into two virulotypes Vi-positive and Vi-negative. Interestingly, SPI-7 and SPI-10 were collectively absent or present in Vi-negative and Vi-positive strains, respectively. Two Vi-negative and 11 Vi-positive S. Typhi strains were also analyzed by whole genome sequencing (WGS) and their results supported the PCR results. Genetic diversity was tested by VNTR-based molecular typing. All 35 isolates were clustered into five groups. Overall, all Vi-negative isolates were placed in a single group (T5) whereas Vi-positive isolates were grouped into four types. Vi-negative and Vi-positive isolates were mutually exclusive. This is the first report on the comparative distribution of SPI and non-SPI related virulence genes in Vi-negative and Vi-positive S. Typhi isolates with an important finding that SPI-10 is absent in all Vi-negative isolates. The distribution of virulence factors in S. Typhi can vary in isolates from different geographical regions and can have significant effect on the disease control. In this study, we have checked the distribution of 56 reported virulence associated factors in 35 local isolates of S. Typhi to identify any variations that can help in designing effective control strategies for typhoid. We have identified four naturally occurring variants which are simultaneously lacking SPI-7 and SPI-10, two adjacently located pathogenicity islands on S. Typhi chromosome. These isolates are not producing Vi capsular antigen hence the Vi based vaccines will not be effective against them. These findings highlight the need to develop typhoid vaccines specifically effective in Pakistan.
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Affiliation(s)
- Sadia Liaquat
- Enteric Pathogen Laboratory, Health Biotechnology Division, National Institute for Biotechnology and Genetic Engineering (NIBGE), Faisalabad, Pakistan affiliated with Pakistan Institute of Engineering and Applied Sciences (PIEAS), Islamabad, Pakistan
- Departments of Bioinformatics and Biotechnology, Government College University Faisalabad, Faisalabad, Pakistan
| | - Yasra Sarwar
- Enteric Pathogen Laboratory, Health Biotechnology Division, National Institute for Biotechnology and Genetic Engineering (NIBGE), Faisalabad, Pakistan affiliated with Pakistan Institute of Engineering and Applied Sciences (PIEAS), Islamabad, Pakistan
- * E-mail:
| | - Aamir Ali
- Enteric Pathogen Laboratory, Health Biotechnology Division, National Institute for Biotechnology and Genetic Engineering (NIBGE), Faisalabad, Pakistan affiliated with Pakistan Institute of Engineering and Applied Sciences (PIEAS), Islamabad, Pakistan
| | - Abdul Haque
- Akhuwat Faisalabad Institute For Research In Science And Technology, Faisalabad, Pakistan
| | - Muhammad Farooq
- Enteric Pathogen Laboratory, Health Biotechnology Division, National Institute for Biotechnology and Genetic Engineering (NIBGE), Faisalabad, Pakistan affiliated with Pakistan Institute of Engineering and Applied Sciences (PIEAS), Islamabad, Pakistan
| | - Ilargi Martinez-Ballesteros
- Department of Immunology, Microbiology and Parasitology, University of the Basque Country, (UPV/EHU), Vitoria-Gasteiz, Spain
| | - Lorena Laorden
- Department of Immunology, Microbiology and Parasitology, University of the Basque Country, (UPV/EHU), Vitoria-Gasteiz, Spain
| | - Javier Garaizar
- Department of Immunology, Microbiology and Parasitology, University of the Basque Country, (UPV/EHU), Vitoria-Gasteiz, Spain
| | - Joseba Bikandi
- Department of Immunology, Microbiology and Parasitology, University of the Basque Country, (UPV/EHU), Vitoria-Gasteiz, Spain
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Reciprocal Regulation of OmpR and Hfq and Their Regulatory Actions on the Vi Polysaccharide Capsular Antigen in Salmonella enterica Serovar Typhi. Curr Microbiol 2018; 75:773-778. [DOI: 10.1007/s00284-018-1447-7] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2017] [Accepted: 01/31/2018] [Indexed: 11/30/2022]
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9
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Bi-valent polysaccharides of Vi capsular and O9 O-antigen in attenuated Salmonella Typhimurium induce strong immune responses against these two antigens. NPJ Vaccines 2018; 3:1. [PMID: 29354293 PMCID: PMC5760606 DOI: 10.1038/s41541-017-0041-5] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2017] [Revised: 12/01/2017] [Accepted: 12/08/2017] [Indexed: 11/17/2022] Open
Abstract
