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Mikucki A, Kahler CM. Microevolution and Its Impact on Hypervirulence, Antimicrobial Resistance, and Vaccine Escape in Neisseria meningitidis. Microorganisms 2023; 11:3005. [PMID: 38138149 PMCID: PMC10745880 DOI: 10.3390/microorganisms11123005] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2023] [Revised: 12/07/2023] [Accepted: 12/14/2023] [Indexed: 12/24/2023] Open
Abstract
Neisseria meningitidis is commensal of the human pharynx and occasionally invades the host, causing the life-threatening illness invasive meningococcal disease. The meningococcus is a highly diverse and adaptable organism thanks to natural competence, a propensity for recombination, and a highly repetitive genome. These mechanisms together result in a high level of antigenic variation to invade diverse human hosts and evade their innate and adaptive immune responses. This review explores the ways in which this diversity contributes to the evolutionary history and population structure of the meningococcus, with a particular focus on microevolution. It examines studies on meningococcal microevolution in the context of within-host evolution and persistent carriage; microevolution in the context of meningococcal outbreaks and epidemics; and the potential of microevolution to contribute to antimicrobial resistance and vaccine escape. A persistent theme is the idea that the process of microevolution contributes to the development of new hyperinvasive meningococcal variants. As such, microevolution in this species has significant potential to drive future public health threats in the form of hypervirulent, antibiotic-resistant, vaccine-escape variants. The implications of this on current vaccination strategies are explored.
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Affiliation(s)
- August Mikucki
- Marshall Centre for Infectious Diseases Research and Training, School of Biomedical Sciences, University of Western Australia, Perth, WA 6009, Australia;
- Wesfarmers Centre of Vaccines and Infectious Diseases, Telethon Kids Institute, University of Western Australia, Perth, WA 6009, Australia
| | - Charlene M. Kahler
- Marshall Centre for Infectious Diseases Research and Training, School of Biomedical Sciences, University of Western Australia, Perth, WA 6009, Australia;
- Wesfarmers Centre of Vaccines and Infectious Diseases, Telethon Kids Institute, University of Western Australia, Perth, WA 6009, Australia
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2
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Jen FEC, Abrahams JL, Schulz BL, Lamelas A, Pluschke G, Jennings MP. High-Frequency Changes in Pilin Glycosylation Patterns during Neisseria meningitidis Serogroup a Meningitis Outbreaks in the African Meningitis Belt. ACS Infect Dis 2023; 9:1451-1457. [PMID: 37467082 PMCID: PMC10425976 DOI: 10.1021/acsinfecdis.3c00149] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2023] [Indexed: 07/21/2023]
Abstract
In the meningitis belt of sub-Saharan Africa, there are cyclic meningococcal epidemics that coincide with clonal waves of Neisseria meningitidis carriage and invasive disease. In the framework of longitudinal colonization and disease studies in Ghana and Burkina Faso, meningococcal isolates belonging to the closely related hypervirulent A:ST-5, A:ST-7, and A:ST-2859 clones have been collected from 1998 to 2011 during meningococcal outbreaks. A comparative whole-genome sequencing study with 100 of these isolates identified the pilin glycosylation (pgl) locus as one hot spot of recombination. Frequent exchange of pgl genes in N. meningitidis by lateral gene transfer results in differences in the glycosylation patterns of pilin and other cell surface glycoproteins. In this study, we looked at both recombination and phase variation of the pgl genes of these clinical isolates and analyzed the glycan structures resulting from different pgl alleles and their variable expression. Our results indicate that the basal O-linked sugar of the glycans expressed by these isolates is masked by various additional mono- or disaccharide structures whose expression is highly variable due to the phase-variable expression of pgl genes. We also observed a distinct glycoform in two isolates with pgl loci that were modified by recombination. These data suggest that variation in N. meningitidis protein glycosylation could be crucial for bacterial adaptation to evade herd immunity in semi-immune populations. Investigating pilin glycosylation in N. meningitidis can shed light on the mechanisms by which this pathogen evades the host immune response, and may help identify potential targets for novel therapies and vaccines.
