1
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In Vitro Analysis of Matched Isolates from Localized and Disseminated Gonococcal Infections Suggests That Opa Expression Impacts Clinical Outcome. Pathogens 2022; 11:pathogens11020217. [PMID: 35215160 PMCID: PMC8880309 DOI: 10.3390/pathogens11020217] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2022] [Revised: 02/04/2022] [Accepted: 02/05/2022] [Indexed: 12/04/2022] Open
Abstract
Gonorrhea is the second most common sexually transmitted infection, which is primarily localized but can be disseminated systemically. The mechanisms by which a localized infection becomes a disseminated infection are unknown. We used five pairs of Neisseria gonorrhoeae isolates from the cervix/urethra (localized) and the blood (disseminated) of patients with disseminated gonococcal infection to examine the mechanisms that confine gonococci to the genital tract or enable them to disseminate to the blood. Multilocus sequence analysis found that the local and disseminated isolates from the same patients were isogenic. When culturing in vitro, disseminated isolates aggregated significantly less and transmigrated across a polarized epithelial monolayer more efficiently than localized isolates. While localized cervical isolates transmigrated across epithelial monolayers inefficiently, those transmigrated bacteria self-aggregated less and transmigrated more than cervical isolates but comparably to disseminating isolates. The local cervical isolates recruited the host receptors of gonococcal Opa proteins carcinoembryonic antigen-related cell adhesion molecules (CEACAMs) on epithelial cells. However, the transmigrated cervical isolate and the disseminated blood isolates recruit CEACAMs significantly less often. Our results collectively suggest that switching off the expression of CEACAM-binding Opa(s), which reduces self-aggregation, promotes gonococcal dissemination.
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2
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Buckley C, Beatson SA, Limnios A, Lahra MM, Whiley DM, Forde BM. Whole-genome sequencing as an improved means of investigating Neisseria gonorrhoeae treatment failures. Sex Health 2020; 16:500-507. [PMID: 31481151 DOI: 10.1071/sh19012] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2019] [Accepted: 08/22/2019] [Indexed: 11/23/2022]
Abstract
Background Although rare, Neisseria gonorrhoeae treatment failures associated with ceftriaxone have been reported. The World Health Organization (WHO) recommends standardised protocols to verify these cases. Two cases from Australia were previously investigated using N. gonorrhoeae multiantigen sequence typing (NG-MAST), which has been used extensively to assess treatment failures. Case 1 pharyngeal isolates were indistinguishable, whereas Case 2 pharyngeal isolates were distinguished based on an 18-bp deletion in the major outer membrane porin encoded by the porB gene, questioning the reliability of NG-MAST results. Here we used whole-genome sequencing (WGS) to reinvestigate Cases 1 and 2, with a view to examining WGS to assess treatment failures. METHODS Pre- and post-treatment isolates for each case underwent Illumina sequencing, and the two post-treatment isolates underwent additional long-read sequencing using Pacific Biosciences. Sequence data were interrogated to identify differences at single nucleotide resolution. RESULTS WGS identified variation in the pilin subunit encoded by the pilE locus for both cases and the specific 18-bp porB deletion in Case 2 was confirmed, but otherwise the isolates in each case were indistinguishable. CONCLUSIONS The WHO recommends standardised protocols for verifying N. gonorrhoeae treatment failures. Case 2 highlights the enhanced resolution of WGS over NG-MAST and emphasises the immediate effect that WGS can have in a direct clinical application for N. gonorrhoeae. Assessing the whole genome compared with two highly variable regions also provides a more confident predictor for determining treatment failure. Furthermore, WGS facilitates rapid comparisons of these cases in the future.