Salmonella Typhi is the causative agent of typhoid fever in humans, responsible for approximately 21 million infections and 222,000 deaths globally each year. The current licensed vaccines provide moderate protection to recipients aged >2 years. Prior work on typhoid vaccines has focused on injectable Vi capsular polysaccharide or Vi–protein conjugates and live, oral attenuated S. Typhi vaccines to induce humoral anti-Vi antibodies, while the value and importance of anti-O9 antibodies is less well established. In this study, we constructed a S. Typhimurium strain that synthesizes Vi capsular antigen in vivo and produces the immunodominant O9-antigen polysaccharide instead of its native O4-antigen. The live recombinant attenuated S. Typhimurium mutants were effective in stimulating anti-Vi and anti-O9 antibodies in a mouse model, and the surface Vi capsular expression did not affect the immune responses against the O9 O-antigen polysaccharide. Moreover, the resulting anti-Vi and anti-O9 antibodies were effective at killing S. Typhi and other Salmonella spp. expressing Vi or O9 antigen polysaccharides and provided efficient protection against lethal challenge by S. Typhimurium and S. Enteritidis. Our work highlights the strategy of developing live attenuated S. Typhimurium vaccines to prevent typhoid fever by targeting the both Vi capsular and O9 O-polysaccharide antigens simultaneously. An attenuated strain of modified Salmonella Typhimurium bacteria could answer calls for a more effective typhoid fever vaccine. Current vaccines against typhoid-causing Salmonella Typhi are only moderately effective and potentially ineffective in children under 5 years. Qingke Kong and Roy Curtiss, leading a team of US and Chinese researchers, developed an attenuated version of the less-pathogenic S. Typhimurium that, when orally dosed in mice, expresses bacterial sugar-chain molecules known to elicit a strong immune response. In an in vitro assay, the antibodies produced by the mice in response to these molecules killed S. Typhi and related Salmonella bacteria with similar surface molecules, indicating a potential cross-protective ability. Further research would reveal whether this two-pronged live vaccine has the potential to protect in vivo, in live animals and in humans.
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10
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Xiong K, Zhu C, Chen Z, Zheng C, Tan Y, Rao X, Cong Y. Vi Capsular Polysaccharide Produced by Recombinant Salmonella enterica Serovar Paratyphi A Confers Immunoprotection against Infection by Salmonella enterica Serovar Typhi. Front Cell Infect Microbiol 2017; 7:135. [PMID: 28484685 PMCID: PMC5401900 DOI: 10.3389/fcimb.2017.00135] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2016] [Accepted: 03/31/2017] [Indexed: 11/28/2022] Open
Abstract
Enteric fever is predominantly caused by Salmonella enterica serovar Typhi and Salmonella enterica serovar Paratyphi A, and accounts for an annual global incidence of 26.9 millions. In recent years, the rate of S. Paratyphi A infection has progressively increased. Currently licensed vaccines for typhoid fever, live Ty21a vaccine, Vi subunit vaccine, and Vi-conjugate vaccine, confer inadequate cross immunoprotection against enteric fever caused by S. Paratyphi A. Therefore, development of bivalent vaccines against enteric fever is urgently required. The immunogenic Vi capsular polysaccharide is characteristically produced in S. Typhi, but it is absent in S. Paratyphi A. We propose that engineering synthesis of Vi in S. Paratyphi A live-attenuated vaccine may expand its protection range to cover S. Typhi. In this study, we cloned the viaB locus, which contains 10 genes responsible for Vi biosynthesis, and integrated into the chromosome of S. Paratyphi A CMCC 50093. Two virulence loci, htrA and phoPQ, were subsequently deleted to achieve a Vi-producing attenuated vaccine candidate. Our data showed that, despite more than 200 passages, the viaB locus was stably maintained in the chromosome of S. Paratyphi A and produced the Vi polysaccharide. Nasal immunization of the vaccine candidate stimulated high levels of Vi-specific and S. Paratyphi A-specific antibodies in mice sera as well as total sIgA in intestinal contents, and showed significant protection against wild-type challenge of S. Paratyphi A or S. Typhi. Our study show that the Vi-producing attenuated S. Paratyphi A is a promising bivalent vaccine candidate for the prevention of enteric fever.
