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Ma L, Dewan KK, Taylor-Mulneix DL, Wagner SM, Linz B, Rivera I, Su Y, Caulfield AD, Blas-Machado U, Harvill ET. Pertactin contributes to shedding and transmission of Bordetella bronchiseptica. PLoS Pathog 2021; 17:e1009735. [PMID: 34347835 PMCID: PMC8336816 DOI: 10.1371/journal.ppat.1009735] [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: 10/22/2020] [Accepted: 06/21/2021] [Indexed: 11/25/2022] Open
Abstract
Whooping cough is resurging in the United States despite high vaccine coverage. The rapid rise of Bordetella pertussis isolates lacking pertactin (PRN), a key vaccine antigen, has led to concerns about vaccine-driven evolution. Previous studies showed that pertactin can mediate binding to mammalian cells in vitro and act as an immunomodulatory factor in resisting neutrophil-mediated clearance. To further investigate the role of PRN in vivo, we examined the functions of pertactin in the context of a more naturally low dose inoculation experimental system using C3H/HeJ mice that is more sensitive to effects on colonization, growth and spread within the respiratory tract, as well as an experimental approach to measure shedding and transmission between hosts. A B. bronchiseptica pertactin deletion mutant was found to behave similarly to its wild-type (WT) parental strain in colonization of the nasal cavity, trachea, and lungs of mice. However, the pertactin-deficient strain was shed from the nares of mice in much lower numbers, resulting in a significantly lower rate of transmission between hosts. Histological examination of respiratory epithelia revealed that pertactin-deficient bacteria induced substantially less inflammation and mucus accumulation than the WT strain and in vitro assays verified the effect of PRN on the induction of TNF-α by murine macrophages. Interestingly, only WT B. bronchiseptica could be recovered from the spleen of infected mice and were further observed to be intracellular among isolated splenocytes, indicating that pertactin contributes to systemic dissemination involving intracellular survival. These results suggest that pertactin can mediate interactions with immune cells and augments inflammation that contributes to bacterial shedding and transmission between hosts. Understanding the relative contributions of various factors to inflammation, mucus production, shedding and transmission will guide novel strategies to interfere with the reemergence of pertussis. B. pertussis strains lacking pertactin have been rising in prevalence especially in countries using acellular vaccines containing pertactin as a key, membrane-associated surface antigen. Previous in vivo studies revealed immunomodulatory properties of pertactin in conventional B. pertussis infection models in which roughly one million bacteria are delivered into lungs, leading to severe pneumonic disease and a strong immune response. However, natural infections begin in the nasopharyngeal region, progress slowly during a prolonged catarrhal stage, only later reaching the trachea and rarely involve the lungs. In this study, a more natural experimental system takes advantage of the ability of B. bronchiseptica, a closely related species, to naturally colonize mice with inocula as low as 5 colony forming units (CFU). In this system B. bronchiseptica can be observed to efficiently colonize, grow, spread within the respiratory tract, is shed from the nares, and transmits between hosts, allowing each of these steps to be measured and studied. Under these conditions, an isogenic pertactin deletion strain was indistinguishable from its parental strain in its abilities to colonize, grow in numbers and spread within the respiratory tract. However, the pertactin-deficient mutant was shed from these mice in lower numbers than wild type, and was defective in transmission between mice. These assays reveal novel roles of pertactin in the induction of inflammation, mucus production, shedding and transmission.
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Affiliation(s)
- Longhuan Ma
- Department of Infectious Diseases, College of Veterinary Medicine, University of Georgia, Athens, Georgia, United States of America
- * E-mail:
| | - Kalyan K. Dewan
- Department of Infectious Diseases, College of Veterinary Medicine, University of Georgia, Athens, Georgia, United States of America
| | - Dawn L. Taylor-Mulneix
- Department of Infectious Diseases, College of Veterinary Medicine, University of Georgia, Athens, Georgia, United States of America
| | - Shannon M. Wagner
- Department of Infectious Diseases, College of Veterinary Medicine, University of Georgia, Athens, Georgia, United States of America
| | - Bodo Linz
- Department of Infectious Diseases, College of Veterinary Medicine, University of Georgia, Athens, Georgia, United States of America
| | - Israel Rivera
- Department of Infectious Diseases, College of Veterinary Medicine, University of Georgia, Athens, Georgia, United States of America
| | - Yang Su
- Department of Infectious Diseases, College of Veterinary Medicine, University of Georgia, Athens, Georgia, United States of America
- Department of Biochemistry, University of Georgia, Athens, Georgia, United States of America
| | - Amanda D. Caulfield
- Department of Infectious Diseases, College of Veterinary Medicine, University of Georgia, Athens, Georgia, United States of America
| | - Uriel Blas-Machado
- Department of Pathology, Athens Veterinary Diagnostic Laboratory, College of Veterinary Medicine, University of Georgia, Athens, Georgia, United States of America
| | - Eric T. Harvill
- Department of Infectious Diseases, College of Veterinary Medicine, University of Georgia, Athens, Georgia, United States of America
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Oviedo JM, Surmann K, Gorgojo JP, Valdez H, Dhople VM, Lamberti Y, Völker U, Rodriguez ME. Shotgun proteomic analysis of Bordetella parapertussis provides insights into the physiological response to iron starvation and potential new virulence determinants absent in Bordetella pertussis. J Proteomics 2019; 206:103448. [PMID: 31325608 DOI: 10.1016/j.jprot.2019.103448] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2019] [Revised: 06/19/2019] [Accepted: 07/11/2019] [Indexed: 01/05/2023]
Abstract
Bordetella parapertussis is one of the pathogens that cause whooping cough. Even though its incidence has been rising in the last decades, this species remained poorly investigated. This study reports the first extensive proteome analysis of this bacterium. In an attempt to gain some insight into the infective phenotype, we evaluated the response of B. parapertussis to iron starvation, a critical stress the bacteria face during infection. Among other relevant findings, we observed that the adaptation to this condition involves significant changes in the abundance of two important virulence factors of this pathogen, namely, adenylate cyclase and the O-antigen. We further used the proteomic data to search for B. parapertussis proteins that are absent or classified as pseudogenes in the genome of Bordetella pertussis to unravel differences between both whooping cough causative agents. Among them, we identified proteins involved in stress resistance and virulence determinants that might help to explain the differences in the pathogenesis of these species and the lack of cross-protection of current acellular vaccines. Altogether, these results contribute to a better understanding of B. parapertussis biology and pathogenesis. SIGNIFICANCE: Whooping cough is a reemerging disease caused by both Bordetella pertussis and Bordetella parapertussis. Current vaccines fail to induce protection against B parapertussis and the incidence of this species has been rising over the years. The proteomic analysis of this study provided relevant insights into potential virulence determinants of this poorly-studied pathogen. It further identified proteins produced by B. parapertussis not present in B. pertussis, which might help to explain both the differences on their respective infectious process and the current vaccine failure. Altogether, the results of this study contribute to the better understanding of B. parapertussis pathogenesis and the eventual design of improved preventive strategies against whooping cough.
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Affiliation(s)
- Juan Marcos Oviedo
- CINDEFI (UNLP CONICET La Plata), Facultad de Ciencias Exactas, Universidad Nacional de La Plata, La Plata, Argentina
| | - Kristin Surmann
- Department of Functional Genomics, Interfaculty Institute for Genetics and Functional Genomics, University Medicine Greifswald, Greifswald, Germany
| | - Juan Pablo Gorgojo
- CINDEFI (UNLP CONICET La Plata), Facultad de Ciencias Exactas, Universidad Nacional de La Plata, La Plata, Argentina
| | - Hugo Valdez
- CINDEFI (UNLP CONICET La Plata), Facultad de Ciencias Exactas, Universidad Nacional de La Plata, La Plata, Argentina
| | - Vishnu M Dhople
- Department of Functional Genomics, Interfaculty Institute for Genetics and Functional Genomics, University Medicine Greifswald, Greifswald, Germany
| | - Yanina Lamberti
- CINDEFI (UNLP CONICET La Plata), Facultad de Ciencias Exactas, Universidad Nacional de La Plata, La Plata, Argentina
| | - Uwe Völker
- Department of Functional Genomics, Interfaculty Institute for Genetics and Functional Genomics, University Medicine Greifswald, Greifswald, Germany
| | - María Eugenia Rodriguez
- CINDEFI (UNLP CONICET La Plata), Facultad de Ciencias Exactas, Universidad Nacional de La Plata, La Plata, Argentina.
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Ekundayo TC, Okoh AI. Pathogenomics of Virulence Traits of Plesiomonas shigelloides That Were Deemed Inconclusive by Traditional Experimental Approaches. Front Microbiol 2018; 9:3077. [PMID: 30627119 PMCID: PMC6309461 DOI: 10.3389/fmicb.2018.03077] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2018] [Accepted: 11/29/2018] [Indexed: 12/31/2022] Open
Abstract
One of the major challenges of modern medicine includes the failure of conventional protocols to characterize the pathogenicity of emerging pathogens. This is particularly apparent in the case of Plesiomonas shigelloides. Although a number of infections have been linked to this microorganism, experimental evidence of its virulence factors (VFs), obtained by traditional approaches, is somewhat inconclusive. Hence, it remains unclear whether P. shigelloides is a true or opportunistic one. In the current study, four publicly available whole-genome sequences of P. shigelloides (GN7, NCTC10360, 302-73, and LS1) were profiled using bioinformatics platforms to determine the putative candidate VFs to characterize the bacterial pathogenicity. Overall, 134 unique open reading frames (ORFs) were identified that were homologous or orthologous to virulence genes identified in other pathogens. Of these, 52.24% (70/134) were jointly shared by the strains. The numbers of strain-specific virulence traits were 4 in LS1; 7 in NCTC10360; 10 in 302-73; and 15 in GN7. The pathogenicity islands (PAIs) common to all the strains accounted for 24.07% ORFs. The numbers of PAIs exclusive to each strain were 8 in 302-73; 11 in NCTC10360; 14 in GN7; and 18 in LS1. A PAI encoding Vibrio cholerae ToxR-activated gene d protein was specific to 302-73, GN7, and NCTC10360 strains. Out of 33 antibiotic multi-resistance genes identified, 16 (48.48%) genes were intrinsic to all strains. Further, 17 (22.08%) of 77 antibiotic resistance islands were found in all the strains. Out of 23 identified distinct insertion sequences, 13 were only harbored by strain LS1. The number of intact prophages identified in the strains was 1 in GN7; 2 in 302-73; and 2 in NCTC10360. Further, 1 CRISPR element was identified in LS1; 2 in NCTC10360; and 8 in 302-73. Fifteen (78.95%) of 19 secretion systems and secretion effector variants were identified in all the strains. In conclusion, certain P. shigelloides strains might possess VFs associated with gastroenteritis and extraintestinal infections. However, the role of host factors in the onset of infections should not be undermined.