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Affiliation(s)
- Cameron Buckley
- Faculty of Medicine, UQ Centre for Clinical Research, The University of Queensland, Herston, Qld 4029, Australia
| | - Scott A Beatson
- Australian Infectious Diseases Research Centre, The University of Queensland, Brisbane, Qld 4072, Australia; and Australian Centre for Ecogenomics, The University of Queensland, Brisbane, Qld 4072, Australia; and School of Chemistry and Molecular Biosciences, The University of Queensland, Brisbane, Qld 4072, Australia
| | - Athena Limnios
- WHO Collaborating Centre for STI and AMR, Microbiology Department, New South Wales Health Pathology, Prince of Wales Hospital, Sydney, NSW 2031, Australia
| | - Monica M Lahra
- WHO Collaborating Centre for STI and AMR, Microbiology Department, New South Wales Health Pathology, Prince of Wales Hospital, Sydney, NSW 2031, Australia; and School of Medical Sciences, UNSW, Sydney, NSW 2052, Australia
| | - David M Whiley
- Faculty of Medicine, UQ Centre for Clinical Research, The University of Queensland, Herston, Qld 4029, Australia; and Australian Infectious Diseases Research Centre, The University of Queensland, Brisbane, Qld 4072, Australia; and Pathology Queensland, Microbiology Department, Herston, Qld 4029, Australia
| | - Brian M Forde
- Australian Infectious Diseases Research Centre, The University of Queensland, Brisbane, Qld 4072, Australia; and Australian Centre for Ecogenomics, The University of Queensland, Brisbane, Qld 4072, Australia; and School of Chemistry and Molecular Biosciences, The University of Queensland, Brisbane, Qld 4072, Australia; and Corresponding author:
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3
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Localized Hypermutation is the Major Driver of Meningococcal Genetic Variability during Persistent Asymptomatic Carriage. mBio 2020; 11:mBio.03068-19. [PMID: 32209693 PMCID: PMC7157529 DOI: 10.1128/mbio.03068-19] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023] Open
Abstract
Host persistence of bacteria is facilitated by mutational and recombinatorial processes that counteract loss of genetic variation during transmission and selection from evolving host responses. Genetic variation was investigated during persistent asymptomatic carriage of Neisseria meningitidis Interrogation of whole-genome sequences for paired isolates from 25 carriers showed that de novo mutations were infrequent, while horizontal gene transfer occurred in 16% of carriers. Examination of multiple isolates per time point enabled separation of sporadic and transient allelic variation from directional variation. A comprehensive comparative analysis of directional allelic variation with hypermutation of simple sequence repeats and hyperrecombination of class 1 type IV pilus genes detected an average of seven events per carrier and 2:1 bias for changes due to localized hypermutation. Directional genetic variation was focused on the outer membrane with 69% of events occurring in genes encoding enzymatic modifiers of surface structures or outer membrane proteins. Multiple carriers exhibited directional and opposed switching of allelic variants of the surface-located Opa proteins that enables continuous expression of these adhesins alongside antigenic variation. A trend for switching from PilC1 to PilC2 expression was detected, indicating selection for specific alterations in the activities of the type IV pilus, whereas phase variation of restriction modification (RM) systems, as well as associated phasevarions, was infrequent. We conclude that asymptomatic meningococcal carriage on mucosal surfaces is facilitated by frequent localized hypermutation and horizontal gene transfer affecting genes encoding surface modifiers such that optimization of adhesive functions occurs alongside escape of immune responses by antigenic variation.IMPORTANCE Many bacterial pathogens coexist with host organisms, rarely causing disease while adapting to host responses. Neisseria meningitidis, a major cause of meningitis and septicemia, is a frequent persistent colonizer of asymptomatic teenagers/young adults. To assess how genetic variation contributes to host persistence, whole-genome sequencing and hypermutable sequence analyses were performed on multiple isolates obtained from students naturally colonized with meningococci. High frequencies of gene transfer were observed, occurring in 16% of carriers and affecting 51% of all nonhypermutable variable genes. Comparative analyses showed that hypermutable sequences were the major mechanism of variation, causing 2-fold more changes in gene function than other mechanisms. Genetic variation was focused on genes affecting the outer membrane, with directional changes in proteins responsible for bacterial adhesion to host surfaces. This comprehensive examination of genetic plasticity in individual hosts provides a significant new platform for rationale design of approaches to prevent the spread of this pathogen.
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4
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Kuhn J, Smirnov A, Criss AK, Columbus L. Quantifying Carcinoembryonic Antigen-like Cell Adhesion Molecule-Targeted Liposome Delivery Using Imaging Flow Cytometry. Mol Pharm 2019; 16:2354-2363. [PMID: 30995063 DOI: 10.1021/acs.molpharmaceut.8b01274] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
Abstract
Carcinoembryonic antigen-like cell adhesion molecules (CEACAMs) are human cell-surface proteins that can exhibit increased expression on tumor cells and are thus a potential target for novel tumor-seeking therapeutic delivery methods. We hypothesize that engineered nanoparticles containing a known interaction partner of CEACAM, Neisseria gonorrhoeae outer membrane protein Opa, can be used to deliver cargo to specific cellular targets. In this study, the cell association and uptake of protein-free liposomes and Opa proteoliposomes into CEACAM-expressing cells were measured using imaging flow cytometry. A size-dependent internalization of liposomes into HeLa cells was observed through endocytic pathways. Opa-dependent, CEACAM1-mediated uptake of liposomes into HeLa cells was observed, with limited colocalization with endosomal and lysosomal trafficking compartments. Given the overexpression of CEACAM1 on several distinct cancers and interest in using CEACAM1 as a component in treatment strategies, these results support further pursuit of investigating Opa-dependent specificity and the internalization mechanism for therapeutic delivery.