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Affiliation(s)
- Kun Xiong
- Department of Microbiology, Third Military Medical UniversityChongqing, China
| | - Chunyue Zhu
- Outpatient Department of 95851 Unit of PLANanjing, China
| | - Zhijin Chen
- Department of Microbiology, Third Military Medical UniversityChongqing, China
| | - Chunping Zheng
- Department of Microbiology, Third Military Medical UniversityChongqing, China
| | - Yong Tan
- Department of Microbiology, Third Military Medical UniversityChongqing, China
| | - Xiancai Rao
- Department of Microbiology, Third Military Medical UniversityChongqing, China
| | - Yanguang Cong
- Department of Microbiology, Third Military Medical UniversityChongqing, China
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Salmonella enterica Serovar Typhi Lipopolysaccharide O-Antigen Modification Impact on Serum Resistance and Antibody Recognition. Infect Immun 2017; 85:IAI.01021-16. [PMID: 28167670 PMCID: PMC5364305 DOI: 10.1128/iai.01021-16] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2016] [Accepted: 01/30/2017] [Indexed: 11/20/2022] Open
Abstract
Salmonella enterica serovar Typhi is a human-restricted Gram-negative bacterial pathogen responsible for causing an estimated 27 million cases of typhoid fever annually, leading to 217,000 deaths, and current vaccines do not offer full protection. The O-antigen side chain of the lipopolysaccharide is an immunodominant antigen, can define host-pathogen interactions, and is under consideration as a vaccine target for some Gram-negative species. The composition of the O-antigen can be modified by the activity of glycosyltransferase (gtr) operons acquired by horizontal gene transfer. Here we investigate the role of two gtr operons that we identified in the S. Typhi genome. Strains were engineered to express specific gtr operons. Full chemical analysis of the O-antigens of these strains identified gtr-dependent glucosylation and acetylation. The glucosylated form of the O-antigen mediated enhanced survival in human serum and decreased complement binding. A single nucleotide deviation from an epigenetic phase variation signature sequence rendered the expression of this glucosylating gtr operon uniform in the population. In contrast, the expression of the acetylating gtrC gene is controlled by epigenetic phase variation. Acetylation did not affect serum survival, but phase variation can be an immune evasion mechanism, and thus, this modification may contribute to persistence in a host. In murine immunization studies, both O-antigen modifications were generally immunodominant. Our results emphasize that natural O-antigen modifications should be taken into consideration when assessing responses to vaccines, especially O-antigen-based vaccines, and that the Salmonellagtr repertoire may confound the protective efficacy of broad-ranging Salmonella lipopolysaccharide conjugate vaccines.
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Hu X, Chen Z, Xiong K, Wang J, Rao X, Cong Y. Vi capsular polysaccharide: Synthesis, virulence, and application. Crit Rev Microbiol 2016; 43:440-452. [PMID: 27869515 DOI: 10.1080/1040841x.2016.1249335] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
Abstract
Vi capsular polysaccharide, a linear homopolymer of α-1,4-linked N-acetylgalactosaminuronate, is characteristically produced by Salmonella enterica serovar Typhi. The Vi capsule covers the surface of the producing bacteria and serves as an virulence factor via inhibition of complement-mediated killing and promoting resistance against phagocytosis. Furthermore, Vi also represents a predominant protective antigen and plays a key role in the development of vaccines against typhoid fever. Herein, we reviewed the latest advances associated with the Vi polysaccharide, from its synthesis and transport within bacterial cells, mechanisms involved in virulence, immunological characteristics, and applications in vaccine, as well as its purification and detection methods.