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Affiliation(s)
- Freda E-C Jen
- Institute for Glycomics, Griffith University, Gold Coast, QLD 4222, Australia
| | - Jodie L Abrahams
- Institute for Glycomics, Griffith University, Gold Coast, QLD 4222, Australia
| | - Benjamin L Schulz
- School of Chemistry and Molecular Biosciences, The University of Queensland, Brisbane, QLD 4072, Australia
| | - Araceli Lamelas
- Swiss Tropical and Public Health Institute, Basel 4051, Switzerland
- University of Basel, Basel 4051, Switzerland
| | - Gerd Pluschke
- Swiss Tropical and Public Health Institute, Basel 4051, Switzerland
- University of Basel, Basel 4051, Switzerland
| | - Michael P Jennings
- Institute for Glycomics, Griffith University, Gold Coast, QLD 4222, Australia
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3
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Nahar N, Tram G, Jen FEC, Phillips ZN, Weinert L, Bossé J, Jabbari J, Gouil Q, Du MM, Ritchie M, Bowden R, Langford P, Tucker A, Jennings M, Turni C, Blackall P, Atack J. Actinobacillus pleuropneumoniae encodes multiple phase-variable DNA methyltransferases that control distinct phasevarions. Nucleic Acids Res 2023; 51:3240-3260. [PMID: 36840716 PMCID: PMC10123105 DOI: 10.1093/nar/gkad091] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2022] [Revised: 01/31/2023] [Accepted: 02/03/2023] [Indexed: 02/26/2023] Open
Abstract
Actinobacillus pleuropneumoniae is the cause of porcine pleuropneumonia, a severe respiratory tract infection that is responsible for major economic losses to the swine industry. Many host-adapted bacterial pathogens encode systems known as phasevarions (phase-variable regulons). Phasevarions result from variable expression of cytoplasmic DNA methyltransferases. Variable expression results in genome-wide methylation differences within a bacterial population, leading to altered expression of multiple genes via epigenetic mechanisms. Our examination of a diverse population of A. pleuropneumoniae strains determined that Type I and Type III DNA methyltransferases with the hallmarks of phase variation were present in this species. We demonstrate that phase variation is occurring in these methyltransferases, and show associations between particular Type III methyltransferase alleles and serovar. Using Pacific BioSciences Single-Molecule, Real-Time (SMRT) sequencing and Oxford Nanopore sequencing, we demonstrate the presence of the first ever characterised phase-variable, cytosine-specific Type III DNA methyltransferase. Phase variation of distinct Type III DNA methyltransferase in A. pleuropneumoniae results in the regulation of distinct phasevarions, and in multiple phenotypic differences relevant to pathobiology. Our characterisation of these newly described phasevarions in A. pleuropneumoniae will aid in the selection of stably expressed antigens, and direct and inform development of a rationally designed subunit vaccine against this major veterinary pathogen.
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Affiliation(s)
- Nusrat Nahar
- Institute for Glycomics, Griffith University, Gold Coast, Queensland 4222, Australia
| | - Greg Tram
- Institute for Glycomics, Griffith University, Gold Coast, Queensland 4222, Australia
| | - Freda E-C Jen
- Institute for Glycomics, Griffith University, Gold Coast, Queensland 4222, Australia
| | - Zachary N Phillips
- Institute for Glycomics, Griffith University, Gold Coast, Queensland 4222, Australia
| | - Lucy A Weinert
- Department of Veterinary Medicine, University of Cambridge, Cambridge CB3 0ES, UK
| | - Janine T Bossé
- Section of Paediatric Infectious Disease, Imperial College London, St Mary's Campus, London W2 1PG, UK
| | - Jafar S Jabbari
- Walter and Eliza Hall Institute of Medical Research, Parkville, Victoria 3052, Australia
- Department of Medical Biology, The University of Melbourne, Parkville 3010, Australia
| | - Quentin Gouil
- Walter and Eliza Hall Institute of Medical Research, Parkville, Victoria 3052, Australia
- Department of Medical Biology, The University of Melbourne, Parkville 3010, Australia
| | - Mei R M Du
- Walter and Eliza Hall Institute of Medical Research, Parkville, Victoria 3052, Australia
| | - Matthew E Ritchie
- Walter and Eliza Hall Institute of Medical Research, Parkville, Victoria 3052, Australia
- Department of Medical Biology, The University of Melbourne, Parkville 3010, Australia
| | - Rory Bowden
- Walter and Eliza Hall Institute of Medical Research, Parkville, Victoria 3052, Australia
- Department of Medical Biology, The University of Melbourne, Parkville 3010, Australia
| | - Paul R Langford
- Section of Paediatric Infectious Disease, Imperial College London, St Mary's Campus, London W2 1PG, UK
| | - Alexander W Tucker
- Department of Veterinary Medicine, University of Cambridge, Cambridge CB3 0ES, UK
| | - Michael P Jennings
- Institute for Glycomics, Griffith University, Gold Coast, Queensland 4222, Australia
| | - Conny Turni
- Queensland Alliance for Agriculture and Food Innovation, The University of Queensland, St. Lucia, Queensland 4072, Australia
| | - Patrick J Blackall
- Queensland Alliance for Agriculture and Food Innovation, The University of Queensland, St. Lucia, Queensland 4072, Australia
| | - John M Atack
- Institute for Glycomics, Griffith University, Gold Coast, Queensland 4222, Australia