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Affiliation(s)
- Temitope C. Ekundayo
- SAMRC Microbial Water Quality Monitoring Centre, University of Fort Hare, Alice, South Africa
- Applied and Environmental Microbiology Research Group, Department of Biochemistry and Microbiology, University of Fort Hare, Alice, South Africa
- Department of Biological Sciences, University of Medical Sciences, Ondo City, Nigeria
| | - Anthony I. Okoh
- SAMRC Microbial Water Quality Monitoring Centre, University of Fort Hare, Alice, South Africa
- Applied and Environmental Microbiology Research Group, Department of Biochemistry and Microbiology, University of Fort Hare, Alice, South Africa
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Novikov A, Marr N, Caroff M. A comparative study of the complete lipopolysaccharide structures and biosynthesis loci of Bordetella avium, B. hinzii, and B. trematum. Biochimie 2018; 159:81-92. [PMID: 30578925 DOI: 10.1016/j.biochi.2018.12.011] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2018] [Accepted: 12/17/2018] [Indexed: 10/27/2022]
Abstract
A dozen species of human and animal pathogens have been described to date in the Bordetella genus, with the majority being respiratory tract pathogens. Bordetella avium lipopolysaccharides have been shown to be important virulence factors for this bird pathogen. B. hinzii is closely related to the B. avium species, but has also been isolated from humans. B. trematum is associated to ear and blood infections in humans. Its lipid A structure, the biological active moiety of LPS, was found to be closely related to those of B. avium and B. hinzii. It is important to unveil the subtle structural modifications orchestrated during the LPS biosynthetic pathway to better understand host adaptation. The present data are also important in the context of deciphering the virulence pathways of this important genus containing the major pathogens B. pertussis and B. parapertussis, responsible for whooping cough. We recently reported the isolated lipid A structures of the three presented species, following the previously identified O-chain structures. In the present study, we provide details on the free and O-chain-linked core oligosaccharides which were required to characterize the complete LPS structures. Data are presented here in relation to relevant biosynthesis genes. The present characterization of the three species is well illustrated by Matrix Assisted Laser Desorption Mass Spectrometry experiments, and data were obtained mainly on native LPS molecules for the first time.
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Affiliation(s)
- Alexey Novikov
- LPS-BioSciences, Bâtiment 409, Université de Paris-Sud, Paris-Saclay, F-91405, Orsay, France
| | | | - Martine Caroff
- LPS-BioSciences, Bâtiment 409, Université de Paris-Sud, Paris-Saclay, F-91405, Orsay, France; Institute for Integrative Biology of the Cell (I2BC), CEA, CNRS, Université de Paris-Sud, Université Paris-Saclay, F-91405, Orsay, France.
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Ectopic Expression of O Antigen in Bordetella pertussis by a Novel Genomic Integration System. mSphere 2018; 3:mSphere00417-17. [PMID: 29404410 PMCID: PMC5784241 DOI: 10.1128/msphere.00417-17] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2017] [Accepted: 12/18/2017] [Indexed: 11/20/2022] Open
Abstract
Some bacterial phenotypes emerge through the cooperative functions of a number of genes residing within a large genetic locus. To transfer the phenotype of one bacterium to another, a means to introduce the large genetic locus into the recipient bacterium is needed. Therefore, we developed a novel system by combining the advantages of a bacterial artificial chromosome vector and phage-derived gene integration machinery. In this study, we succeeded for the first time in introducing a gene locus involved in O antigen biosynthesis of Bordetella bronchiseptica into the chromosome of B. pertussis, which intrinsically lacks O antigen, and using this system we analyzed phenotypic alterations in the resultant mutant strain of B. pertussis. The present results demonstrate that this system successfully accomplished the above-described purpose. We consider this system to be applicable to a number of bacteria other than Bordetella. We describe a novel genome integration system that enables the introduction of DNA fragments as large as 50 kbp into the chromosomes of recipient bacteria. This system, named BPI, comprises a bacterial artificial chromosome vector and phage-derived gene integration machinery. We introduced the wbm locus of Bordetella bronchiseptica, which is required for O antigen biosynthesis, into the chromosome of B. pertussis, which intrinsically lacks O antigen, using the BPI system. After the introduction of the wbm locus, B. pertussis presented an additional substance in the lipooligosaccharide fraction that was specifically recognized by the anti-B. bronchiseptica antibody but not the anti-B. pertussis antibody, indicating that B. pertussis expressed O antigen corresponding to that of B. bronchiseptica. O antigen-expressing B. pertussis was less sensitive to the bactericidal effects of serum and polymyxin B than the isogenic parental strain. In addition, an in vivo competitive infection assay showed that O antigen-expressing B. pertussis dominantly colonized the mouse respiratory tract over the parental strain. These results indicate that the BPI system provides a means to alter the phenotypes of bacteria by introducing large exogenous DNA fragments. IMPORTANCE Some bacterial phenotypes emerge through the cooperative functions of a number of genes residing within a large genetic locus. To transfer the phenotype of one bacterium to another, a means to introduce the large genetic locus into the recipient bacterium is needed. Therefore, we developed a novel system by combining the advantages of a bacterial artificial chromosome vector and phage-derived gene integration machinery. In this study, we succeeded for the first time in introducing a gene locus involved in O antigen biosynthesis of Bordetella bronchiseptica into the chromosome of B. pertussis, which intrinsically lacks O antigen, and using this system we analyzed phenotypic alterations in the resultant mutant strain of B. pertussis. The present results demonstrate that this system successfully accomplished the above-described purpose. We consider this system to be applicable to a number of bacteria other than Bordetella.
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Dewan KK, Taylor-Mulneix DL, Hilburger LJ, Rivera I, Preston A, Harvill ET. An Extracellular Polysaccharide Locus Required for Transmission of Bordetella bronchiseptica. J Infect Dis 2017; 216:899-906. [PMID: 28973366 PMCID: PMC5853889 DOI: 10.1093/infdis/jix251] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2016] [Accepted: 06/19/2017] [Indexed: 12/02/2022] Open
Abstract
Background The lack of animal models to experimentally study how infectious agents transmit between hosts limits our understanding of what makes some pathogens so contagious. Methods We recently developed a Bordetella bronchiseptica mouse model to study transmission and have used it to assess, for the first time, which of several well-studied "virulence factors" common to classical Bordetella species contribute to transmission. Results Among 13 mutants screened, a mutant lacking an extracellular polysaccharide (EPS) locus consistently failed to transmit. The loss of EPS had no obvious effect on in vitro characteristics of growth, adherence, cytotoxicity, or serum resistance, though it profoundly reduced the ability of the mutant to colonize the lower respiratory tract of mice. While wild-type B. bronchiseptica was shed from colonized mice and efficiently transmitted to cage-mates, the mutant colonized less efficiently, shed at lower numbers, and consequently did not transmit to naive animals. Conclusions These results have important implications for potential roles of polysaccharides in the pathogenesis and transmission of Bordetella species as well as other respiratory pathogens. Cases of pertussis (whooping cough) caused by Bordetella pertussis are on the rise, and understanding factors that contribute to their spread is critical to its control.
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Affiliation(s)
- Kalyan K Dewan
- Center for Vaccines and Immunology, Department of Infectious Diseases, University of Georgia, Athens
| | - Dawn L Taylor-Mulneix
- Center for Vaccines and Immunology, Department of Infectious Diseases, University of Georgia, Athens
| | | | - Israel Rivera
- Infectious Disease Graduate Program, University of Georgia, Athens
| | - Andrew Preston
- Milner Centre for Evolution and Department of Biology and Biochemistry, University of Bath, United Kingdom
| | - Eric T Harvill
- Center for Vaccines and Immunology, Department of Infectious Diseases, University of Georgia, Athens
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Linz B, Ivanov YV, Preston A, Brinkac L, Parkhill J, Kim M, Harris SR, Goodfield LL, Fry NK, Gorringe AR, Nicholson TL, Register KB, Losada L, Harvill ET. Acquisition and loss of virulence-associated factors during genome evolution and speciation in three clades of Bordetella species. BMC Genomics 2016; 17:767. [PMID: 27716057 PMCID: PMC5045587 DOI: 10.1186/s12864-016-3112-5] [Citation(s) in RCA: 53] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/24/2015] [Accepted: 09/23/2016] [Indexed: 11/10/2022] Open
Abstract
Background The genus Bordetella consists of nine species that include important respiratory pathogens such as the ‘classical’ species B. bronchiseptica, B. pertussis and B. parapertussis and six more distantly related and less extensively studied species. Here we analyze sequence diversity and gene content of 128 genome sequences from all nine species with focus on the evolution of virulence-associated factors. Results Both genome-wide sequence-based and gene content-based phylogenetic trees divide the genus into three species clades. The phylogenies are congruent between species suggesting genus-wide co-evolution of sequence diversity and gene content, but less correlated within species, mainly because of strain-specific presence of many different prophages. We compared the genomes with focus on virulence-associated genes and identified multiple clade-specific, species-specific and strain-specific events of gene acquisition and gene loss, including genes encoding O-antigens, protein secretion systems and bacterial toxins. Gene loss was more frequent than gene gain throughout the evolution, and loss of hundreds of genes was associated with the origin of several species, including the recently evolved human-restricted B. pertussis and B. holmesii, B. parapertussis and the avian pathogen B. avium. Conclusions Acquisition and loss of multiple genes drive the evolution and speciation in the genus Bordetella, including large scale gene loss associated with the origin of several species. Recent loss and functional inactivation of genes, including those encoding pertussis vaccine components and bacterial toxins, in individual strains emphasize ongoing evolution. Electronic supplementary material The online version of this article (doi:10.1186/s12864-016-3112-5) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Bodo Linz
- Department of Veterinary and Biomedical Sciences, Pennsylvania State University, University Park, PA 16802, USA.
| | - Yury V Ivanov
- Department of Veterinary and Biomedical Sciences, Pennsylvania State University, University Park, PA 16802, USA
| | - Andrew Preston
- The Millner Centre for Evolution and Department of Biology and Biochemistry, University of Bath, Bath, UK
| | | | - Julian Parkhill
- Pathogen Genomics, The Wellcome Trust Sanger Institute, Wellcome Trust Genome Campus, Hinxton, Cambridge, UK
| | - Maria Kim
- J. Craig Venter Institute, Rockville, MD, USA
| | - Simon R Harris
- Pathogen Genomics, The Wellcome Trust Sanger Institute, Wellcome Trust Genome Campus, Hinxton, Cambridge, UK
| | - Laura L Goodfield
- Department of Veterinary and Biomedical Sciences, Pennsylvania State University, University Park, PA 16802, USA
| | - Norman K Fry
- Public Health England, Respiratory and Vaccine Preventable Bacteria Reference Unit, London, UK
| | | | - Tracy L Nicholson
- USDA, Agricultural Research Service, National Animal Disease Center, Ames, IA, USA
| | - Karen B Register
- USDA, Agricultural Research Service, National Animal Disease Center, Ames, IA, USA
| | | | - Eric T Harvill
- Department of Veterinary and Biomedical Sciences, Pennsylvania State University, University Park, PA 16802, USA. .,Singapore Centre on Environmental Life Sciences Engineering, Lee Kong Chian School of Medicine, Nanyang Technological University, Singapore 637551, Singapore. .,Department of Infectious Diseases, College of Veterinary Medicine, University of Georgia, Athens, GA 30602, USA.