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5
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Whittles LK, White PJ, Paul J, Didelot X. Epidemiological Trends of Antibiotic Resistant Gonorrhoea in the United Kingdom. Antibiotics (Basel) 2018; 7:antibiotics7030060. [PMID: 30011825 PMCID: PMC6165062 DOI: 10.3390/antibiotics7030060] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2018] [Revised: 07/06/2018] [Accepted: 07/11/2018] [Indexed: 11/16/2022] Open
Abstract
Gonorrhoea is one of the most common sexually-transmitted bacterial infections, globally and in the United Kingdom. The levels of antibiotic resistance in gonorrhoea reported in recent years represent a critical public health issue. From penicillins to cefixime, the gonococcus has become resistant to all antibiotics that have been previously used against it, in each case only a matter of years after introduction as a first-line therapy. After each instance of resistance emergence, the treatment recommendations have required revision, to the point that only a few antibiotics can reliably be prescribed to treat infected individuals. Most countries, including the UK, now recommend that gonorrhoea be treated with a dual therapy combining ceftriaxone and azithromycin. While this treatment is still currently effective for the vast majority of cases, there are concerning signs that this will not always remain the case, and there is no readily apparent alternative. Here, we review the use of antibiotics and epidemiological trends of antibiotic resistance in gonorrhoea from surveillance data over the past 15 years in the UK and describe how surveillance could be improved.
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Affiliation(s)
- Lilith K Whittles
- Department of Infectious Disease Epidemiology, School of Public Health, Imperial College London, London W2 1PG, UK.
| | - Peter J White
- Department of Infectious Disease Epidemiology, School of Public Health, Imperial College London, London W2 1PG, UK.
- MRC Centre for Outbreak Analysis and Modelling, School of Public Health, Imperial College London, London W2 1PG, UK.
- NIHR Health Protection Research Unit in Modelling Methodology, School of Public Health, Imperial College London, London W2 1PG, UK.
- Modelling and Economics Unit, National Infection Service, Public Health England, London NW9 5EQ, UK.
| | - John Paul
- Department of Microbiology, Public Health England Collaborative Centre, Royal Sussex County Hospital, Brighton BN2 5BE, UK.
- Department of Global Health and Infection, Brighton and Sussex Medical School, University of Sussex, Falmer BN1 9PH, UK.
| | - Xavier Didelot
- Department of Infectious Disease Epidemiology, School of Public Health, Imperial College London, London W2 1PG, UK.
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6
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Watkins ER, Maiden MC, Gupta S. Metabolic competition as a driver of bacterial population structure. Future Microbiol 2016; 11:1339-1357. [PMID: 27660887 DOI: 10.2217/fmb-2016-0079] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
Abstract
Understanding the processes whereby diversity arises and is maintained in pathogen populations is pivotal for designing disease control interventions. A particular problem is the maintenance of strain structure in bacterial pathogen populations despite frequent genetic exchange. Although several theoretical frameworks have been put forward to explain this widespread phenomenon, few have focused on the role of genes encoding metabolic functions, despite an increasing recognition of their importance in pathogenesis and transmission. In this article, we review the literature for evidence of metabolic niches within the host and discuss theoretical frameworks which examine ecological interactions between metabolic genes. We contend that metabolic competition is an important phenomenon which contributes to the maintenance of population structure and diversity of many bacterial pathogens.
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Affiliation(s)
- Eleanor R Watkins
- Department of Zoology, University of Oxford, South Parks Road, Oxford, OX1 3PS, UK
| | - Martin Cj Maiden
- Department of Zoology, University of Oxford, South Parks Road, Oxford, OX1 3PS, UK
| | - Sunetra Gupta
- Department of Zoology, University of Oxford, South Parks Road, Oxford, OX1 3PS, UK
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7
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Wachter J, Hill S. Positive Selection Pressure Drives Variation on the Surface-Exposed Variable Proteins of the Pathogenic Neisseria. PLoS One 2016; 11:e0161348. [PMID: 27532335 PMCID: PMC5020929 DOI: 10.1371/journal.pone.0161348] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2016] [Accepted: 08/03/2016] [Indexed: 11/19/2022] Open
Abstract
Pathogenic species of Neisseria utilize variable outer membrane proteins to facilitate infection and proliferation within the human host. However, the mechanisms behind the evolution of these variable alleles remain largely unknown due to analysis of previously limited datasets. In this study, we have expanded upon the previous analyses to substantially increase the number of analyzed sequences by including multiple diverse strains, from various geographic locations, to determine whether positive selective pressure is exerted on the evolution of these variable genes. Although Neisseria are naturally competent, this analysis indicates that only intrastrain horizontal gene transfer among the pathogenic Neisseria principally account for these genes exhibiting linkage equilibrium which drives the polymorphisms evidenced within these alleles. As the majority of polymorphisms occur across species, the divergence of these variable genes is dependent upon the species and is independent of geographical location, disease severity, or serogroup. Tests of neutrality were able to detect strong selection pressures acting upon both the opa and pil gene families, and were able to locate the majority of these sites within the exposed variable regions of the encoded proteins. Evidence of positive selection acting upon the hypervariable domains of Opa contradicts previous beliefs and provides evidence for selection of receptor binding. As the pathogenic Neisseria reside exclusively within the human host, the strong selection pressures acting upon both the opa and pil gene families provide support for host immune system pressure driving sequence polymorphisms within these variable genes.