- School of Environment and Science, Griffith University, Gold Coast, Queensland 4222, Australia
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4
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Shaughnessy J, Chabeda A, Lewis LA, Ram S. Alternative pathway amplification and infections. Immunol Rev 2023; 313:162-180. [PMID: 36336911 DOI: 10.1111/imr.13160] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
The alternative pathway (AP) is the phylogenetically oldest arm of the complement system and may have evolved to mark pathogens for elimination by phagocytes. Studies using purified AP proteins or AP-specific serum showed that C3b amplification on bacteria commenced following a lag phase of about 5 min and was highly dependent on the concentration of complement. Most pathogens have evolved several elegant mechanisms to evade complement, including expressing proteases that degrade AP proteins and secreting proteins that block function of C3 convertases. In an example of convergent evolution, many microbes recruit the AP inhibitor factor H (FH) using molecular mechanisms that mimic FH interactions with host cells. In most instances, the AP serves to amplify C3b deposited on microbes by the classical pathway (CP). The role of properdin on microbes appears to be restricted to stabilization of C3 convertases; scant evidence exists for its role as an initiator of the AP on pathogens in the context of serum. Therapeutic complement inhibition carries with it an increased risk of infection. Antibody (Ab)-dependent AP activation may be critical for complement activation by vaccine-elicited Ab when the CP is blocked, and its molecular mechanism is discussed.
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Affiliation(s)
- Jutamas Shaughnessy
- Division of Infectious Diseases and Immunology, University of Massachusetts Chan Medical School, Worcester, Massachusetts, USA
| | - Aleyo Chabeda
- Division of Infectious Diseases and Immunology, University of Massachusetts Chan Medical School, Worcester, Massachusetts, USA
| | - Lisa A Lewis
- Division of Infectious Diseases and Immunology, University of Massachusetts Chan Medical School, Worcester, Massachusetts, USA
| | - Sanjay Ram
- Division of Infectious Diseases and Immunology, University of Massachusetts Chan Medical School, Worcester, Massachusetts, USA
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5
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Comparative Genome Analysis Reveals Accumulation of Single-Nucleotide Repeats in Pathogenic Escherichia Lineages. Curr Issues Mol Biol 2022; 44:498-504. [PMID: 35723320 PMCID: PMC8928963 DOI: 10.3390/cimb44020034] [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: 11/02/2021] [Revised: 01/13/2022] [Accepted: 01/17/2022] [Indexed: 11/17/2022] Open
Abstract
Homopolymeric tracts (HPTs) can lead to phase variation and DNA replication slippage, driving adaptation to environmental changes and evolution of genes and genomes. However, there is limited information on HPTs in Escherichia; therefore, we conducted a comprehensive cross-strain search for HPTs in Escherichia genomes. We determined the HPT genomic distribution and identified a pattern of high-frequency HPT localization in pathogenic Escherichia lineages. Notably, HPTs localized near transcriptional regulatory genes. Additionally, excessive repeats accumulated in toxin-coding genes. Moreover, the genomic localization of some HPTs might be derived from exogenous DNA, such as that of bacteriophages. Altogether, our findings may prove useful for understanding the role of HPTs in Escherichia genomes.
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6
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Arenas J, Szabo Z, van der Wal J, Maas C, Riaz T, Tønjum T, Tommassen J. Serum proteases prevent bacterial biofilm formation: role of kallikrein and plasmin. Virulence 2021; 12:2902-2917. [PMID: 34903146 PMCID: PMC8677018 DOI: 10.1080/21505594.2021.2003115] [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] [Indexed: 11/01/2022] Open
Abstract
Biofilm formation is a general strategy for bacterial pathogens to withstand host defense mechanisms. In this study, we found that serum proteases inhibit biofilm formation by Neisseria meningitidis, Neisseria gonorrhoeae, Haemophilus influenzae, and Bordetella pertussis. Confocal laser-scanning microscopy analysis revealed that these proteins reduce the biomass and alter the architecture of meningococcal biofilms. To understand the underlying mechanism, the serum was fractionated through size-exclusion chromatography and anion-exchange chromatography, and the composition of the fractions that retained anti-biofilm activity against N. meningitidis was analyzed by intensity-based absolute quantification mass spectrometry. Among the identified serum proteins, plasma kallikrein (PKLK), FXIIa, and plasmin were found to cleave neisserial heparin-binding antigen and the α-peptide of IgA protease on the meningococcal cell surface, resulting in the release of positively charged polypeptides implicated in biofilm formation by binding extracellular DNA. Further experiments also revealed that plasmin and PKLK inhibited biofilm formation of B. pertussis by cleaving filamentous hemagglutinin. We conclude that the proteolytic activity of serum proteases toward bacterial adhesins involved in biofilm formation could constitute a defense mechanism for the clearance of pathogens.