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Kilgore PE, Salim AM, Zervos MJ, Schmitt HJ. Pertussis: Microbiology, Disease, Treatment, and Prevention. Clin Microbiol Rev 2016; 29:449-86. [PMID: 27029594 PMCID: PMC4861987 DOI: 10.1128/cmr.00083-15] [Citation(s) in RCA: 226] [Impact Index Per Article: 28.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
Pertussis is a severe respiratory infection caused by Bordetella pertussis, and in 2008, pertussis was associated with an estimated 16 million cases and 195,000 deaths globally. Sizeable outbreaks of pertussis have been reported over the past 5 years, and disease reemergence has been the focus of international attention to develop a deeper understanding of pathogen virulence and genetic evolution of B. pertussis strains. During the past 20 years, the scientific community has recognized pertussis among adults as well as infants and children. Increased recognition that older children and adolescents are at risk for disease and may transmit B. pertussis to younger siblings has underscored the need to better understand the role of innate, humoral, and cell-mediated immunity, including the role of waning immunity. Although recognition of adult pertussis has increased in tandem with a better understanding of B. pertussis pathogenesis, pertussis in neonates and adults can manifest with atypical clinical presentations. Such disease patterns make pertussis recognition difficult and lead to delays in treatment. Ongoing research using newer tools for molecular analysis holds promise for improved understanding of pertussis epidemiology, bacterial pathogenesis, bioinformatics, and immunology. Together, these advances provide a foundation for the development of new-generation diagnostics, therapeutics, and vaccines.
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Affiliation(s)
- Paul E Kilgore
- Department of Pharmacy Practice, Eugene Applebaum Collage of Pharmacy and Health Sciences, Wayne State University, Detroit, Michigan, USA Department of Family Medicine and Public Health Sciences, Wayne State University School of Medicine, Detroit, Michigan, USA
| | - Abdulbaset M Salim
- Department of Pharmacy Practice, Eugene Applebaum Collage of Pharmacy and Health Sciences, Wayne State University, Detroit, Michigan, USA
| | - Marcus J Zervos
- Division of Infectious Diseases, Department of Internal Medicine, Henry Ford Health System and Wayne State University School of Medicine, Detroit, Michigan, USA
| | - Heinz-Josef Schmitt
- Medical and Scientific Affairs, Pfizer Vaccines, Paris, France Department of Pediatrics, Johannes Gutenberg-University, Mainz, Germany
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Hester SE, Goodfield LL, Park J, Feaga HA, Ivanov YV, Bendor L, Taylor DL, Harvill ET. Host Specificity of Ovine Bordetella parapertussis and the Role of Complement. PLoS One 2015; 10:e0130964. [PMID: 26158540 PMCID: PMC4497623 DOI: 10.1371/journal.pone.0130964] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2014] [Accepted: 05/27/2015] [Indexed: 11/30/2022] Open
Abstract
The classical bordetellae are comprised of three subspecies that differ from broad to very limited host specificity. Although several lineages appear to have specialized to particular host species, most retain the ability to colonize and grow in mice, providing a powerful common experimental model to study their differences. One of the subspecies, Bordetella parapertussis, is composed of two distinct clades that have specialized to different hosts: one to humans (Bpphu), and the other to sheep (Bppov). While Bpphu and the other classical bordetellae can efficiently colonize mice, Bppov strains are severely defective in their ability to colonize the murine respiratory tract. Bppov genomic analysis did not reveal the loss of adherence genes, but substantial mutations and deletions of multiple genes involved in the production of O-antigen, which is required to prevent complement deposition on B. bronchiseptica and Bpphu strains. Bppov lacks O-antigen and, like O-antigen mutants of other bordetellae, is highly sensitive to murine complement-mediated killing in vitro. Based on these results, we hypothesized that Bppov failed to colonize mice because of its sensitivity to murine complement. Consistent with this, the Bppov defect in the colonization of wild type mice was not observed in mice lacking the central complement component C3. Furthermore, Bppov strains were highly susceptible to killing by murine complement, but not by sheep complement. These data demonstrate that the failure of Bppov to colonize mice is due to sensitivity to murine, but not sheep, complement, providing a mechanistic example of how specialization that accompanies expansion in one host can limit host range.
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Affiliation(s)
- Sara E. Hester
- Department of Veterinary and Biomedical Sciences, The Pennsylvania State University, University Park, Pennsylvania, United States of America
- Graduate Program in Biochemistry, Microbiology and Molecular Biology, The Pennsylvania State University, University Park, Pennsylvania, United States of America
| | - Laura L. Goodfield
- Department of Veterinary and Biomedical Sciences, The Pennsylvania State University, University Park, Pennsylvania, United States of America
- Graduate Program in Immunology and Infectious Disease, The Pennsylvania State University, University Park, Pennsylvania, United States of America
| | - Jihye Park
- Department of Veterinary and Biomedical Sciences, The Pennsylvania State University, University Park, Pennsylvania, United States of America
- Graduate Program in Bioinformatics and Genomics, The Pennsylvania State University, University Park, Pennsylvania, United States of America
| | - Heather A. Feaga
- Department of Veterinary and Biomedical Sciences, The Pennsylvania State University, University Park, Pennsylvania, United States of America
- Graduate Program in Biochemistry, Microbiology and Molecular Biology, The Pennsylvania State University, University Park, Pennsylvania, United States of America
| | - Yury V. Ivanov
- Department of Veterinary and Biomedical Sciences, The Pennsylvania State University, University Park, Pennsylvania, United States of America
| | - Liron Bendor
- Department of Veterinary and Biomedical Sciences, The Pennsylvania State University, University Park, Pennsylvania, United States of America
- Graduate Program in Genetics, The Pennsylvania State University, University Park, Pennsylvania, United States of America
| | - Dawn L. Taylor
- Department of Veterinary and Biomedical Sciences, The Pennsylvania State University, University Park, Pennsylvania, United States of America
| | - Eric T. Harvill
- Department of Veterinary and Biomedical Sciences, The Pennsylvania State University, University Park, Pennsylvania, United States of America
- * E-mail:
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Jongerius I, Schuijt TJ, Mooi FR, Pinelli E. Complement evasion by Bordetella pertussis: implications for improving current vaccines. J Mol Med (Berl) 2015; 93:395-402. [PMID: 25686752 PMCID: PMC4366546 DOI: 10.1007/s00109-015-1259-1] [Citation(s) in RCA: 26] [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: 12/11/2014] [Revised: 01/19/2015] [Accepted: 01/27/2015] [Indexed: 12/17/2022]
Abstract
Bordetella pertussis causes whooping cough or pertussis, a highly contagious disease of the respiratory tract. Despite high vaccination coverage, reported cases of pertussis are rising worldwide and it has become clear that the current vaccines must be improved. In addition to the well-known protective role of antibodies and T cells during B. pertussis infection, innate immune responses such as the complement system play an essential role in B. pertussis killing. In order to evade this complement activation and colonize the human host, B. pertussis expresses several molecules that inhibit complement activation. Interestingly, one of the known complement evasion proteins, autotransporter Vag8, is highly expressed in the recently emerged B. pertussis isolates. Here, we describe the current knowledge on how B. pertussis evades complement-mediated killing. In addition, we compare this to complement evasion strategies used by other bacterial species. Finally, we discuss the consequences of complement evasion by B. pertussis on adaptive immunity and how identification of the bacterial molecules and the mechanisms involved in complement evasion might help improve pertussis vaccines.
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Affiliation(s)
- Ilse Jongerius
- Centre for Infectious Disease Control, National Institute for Public Health and the Environment, Antonie van Leeuwenhoeklaan 9, P.O. Box 1, 3720 BA Bilthoven, The Netherlands
- Present Address: Department of Medical Microbiology, University Medical Center Utrecht, Heidelberglaan 100, 3584 CX Utrecht, The Netherlands
| | - Tim J. Schuijt
- Centre for Infectious Disease Control, National Institute for Public Health and the Environment, Antonie van Leeuwenhoeklaan 9, P.O. Box 1, 3720 BA Bilthoven, The Netherlands
- Present Address: Department of Clinical Chemistry, Hematology and Immunology, Diakonessenhuis, Bosboomstraat 1, 3582 KE Utrecht, The Netherlands
| | - Frits R. Mooi
- Centre for Infectious Disease Control, National Institute for Public Health and the Environment, Antonie van Leeuwenhoeklaan 9, P.O. Box 1, 3720 BA Bilthoven, The Netherlands
| | - Elena Pinelli
- Centre for Infectious Disease Control, National Institute for Public Health and the Environment, Antonie van Leeuwenhoeklaan 9, P.O. Box 1, 3720 BA Bilthoven, The Netherlands
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Geurtsen J, Fae KC, van den Dobbelsteen GPJM. Importance of (antibody-dependent) complement-mediated serum killing in protection against Bordetella pertussis. Expert Rev Vaccines 2014; 13:1229-40. [PMID: 25081731 DOI: 10.1586/14760584.2014.944901] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Pertussis is a highly contagious respiratory disease that is caused by Bordetella pertussis. Despite being vaccine preventable, pertussis rates have been rising steadily over the last decades, even in areas with high vaccine uptake. Recently, experiments with infant baboons indicated that although vaccination with acellular pertussis vaccines prevented disease, no apparent effect was observed on infection and transmission. One explanation may be that current acellular pertussis vaccines do not induce high levels of opsonophagocytic and/or bactericidal activity, implying that engineering of vaccines that promote bacterial killing may improve efficacy. Here, we discuss the importance of complement-mediated killing in vaccine-induced protection against B. pertussis. We first examine how B. pertussis may have evolved different complement evasion strategies. Second, we explore the benefits of opsonophagocytic and/or bactericidal killing in vaccine-induced protection and discuss whether or not inclusion of new opsonophagocytic or bactericidal target antigens in pertussis vaccines may benefit efficacy.
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Affiliation(s)
- Jeroen Geurtsen
- Crucell Holland B.V, one of the Janssen Pharmaceutical Companies of Johnson & Johnson - Bacterial Vaccines Research and Development, PO Box 2048, Archimedesweg 4-6, 2333 CN Leiden, The Netherlands
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12
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Lipopolysaccharide O antigen size distribution is determined by a chain extension complex of variable stoichiometry in Escherichia coli O9a. Proc Natl Acad Sci U S A 2014; 111:6407-12. [PMID: 24733938 DOI: 10.1073/pnas.1400814111] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The lengths of bacterial polysaccharides can be critical for their biological function. Unlike DNA or protein synthesis, where polymer length is implicit in the nucleic acid template, the molecular mechanisms for regulating polysaccharide length are poorly understood. Two models are commonly cited: a "molecular clock" regulates length by controlling the duration of the polymer extension process, whereas a "molecular ruler" determines length by measurement against a physical structure in the biosynthetic complex. Escherichia coli O9a is a prototype for the biosynthesis of O polysaccharides by ATP-binding cassette transporter-dependent processes. The length of the O9a polysaccharide is determined by two proteins: an extension enzyme, WbdA, and a termination enzyme, WbdD. WbdD is known to self-oligomerize and also to interact with WbdA. Changing either enzyme's concentration can alter the polysaccharide length. We quantified the O9a polysaccharide length distribution and the enzyme concentration dependence in vivo, then made mathematical models to predict the polymer length distributions resulting from hypothetical length-regulation mechanisms. Our data show qualitative features that cannot be explained by either a molecular clock or a molecular ruler model. Therefore, we propose a "variable geometry" model, in which a postulated biosynthetic WbdA-WbdD complex assembles with variable stoichiometry dependent on relative enzyme concentration. Each stoichiometry produces polymers with a distinct, geometrically determined, modal length. This model reproduces the enzyme concentration dependence and modality of the observed polysaccharide length distributions. Our work highlights limitations of previous models and provides new insight into the mechanisms of length control in polysaccharide biosynthesis.