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Affiliation(s)
- Jenny Wachter
- Department of Biological Sciences, Northern Illinois University, DeKalb, IL, 60115, United States of America
| | - Stuart Hill
- Department of Biological Sciences, Northern Illinois University, DeKalb, IL, 60115, United States of America
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8
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Martin JN, Ball LM, Solomon TL, Dewald AH, Criss AK, Columbus L. Neisserial Opa Protein-CEACAM Interactions: Competition for Receptors as a Means of Bacterial Invasion and Pathogenesis. Biochemistry 2016; 55:4286-94. [PMID: 27442026 DOI: 10.1021/acs.biochem.6b00124] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
Carcino-embryonic antigen-like cellular adhesion molecules (CEACAMs), members of the immunoglobulin superfamily, are responsible for cell-cell interactions and cellular signaling events. Extracellular interactions with CEACAMs have the potential to induce phagocytosis, as is the case with pathogenic Neisseria bacteria. Pathogenic Neisseria species express opacity-associated (Opa) proteins, which interact with a subset of CEACAMs on human cells, and initiate the engulfment of the bacterium. We demonstrate that recombinant Opa proteins reconstituted into liposomes retain the ability to recognize and interact with CEACAMs in vitro but do not maintain receptor specificity compared to that of Opa proteins natively expressed by Neisseria gonorrhoeae. We report that two Opa proteins interact with CEACAMs with nanomolar affinity, and we hypothesize that this high affinity is necessary to compete with the native CEACAM homo- and heterotypic interactions in the host. Understanding the mechanisms of Opa protein-receptor recognition and engulfment enhances our understanding of Neisserial pathogenesis. Additionally, these mechanisms provide insight into how human cells that are typically nonphagocytic can utilize CEACAM receptors to internalize exogenous matter, with implications for the targeted delivery of therapeutics and development of imaging agents.
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Affiliation(s)
- Jennifer N Martin
- Department of Chemistry and ‡Department of Microbiology, Immunology, and Cancer Biology, University of Virginia , Charlottesville, Virginia 22903, United States
| | - Louise M Ball
- Department of Chemistry and ‡Department of Microbiology, Immunology, and Cancer Biology, University of Virginia , Charlottesville, Virginia 22903, United States
| | - Tsega L Solomon
- Department of Chemistry and ‡Department of Microbiology, Immunology, and Cancer Biology, University of Virginia , Charlottesville, Virginia 22903, United States
| | - Alison H Dewald
- Department of Chemistry and ‡Department of Microbiology, Immunology, and Cancer Biology, University of Virginia , Charlottesville, Virginia 22903, United States
| | - Alison K Criss
- Department of Chemistry and ‡Department of Microbiology, Immunology, and Cancer Biology, University of Virginia , Charlottesville, Virginia 22903, United States
| | - Linda Columbus
- Department of Chemistry and ‡Department of Microbiology, Immunology, and Cancer Biology, University of Virginia , Charlottesville, Virginia 22903, United States
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9
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Abstract
Gonorrhea is a sexually transmitted disease causing growing concern, with a substantial increase in reported incidence over the past few years in the United Kingdom and rising levels of resistance to a wide range of antibiotics. Understanding its epidemiology is therefore of major biomedical importance, not only on a population scale but also at the level of direct transmission. However, the molecular typing techniques traditionally used for gonorrhea infections do not provide sufficient resolution to investigate such fine-scale patterns. Here we sequenced the genomes of 237 isolates from two local collections of isolates from Sheffield and London, each of which was resolved into a single type using traditional methods. The two data sets were selected to have different epidemiological properties: the Sheffield data were collected over 6 years from a predominantly heterosexual population, whereas the London data were gathered within half a year and strongly associated with men who have sex with men. Based on contact tracing information between individuals in Sheffield, we found that transmission is associated with a median time to most recent common ancestor of 3.4 months, with an upper bound of 8 months, which we used as a criterion to identify likely transmission links in both data sets. In London, we found that transmission happened predominantly between individuals of similar age, sexual orientation, and location and also with the same HIV serostatus, which may reflect serosorting and associated risk behaviors. Comparison of the two data sets suggests that the London epidemic involved about ten times more cases than the Sheffield outbreak. The recent increases in gonorrhea incidence and antibiotic resistance are cause for public health concern. Successful intervention requires a better understanding of transmission patterns, which is not uncovered by traditional molecular epidemiology techniques. Here we studied two outbreaks that took place in Sheffield and London, United Kingdom. We show that whole-genome sequencing provides the resolution to investigate direct gonorrhea transmission between infected individuals. Combining genome sequencing with rich epidemiological information about infected individuals reveals the importance of several transmission routes and risk factors, which can be used to design better control measures.