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Affiliation(s)
- Jesús Arenas
- Department of Molecular Microbiology and Institute of Biomembranes, Utrecht University, Utrecht, The Netherlands.,Unit of Microbiology and Immunology, Faculty of Veterinary, University of Zaragoza, Zaragoza, Spain
| | - Zalan Szabo
- Research and Development Department, U-Protein Express BV, Utrecht, The Netherlands
| | - Jelle van der Wal
- Department of Molecular Microbiology and Institute of Biomembranes, Utrecht University, Utrecht, The Netherlands
| | - Coen Maas
- Department of Clinical Chemistry and Haematology, University Medical Center Utrecht, Utrecht, The Netherlands
| | - Tahira Riaz
- Department of Microbiology, University of Oslo, Oslo, Norway
| | - Tone Tønjum
- Department of Microbiology, University of Oslo, Oslo, Norway
| | - Jan Tommassen
- Department of Molecular Microbiology and Institute of Biomembranes, Utrecht University, Utrecht, The Netherlands
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Jen FEC, Atack JM, Zhang Y, Edwards JL, Jennings MP. Complete Genome Sequence of Serogroup B Neisseria meningitidis Strain C311. Microbiol Resour Announc 2021; 10:e0078821. [PMID: 34672707 PMCID: PMC8530086 DOI: 10.1128/mra.00788-21] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2021] [Accepted: 09/26/2021] [Indexed: 12/05/2022] Open
Abstract
Neisseria meningitidis strain C311 has been widely used to study meningococcal pathogenesis in the past 30 years, but its genome is not available. Here, we report that the complete C311 genome is 2,311,508 bp in length, contains a total of 2,274 genes, and has a GC content of 51.25%.
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Affiliation(s)
- Freda E.-C. Jen
- Institute for Glycomics, Griffith University, Brisbane, Queensland, Australia
| | - John M. Atack
- Institute for Glycomics, Griffith University, Brisbane, Queensland, Australia
| | - Yuan Zhang
- Institute for Glycomics, Griffith University, Brisbane, Queensland, Australia
| | - Jennifer L. Edwards
- Center for Microbial Pathogenesis, The Abigail Wexner Research Institute at Nationwide Children’s Hospital, Columbus, Ohio, USA
- Department of Pediatrics, The Ohio State University, Columbus, Ohio, USA
| | - Michael P. Jennings
- Institute for Glycomics, Griffith University, Brisbane, Queensland, Australia
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Sandhu SK, Bayliss CD, Morozov AY. How does feedback from phage infections influence the evolution of phase variation in Campylobacter? PLoS Comput Biol 2021; 17:e1009067. [PMID: 34125841 PMCID: PMC8224891 DOI: 10.1371/journal.pcbi.1009067] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2020] [Revised: 06/24/2021] [Accepted: 05/11/2021] [Indexed: 02/06/2023] Open
Abstract
Campylobacter jejuni (C. jejuni) causes gastroenteritis following the consumption of contaminated poultry meat, resulting in a large health and economic burden worldwide. Phage therapy is a promising technique for eradicating C. jejuni from poultry flocks and chicken carcasses. However, C. jejuni can resist infections by some phages through stochastic, phase-variable ON/OFF switching of the phage receptors mediated by simple sequence repeats (SSR). While selection strength and exposure time influence the evolution of SSR-mediated phase variation (PV), phages offer a more complex evolutionary environment as phage replication depends on having a permissive host organism. Here, we build and explore several continuous culture bacteria-phage computational models, each analysing different phase-variable scenarios calibrated to the experimental SSR rates of C. jejuni loci and replication parameters for the F336 phage. We simulate the evolution of PV rates via the adaptive dynamics framework for varying levels of selective pressures that act on the phage-resistant state. Our results indicate that growth reducing counter-selection on a single PV locus results in the stable maintenance of the phage, while compensatory selection between bacterial states affects the evolutionary stable mutation rates (i.e. very high and very low mutation rates are evolutionarily disadvantageous), whereas, in the absence of either selective pressure the evolution of PV rates results in mutation rates below the basal values. Contrastingly, a