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Abstract
Pertussis, also known as whooping cough, has recently re-emerged as a major public health threat despite high levels of vaccination against the aetiological agent Bordetella pertussis. In this Review, we describe the pathogenesis of this disease, with a focus on recent mechanistic insights into B. pertussis virulence-factor function. We also discuss the changing epidemiology of pertussis and the challenges facing vaccine development. Despite decades of research, many aspects of B. pertussis physiology and pathogenesis remain poorly understood. We highlight knowledge gaps that must be addressed to develop improved vaccines and therapeutic strategies.
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Ganguly T, Johnson JB, Kock ND, Parks GD, Deora R. The Bordetella pertussis Bps polysaccharide enhances lung colonization by conferring protection from complement-mediated killing. Cell Microbiol 2014; 16:1105-18. [PMID: 24438122 DOI: 10.1111/cmi.12264] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2013] [Revised: 12/24/2013] [Accepted: 01/06/2014] [Indexed: 01/01/2023]
Abstract
Bordetella pertussis is a human-restricted Gram-negative bacterial pathogen that causes whooping cough or pertussis. Pertussis is the leading vaccine preventable disease that is resurging in the USA and other parts of the developed world. There is an incomplete understanding of the mechanisms by which B. pertussis evades killing and clearance by the complement system, a first line of host innate immune defence. The present study examined the role of the Bps polysaccharide to resist complement activity in vitro and in the mouse respiratory tract. The isogenic bps mutant strain containing a large non-polar in-frame deletion of the bpsA-D locus was more sensitive to serum and complement mediated killing than the WT strain. As determined by Western blotting, flow cytometry and electron microscopic studies, the heightened sensitivity of the mutant strain was due to enhanced deposition of complement proteins and the formation of membrane attack complex, the end-product of complement activation. Bps was sufficient to confer complement resistance as evidenced by a Bps-expressing Escherichia coli being protected by serum killing. Additionally, Western blotting and flow cytometry assays revealed that Bps inhibited the deposition of complement proteins independent of other B. pertussis factors. The bps mutant strain colonized the lungs of complement-deficient mice at higher levels than that observed in C57Bl/6 mice. These results reveal a previously unknown interaction between Bps and the complement system in controlling B. pertussis colonization of the respiratory tract. These findings also make Bps a potential target for the prevention and therapy of whooping cough.
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Affiliation(s)
- Tridib Ganguly
- Department of Microbiology and Immunology, Medical Center Blvd., Wake Forest School of Medicine, Winston-Salem, NC, 27157, USA
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15
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Fisher ML, Sun W, Curtiss R. The route less taken: pulmonary models of enteric Gram-negative infection. Pathog Dis 2013; 70:99-109. [PMID: 24259516 DOI: 10.1111/2049-632x.12109] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2013] [Accepted: 10/16/2013] [Indexed: 11/29/2022] Open
Abstract
Many pathogens are capable of causing a fulminant infection in pulmonary tissues of mammals. Animal models have provided an extensive understanding of the genetic and molecular mechanisms of bacterial pathogenesis as well as host immune response in the lungs. Many clinically relevant Gram-negative bacteria are host-restricted. Thus, the powerful, informative tools of mouse models are not available for study with these organisms. However, over the past 30 years, enterprising work has demonstrated the utility of pulmonary infection with enteric pathogens. Such infection models have increased our understanding host-pathogen interactions in these organisms. Here, we provide a review and comparison of lung models of infection with enteric, Gram-negative bacteria relative to naturally occurring lung pathogens.
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Affiliation(s)
- Michael L Fisher
- Center for Infectious Diseases and Vaccinology, Arizona State University, Tempe, AZ, USA
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16
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Enzymatic modification of lipid A by ArnT protects Bordetella bronchiseptica against cationic peptides and is required for transmission. Infect Immun 2013; 82:491-9. [PMID: 24478065 DOI: 10.1128/iai.01260-12] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023] Open
Abstract
Pathogen transmission cycles require many steps: initial colonization, growth and persistence, shedding, and transmission to new hosts. Alterations in the membrane components of the bacteria, including lipid A, the membrane anchor of lipopolysaccharide, could affect any of these steps via its structural role protecting bacteria from host innate immune defenses, including antimicrobial peptides and signaling through Toll-like receptor 4 (TLR4). To date, lipid A has been shown to affect only the within-host dynamics of infection, not the between-host dynamics of transmission. Here, we investigate the effects of lipid A modification in a mouse infection and transmission model. Disruption of the Bordetella bronchiseptica locus (BB4268) revealed that ArnT is required for addition of glucosamine (GlcN) to B. bronchiseptica lipid A. ArnT modification of lipid A did not change its TLR4 agonist activity in J774 cells, but deleting arnT decreased resistance to killing by cationic antimicrobial peptides, such as polymyxin B and β-defensins. In the standard infection model, mutation of arnT did not affect B. bronchiseptica colonization, growth, persistence throughout the respiratory tract, recruitment of neutrophils to the nasal cavity, or shedding of the pathogen. However, the number of bacteria necessary to colonize a host (50% infective dose [ID50]) was 5-fold higher for the arnT mutant. Furthermore, the arnT mutant was defective in transmission between hosts. These results reveal novel functions of the ArnT lipid A modification and highlight the sensitivity of low-dose infections and transmission experiments for illuminating aspects of infectious diseases between hosts. Factors such as ArnT can have important effects on the burden of disease and are potential targets for interventions that can interrupt transmission.
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Zelazny AM, Ding L, Goldberg JB, Mijares LA, Conlan S, Conville PS, Stock F, Ballentine SJ, Olivier KN, Sampaio EP, Murray PR, Holland SM. Adaptability and persistence of the emerging pathogen Bordetella petrii. PLoS One 2013; 8:e65102. [PMID: 23750235 PMCID: PMC3672207 DOI: 10.1371/journal.pone.0065102] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2012] [Accepted: 04/22/2013] [Indexed: 12/03/2022] Open
Abstract
The first described, environmentally isolated, Bordetella petrii was shown to undergo massive genomic rearrangements in vitro. More recently, B. petrii was isolated from clinical samples associated with jaw, ear bone, cystic fibrosis and chronic pulmonary disease. However, the in vivo consequences of B. petrii genome plasticity and its pathogenicity remain obscure. B. petrii was identified from four sequential respiratory samples and a post-mortem spleen sample of a woman presenting with bronchiectasis and cavitary lung disease associated with nontuberculous mycobacterial infection. Strains were compared genetically, phenotypically and by antibody recognition from the patient and from inoculated mice. The successive B. petrii strains exhibited differences in growth, antibiotic susceptibility and recognition by the patient’s antibodies. Antibodies from mice inoculated with these strains recapitulated the specificity and strain dependent response that was seen with the patient’s serum. Finally, we characterize one strain that was poorly recognized by the patient’s antibodies, due to a defect in the lipopolysaccharide O-antigen, and identify a mutation associated with this phenotype. We propose that B. petrii is remarkably adaptable in vivo, providing a possible connection between immune response and bacterial evasion and supporting infection persistence.
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Affiliation(s)
- Adrian M Zelazny
- Laboratory of Clinical Infectious Diseases, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland, USA.
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18
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Nguyen TM, Ravindra D, Kwong B, Waheed S, Ferguson R, Tarlton N, Wu V, Sequeira CS, Bremer M, Abramson T. Differential expression of alpha 4 integrins on effector memory T helper cells during Bordetella infections. Delayed responses in Bordetella pertussis. PLoS One 2012; 7:e52903. [PMID: 23300813 PMCID: PMC3531986 DOI: 10.1371/journal.pone.0052903] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2012] [Accepted: 11/23/2012] [Indexed: 11/18/2022] Open
Abstract
Bordetella pertussis (B. pertussis) is the causative agent of whooping cough, a respiratory disease that is reemerging worldwide. Mechanisms of selective lymphocyte trafficking to the airways are likely to be critical in the immune response to this pathogen. We compared murine infection by B. pertussis, B. parapertussis, and a pertussis toxin-deleted B. pertussis mutant (BpΔPTX) to test the hypothesis that effector memory T-helper cells (emTh) display an altered pattern of trafficking receptor expression in B. pertussis infection due to a defect in imprinting. Increased cell recruitment to the lungs at 5 days post infection (p.i.) with B. parapertussis, and to a lesser extent with BpΔPTX, coincided with an increased frequency of circulating emTh cells expressing the mucosal-associated trafficking receptors α4β7 and α4β1 while a reduced population of these cells was observed in B. pertussis infection. These cells were highly evident in the blood and lungs in B. pertussis infection only at 25 days p.i. when B. parapertussis and BpΔPTX infections were resolved. Although at 5 days p.i., an equally high percentage of lung dendritic cells (DCs) from all infections expressed maturation markers, this expression persisted only in B. pertussis infection at 25 days p.i. Furthermore, at 5 days p.i with B. pertussis, lung DCs migration to draining lymph nodes may be compromised as evidenced by decreased frequency of CCR7(+) DCs, inhibited CCR7-mediated in vitro migration, and fewer DCs in lung draining lymph nodes. Lastly, a reduced frequency of allogeneic CD4(+) cells expressing α4β1 was detected following co-culture with lung DCs from B. pertussis-infected mice, suggesting a defect in DC imprinting in comparison to the other infection groups. The findings in this study suggest that B. pertussis may interfere with imprinting of lung-associated trafficking receptors on T lymphocytes leading to extended survival in the host and a prolonged course of disease.
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Affiliation(s)
- Tuan M. Nguyen
- Department of Biology, San Jose State University, San Jose, California, United States of America
| | - Dipti Ravindra
- Department of Biology, San Jose State University, San Jose, California, United States of America
| | - Brian Kwong
- Department of Biology, San Jose State University, San Jose, California, United States of America
| | - Sana Waheed
- Department of Biology, San Jose State University, San Jose, California, United States of America
| | - Ryan Ferguson
- Department of Biology, San Jose State University, San Jose, California, United States of America
| | - Nicole Tarlton
- Department of Biology, San Jose State University, San Jose, California, United States of America
| | - Victoria Wu
- Department of Biology, San Jose State University, San Jose, California, United States of America
| | - Christopher S. Sequeira
- Department of Biology, San Jose State University, San Jose, California, United States of America
| | - Martina Bremer
- Department of Mathematics, San Jose State University, San Jose, California, United States of America
| | - Tzvia Abramson
- Department of Biology, San Jose State University, San Jose, California, United States of America
- * E-mail:
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Bordetella parapertussis survives the innate interaction with human neutrophils by impairing bactericidal trafficking inside the cell through a lipid raft-dependent mechanism mediated by the lipopolysaccharide O antigen. Infect Immun 2012; 80:4309-16. [PMID: 23027528 DOI: 10.1128/iai.00662-12] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
Whooping cough is a reemerging disease caused by two closely related pathogens, Bordetella pertussis and Bordetella parapertussis. The incidence of B. parapertussis in whooping cough cases has been increasing since the introduction of acellular pertussis vaccines containing purified antigens that are common to both strains. Recently published results demonstrated that these vaccines do not protect against B. parapertussis due to the presence of the O antigen on the bacterial surface that impairs antibody access to shared antigens. We have investigated the effect of the lack of opsonization of B. parapertussis on the outcome of its interaction with human neutrophils (polymorphonuclear leukocytes [PMNs]). In the absence of opsonic antibodies, PMN interaction with B. parapertussis resulted in nonbactericidal trafficking upon phagocytosis. A high percentage of nonopsonized B. parapertussis was found in nonacidic lysosome marker (lysosome-associated membrane protein [LAMP])-negative phagosomes with access to the host cell-recycling pathway of external nutrients, allowing bacterial survival as determined by intracellular CFU counts. The lipopolysaccharide (LPS) O antigen was found to be involved in directing B. parapertussis to PMN lipid rafts, eventually determining the nonbactericidal fate inside the PMN. IgG opsonization of B. parapertussis drastically changed this interaction by not only inducing efficient PMN phagocytosis but also promoting PMN bacterial killing. These data provide new insights into the immune mechanisms of hosts against B. parapertussis and document the crucial importance of opsonic antibodies in immunity to this pathogen.