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Affiliation(s)
- Xiaomei Hu
- a Department of Microbiology , Third Military Medical University , Chongqing , China
| | - Zhijin Chen
- a Department of Microbiology , Third Military Medical University , Chongqing , China
| | - Kun Xiong
- a Department of Microbiology , Third Military Medical University , Chongqing , China
| | - Jing Wang
- a Department of Microbiology , Third Military Medical University , Chongqing , China
| | - Xiancai Rao
- a Department of Microbiology , Third Military Medical University , Chongqing , China
| | - Yanguang Cong
- a Department of Microbiology , Third Military Medical University , Chongqing , China
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13
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Salmonella Extracellular Matrix Components Influence Biofilm Formation and Gallbladder Colonization. Infect Immun 2016; 84:3243-3251. [PMID: 27600501 DOI: 10.1128/iai.00532-16] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2016] [Accepted: 08/24/2016] [Indexed: 12/22/2022] Open
Abstract
Salmonella enterica serovar Typhi, the causative agent of typhoid fever in humans, forms biofilms encapsulated by an extracellular matrix (ECM). Biofilms facilitate colonization and persistent infection in gallbladders of humans and mouse models of chronic carriage. Individual roles of matrix components have not been completely elucidated in vitro or in vivo To examine individual functions, strains of Salmonella enterica serovar Typhimurium, the murine model of S Typhi, in which various ECM genes were deleted or added, were created to examine biofilm formation, colonization, and persistence in the gallbladder. Studies show that curli contributes most significantly to biofilm formation. Expression of Vi antigen decreased biofilm formation in vitro and virulence and bacterial survival in vivo without altering the examined gallbladder pro- or anti-inflammatory cytokines. Oppositely, loss of all ECM components (ΔwcaM ΔcsgA ΔyihO ΔbcsE) increased virulence and bacterial survival in vivo and reduced gallbladder interleukin-10 (IL-10) levels. Colanic acid and curli mutants had the largest defects in biofilm-forming ability and contributed most significantly to the virulence increase of the ΔwcaM ΔcsgA ΔyihO ΔbcsE mutant strain. While the ΔwcaM ΔcsgA ΔyihO ΔbcsE mutant was not altered in resistance to complement or growth in macrophages, it attached and invaded macrophages better than the wild-type (WT) strain. These data suggest that ECM components have various levels of importance in biofilm formation and gallbladder colonization and that the ECM diminishes disseminated disease in our model, perhaps by reducing cell attachment/invasion and dampening inflammation by maintaining/inducing IL-10 production. Understanding how ECM components aid acute disease and persistence could lead to improvements in therapeutic treatment of typhoid fever patients.
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Nieto PA, Pardo-Roa C, Salazar-Echegarai FJ, Tobar HE, Coronado-Arrázola I, Riedel CA, Kalergis AM, Bueno SM. New insights about excisable pathogenicity islands in Salmonella and their contribution to virulence. Microbes Infect 2016; 18:302-9. [DOI: 10.1016/j.micinf.2016.02.001] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2015] [Revised: 02/05/2016] [Accepted: 02/09/2016] [Indexed: 12/15/2022]
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15
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Hart PJ, O’Shaughnessy CM, Siggins MK, Bobat S, Kingsley RA, Goulding DA, Crump JA, Reyburn H, Micoli F, Dougan G, Cunningham AF, MacLennan CA. Differential Killing of Salmonella enterica Serovar Typhi by Antibodies Targeting Vi and Lipopolysaccharide O:9 Antigen. PLoS One 2016; 11:e0145945. [PMID: 26741681 PMCID: PMC4712142 DOI: 10.1371/journal.pone.0145945] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2015] [Accepted: 12/10/2015] [Indexed: 01/08/2023] Open
Abstract
Salmonella enterica serovar Typhi expresses a capsule of Vi polysaccharide, while most Salmonella serovars, including S. Enteritidis and S. Typhimurium, do not. Both S. Typhi and S. Enteritidis express the lipopolysaccharide O:9 antigen, yet there is little evidence of cross-protection from anti-O:9 antibodies. Vaccines based on Vi polysaccharide have efficacy against typhoid fever, indicating that antibodies against Vi confer protection. Here we investigate the role of Vi capsule and antibodies against Vi and O:9 in antibody-dependent complement- and phagocyte-mediated killing of Salmonella. Using isogenic Vi-expressing and non-Vi-expressing derivatives of S. Typhi and S. Typhimurium, we show that S. Typhi is inherently more sensitive to serum and blood than S. Typhimurium. Vi expression confers increased resistance to both complement- and phagocyte-mediated modalities of antibody-dependent killing in human blood. The Vi capsule is associated with reduced C3 and C5b-9 deposition, and decreased overall antibody binding to S. Typhi. However, purified human anti-Vi antibodies in the presence of complement are able to kill Vi-expressing Salmonella, while killing by anti-O:9 antibodies is inversely related to Vi expression. Human serum depleted of antibodies to antigens other than Vi retains the ability to kill Vi-expressing bacteria. Our findings support a protective role for Vi capsule in preventing complement and phagocyte killing of Salmonella that can be overcome by specific anti-Vi antibodies, but only to a limited extent by anti-O:9 antibodies.