biologically-relevant model with two phase-variable loci resulted in phage extinction and locking of the bacteria into a phage-resistant state suggesting that another counter-selective pressure is required, instance, the use of a distinct phage whose receptor is an F336-phage-resistant state. We conclude that a delicate balance between counter-selection and phage-attack can result in both the evolution of phase-variable phage receptors and persistence of PV-receptor-specific phage. Globally rising rates of antibiotic resistance have renewed interest in phage therapy. Bacteriophages (phages) act on bacteria to select for resistance mechanisms such as loss of phage receptors by phase variation (PV). Phase-variable genes mediate rapid adaption by stochastic switching of gene expression. Campylobacter jejuni is a common commensal of birds but also causes serious gastrointestinal infections in humans. Optimisation of phage therapy against C. jejuni requires an in-depth understanding of how PV has evolved and mediates phage resistance. Here, we use a detailed continuous culture model for nutrient-limited bacteria-phage interactions, with PV rates calibrated to match the experimental observations for C.jejuni and phage F336. Evolution within a model accounting for two phase-variable loci closely matches the experimental results when growth reducing counter-selection is imposed on all phage-resistant states, but, not when restricted to the particular states associated with resistance to immune effectors. Our results emphasize that delicate balancing of selective pressures, imposed by single and multiple distinct phages, are necessary for effective use of phage therapy against C. jejuni.
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Affiliation(s)
- Simran K. Sandhu
- Department of Mathematics, University of Leicester, Leicester, United Kingdom
| | - Christopher D. Bayliss
- Department of Genetics and Genome Biology, University of Leicester, Leicester, United Kingdom
| | - Andrew Yu. Morozov
- Department of Mathematics, University of Leicester, Leicester, United Kingdom
- Institute of Ecology and Evolution, Russian Academy of Sciences, Moscow, Russia
- * E-mail:
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Moraxella catarrhalis phase-variable loci show differences in expression during conditions relevant to disease. PLoS One 2020; 15:e0234306. [PMID: 32555615 PMCID: PMC7302503 DOI: 10.1371/journal.pone.0234306] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2019] [Accepted: 05/22/2020] [Indexed: 11/29/2022] Open
Abstract
Moraxella catarrhalis is a human-adapted, opportunistic bacterial pathogen of the respiratory mucosa. Although asymptomatic colonization of the nasopharynx is common, M. catarrhalis can ascend into the middle ear, where it is a prevalent causative agent of otitis media in children, or enter the lower respiratory tract, where it is associated with acute exacerbations of chronic obstructive pulmonary disease in adults. Phase variation is the high frequency, random, reversible switching of gene expression that allows bacteria to adapt to different host microenvironments and evade host defences, and is most commonly mediated by simple DNA sequence repeats. Bioinformatic analysis of five closed M. catarrhalis genomes identified 17 unique simple DNA sequence repeat tracts that were variable between strains, indicating the potential to mediate phase variable expression of the associated genes. Assays designed to assess simple sequence repeat variation under conditions mimicking host infection demonstrated that phase variation of uspA1 (ubiquitous surface protein A1) from high to low expression occurs over 72 hours of biofilm passage, while phase variation of uspA2 (ubiquitous surface protein A2) to high expression variants occurs during repeated exposure to human serum, as measured by mRNA levels. We also identify and confirm the variable expression of two novel phase variable genes encoding a Type III DNA methyltransferase (modO), and a conserved hypothetical permease (MC25239_RS00020). These data reveal the repertoire of phase variable genes mediated by simple sequence repeats in M. catarrhalis and demonstrate that modulation of expression under conditions mimicking human infection is attributed to changes in simple sequence repeat length.