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Barchinger SE, Zhang X, Hester SE, Rodriguez ME, Harvill ET, Ades SE. sigE facilitates the adaptation of Bordetella bronchiseptica to stress conditions and lethal infection in immunocompromised mice. BMC Microbiol 2012; 12:179. [PMID: 22897969 PMCID: PMC3490749 DOI: 10.1186/1471-2180-12-179] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2011] [Accepted: 06/25/2012] [Indexed: 11/28/2022] Open
Abstract
Background The cell envelope of a bacterial pathogen can be damaged by harsh conditions in the environment outside a host and by immune factors during infection. Cell envelope stress responses preserve the integrity of this essential compartment and are often required for virulence. Bordetella species are important respiratory pathogens that possess a large number of putative transcription factors. However, no cell envelope stress responses have been described in these species. Among the putative Bordetella transcription factors are a number of genes belonging to the extracytoplasmic function (ECF) group of alternative sigma factors, some of which are known to mediate cell envelope stress responses in other bacteria. Here we investigate the role of one such gene, sigE, in stress survival and pathogenesis of Bordetella bronchiseptica. Results We demonstrate that sigE encodes a functional sigma factor that mediates a cell envelope stress response. Mutants of B. bronchiseptica strain RB50 lacking sigE are more sensitive to high temperature, ethanol, and perturbation of the envelope by SDS-EDTA and certain β-lactam antibiotics. Using a series of immunocompromised mice deficient in different components of the innate and adaptive immune responses, we show that SigE plays an important role in evading the innate immune response during lethal infections of mice lacking B cells and T cells. SigE is not required, however, for colonization of the respiratory tract of immunocompetent mice. The sigE mutant is more efficiently phagocytosed and killed by peripheral blood polymorphonuclear leukocytes (PMNs) than RB50, and exhibits decreased cytotoxicity toward macrophages. These altered interactions with phagocytes could contribute to the defects observed during lethal infection. Conclusions Much of the work on transcriptional regulation during infection in B. bronchiseptica has focused on the BvgAS two-component system. This study reveals that the SigE regulon also mediates a discrete subset of functions associated with virulence. SigE is the first cell envelope stress-sensing system to be described in the bordetellae. In addition to its role during lethal infection of mice deficient in adaptive immunity, our results indicate that SigE is likely to be important for survival in the face of stresses encountered in the environment between hosts.
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Affiliation(s)
- Sarah E Barchinger
- Department of Biochemistry and Molecular Biology, Pennsylvania State University, University Park, 16802, USA
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21
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Effectiveness of the whole-cell pertussis vaccine produced in Poland against different Bordetella parapertussis isolates in the mouse intranasal challenge model. Vaccine 2011; 29:5488-94. [DOI: 10.1016/j.vaccine.2011.05.053] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2011] [Revised: 05/12/2011] [Accepted: 05/15/2011] [Indexed: 11/23/2022]
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Noofeli M, Bokhari H, Blackburn P, Roberts M, Coote JG, Parton R. BapC autotransporter protein is a virulence determinant of Bordetella pertussis. Microb Pathog 2011; 51:169-77. [PMID: 21554944 DOI: 10.1016/j.micpath.2011.04.004] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2010] [Revised: 04/05/2011] [Accepted: 04/06/2011] [Indexed: 10/18/2022]
Abstract
A protein designated Bap-5 (GenBank accession no. AF081494) or BapC (GenBank accession no. AJ277634) has been identified as a member of the Bordetella pertussis autotransporter family and the present work suggests that this protein, like the previously characterised BrkA, is a Bvg-regulated serum resistance factor and virulence determinant. B. pertussis bapC and brkA, bapC mutants were created and, like a brkA mutant, showed greater sensitivity to killing by normal human serum than their parent strains but they were not as sensitive as a bvg mutant. Competition assays also showed an important role for BapC, like BrkA, in virulence of B. pertussis in mice after intranasal infection. Moreover, the bapC and brkA, bapC mutants, like the brkA mutant, were found to be more sensitive to the antimicrobial peptide cecropin P1 than the parent strains. In the genome sequence of B. pertussis strain Tohama, bapC is designated as a pseudogene due, in part, to a frameshift in a poly(C) tract near the 5' end of the gene which creates a truncated BapC protein. Sequence analyses of the bapC region spanning the poly(C) tract of a number of B. pertussis strains showed minor nucleotide and amino acid polymorphisms but it appeared that all had an ORF that would be able to produce BapC.
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Affiliation(s)
- Mojtaba Noofeli
- Institute of Infection, Immunity and Inflammation, University of Glasgow, Glasgow, UK
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23
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Vinogradov E, King JD, Pathak AK, Harvill ET, Preston A. Antigenic Variation among Bordetella: Bordetella bronchiseptica strain MO149 expresses a novel o chain that is poorly immunogenic. J Biol Chem 2010; 285:26869-26877. [PMID: 20592026 DOI: 10.1074/jbc.m110.115121] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023] Open
Abstract
The O chain polysaccharide (O PS) of Bordetella bronchiseptica and Bordetella parapertussis lipopolysaccharide is a homopolymer of 2,3-diacetamido-2,3-dideoxygalacturonic acid (GalNAc3NAcA) in which some of the sugars are present as uronamides. The terminal residue contains several unusual modifications. To date, two types of modification have been characterized, and a survey of numerous strains demonstrated that each contained one of these two modification types. Host antibody responses against the O PS are directed against the terminal residue modifications, and there is little cross-reactivity between the two types. This suggests that Bordetella O PS modifications represent a means of antigenic variation. Here we report the characterization of the O PS of B. bronchiseptica strain MO149. It consists of a novel two-sugar repeating unit and a novel terminal residue modification, with the structure Me-4-alpha-L-GalNAc3NAcA-(4-beta-D-GlcNAc3NAcA-4-alpha-L-GalNAc3NAcA-)(5-6)-, which we propose be defined as the B. bronchiseptica O3 PS. We show that the O3 PS is very poorly immunogenic and that the MO149 strain contains a novel wbm (O PS biosynthesis) locus. Thus, there is greater diversity among Bordetella O PSs than previously recognized, which is likely to be a result of selection pressure from host immunity. We also determine experimentally, for the first time, the absolute configuration of the diacetimido-uronic acid sugars in Bordetella O PS.
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Affiliation(s)
- Evgeny Vinogradov
- Institute for Biological Sciences, National Research Council, Ottawa, Ontario K1A 0R6, Canada
| | - Jerry D King
- Department of Molecular and Cellular Biology, University of Guelph, Guelph, Ontario N1G 2W1, Canada
| | - Ashutosh K Pathak
- Department of Veterinary and Biomedical Science, Pennsylvania State University, University Park, Pennsylvania 16802, United Kingdom
| | - Eric T Harvill
- Department of Veterinary and Biomedical Science, Pennsylvania State University, University Park, Pennsylvania 16802, United Kingdom
| | - Andrew Preston
- Department of Clinical Veterinary Science, University of Bristol, Langford, North Somerset BS40 5DU, United Kingdom.
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Zhang X, Rodríguez ME, Harvill ET. O antigen allows B. parapertussis to evade B. pertussis vaccine-induced immunity by blocking binding and functions of cross-reactive antibodies. PLoS One 2009; 4:e6989. [PMID: 19750010 PMCID: PMC2737124 DOI: 10.1371/journal.pone.0006989] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2009] [Accepted: 08/19/2009] [Indexed: 02/06/2023] Open
Abstract
Although the prevalence of Bordetella parapertussis varies dramatically among studies in different populations with different vaccination regimens, there is broad agreement that whooping cough vaccines, composed only of B. pertussis antigens, provide little if any protection against B. parapertussis. In C57BL/6 mice, a B. pertussis whole-cell vaccine (wP) provided modest protection against B. parapertussis, which was dependent on IFN-gamma. The wP was much more protective against an isogenic B. parapertussis strain lacking O-antigen than its wild-type counterpart. O-antigen inhibited binding of wP-induced antibodies to B. parapertussis, as well as antibody-mediated opsonophagocytosis in vitro and clearance in vivo. aP-induced antibodies also bound better in vitro to the O-antigen mutant than to wild-type B. parapertussis, but aP failed to confer protection against wild-type or O antigen-deficient B. parapertussis in mice. Interestingly, B. parapertussis-specific antibodies provided in addition to either wP or aP were sufficient to very rapidly reduce B. parapertussis numbers in mouse lungs. This study identifies a mechanism by which one pathogen escapes immunity induced by vaccination against a closely related pathogen and may explain why B. parapertussis prevalence varies substantially between populations with different vaccination strategies.
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Affiliation(s)
- Xuqing Zhang
- Department of Veterinary and Biomedical Sciences, Pennsylvania State University, University Park, Pennsylvania, United States of America
| | - Maria Eugenia Rodríguez
- Department of Chemistry, Centre of Applied Biotechnology (CINDEFI, CCyT La Plata), School of Science, La Plata University, La Plata, Argentina
| | - Eric T. Harvill
- Department of Veterinary and Biomedical Sciences, Pennsylvania State University, University Park, Pennsylvania, United States of America
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Role of the type III secretion system in a hypervirulent lineage of Bordetella bronchiseptica. Infect Immun 2009; 77:3969-77. [PMID: 19596779 DOI: 10.1128/iai.01362-08] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Despite the fact that closely related bacteria can cause different levels of disease, the genetic changes that cause some isolates to be more pathogenic than others are generally not well understood. We use a combination of approaches to determine which factors contribute to the increased virulence of a Bordetella bronchiseptica lineage. A strain isolated from a host with B. bronchiseptica-induced disease, strain 1289, was 60-fold more virulent in mice than one isolated from an asymptomatically infected host, strain RB50. Transcriptome analysis and quantitative reverse transcription-PCR showed that the type III secretion system (TTSS) genes were more highly expressed by strain 1289 than strain RB50. Compared to strain RB50, strain 1289 exhibited greater TTSS-mediated cytotoxicity of a mammalian cell line. Additionally, we show that the increase in virulence of strain 1289 compared to that of RB50 was partially attributable to the TTSS. Using multilocus sequence typing, we identified another strain from the same lineage as strain 1289. Similar to strain 1289, we implicate the TTSS in the increased virulence of this strain. Together, our data suggest that the TTSS is involved in the increased virulence of a B. bronchiseptica lineage which appears to be disproportionately associated with disease. These data are consistent with the view that B. bronchiseptica lineages can have different levels of virulence, which may contribute to this species' ability to cause different severities of respiratory disease.