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Affiliation(s)
- Peter J. Hart
- School of Immunity and Infection, College of Medicine and Dental Sciences, University of Birmingham, Birmingham, United Kingdom
| | - Colette M. O’Shaughnessy
- School of Immunity and Infection, College of Medicine and Dental Sciences, University of Birmingham, Birmingham, United Kingdom
| | - Matthew K. Siggins
- School of Immunity and Infection, College of Medicine and Dental Sciences, University of Birmingham, Birmingham, United Kingdom
| | - Saeeda Bobat
- School of Immunity and Infection, College of Medicine and Dental Sciences, University of Birmingham, Birmingham, United Kingdom
| | - Robert A. Kingsley
- Wellcome Trust Sanger Institute, Wellcome Trust Genome Campus, Hinxton, Cambridge, United Kingdom
| | - David A. Goulding
- Wellcome Trust Sanger Institute, Wellcome Trust Genome Campus, Hinxton, Cambridge, United Kingdom
| | - John A. Crump
- Centre for International Health, University of Otago, Dunedin, New Zealand
- Kilimanjaro Christian Medical Centre and Kilimanjaro Christian Medical University College, Tumaini University, Moshi, Tanzania
- Division of Infectious Diseases and International Health, Duke University Medical Center, Durham, United States of America
- Duke Global Health Institute, Duke University, Durham, United States of America
| | - Hugh Reyburn
- London School of Hygiene and Tropical Medicine, Keppel Street, London, United Kingdom
| | - Francesca Micoli
- Sclavo-Behring Vaccines Institute for Global Health, a GlaxoSmithKline Company, Siena, Italy
| | - Gordon Dougan
- Centre for International Health, University of Otago, Dunedin, New Zealand
| | - Adam F. Cunningham
- School of Immunity and Infection, College of Medicine and Dental Sciences, University of Birmingham, Birmingham, United Kingdom
| | - Calman A. MacLennan
- School of Immunity and Infection, College of Medicine and Dental Sciences, University of Birmingham, Birmingham, United Kingdom
- Wellcome Trust Sanger Institute, Wellcome Trust Genome Campus, Hinxton, Cambridge, United Kingdom
- Jenner Institute, Nuffield Department of Medicine, University of Oxford, Oxford, United Kingdom
- * E-mail:
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16
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Now you see me, now you don't: the interaction of Salmonella with innate immune receptors. Nat Rev Microbiol 2015; 13:206-16. [PMID: 25749454 DOI: 10.1038/nrmicro3428] [Citation(s) in RCA: 105] [Impact Index Per Article: 11.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Salmonella enterica serovars are associated with an estimated 1 million deaths annually and are also useful model organisms for investigating the mechanisms of host-bacterium interactions. The insights gained from studies on non-typhoidal Salmonella (NTS) serovars have provided a fascinating overview of the mechanisms by which the innate immune system detects and responds to bacterial pathogens. However, specific virulence factors and changes in virulence gene regulation in S. enterica subsp. enterica serovar Typhi alter the innate immune responses to this pathogen. In this Review, we compare and contrast the interactions of S. Typhi and NTS serovars with host innate immune receptors and discuss why the disease manifestations associated with S. Typhi infection differ considerably from those associated with the closely related NTS serovars.
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Abstract
Attenuated Salmonella vaccines can be administered orally to deliver recombinant antigens to mucosal surfaces inducing a protective immune response against a variety of targeted pathogens. A number of exciting new approaches and technologies for attenuated Salmonella vaccines have been developed recently. However, a disconnect remains between results obtained with mice in preclinical studies and results obtained in human clinical trials. This is due to an incomplete understanding of Salmonella Typhi interactions with human hosts and inadequate animal models available for study. In this review, the authors describe recent progress in identifying important differences underlying S. Typhi-host interactions, the development of novel approaches to vaccine design and six recent clinical trials evaluating Salmonella-vectored vaccines.
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Affiliation(s)
- Kenneth L Roland
- The Biodesign Institute, Arizona State University, 1001 S. McAllister Avenue, Tempe, AZ 85287-5401, USA
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18
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Mastroeni P, Grant A. Dynamics of spread of Salmonella enterica in the systemic compartment. Microbes Infect 2013; 15:849-57. [PMID: 24183878 DOI: 10.1016/j.micinf.2013.10.003] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2013] [Accepted: 10/09/2013] [Indexed: 12/21/2022]
Abstract
Traditional microbiological and immunological tools, combined with modern imaging, and molecular and mathematical approaches, have revealed the dispersive nature of Salmonella infections. Bacterial escape from infected cells, spread in the tissues and attempts to restrain this process by the host give rise to fascinating scenarios that underpin the pathogenesis of salmonelloses.