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10
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Quintero CA, Tudela JG, Damiani MT. Rho GTPases as pathogen targets: Focus on curable sexually transmitted infections. Small GTPases 2015; 6:108-18. [PMID: 26023809 DOI: 10.4161/21541248.2014.991233] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
Pathogens have evolved highly specialized mechanisms to infect hosts. Several microorganisms modulate the eukaryotic cell surface to facilitate their engulfment. Once internalized, they hijack the molecular machinery of the infected cell for their own benefit. At different stages of phagocytosis, particularly during invasion, certain pathogens manipulate pathways governed by small GTPases. In this review, we focus on the role of Rho proteins on curable, sexually transmitted infections caused by Chlamydia trachomatis, Neisseria gonorrhoeae, Trichomonas vaginalis and Treponema pallidum. Despite the high, worldwide frequencies of these sexually-transmitted diseases, very little is known about the strategies developed by these microorganisms to usurp key eukaryotic proteins that control intracellular signaling and actin dynamics. Improved knowledge of these molecular mechanisms will contribute to the elucidation of how these clinically important pathogens manipulate intracellular processes and parasitize their hosts.
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Affiliation(s)
- Cristián A Quintero
- a Laboratory of Phagocytosis and Intracellular Trafficking; IHEM-CONICET; School of Medicine; University of Cuyo ; Mendoza , Argentina
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11
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Contrasting within- and between-host immune selection shapes Neisseria Opa repertoires. Sci Rep 2014; 4:6554. [PMID: 25296566 PMCID: PMC4894414 DOI: 10.1038/srep06554] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2014] [Accepted: 09/08/2014] [Indexed: 11/30/2022] Open
Abstract
Pathogen evolution is influenced strongly by the host immune response. Previous studies of the effects of herd immunity on the population structure of directly transmitted, short-lived pathogens have primarily focused on the impact of competition for hosts. In contrast, for long-lived infections like HIV, theoretical work has focused on the mechanisms promoting antigenic variation within the host. In reality, successful transmission requires that pathogens balance both within- and between-host immune selection. The Opa adhesins in the bacterial Neisseria genus provide a unique system to study the evolution of the same antigens across two major pathogens: while N. meningitidis is an airborne, respiratory pathogen colonising the nasopharynx relatively transiently, N. gonorrhoeae can cause sexually transmitted, long-lived infections. We use a simple mathematical model and genomic data to show that trade-offs between immune selection pressures within- and between-hosts can explain the contrasting Opa repertoires observed in meningococci and gonococci.
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12
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Fox D, Larsson P, Lo RH, Kroncke BM, Kasson PM, Columbus L. Structure of the Neisserial outer membrane protein Opa₆₀: loop flexibility essential to receptor recognition and bacterial engulfment. J Am Chem Soc 2014; 136:9938-46. [PMID: 24813921 PMCID: PMC4105060 DOI: 10.1021/ja503093y] [Citation(s) in RCA: 42] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2013] [Revised: 03/27/2014] [Indexed: 12/27/2022]
Abstract
The structure and dynamics of Opa proteins, which we report herein, are responsible for the receptor-mediated engulfment of Neisseria gonorrheae or Neisseria meningitidis by human cells and can offer deep understanding into the molecular recognition of pathogen-host receptor interactions. Such interactions are vital to understanding bacterial pathogenesis as well as the mechanism of foreign body entry to a human cell, which may provide insights for the development of targeted pharmaceutical delivery systems. The size and dynamics of the extracellular loops of Opa60 required a hybrid refinement approach wherein membrane and distance restraints were used to generate an initial NMR structural ensemble, which was then further refined using molecular dynamics in a DMPC bilayer. The resulting ensemble revealed that the extracellular loops, which bind host receptors, occupy compact conformations, interact with each other weakly, and are dynamic on the nanosecond time scale. We predict that this conformational sampling is critical for enabling diverse Opa loop sequences to engage a common set of receptors.