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Evidence for horizontal gene transfer of two antigenically distinct O antigens in Bordetella bronchiseptica. Infect Immun 2009; 77:3249-57. [PMID: 19528223 DOI: 10.1128/iai.01448-08] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
Host immunity is a major driving force of antigenic diversity, resulting in pathogens that can evade immunity induced by closely related strains. Here we show that two Bordetella bronchiseptica strains, RB50 and 1289, express two antigenically distinct O-antigen serotypes (O1 and O2, respectively). When 18 additional B. bronchiseptica strains were serotyped, all were found to express either the O1 or O2 serotype. Comparative genomic hybridization and PCR screening showed that the expression of either the O1 or O2 serotype correlated with the strain containing either the classical or alternative O-antigen locus, respectively. Multilocus sequence typing analysis of 49 B. bronchiseptica strains was used to build a phylogenetic tree, which revealed that the two O-antigen loci did not associate with a particular lineage, evidence that these loci are horizontally transferred between B. bronchiseptica strains. From experiments using mice vaccinated with purified lipopolysaccharide from strain RB50 (O1), 1289 (O2), or RB50Deltawbm (O antigen deficient), our data indicate that these O antigens do not confer cross-protection in vivo. The lack of cross-immunity between O-antigen serotypes appears to contribute to inefficient antibody-mediated clearance between strains. Together, these data are consistent with the idea that the O-antigen loci of B. bronchiseptica are horizontally transferred between strains and encode antigenically distinct serotypes, resulting in inefficient cross-immunity.
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King JD, Vinogradov E, Preston A, Li J, Maskell DJ. Post-assembly modification of Bordetella bronchiseptica O polysaccharide by a novel periplasmic enzyme encoded by wbmE. J Biol Chem 2008; 284:1474-83. [PMID: 19015265 PMCID: PMC2615507 DOI: 10.1074/jbc.m807729200] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023] Open
Abstract
Bordetella bronchiseptica is a pathogen of humans and animals that
colonizes the respiratory tract. It produces a lipopolysaccharide O antigen
that contains a homopolymer of
2,3-dideoxy-2,3-diacetamido-l-galacturonic acid
(l-GalNAc3NAcA). Some of these sugars are found in the uronamide
form (l-GalNAc3NAcAN), and there is no discernible pattern in the
distribution of amides along the chain. A B. bronchiseptica wbmE
mutant expresses an O polysaccharide unusually rich in uronamides. The WbmE
protein localizes to the periplasm and catalyzes the deamidation of
uronamide-rich O chains in lipopolysaccharide purified from the mutant, to
attain a wild-type uronamide/uronic acid ratio. WbmE is a member of the
papain-like transglutaminase superfamily, and this categorization is
consistent with a deamidase role. The periplasmic location of WbmE and its
acceptance of complete lipopolysaccharide as substrate indicate that it
operates at a late stage in lipopolysaccharide biosynthesis, after
polymerization and export of the O chain from the cytoplasm. This is the first
report of such a modification of O antigen after assembly. The expression of
wbmE is controlled by the Bordetella virulence gene
two-component regulatory system, BvgAS, suggesting that this deamidation is a
novel mechanism by which these bacteria modify their cell surface charge in
response to environmental stimuli.
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Affiliation(s)
- Jerry D King
- Department of Veterinary Medicine, University of Cambridge, Cambridge CB3 0ES, United Kingdom.
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Thakar J, Saadatpour-Moghaddam A, Harvill ET, Albert R. Constraint-based network model of pathogen-immune system interactions. J R Soc Interface 2008; 6:599-612. [PMID: 18952547 PMCID: PMC2696137 DOI: 10.1098/rsif.2008.0363] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023] Open
Abstract
Pathogenic bacteria such as Bordetella bronchiseptica modulate host immune responses to enable their establishment and persistence; however, the immune response is generally successful in clearing these bacteria. Here, we model the dynamic outcome of the interplay between host immune components and B. bronchiseptica virulence factors. The model extends our previously published interaction network of B. bronchiseptica and includes the existing experimental information on the relative timing of IL10 and IFNgamma activation in the form of qualitative inequalities. The current model improves the previous one in two directions: (i) by augmenting the network with new nodes with specific function in T helper cell differentiation and effector mechanisms and (ii) by using a dynamic approach that allows us to quantify node states and mechanisms revealed to be important from our previous model. The model makes predictions about the time scales of each process, the activity thresholds of each node and novel regulatory interactions. For example, the model predicts that the activity threshold of IL4 is higher than that of IL12 and that pro-inflammatory cytokines regulate the activity of Th2 cells. Some of these predictions are supported by the literature, and many can serve as targets of future experiments.
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Affiliation(s)
- Juilee Thakar
- Department of Physics, 104 Davey Laboratory, Pennsylvania State University, University Park, PA 16802, USA
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Abstract
Bordetella pertussis, a causative agent of whooping cough, expresses BrkA, which confers serum resistance, but the closely related human pathogen that also causes whooping cough, Bordetella parapertussis, does not. Interestingly, B. parapertussis, but not B. pertussis, produces an O antigen, a factor shown in other models to confer serum resistance. Using a murine model of infection, we determined that O antigen contributes to the ability of B. parapertussis to colonize the respiratory tract during the first week of infection, but not thereafter. Interestingly, an O antigen-deficient strain of B. parapertussis was not defective in colonizing mice lacking the complement cascade. O antigen prevented both complement component C3 deposition on the surface and complement-mediated killing of B. parapertussis. In addition, O antigen was required for B. parapertussis to systemically spread in complement-sufficient mice, but not complement-deficient mice. These data indicate that O antigen enables B. parapertussis to efficiently colonize the lower respiratory tract by protecting against complement-mediated control and clearance.
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King JD, Harmer NJ, Preston A, Palmer CM, Rejzek M, Field RA, Blundell TL, Maskell DJ. Predicting protein function from structure--the roles of short-chain dehydrogenase/reductase enzymes in Bordetella O-antigen biosynthesis. J Mol Biol 2007; 374:749-63. [PMID: 17950751 PMCID: PMC2279256 DOI: 10.1016/j.jmb.2007.09.055] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2007] [Revised: 09/19/2007] [Accepted: 09/20/2007] [Indexed: 11/16/2022]
Abstract
The pathogenic bacteria Bordetella parapertussis and Bordetella bronchiseptica express a lipopolysaccharide O antigen containing a polymer of 2,3-diacetamido-2,3-dideoxy-l-galacturonic acid. The O-antigen cluster contains three neighbouring genes that encode proteins belonging to the short-chain dehydrogenase/reductase (SDR) family, wbmF, wbmG and wbmH, and we aimed to elucidate their individual functions. Mutation and complementation implicate each gene in O-antigen expression but, as their putative sugar nucleotide substrates are not currently available, biochemical characterisation of WbmF, WbmG and WbmH is impractical at the present time. SDR family members catalyse a wide range of chemical reactions including oxidation, reduction and epimerisation. Because they typically share low sequence conservation, however, catalytic function cannot be predicted from sequence analysis alone. In this context, structural characterisation of the native proteins, co-crystals and small-molecule soaks enables differentiation of the functions of WbmF, WbmG and WbmH. These proteins exhibit typical SDR architecture and coordinate NAD. In the substrate-binding domain, all three enzymes bind uridyl nucleotides. WbmG contains a typical SDR catalytic TYK triad, which is required for oxidoreductase function, but the active site is devoid of additional acid-base functionality. Similarly, WbmH possesses a TYK triad, but an otherwise feature-poor active site. Consequently, 3,5-epimerase function can probably be ruled out for these enzymes. The WbmF active site contains conserved 3,5-epimerase features, namely, a positionally conserved cysteine (Cys133) and basic side chain (His90 or Asn213), but lacks the serine/threonine component of the SDR triad and therefore may not act as an oxidoreductase. The data suggest a pathway for synthesis of the O-antigen precursor UDP-2,3-diacetamido-2,3-dideoxy-l-galacturonic acid and illustrate the usefulness of structural data in predicting protein function.
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Affiliation(s)
- Jerry D King
- Department of Veterinary Medicine, Madingley Road, University of Cambridge, Cambridge CB3 0ES, UK.
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31
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Wolfe DN, Goebel EM, Bjornstad ON, Restif O, Harvill ET. The O antigen enables Bordetella parapertussis to avoid Bordetella pertussis-induced immunity. Infect Immun 2007; 75:4972-9. [PMID: 17698566 PMCID: PMC2044517 DOI: 10.1128/iai.00763-07] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Bordetella pertussis and Bordetella parapertussis are closely related endemic human pathogens which cause whooping cough, a disease that is reemerging in human populations. Despite how closely related these pathogens are, their coexistence and the limited efficacy of B. pertussis vaccines against B. parapertussis suggest a lack of cross-protective immunity between the two. We sought to address the ability of infection-induced immunity against one of these pathogens to protect against subsequent infection by the other using a mouse model of infection. Immunity induced by B. parapertussis infection protected against subsequent infections by either species. However, immunity induced by B. pertussis infection prevented subsequent B. pertussis infections but did not protect against B. parapertussis infections. The O antigen of B. parapertussis inhibited binding of antibodies to the bacterial surface and was required for B. parapertussis to colonize mice convalescent from B. pertussis infection. Thus, the O antigen of B. parapertussis confers asymmetrical cross-immunity between the causative agents of whooping cough. We propose that these findings warrant investigation of the relative role of B. parapertussis in the resurgence of whooping cough.
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Affiliation(s)
- Daniel N Wolfe
- Department of Veterinary and Biomedical Sciences, The Pennsylvania State University, 115 Henning Building, University Park, PA 16802, USA
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32
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Harmer NJ, King JD, Palmer CM, Preston A, Maskell DJ, Blundell TL. Cloning, expression, purification and preliminary crystallographic analysis of the short-chain dehydrogenase enzymes WbmF, WbmG and WbmH from Bordetella bronchiseptica. Acta Crystallogr Sect F Struct Biol Cryst Commun 2007; 63:711-5. [PMID: 17671375 PMCID: PMC2335155 DOI: 10.1107/s174430910703477x] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2007] [Accepted: 07/17/2007] [Indexed: 11/10/2022]
Abstract
The short-chain dehydrogenase enzymes WbmF, WbmG and WbmH from Bordetella bronchiseptica were cloned into Escherichia coli expression vectors, overexpressed and purified to homogeneity. Crystals of all three wild-type enzymes were obtained using vapour-diffusion crystallization with high-molecular-weight PEGs as a primary precipitant at alkaline pH. Some of the crystallization conditions permitted the soaking of crystals with cofactors and nucleotides or nucleotide sugars, which are possible substrate compounds, and further conditions provided co-complexes of two of the proteins with these compounds. The crystals diffracted to resolutions of between 1.50 and 2.40 A at synchrotron X-ray sources. The synchrotron data obtained were sufficient to determine eight structures of the three enzymes in complex with a variety of cofactors and substrate molecules.
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Affiliation(s)
- Nicholas J Harmer
- Department of Biochemistry, 80 Tennis Court Road, Cambridge CB2 1GA, England.