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Affiliation(s)
- Pietro Mastroeni
- Department of Veterinary Medicine, University of Cambridge, Madingley Road, Cambridge CB3 0ES, United Kingdom.
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19
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Marshall JL, Flores-Langarica A, Kingsley RA, Hitchcock JR, Ross EA, Lopez-Macias C, Lakey J, Martin LB, Toellner KM, MacLennan CA, MacLennan IC, Henderson IR, Dougan G, Cunningham AF. The capsular polysaccharide Vi from Salmonella typhi is a B1b antigen. JOURNAL OF IMMUNOLOGY (BALTIMORE, MD. : 1950) 2012; 189:5527-32. [PMID: 23162127 PMCID: PMC3605773 DOI: 10.4049/jimmunol.1103166] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Vaccination with purified capsular polysaccharide Vi Ag from Salmonella typhi can protect against typhoid fever, although the mechanism for its efficacy is not clearly established. In this study, we have characterized the B cell response to this vaccine in wild-type and T cell-deficient mice. We show that immunization with typhoid Vi polysaccharide vaccine rapidly induces proliferation in B1b peritoneal cells, but not in B1a cells or marginal zone B cells. This induction of B1b proliferation is concomitant with the detection of splenic Vi-specific Ab-secreting cells and protective Ab in Rag1-deficient B1b cell chimeras generated by adoptive transfer-induced specific Ab after Vi immunization. Furthermore, Ab derived from peritoneal B cells is sufficient to confer protection against Salmonella that express Vi Ag. Expression of Vi by Salmonella during infection did not inhibit the development of early Ab responses to non-Vi Ags. Despite this, the protection conferred by immunization of mice with porin proteins from Salmonella, which induce Ab-mediated protection, was reduced postinfection with Vi-expressing Salmonella, although protection was not totally abrogated. This work therefore suggests that, in mice, B1b cells contribute to the protection induced by Vi Ag, and targeting non-Vi Ags as subunit vaccines may offer an attractive strategy to augment current Vi-based vaccine strategies.
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Affiliation(s)
- Jennifer L. Marshall
- Medical Research Council Centre for Immune Regulation, School of Immunity and Infection and Institute for Biomedical Research, University of Birmingham, Edgbaston, Birmingham, B15 2TT, UK
| | - Adriana Flores-Langarica
- Medical Research Council Centre for Immune Regulation, School of Immunity and Infection and Institute for Biomedical Research, University of Birmingham, Edgbaston, Birmingham, B15 2TT, UK
| | - Robert A. Kingsley
- Wellcome Trust Sanger Institute, Wellcome Trust Genome Campus, Hinxton, Cambridge, CB10 1SA, UK
| | - Jessica R. Hitchcock
- Medical Research Council Centre for Immune Regulation, School of Immunity and Infection and Institute for Biomedical Research, University of Birmingham, Edgbaston, Birmingham, B15 2TT, UK
| | - Ewan A. Ross
- Medical Research Council Centre for Immune Regulation, School of Immunity and Infection and Institute for Biomedical Research, University of Birmingham, Edgbaston, Birmingham, B15 2TT, UK
| | - Constantino Lopez-Macias
- Medical Research Unit on Immunochemistry, Specialties Hospital, National Medical Centre “Siglo XXI” Mexican Institute for Social Security (IMSS), Mexico City, Mexico
| | - Jeremy Lakey
- Institute for Cell and Molecular Biosciences, University of Newcastle, Newcastle upon Tyne, NE2 4HH, UK
| | - Laura B. Martin
- Novartis Vaccines Institute for Global Health, Via Fiorentina 1, 53100 Siena, Italy
| | - Kai-Michael Toellner
- Medical Research Council Centre for Immune Regulation, School of Immunity and Infection and Institute for Biomedical Research, University of Birmingham, Edgbaston, Birmingham, B15 2TT, UK
| | - Calman A. MacLennan
- Novartis Vaccines Institute for Global Health, Via Fiorentina 1, 53100 Siena, Italy
| | - Ian C MacLennan
- Medical Research Council Centre for Immune Regulation, School of Immunity and Infection and Institute for Biomedical Research, University of Birmingham, Edgbaston, Birmingham, B15 2TT, UK
| | - Ian R. Henderson
- Medical Research Council Centre for Immune Regulation, School of Immunity and Infection and Institute for Biomedical Research, University of Birmingham, Edgbaston, Birmingham, B15 2TT, UK