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Wanford JJ, Holmes JC, Bayliss CD, Green LR. Meningococcal core and accessory phasomes vary by clonal complex. Microb Genom 2020; 6:e000367. [PMID: 32375989 PMCID: PMC7371114 DOI: 10.1099/mgen.0.000367] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2019] [Accepted: 03/27/2020] [Indexed: 11/21/2022] Open
Abstract
Neisseria meningitidis is a Gram-negative human commensal pathogen, with extensive phenotypic plasticity afforded by phase-variable (PV) gene expression. Phase variation is a stochastic switch in gene expression from an ON to an OFF state, mediated by localized hypermutation of simple sequence repeats (SSRs). Circulating N. meningitidis clones vary in propensity to cause disease, with some clonal complexes (ccs) classified as hypervirulent and others as carriage-associated. We examined the PV gene repertoires, or phasome, of these lineages in order to determine whether phase variation contributes to disease propensity. We analysed 3328 genomes representative of nine circulating meningococcal ccs with PhasomeIt, a tool that identifies PV genes by the presence of SSRs and homologous gene clusters. The presence, absence and functions of all identified PV gene clusters were confirmed by annotation or blast searches within the Neisseria PubMLST database. While no significant differences were detected in the number of PV genes or the core, conserved phasome content between hypervirulent and carriage lineages, individual ccs exhibited major variations in PV gene numbers. Phylogenetic clusters produced by phasome or core genome analyses were similar, indicating co-evolution of PV genes with the core genome. While conservation of PV clusters is high, with 76 % present in all meningococcal isolates, maintenance of an SSR is variable, ranging from conserved in all isolates to present only in a single cc, indicating differing evolutionary trajectories for each lineage. Diverse functional groups of PV genes were present across the meningococcal lineages; however, the majority directly or indirectly influence bacterial surface antigens and could impact on future vaccine development. Finally, we observe that meningococci have open pan phasomes, indicating ongoing evolution of PV gene content and a significant potential for adaptive changes in this clinically relevant genus.
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Affiliation(s)
- Joseph J. Wanford
- Department of Genetics and Genome Biology, University of Leicester, Leicester, UK
| | - Jonathan C. Holmes
- Department of Genetics and Genome Biology, University of Leicester, Leicester, UK
| | | | - Luke R. Green
- Department of Infection, Immunity and Cardiovascular Disease, University of Sheffield, Sheffield, UK
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11
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Brynildsrud OB, Eldholm V, Rakhimova A, Kristiansen PA, Caugant DA. Gauging the epidemic potential of a widely circulating non-invasive meningococcal strain in Africa. Microb Genom 2020; 5. [PMID: 31454306 PMCID: PMC6755499 DOI: 10.1099/mgen.0.000290] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
Abstract
Neisseria meningitidis colonizes the human oropharynx and transmits mainly via asymptomatic carriage. Actual outbreaks of meningococcal meningitis are comparatively rare and occur when susceptible populations are exposed to hypervirulent clones, genetically distinct from the main carriage isolates. However, carriage isolates can evolve into pathogens through a limited number of recombination events. The present study examines the potential for the sequence type (ST)-192, by far the dominant clone recovered in recent meningococcal carriage studies in sub-Saharan Africa, to evolve into a pathogen. We used whole-genome sequencing on a collection of 478 meningococcal isolates sampled from 1- to 29- year-old healthy individuals in Arba Minch, southern Ethiopia in 2014. The ST-192 clone was identified in nearly 60 % of the carriers. Using complementary short- and long-read techniques for whole-genome sequencing, we were able to completely resolve genomes and thereby identify genomic differences between the ST-192 carriage strain and known pathogenic clones with the highest possible resolution. We conclude that it is possible, but unlikely, that ST-192 could evolve into a significant pathogen, thus, becoming the major invasive meningococcus clone in the meningitis belt of Africa following upcoming mass vaccination with a polyvalent conjugate vaccine that targets the A, C, W, Y and X capsules.