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33
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Thakar J, Pilione M, Kirimanjeswara G, Harvill ET, Albert R. Modeling systems-level regulation of host immune responses. PLoS Comput Biol 2007; 3:e109. [PMID: 17559300 PMCID: PMC1892604 DOI: 10.1371/journal.pcbi.0030109] [Citation(s) in RCA: 110] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2006] [Accepted: 04/29/2007] [Indexed: 01/15/2023] Open
Abstract
Many pathogens are able to manipulate the signaling pathways responsible for the generation of host immune responses. Here we examine and model a respiratory infection system in which disruption of host immune functions or of bacterial factors changes the dynamics of the infection. We synthesize the network of interactions between host immune components and two closely related bacteria in the genus Bordetellae. We incorporate existing experimental information on the timing of immune regulatory events into a discrete dynamic model, and verify the model by comparing the effects of simulated disruptions to the experimental outcome of knockout mutations. Our model indicates that the infection time course of both Bordetellae can be separated into three distinct phases based on the most active immune processes. We compare and discuss the effect of the species-specific virulence factors on disrupting the immune response during their infection of naive, antibody-treated, diseased, or convalescent hosts. Our model offers predictions regarding cytokine regulation, key immune components, and clearance of secondary infections; we experimentally validate two of these predictions. This type of modeling provides new insights into the virulence, pathogenesis, and host adaptation of disease-causing microorganisms and allows systems-level analysis that is not always possible using traditional methods. The immune response is a complex network of processes activated in a host upon infection. Pathogens seek to disrupt or evade these processes to ensure their own survival and proliferation. This article provides a systems-level analysis of the immune response against two related bacterial species in the Bordetella genus, B. bronchiseptica and B. pertussis. B. pertussis, the causative agent of whooping cough, has lost many of the virulence factors of its B. bronchiseptica–like progenitor, and is using different strategies for the modulation of the immune system. We have synthesized two separate network models for the interaction of these pathogens with their hosts. Each network is then translated into a predictive dynamic model and is validated by comparison with available experimental data. The model offers predictions regarding cytokine regulation and the effects of perturbations of the immune system, as well as the time course of infections in hosts that had previously encountered the pathogens. We experimentally validate the prediction that convalescent hosts can rapidly clear both pathogens, while antibody transfer cannot substantially reduce the duration of a B. pertussis infection. This type of modeling provides new insights into the virulence, pathogenesis, and host adaptation of disease-causing microorganisms and can be readily extended to other pathogens.
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Affiliation(s)
- Juilee Thakar
- Department of Physics, Pennsylvania State University, University Park, Pennsylvania, United States of America
| | - Mylisa Pilione
- Department of Veterinary and Biomedical Sciences, Pennsylvania State University, University Park, Pennsylvania, United States of America
| | - Girish Kirimanjeswara
- Department of Veterinary and Biomedical Sciences, Pennsylvania State University, University Park, Pennsylvania, United States of America
| | - Eric T Harvill
- Department of Veterinary and Biomedical Sciences, Pennsylvania State University, University Park, Pennsylvania, United States of America
| | - Réka Albert
- Department of Physics, Pennsylvania State University, University Park, Pennsylvania, United States of America
- * To whom correspondence should be addressed. E-mail:
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34
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Rejzek M, Mukhopadhyay B, Wenzel CQ, Lam JS, Field RA. Direct oxidation of sugar nucleotides to the corresponding uronic acids: TEMPO and platinum-based procedures. Carbohydr Res 2006; 342:460-6. [PMID: 17087923 DOI: 10.1016/j.carres.2006.10.016] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2006] [Revised: 10/17/2006] [Accepted: 10/17/2006] [Indexed: 11/22/2022]
Abstract
The direct oxidation of UDP-alpha-d-glucose and UDP-N-acetyl-alpha-d-glucosamine to the corresponding uronic acids was explored using either TEMPO or platinum-catalysed oxidation with molecular oxygen. Whilst TEMPO-based procedures gave rise to substantial over-oxidation and/or degradation of UDP-glucose, oxidation of UDP-N-acetyl-glucosamine to UDP-N-acetyl-glucosaminuronic acid was achieved with >90% conversion and ca. 65% isolated yield using a platinum-catalysed procedure.
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Affiliation(s)
- Martin Rejzek
- Centre for Carbohydrate Chemistry, School of Chemical Sciences and Pharmacy, University of East Anglia, Norwich NR4 7TJ, UK
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35
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Preston A, Petersen BO, Duus JØ, Kubler-Kielb J, Ben-Menachem G, Li J, Vinogradov E. Complete structures of Bordetella bronchiseptica and Bordetella parapertussis lipopolysaccharides. J Biol Chem 2006; 281:18135-44. [PMID: 16632471 DOI: 10.1074/jbc.m513904200] [Citation(s) in RCA: 50] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The structures of the lipopolysaccharide (LPS) core and O antigen of Bordetella bronchiseptica and Bordetella parapertussis are known, but how these two regions are linked to each other had not been determined. We have studied LPS from several strains of these microorganisms to determine the complete carbohydrate structure of the LPS. LPS was analyzed using different chemical degradations, NMR spectroscopy, and mass spectrometry. This identified a novel pentasaccharide fragment that links the O chain to the core in all the LPS studied. In addition, although the O chain of these bacteria was reported as a homopolymer of 1,4-linked 2,3-diacetamido-2,3-dideoxy-alpha-galacturonic acid, we discovered that the polymer contains several amidated uronic acids, the number of which varies between strains. These new data describe the complete structure of the LPS carbohydrate backbone for both Bordetella species and help to explain the complex genetics of LPS biosynthesis in these bacteria.
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Affiliation(s)
- Andrew Preston
- Institute for Biological Sciences, National Research Council, 100 Sussex Drive, Ottawa, Ontario K1A OR6, Canada
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36
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Dworzanski JP, Deshpande SV, Chen R, Jabbour RE, Snyder AP, Wick CH, Li L. Mass spectrometry-based proteomics combined with bioinformatic tools for bacterial classification. J Proteome Res 2006; 5:76-87. [PMID: 16396497 DOI: 10.1021/pr050294t] [Citation(s) in RCA: 70] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Timely classification and identification of bacteria is of vital importance in many areas of public health. We present a mass spectrometry (MS)-based proteomics approach for bacterial classification. In this method, a bacterial proteome database is derived from all potential protein coding open reading frames (ORFs) found in 170 fully sequenced bacterial genomes. Amino acid sequences of tryptic peptides obtained by LC-ESI MS/MS analysis of the digest of bacterial cell extracts are assigned to individual bacterial proteomes in the database. Phylogenetic profiles of these peptides are used to create a matrix of sequence-to-bacterium assignments. These matrixes, viewed as specific assignment bitmaps, are analyzed using statistical tools to reveal the relatedness between a test bacterial sample and the microorganism database. It is shown that, if a sufficient amount of sequence information is obtained from the MS/MS experiments, a bacterial sample can be classified to a strain level by using this proteomics method, leading to its positive identification.
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37
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Pilione MR, Harvill ET. The Bordetella bronchiseptica type III secretion system inhibits gamma interferon production that is required for efficient antibody-mediated bacterial clearance. Infect Immun 2006; 74:1043-9. [PMID: 16428751 PMCID: PMC1360352 DOI: 10.1128/iai.74.2.1043-1049.2006] [Citation(s) in RCA: 56] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
Several species of pathogenic microorganisms have developed strategies to survive and persist in vital organs which are normally maintained as sterile by the generation of strong immune responses. Here, we report an immunomodulation involving the Bordetella bronchiseptica type III secretion system (TTSS) which contributes to bacterial survival in the lower respiratory tract of the host. The prolonged persistence of B. bronchiseptica that was observed in gamma interferon (IFN-gamma)-/- mice indicates that the efficient clearance of bacteria from the lower respiratory tract requires not only B cells and antibodies but also IFN-gamma production. Our data also suggest that interleukin-10 (IL-10)-producing splenocytes are generated early during infection and that IL-10 inhibits IFN-gamma-producing cells and delays the clearance of B. bronchiseptica from the lungs. The TTSS of B. bronchiseptica inhibits the generation of IFN-gamma-producing splenocytes and is required for long-term bacterial persistence in the lower respiratory tract in wild-type mice. This suggests that a mechanism involving the modulation of IFN-gamma production by the TTSS facilitates B. bronchiseptica survival in the lower respiratory tract.
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Affiliation(s)
- Mylisa R Pilione
- Department of Veterinary and Biomedical Science, The Pennsylvania State University, 115 Henning, University Park, PA 16802, USA
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38
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Inatsuka CS, Julio SM, Cotter PA. Bordetella filamentous hemagglutinin plays a critical role in immunomodulation, suggesting a mechanism for host specificity. Proc Natl Acad Sci U S A 2005; 102:18578-83. [PMID: 16339899 PMCID: PMC1317942 DOI: 10.1073/pnas.0507910102] [Citation(s) in RCA: 76] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Bordetella pertussis, the causative agent of the acute childhood respiratory disease whooping cough, is a human-adapted variant of Bordetella bronchiseptica, which displays a broad host range and typically causes chronic, asymptomatic infections. These pathogens express a similar but not identical surface-exposed and secreted protein called filamentous hemagglutinin (FHA) that has been proposed to function as both a primary adhesin and an immunomodulator. To test the hypothesis that FHA plays an important role in determining host specificity and/or the propensity to cause acute versus chronic disease, we constructed a B. bronchiseptica strain expressing FHA from B. pertussis (FHA(Bp)) and compared it with wild-type B. bronchiseptica in several natural-host infection models. FHA(Bp) was able to substitute for FHA from B. bronchiseptica (FHA(Bb)) with regard to its ability to mediate adherence to several epithelial and macrophage-like cell lines in vitro, but it was unable to substitute for FHA(Bb) in vivo. Specifically, FHA(Bb), but not FHA(Bp), allowed B. bronchiseptica to colonize the lower respiratory tracts of rats, to modulate the inflammatory response in the lungs of immunocompetent mice, resulting in decreased lung damage and increased bacterial persistence, to induce a robust anti-Bordetella antibody response in these immunocompetent mice, and to overcome innate immunity and cause a lethal infection in immunodeficient mice. These results indicate a critical role for FHA in B. bronchiseptica-mediated immunomodulation, and they suggest a role for FHA in host specificity.
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Affiliation(s)
- Carol S Inatsuka
- Department of Molecular, Cellular, and Developmental Biology, University of California, Santa Barbara, CA 93106-9610, USA
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39
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Wolfe DN, Kirimanjeswara GS, Harvill ET. Clearance of Bordetella parapertussis from the lower respiratory tract requires humoral and cellular immunity. Infect Immun 2005; 73:6508-13. [PMID: 16177324 PMCID: PMC1230969 DOI: 10.1128/iai.73.10.6508-6513.2005] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Bordetella parapertussis and Bordetella pertussis are closely related species that cause whooping cough, an acute, immunizing disease. Their coexistence in the same host populations at the same time and vaccine studies showing that B. pertussis vaccines have little effect on B. parapertussis infection or disease suggest that the protective immunity induced by each does not efficiently cross protect against the other. Although the mechanisms of protective immunity to B. pertussis have been well studied, those of B. parapertussis have not. The present study explores the mechanism by which B. parapertussis is cleared from the lower respiratory tract by anamnestic immunity. Serum antibodies are necessary and sufficient for elimination of this bacterium, and CD4(+) T cells, complement, and neutrophils are required for serum antibody-mediated clearance. Mice lacking immunoglobulin A had no defect in their ability to control or clear infection. Interestingly, serum antibody-mediated clearance of B. parapertussis did not require Fc receptors that are required for antibody-mediated clearance of B. pertussis. Together these data support a model for the mechanism of protective immunity to B. parapertussis that is similar but distinct from that of B. pertussis.