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Affiliation(s)
- Daniel
A. Fox
- Department
of Chemistry, University of Virginia, Charlottesville, Virginia 22904, United States
| | - Per Larsson
- Center
for Membrane Biology and Department of Molecular Physiology and Biological
Physics, University of Virginia, Charlottesville, Virginia 22908, United States
| | - Ryan H. Lo
- Department
of Chemistry, University of Virginia, Charlottesville, Virginia 22904, United States
| | - Brett M. Kroncke
- Department
of Chemistry, University of Virginia, Charlottesville, Virginia 22904, United States
| | - Peter M. Kasson
- Center
for Membrane Biology and Department of Molecular Physiology and Biological
Physics, University of Virginia, Charlottesville, Virginia 22908, United States
| | - Linda Columbus
- Department
of Chemistry, University of Virginia, Charlottesville, Virginia 22904, United States
- Center
for Membrane Biology and Department of Molecular Physiology and Biological
Physics, University of Virginia, Charlottesville, Virginia 22908, United States
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13
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Genomic and global approaches to unravelling how hypermutable sequences influence bacterial pathogenesis. Pathogens 2014; 3:164-84. [PMID: 25437613 PMCID: PMC4235727 DOI: 10.3390/pathogens3010164] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2013] [Revised: 01/06/2014] [Accepted: 02/13/2014] [Indexed: 12/23/2022] Open
Abstract
Rapid adaptation to fluctuations in the host milieu contributes to the host persistence and virulence of bacterial pathogens. Adaptation is frequently mediated by hypermutable sequences in bacterial pathogens. Early bacterial genomic studies identified the multiplicity and virulence-associated functions of these hypermutable sequences. Thus, simple sequence repeat tracts (SSRs) and site-specific recombination were found to control capsular type, lipopolysaccharide structure, pilin diversity and the expression of outer membrane proteins. We review how the population diversity inherent in the SSR-mediated mechanism of localised hypermutation is being unlocked by the investigation of whole genome sequences of disease isolates, analysis of clinical samples and use of model systems. A contrast is presented between the problematical nature of analysing simple sequence repeats in next generation sequencing data and in simpler, pragmatic PCR-based approaches. Specific examples are presented of the potential relevance of this localized hypermutation to meningococcal pathogenesis. This leads us to speculate on the future prospects for unravelling how hypermutable mechanisms may contribute to the transmission, spread and persistence of bacterial pathogens.
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14
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Davies JK, Harrison PF, Lin YH, Bartley S, Khoo CA, Seemann T, Ryan CS, Kahler CM, Hill SA. The use of high-throughput DNA sequencing in the investigation of antigenic variation: application to Neisseria species. PLoS One 2014; 9:e86704. [PMID: 24466206 PMCID: PMC3899283 DOI: 10.1371/journal.pone.0086704] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2013] [Accepted: 12/11/2013] [Indexed: 11/18/2022] Open
Abstract
Antigenic variation occurs in a broad range of species. This process resembles gene conversion in that variant DNA is unidirectionally transferred from partial gene copies (or silent loci) into an expression locus. Previous studies of antigenic variation have involved the amplification and sequencing of individual genes from hundreds of colonies. Using the pilE gene from Neisseria gonorrhoeae we have demonstrated that it is possible to use PCR amplification, followed by high-throughput DNA sequencing and a novel assembly process, to detect individual antigenic variation events. The ability to detect these events was much greater than has previously been possible. In N. gonorrhoeae most silent loci contain multiple partial gene copies. Here we show that there is a bias towards using the copy at the 3' end of the silent loci (copy 1) as the donor sequence. The pilE gene of N. gonorrhoeae and some strains of Neisseria meningitidis encode class I pilin, but strains of N. meningitidis from clonal complexes 8 and 11 encode a class II pilin. We have confirmed that the class II pili of meningococcal strain FAM18 (clonal complex 11) are non-variable, and this is also true for the class II pili of strain NMB from clonal complex 8. In addition when a gene encoding class I pilin was moved into the meningococcal strain NMB background there was no evidence of antigenic variation. Finally we investigated several members of the opa gene family of N. gonorrhoeae, where it has been suggested that limited variation occurs. Variation was detected in the opaK gene that is located close to pilE, but not at the opaJ gene located elsewhere on the genome. The approach described here promises to dramatically improve studies of the extent and nature of antigenic variation systems in a variety of species.