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Affiliation(s)
- Ola Brønstad Brynildsrud
- Department of Food Safety and Infection Biology, Faculty of Veterinary Science, Norwegian University of Life Science, Oslo, Norway.,Division for Infection Control and Environmental Health, Norwegian Institute of Public Health, Oslo, Norway
| | - Vegard Eldholm
- Division for Infection Control and Environmental Health, Norwegian Institute of Public Health, Oslo, Norway
| | - Adelina Rakhimova
- Division for Infection Control and Environmental Health, Norwegian Institute of Public Health, Oslo, Norway
| | | | - Dominique A Caugant
- Division for Infection Control and Environmental Health, Norwegian Institute of Public Health, Oslo, Norway.,WHO Collaborating Centre for Reference and Research on Meningococci, Norwegian Institute of Public Health, Oslo, Norway.,Department of Community Medicine, Faculty of Medicine, University of Oslo, Oslo, Norway
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12
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Joseph SJ, Topaz N, Chang HY, Whaley MJ, Vuong JT, Chen A, Hu F, Schmink SE, Jenkins LT, Rodriguez-Rivera LD, Thomas JD, Acosta AM, McNamara L, Soeters HM, Mbaeyi S, Wang X. Insights on Population Structure and Within-Host Genetic Changes among Meningococcal Carriage Isolates from U.S. Universities. mSphere 2020; 5:e00197-20. [PMID: 32269159 PMCID: PMC7142301 DOI: 10.1128/msphere.00197-20] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2020] [Accepted: 03/17/2020] [Indexed: 01/15/2023] Open
Abstract
In 2015 and 2016, meningococcal carriage evaluations were conducted at two universities in the United States following mass vaccination campaigns in response to Neisseria meningitidis serogroup B (NmB) disease outbreaks. A simultaneous carriage evaluation was also conducted at a university near one of the outbreaks, where no NmB cases were reported and no mass vaccination occurred. A total of ten cross-sectional carriage evaluation rounds were conducted, resulting in 1,514 meningococcal carriage isolates collected from 7,001 unique participants; 1,587 individuals were swabbed at multiple time points (repeat participants). All isolates underwent whole-genome sequencing. The most frequently observed clonal complexes (CC) were CC198 (27.3%), followed by CC1157 (17.4%), CC41/44 (9.8%), CC35 (7.4%), and CC32 (5.6%). Phylogenetic analysis identified carriage isolates that were highly similar to the NmB outbreak strains; comparative genomics between these outbreak and carriage isolates revealed genetic changes in virulence genes. Among repeat participants, 348 individuals carried meningococcal bacteria during at least one carriage evaluation round; 50.3% retained N. meningitidis carriage of a strain with the same sequence type (ST) and CC across rounds, 44.3% only carried N. meningitidis in one round, and 5.4% acquired a new N. meningitidis strain between rounds. Recombination, point mutations, deletions, and simple sequence repeats were the most frequent genetic mechanisms found in isolates collected from hosts carrying a strain of the same ST and CC across rounds. Our findings provide insight on the dynamics of meningococcal carriage among a population that is at higher risk for invasive meningococcal disease than the general population.IMPORTANCE U.S. university students are at a higher risk of invasive meningococcal disease than the general population. The responsible pathogen, Neisseria meningitidis, can be carried asymptomatically in the oropharynx; the dynamics of meningococcal carriage and the genetic features that distinguish carriage versus disease states are not completely understood. Through our analyses, we aimed to provide data to address these topics. We whole-genome sequenced 1,514 meningococcal carriage isolates from individuals at three U.S. universities, two of which underwent mass vaccination campaigns following recent meningococcal outbreaks. We describe the within-host genetic changes among individuals carrying a strain with the same molecular type over time, the primary strains being carried in this population, and the genetic differences between closely related outbreak and carriage strains. Our results provide detailed information on the dynamics of meningococcal carriage and the genetic differences in carriage and outbreak strains, which can inform future efforts to reduce the incidence of invasive meningococcal disease.
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Affiliation(s)
| | | | | | - Melissa J Whaley
- Meningitis and Vaccine Preventable Diseases Branch, Centers for Disease Control and Prevention, Atlanta, Georgia, USA
| | - Jeni T Vuong
- Meningitis and Vaccine Preventable Diseases Branch, Centers for Disease Control and Prevention, Atlanta, Georgia, USA
| | - Alexander Chen
- Meningitis and Vaccine Preventable Diseases Branch, Centers for Disease Control and Prevention, Atlanta, Georgia, USA
| | - Fang Hu
- IHRC Inc., Atlanta, Georgia, USA
| | - Susanna E Schmink
- Meningitis and Vaccine Preventable Diseases Branch, Centers for Disease Control and Prevention, Atlanta, Georgia, USA
| | - Laurel T Jenkins
- Meningitis and Vaccine Preventable Diseases Branch, Centers for Disease Control and Prevention, Atlanta, Georgia, USA
| | | | - Jennifer D Thomas
- Meningitis and Vaccine Preventable Diseases Branch, Centers for Disease Control and Prevention, Atlanta, Georgia, USA
| | - Anna M Acosta
- Meningitis and Vaccine Preventable Diseases Branch, Centers for Disease Control and Prevention, Atlanta, Georgia, USA
| | - Lucy McNamara
- Meningitis and Vaccine Preventable Diseases Branch, Centers for Disease Control and Prevention, Atlanta, Georgia, USA
| | - Heidi M Soeters