| | - Gordon Dougan
- Wellcome Trust Sanger Institute, Wellcome Trust Genome Campus, Hinxton, Cambridge, CB10 1SA, UK
| | - Adam F. Cunningham
- Medical Research Council Centre for Immune Regulation, School of Immunity and Infection and Institute for Biomedical Research, University of Birmingham, Edgbaston, Birmingham, B15 2TT, UK
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20
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Vi antigen of Salmonella enetrica serovar Typhi — biosynthesis, regulation and its use as vaccine candidate. Open Life Sci 2012. [DOI: 10.2478/s11535-012-0082-8] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
AbstractVi capsular polysaccharide (Vi antigen) was first identified as the virulence antigen of Salmonella enterica serovar Typhi (S. Typhi), the causative agent of typhoid fever in humans. The presence of Vi antigen differentiates S. Typhi from other serovars of Salmonella. Vi antigen is a linear polymer consisting of α-1,4-linked-N-acetyl-galactosaminuronate, whose expression is controlled by three chromosomal loci, namely viaA, viaB and ompB. Both viaA and viaB region are present on Salmonella Pathogenicity Island-7, a large, mosaic, genetic island. The viaA region encodes a positive regulator and the viaB locus is composed of 11 genes designated tviA-tviE (for Vi biosyhthesis), vexA-vexE (for Vi antigen export) and ORF 11. Vi polysaccharide is synthesized from UDP-N-acetyl glucosamine in a series of steps requiring TviB, TviC, and TviE, and regulation of Vi polysaccharide synthesis is controlled by two regulatory systems, rscB-rscC (viaA locus) and ompR-envZ (ompB locus), which respond to changes in osmolarity. This antigen is highly immunogenic and has been used for the formulation of one of the currently available vaccines against typhoid. Despite advancement in the area of vaccinology, its pace of progress needs to be accelerated and effective control programmes will be needed for proper disease management.
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Holt KE, Dutta S, Manna B, Bhattacharya SK, Bhaduri B, Pickard DJ, Ochiai RL, Ali M, Clemens JD, Dougan G. High-resolution genotyping of the endemic Salmonella Typhi population during a Vi (typhoid) vaccination trial in Kolkata. PLoS Negl Trop Dis 2012; 6:e1490. [PMID: 22303491 PMCID: PMC3269425 DOI: 10.1371/journal.pntd.0001490] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2011] [Accepted: 12/09/2011] [Indexed: 11/18/2022] Open
Abstract
BACKGROUND Typhoid fever, caused by Salmonella enterica serovar Typhi (S. Typhi), is a major health problem especially in developing countries. Vaccines against typhoid are commonly used by travelers but less so by residents of endemic areas. METHODOLOGY We used single nucleotide polymorphism (SNP) typing to investigate the population structure of 372 S. Typhi isolated during a typhoid disease burden study and Vi vaccine trial in Kolkata, India. Approximately sixty thousand people were enrolled for fever surveillance for 19 months prior to, and 24 months following, Vi vaccination of one third of the study population (May 2003-December 2006, vaccinations given December 2004). PRINCIPAL FINDINGS A diverse S. Typhi population was detected, including 21 haplotypes. The most common were of the H58 haplogroup (69%), which included all multidrug resistant isolates (defined as resistance to chloramphenicol, ampicillin and co-trimoxazole). Quinolone resistance was particularly high among H58-G isolates (97% Nalidixic acid resistant, 30% with reduced susceptibility to ciprofloxacin). Multiple typhoid fever episodes were detected in 22 households, however household clustering was not associated with specific S. Typhi haplotypes. CONCLUSIONS Typhoid fever in Kolkata is caused by a diverse population of S. Typhi, however H58 haplotypes dominate and are associated with multidrug and quinolone resistance. Vi vaccination did not obviously impact on the haplotype population structure of the S. Typhi circulating during the study period.
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Affiliation(s)
- Kathryn E Holt
- Department of Microbiology and Immunology, University of Melbourne, Melbourne, Australia.