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Affiliation(s)
- Daniel N Wolfe
- Department of Veterinary Science, The Pennsylvania State University, University Park, 16802, USA
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40
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Julio SM, Cotter PA. Characterization of the filamentous hemagglutinin-like protein FhaS in Bordetella bronchiseptica. Infect Immun 2005; 73:4960-71. [PMID: 16041011 PMCID: PMC1201180 DOI: 10.1128/iai.73.8.4960-4971.2005] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Filamentous hemagglutinin (FHA) is a large (>200 kDa), rod-shaped protein expressed by bordetellae that is both surface-associated and secreted. FHA mediates bacterial adherence to epithelial cells and macrophages in vitro and is absolutely required for tracheal colonization in vivo. The recently sequenced Bordetella bronchiseptica genome revealed the presence of a gene, fhaS, that is nearly identical to fhaB, the FHA structural gene. We show that although fhaS expression requires the BvgAS virulence control system, it is maximal only under a subset of conditions in which BvgAS is active, suggesting an additional level of regulation. We also show that, like FHA, FhaS undergoes a C-terminal proteolytic processing event and is both surface-associated and secreted and that export across the outer membrane requires the channel-forming protein FhaC. Unlike FHA, however, FhaS was unable to mediate adherence of B. bronchiseptica to epithelial cell lines in vitro and was not required for respiratory tract colonization in vivo. In a coinfection experiment, a DeltafhaS strain was out-competed by wild-type B. bronchiseptica, indicating that fhaS is expressed in vivo and that FhaS contributes to bacterial fitness in a manner revealed when the mutant must compete with wild-type bacteria. These data suggest that FHA and FhaS perform distinct functions during the Bordetella infectious cycle. A survey of various Bordetella strains revealed two distinct fhaS alleles that segregate according to pathogen host range and that B. parapertussis(hu) most likely acquired its fhaS allele from B. pertussis horizontally, suggesting fhaS may contribute to host-species specificity.
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Affiliation(s)
- Steven M Julio
- Department of Molecular, Cellular and Developmental Biology, University of California, Santa Barbara, Santa Barbara, CA 93106-9610, USA
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Bjørnstad ON, Harvill ET. Evolution and emergence of Bordetella in humans. Trends Microbiol 2005; 13:355-9. [PMID: 15990312 DOI: 10.1016/j.tim.2005.06.007] [Citation(s) in RCA: 75] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2005] [Revised: 06/01/2005] [Accepted: 06/20/2005] [Indexed: 11/23/2022]
Abstract
Two highly infectious bordetellae, Bordetella pertussis and B. parapertussis, have emerged in historical times as co-dominant in human populations. Both of these cause acute disease (whooping cough), whereas their progenitor, B. bronchiseptica, is of variable virulence in a wide variety of animals. The remarkably close phylogenetic relatedness of these three bordetellae and the two independent jumps to humans provide a unique opportunity to examine the evolution and genetics involved in the emergence of acute human pathogens. We hypothesize that the more virulent strains in humans reflects how acutely infectious pathogens might be favored in communities with large contact networks. Furthermore, we suggest that the differential expression of the various virulence factors by the two human pathogens can be explained by immune-mediated competition between the strains. The evolutionarily favored strategies of both of the human bordetellae result in immunizing infections and acute epidemics.
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Affiliation(s)
- Ottar N Bjørnstad
- Departments of Entomology and Biology Penn State University, 501 ASI Building, University Park, PA 16803, USA.
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Mattoo S, Cherry JD. Molecular pathogenesis, epidemiology, and clinical manifestations of respiratory infections due to Bordetella pertussis and other Bordetella subspecies. Clin Microbiol Rev 2005; 18:326-82. [PMID: 15831828 PMCID: PMC1082800 DOI: 10.1128/cmr.18.2.326-382.2005] [Citation(s) in RCA: 778] [Impact Index Per Article: 40.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Bordetella respiratory infections are common in people (B. pertussis) and in animals (B. bronchiseptica). During the last two decades, much has been learned about the virulence determinants, pathogenesis, and immunity of Bordetella. Clinically, the full spectrum of disease due to B. pertussis infection is now understood, and infections in adolescents and adults are recognized as the reservoir for cyclic outbreaks of disease. DTaP vaccines, which are less reactogenic than DTP vaccines, are now in general use in many developed countries, and it is expected that the expansion of their use to adolescents and adults will have a significant impact on reducing pertussis and perhaps decrease the circulation of B. pertussis. Future studies should seek to determine the cause of the unique cough which is associated with Bordetella respiratory infections. It is also hoped that data gathered from molecular Bordetella research will lead to a new generation of DTaP vaccines which provide greater efficacy than is provided by today's vaccines.
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Affiliation(s)
- Seema Mattoo
- Department of Microbiology, Immunology, and Molecular Genetics, David Geffen School of Medicine, University of California, Los Angeles, California 90095-1752, USA
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Elder KD, Harvill ET. Strain-dependent role of BrkA during Bordetella pertussis infection of the murine respiratory tract. Infect Immun 2004; 72:5919-24. [PMID: 15385494 PMCID: PMC517575 DOI: 10.1128/iai.72.10.5919-5924.2004] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2004] [Revised: 06/10/2004] [Accepted: 06/16/2004] [Indexed: 11/20/2022] Open
Abstract
Bordetella pertussis, the causative agent of whooping cough, expresses many virulence factors believed to be involved in infection and disease progression. While these factors as a group are required for infection, deletion of individual virulence factor genes generally has limited effects on the ability of B. pertussis to efficiently infect the respiratory tract of mice, suggesting they may perform noncritical or redundant functions. We have recently observed that a B. pertussis strain, putatively with a mutation of a single gene, brkA, results in a severe defect in vivo. Although BrkA has been shown to be required for B. pertussis to resist complement-mediated killing in vitro, the relevance of these findings to the in vivo role of BrkA during infection has not been examined. Transducing this mutation into multiple wild-type B. pertussis strains allowed us to confirm the in vitro phenotype of reduced resistance to serum complement. All DeltabrkA mutants were increased in their sensitivity to complement in vitro, both in the presence and absence of antibodies. However, these strains differed substantially in their phenotypes in vivo. DeltabrkA mutants of recent clinical isolates were indistinguishable from wild-type strains in their efficient infection of respiratory organs, suggesting that the function of BrkA in these strains is noncritical or redundant. In contrast, multiple DeltabrkA strains derived from Tohama I were severely defective during the first week postinoculation compared to their wild-type parent. This defect was present even in complement-deficient mice, revealing a complement-independent phenotype for the DeltabrkA mutant in respiratory tract infection.
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Affiliation(s)
- Kelly D Elder
- Department of Veterinary Science, The Pennsylvania State University, University Park, Pennsylvania 16802, USA
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Pilione MR, Pishko EJ, Preston A, Maskell DJ, Harvill ET. pagP is required for resistance to antibody-mediated complement lysis during Bordetella bronchiseptica respiratory infection. Infect Immun 2004; 72:2837-42. [PMID: 15102794 PMCID: PMC387902 DOI: 10.1128/iai.72.5.2837-2842.2004] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023] Open
Abstract
To efficiently colonize and persist in the lower respiratory tract, bacteria must survive multiple host immune mechanisms. Bordetella bronchiseptica is a gram-negative respiratory pathogen that naturally infects mice and persists in the lower respiratory tract for up to 49 days postinoculation. In this work, we examined the effect of mutation of the pagP gene on the persistence of B. bronchiseptica in the lower respiratory tract of mice. The pagP gene encodes a palmitoyl transferase that is responsible for the addition of a palmitoyl group to the lipid A region of B. bronchiseptica lipopolysaccharide. Data presented here confirm that a B. bronchiseptica deltapagP mutant demonstrates defective persistence in the lower respiratory tract of wild-type mice. We hypothesized that the defective persistence of the B. bronchiseptica deltapagP mutant was due to an increased susceptibility of this mutant to a host immune response. In vivo data indicate that both B cells and the complement component C3 are required for the reduced bacterial numbers of the deltapagP mutant on day 14 postinoculation. In addition, an in vitro complement killing assay demonstrated that B. bronchiseptica exhibits pagP-dependent resistance to antibody-mediated complement killing at low concentrations of immune serum. Taken together, these results suggest that pagP is required for B. bronchiseptica to resist antibody-mediated complement lysis during respiratory infection.
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Affiliation(s)
- Mylisa R Pilione
- Department of Veterinary Science, The Pennsylvania State University, University Park, Pennsylvania, PA 16802, USA
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Pishko EJ, Betting DJ, Hutter CS, Harvill ET. Bordetella pertussis acquires resistance to complement-mediated killing in vivo. Infect Immun 2003; 71:4936-42. [PMID: 12933835 PMCID: PMC187338 DOI: 10.1128/iai.71.9.4936-4942.2003] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
In order to initially colonize a host, bacteria must avoid various components of the innate immune system, one of which is complement. The genus Bordetella includes three closely related species that differ in their ability to resist complement-mediated killing. Bordetella parapertussis and Bordetella bronchiseptica resist killing in naïve serum, a characteristic that may aid in efficient respiratory tract colonization and has been attributed to expression of O antigen. Bordetella pertussis lacks O antigen and is sensitive to naïve serum in vitro, yet it also efficiently colonizes the respiratory tract. Based on these observations, we hypothesized that B. pertussis may have an alternate mechanism to resist complement in vivo. While a number of reports on serum sensitivity of the bordetellae have been published, we show here that serum concentration and growth conditions can greatly alter the observed level of sensitivity to complement and that all but one strain of B. pertussis observed were sensitive to some level of naïve serum in vitro, particularly when there was excess complement. However, B. pertussis rapidly acquires increased resistance in vivo to naïve serum that is specific to the alternative pathway. Resistance is not efficiently acquired by B. parapertussis and B. bronchiseptica mutants lacking O antigen. This B. pertussis-specific mechanism of complement resistance does not appear to be dependent on either brkA or other genes expressed specifically in the Bvg(+) phase. This in vivo acquisition of alternative pathway resistance suggests that there is a novel O antigen-independent method by which B. pertussis evades complement-mediated killing.
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Affiliation(s)
- Elizabeth J Pishko
- Department of Veterinary Science, The Pennsylvania State University, University Park, Pennsylvania 16802, USA
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Preston A, Maxim E, Toland E, Pishko EJ, Harvill ET, Caroff M, Maskell DJ. Bordetella bronchiseptica PagP is a Bvg-regulated lipid A palmitoyl transferase that is required for persistent colonization of the mouse respiratory tract. Mol Microbiol 2003; 48:725-36. [PMID: 12694617 DOI: 10.1046/j.1365-2958.2003.03484.x] [Citation(s) in RCA: 79] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Bordetella bronchiseptica lipopolysaccharide (LPS) expression varies depending on growth conditions, regulated by the Bvg system. A B. bronchiseptica pagP homologue was identified that is required for Bvg-mediated modification of the lipid A core region of LPS that occurs on switching from the Bvg- to the Bvg+ phase. Structural analysis demonstrated that the lipid A of a B. bronchiseptica pagP mutant differed from wild-type lipid A by the absence of a palmitate group in secondary acylation at the C3' position. The putative pagP promoter drove the expression of a green fluorescent protein (GFP) reporter gene in a Bvg-regulated fashion. These data suggest that B. bronchiseptica pagP encodes a Bvg-regulated lipid A palmitoyl transferase that mediates modification of the lipid A as part of the overall Bvg-mediated adaptation of this organism to changing environmental conditions. We also show that pagP is not required for the initial colonization of the mouse respiratory tract by B. bronchiseptica, but is required for persistence of the organism within this organ.
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Affiliation(s)
- Andrew Preston
- Centre for Veterinary Science, Department of Clinical Veterinary Medicine, University of Cambridge, Madingley Road, Cambridge CB3 0ES, UK.
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