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Affiliation(s)
- John K. Davies
- Department of Microbiology, Monash University, Clayton, Victoria, Australia
- * E-mail:
| | - Paul F. Harrison
- Victorian Bioinformatics Consortium, Monash University, Clayton, Victoria, Australia
| | - Ya-Hsun Lin
- Department of Microbiology, Monash University, Clayton, Victoria, Australia
| | | | - Chen Ai Khoo
- Department of Microbiology, Monash University, Clayton, Victoria, Australia
| | - Torsten Seemann
- Victorian Bioinformatics Consortium, Monash University, Clayton, Victoria, Australia
| | - Catherine S. Ryan
- Department of Microbiology, Monash University, Clayton, Victoria, Australia
| | - Charlene M. Kahler
- School of Pathology and Laboratory Medicine
- The Marshall Centre for Infectious Diseases, Research and Training, University of Western Australia, Nedlands, Western Australia, Australia
- Telethon Institute of Child Health Research, University of Western Australia, Nedlands, Western Australia, Australia
| | - Stuart A. Hill
- Department of Biological Sciences, Northern Illinois University, DeKalb, Illinois, United States of America
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15
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Hung MC, Christodoulides M. The biology of Neisseria adhesins. BIOLOGY 2013; 2:1054-109. [PMID: 24833056 PMCID: PMC3960869 DOI: 10.3390/biology2031054] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/02/2013] [Revised: 07/01/2013] [Accepted: 07/03/2013] [Indexed: 01/15/2023]
Abstract
Members of the genus Neisseria include pathogens causing important human diseases such as meningitis, septicaemia, gonorrhoea and pelvic inflammatory disease syndrome. Neisseriae are found on the exposed epithelia of the upper respiratory tract and the urogenital tract. Colonisation of these exposed epithelia is dependent on a repertoire of diverse bacterial molecules, extending not only from the surface of the bacteria but also found within the outer membrane. During invasive disease, pathogenic Neisseriae also interact with immune effector cells, vascular endothelia and the meninges. Neisseria adhesion involves the interplay of these multiple surface factors and in this review we discuss the structure and function of these important molecules and the nature of the host cell receptors and mechanisms involved in their recognition. We also describe the current status for recently identified Neisseria adhesins. Understanding the biology of Neisseria adhesins has an impact not only on the development of new vaccines but also in revealing fundamental knowledge about human biology.
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Affiliation(s)
- Miao-Chiu Hung
- Neisseria Research, Molecular Microbiology, Clinical and Experimental Sciences, Sir Henry Wellcome Laboratories, Faculty of Medicine, University of Southampton, Southampton General Hospital, Southampton, SO16 6YD, UK.
| | - Myron Christodoulides
- Neisseria Research, Molecular Microbiology, Clinical and Experimental Sciences, Sir Henry Wellcome Laboratories, Faculty of Medicine, University of Southampton, Southampton General Hospital, Southampton, SO16 6YD, UK.
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Construction and characterization of a derivative of Neisseria gonorrhoeae strain MS11 devoid of all opa genes. J Bacteriol 2012; 194:6468-78. [PMID: 23002223 DOI: 10.1128/jb.00969-12] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
To better understand the role of Opa in gonococcal infections, we created and characterized a derivative of MS11 (MS11Δopa) that had the coding sequence for all 11 Opa proteins deleted. The MS11Δopa bacterium lost the ability to bind to purified lipooligosaccharide (LOS). While nonpiliated MS11Δopa and nonpiliated Opa-expressing MS11 cells grew at the same rate, nonpiliated MS11Δopa cells rarely formed clumps of more than four bacteria when grown in broth with vigorous shaking. Using flow cytometry analysis, we demonstrated that MS11Δopa produced a homogeneous population of bacteria that failed to bind monoclonal antibody (MAb) 4B12, a MAb specific for Opa. Opa-expressing MS11 cells consisted of two predominant populations, where ∼85% bound MAb 4B12 to a significant level and the other population bound little if any MAb. Approximately 90% of bacteria isolated from a phenotypically Opa-negative colony (a colony that does not refract light) failed to bind MAb 4B12; the remaining 10% bound MAb to various degrees. Piliated MS11Δopa cells formed dispersed microcolonies on ME180 cells which were visually distinct from those of piliated Opa-expressing MS11 cells. When Opa expression was reintroduced into MS11Δopa, the adherence ability of the strain recovered to wild-type levels. These data indicate that Opa contributes to both bacterium-bacterium and bacterium-host cell interactions.
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Review and international recommendation of methods for typing neisseria gonorrhoeae isolates and their implications for improved knowledge of gonococcal epidemiology, treatment, and biology. Clin Microbiol Rev 2011; 24:447-58. [PMID: 21734242 DOI: 10.1128/cmr.00040-10] [Citation(s) in RCA: 102] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Gonorrhea, which may become untreatable due to multiple resistance to available antibiotics, remains a public health problem worldwide. Precise methods for typing Neisseria gonorrhoeae, together with epidemiological information, are crucial for an enhanced understanding regarding issues involving epidemiology, test of cure and contact tracing, identifying core groups and risk behaviors, and recommending effective antimicrobial treatment, control, and preventive measures. This review evaluates methods for typing N. gonorrhoeae isolates and recommends various methods for different situations. Phenotypic typing methods, as well as some now-outdated DNA-based methods, have limited usefulness in differentiating between strains of N. gonorrhoeae. Genotypic methods based on DNA sequencing are preferred, and the selection of the appropriate genotypic method should be guided by its performance characteristics and whether short-term epidemiology (microepidemiology) or long-term and/or global epidemiology (macroepidemiology) matters are being investigated. Currently, for microepidemiological questions, the best methods for fast, objective, portable, highly discriminatory, reproducible, typeable, and high-throughput characterization are N. gonorrhoeae multiantigen sequence typing (NG-MAST) or full- or extended-length porB gene sequencing. However, pulsed-field gel electrophoresis (PFGE) and Opa typing can be valuable in specific situations, i.e., extreme microepidemiology, despite their limitations. For macroepidemiological studies and phylogenetic studies, DNA sequencing of chromosomal housekeeping genes, such as multilocus sequence typing (MLST), provides a more nuanced understanding.