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22
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Jansen AM, Hall LJ, Clare S, Goulding D, Holt KE, Grant AJ, Mastroeni P, Dougan G, Kingsley RA. A Salmonella Typhimurium-Typhi genomic chimera: a model to study Vi polysaccharide capsule function in vivo. PLoS Pathog 2011; 7:e1002131. [PMID: 21829346 PMCID: PMC3145788 DOI: 10.1371/journal.ppat.1002131] [Citation(s) in RCA: 38] [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: 12/21/2010] [Accepted: 05/04/2011] [Indexed: 11/18/2022] Open
Abstract
The Vi capsular polysaccharide is a virulence-associated factor expressed by Salmonella enterica serotype Typhi but absent from virtually all other Salmonella serotypes. In order to study this determinant in vivo, we characterised a Vi-positive S. Typhimurium (C5.507 Vi+), harbouring the Salmonella pathogenicity island (SPI)-7, which encodes the Vi locus. S. Typhimurium C5.507 Vi+ colonised and persisted in mice at similar levels compared to the parent strain, S. Typhimurium C5. However, the innate immune response to infection with C5.507 Vi+ and SGB1, an isogenic derivative not expressing Vi, differed markedly. Infection with C5.507 Vi+ resulted in a significant reduction in cellular trafficking of innate immune cells, including PMN and NK cells, compared to SGB1 Vi− infected animals. C5.507 Vi+ infection stimulated reduced numbers of TNF-α, MIP-2 and perforin producing cells compared to SGB1 Vi−. The modulating effect associated with Vi was not observed in MyD88−/− and was reduced in TLR4−/− mice. The presence of the Vi capsule also correlated with induction of the anti-inflammatory cytokine IL-10 in vivo, a factor that impacted on chemotaxis and the activation of immune cells in vitro. Pathogens of the genus Salmonella are closely related yet cause distinct diseases and have different host-range. Salmonella Typhi causes a systemic disease called typhoid fever specifically in humans, and is commonly modelled using a surrogate host-pathogen combination, namely Salmonella Typhimurium infection in mice. However, key virulence mechanisms of S. Typhi depend on the Vi polysaccharide capsule that is not expressed by S. Typhimurium. In order to study the function of the Vi capsule we characterised a S. Typhimurium/S. Typhi chimera that expresses the Vi polysaccharide in a regulated manner similar to that previously described in S. Typhi. The impact of Vi expression on immune cell populations in the spleen and mesenteric lymph nodes, and the pattern of intracellular cytokine response was determined 24 hours after i.v or i.g inoculation. Infection of mice with S. Typhimurium expressing Vi polysaccharide resulted in a blunted response in recruitment of NK and PMN cells. This was reflected in a blunted proinflammatory cytokine response, but a striking increase in the anti-inflammatory cytokine IL-10. IL-10 was expressed in macrophage, dendritic cells and NK cells in the mouse spleen, specifically in response to infection with S. Typhimurium expressing Vi polysaccharide. Indeed, neutralisation of this IL-10 production lead to increased migration and activation of splenocytes in vitro. This model can be used to develop Vi based vaccines as well as to study the impact of Vi expression on pathogenesis.
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Affiliation(s)
- Angela M. Jansen
- The Wellcome Trust Sanger Institute, The Wellcome Trust Genome Campus, Hinxton, Cambridge, United Kingdom
| | - Lindsay J. Hall
- The Wellcome Trust Sanger Institute, The Wellcome Trust Genome Campus, Hinxton, Cambridge, United Kingdom
| | - Simon Clare
- The Wellcome Trust Sanger Institute, The Wellcome Trust Genome Campus, Hinxton, Cambridge, United Kingdom
| | - David Goulding
- The Wellcome Trust Sanger Institute, The Wellcome Trust Genome Campus, Hinxton, Cambridge, United Kingdom
| | - Kathryn E. Holt
- The Wellcome Trust Sanger Institute, The Wellcome Trust Genome Campus, Hinxton, Cambridge, United Kingdom
| | - Andrew J. Grant
- Department of Veterinary Medicine, University of Cambridge, Cambridge, United Kingdom
| | - Piero Mastroeni
- Department of Veterinary Medicine, University of Cambridge, Cambridge, United Kingdom
| | - Gordon Dougan
- The Wellcome Trust Sanger Institute, The Wellcome Trust Genome Campus, Hinxton, Cambridge, United Kingdom
| | - Robert A. Kingsley
- The Wellcome Trust Sanger Institute, The Wellcome Trust Genome Campus, Hinxton, Cambridge, United Kingdom
- * E-mail:
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