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Sadarangani M, Pollard AJ, Gray-Owen SD. Opa proteins and CEACAMs: pathways of immune engagement for pathogenic Neisseria. FEMS Microbiol Rev 2011; 35:498-514. [PMID: 21204865 DOI: 10.1111/j.1574-6976.2010.00260.x] [Citation(s) in RCA: 107] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
Neisseria meningitidis and Neisseria gonorrhoeae are globally important pathogens, which in part owe their success to their ability to successfully evade human immune responses over long periods. The phase-variable opacity-associated (Opa) adhesin proteins are a major surface component of these organisms, and are responsible for bacterial adherence and entry into host cells and interactions with the immune system. Most immune interactions are mediated via binding to members of the carcinoembryonic antigen cell adhesion molecule (CEACAM) family. These Opa variants are able to bind to different receptors of the CEACAM family on epithelial cells, neutrophils, and T and B lymphocytes, influencing the innate and adaptive immune responses. Increased epithelial cell adhesion creates the potential for prolonged infection, invasion and dissemination. Furthermore, Opa proteins may inhibit T-lymphocyte activation and proliferation, B-cell antibody production, and innate inflammatory responses by infected epithelia, in addition to conferring increased resistance to antibody-dependent, complement-mediated killing. While vaccines containing Opa proteins could induce adhesion-blocking and bactericidal antibodies, the consequence of CEACAM binding by a candidate Opa-containing vaccine requires further investigation. This review summarizes current knowledge of the immunological consequences of the interaction between meningococcal and gonococcal Opa proteins and human CEACAMs, considering the implications for pathogenesis and vaccine development.
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Affiliation(s)
- Manish Sadarangani
- Oxford Vaccine Group, Department of Paediatrics, Centre for Clinical Vaccinology and Tropical Medicine, University of Oxford, Churchill Hospital, Oxford, UK.
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Beernink PT, Granoff DM. The modular architecture of meningococcal factor H-binding protein. MICROBIOLOGY-SGM 2009; 155:2873-2883. [PMID: 19574307 DOI: 10.1099/mic.0.029876-0] [Citation(s) in RCA: 59] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
Meningococcal factor H binding protein (fHbp) is a promising vaccine antigen that binds the human complement downregulatory molecule factor H (fH), and this binding enhances the survival of the organism in serum. Based on sequence variability of the entire protein, fHbp has been divided into three variant groups or two subfamilies. Here, we present evidence based on phylogenetic analysis of 70 unique fHbp amino acid sequences that the molecular architecture is modular. From sequences of natural chimeras we identified blocks of two to five invariant residues that flanked five modular variable segments. Although overall, 46 % of the fHbp amino acids were invariant, based on a crystal structure, the invariant blocks that flanked the modular variable segments clustered on the membrane surface containing the amino-terminal lipid anchor, while the remaining invariant residues were located throughout the protein. Each of the five modular variable segments could be classified into one of two types, designated alpha or beta, based on homology with segments encoded by variant 1 or 3 fHbp genes, respectively. Forty of the fHbps (57 %) comprised only alpha (n=33) or beta (n=7) type segments. The remaining 30 proteins (43 %) were chimeras and could be classified into one of four modular groups. These included all 15 proteins assigned to the previously described variant 2 in subfamily A. The modular segments of one chimeric modular group had 96 % amino acid identity with those of fHbp orthologs in Neisseria gonorrhoeae. Collectively, the data suggest that recombination between Neisseria meningitidis and N. gonorrhoeae progenitors generated a family of modular, antigenically diverse meningococcal fHbps.
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Affiliation(s)
- Peter T Beernink
- Center for Immunobiology and Vaccine Development, Children's Hospital Oakland Research Institute, Oakland, CA 94609, USA
| | - Dan M Granoff
- Center for Immunobiology and Vaccine Development, Children's Hospital Oakland Research Institute, Oakland, CA 94609, USA
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