- Meningitis and Vaccine Preventable Diseases Branch, Centers for Disease Control and Prevention, Atlanta, Georgia, USA
| | - Sarah Mbaeyi
- Meningitis and Vaccine Preventable Diseases Branch, Centers for Disease Control and Prevention, Atlanta, Georgia, USA
| | - Xin Wang
- Meningitis and Vaccine Preventable Diseases Branch, Centers for Disease Control and Prevention, Atlanta, Georgia, USA
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13
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Caugant DA, Brynildsrud OB. Neisseria meningitidis: using genomics to understand diversity, evolution and pathogenesis. Nat Rev Microbiol 2019; 18:84-96. [PMID: 31705134 DOI: 10.1038/s41579-019-0282-6] [Citation(s) in RCA: 53] [Impact Index Per Article: 10.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 09/25/2019] [Indexed: 01/30/2023]
Abstract
Meningococcal disease remains an important cause of morbidity and death worldwide despite the development and increasing implementation of effective vaccines. Elimination of the disease is hampered by the enormous diversity and antigenic variability of the causative agent, Neisseria meningitidis, one of the most variable bacteria in nature. These features are attained mainly through high rates of horizontal gene transfer and alteration of protein expression through phase variation. The recent availability of whole-genome sequencing (WGS) of large-scale collections of N. meningitidis isolates from various origins, databases to facilitate storage and sharing of WGS data and the concomitant development of effective bioinformatics tools have led to a much more thorough understanding of the diversity of the species, its evolution and population structure and how virulent traits may emerge. Implementation of WGS is already contributing to enhanced epidemiological surveillance and is essential to ascertain the impact of vaccination strategies. This Review summarizes the recent advances provided by WGS studies in our understanding of the biology of N. meningitidis and the epidemiology of meningococcal disease.
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Affiliation(s)
- Dominique A Caugant
- Division for Infection Control and Environmental Health, Norwegian Institute of Public Health, Oslo, Norway. .,Department of Community Medicine, Faculty of Medicine, University of Oslo, Oslo, Norway.
| | - Ola B Brynildsrud
- Division for Infection Control and Environmental Health, Norwegian Institute of Public Health, Oslo, Norway.,Department of Food Safety and Infection Biology, Faculty of Veterinary Science, Norwegian University of Life Science, Oslo, Norway
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14
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Masignani V, Pizza M, Moxon ER. The Development of a Vaccine Against Meningococcus B Using Reverse Vaccinology. Front Immunol 2019; 10:751. [PMID: 31040844 PMCID: PMC6477034 DOI: 10.3389/fimmu.2019.00751] [Citation(s) in RCA: 83] [Impact Index Per Article: 16.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2018] [Accepted: 03/20/2019] [Indexed: 12/04/2022] Open
Abstract
The discovery of vaccine antigens through whole genome sequencing (WGS) contrasts with the classical hypothesis-driven laboratory-based analysis of microbes to identify components to elicit protective immunity. This radical change in scientific direction and action in vaccine research is captured in the term reverse vaccinology. The complete genome sequence of an isolate of Neisseria meningitidis serogroup B (MenB) was systematically analyzed to identify proteins predicted to be secreted or exported to the outer membrane. This identified hundreds of genes coding for potential surface-exposed antigens. These were amplified, cloned in expression vectors and used to immunize mice. Antisera against 350 recombinant antigens were obtained and analyzed in a panel of immunological assays from which 28 were selected as potentially protective based on the -antibody dependent, complement mediated- serum bactericidal activity assay. Testing of these candidate vaccine antigens, using a large globally representative strain collection of Neisseria species isolated from cases of disease and carriage, indicated that no single component would be sufficient to induce broad coverage and that a “universal” vaccine should contain multiple antigens. The final choice of antigens to be included was based on cross-protective ability, assayed by serum bactericidal activity and maximum coverage of the extensive antigenic variability of MenB strains. The resulting multivalent vaccine formulation selected consisted of three recombinant antigens (Neisserial Heparin Binding Antigen or NHBA, Factor H binding protein or fHbp and Neisseria Adhesin A or NadA). To improve immunogenicity and potential strain coverage, an outer membrane vesicle component obtained from the epidemic New Zealand strain (OMVNz) was added to the formulation to create a four component vaccine, called 4CMenB. A series of phase 2 and 3 clinical trials were conducted to evaluate safety and tolerability and to estimate the vaccine effectiveness of human immune responses at different ages and how these were affected by various factors including concomitant vaccine use and lot-to-lot consistency. 4CMenB was approved in Europe in 2013 and introduced in the National Immunization Program in the UK starting from September 2015 when the vaccine was offered to all newborns using a 2, 4, and 12 months schedule., The effectiveness against invasive MenB disease measured at 11 months after the study start and 5 months after the second vaccination was 83% and there have been no safety concerns.
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Affiliation(s)
| | | | - E Richard Moxon
- Department of Pediatrics, Oxford University, Oxford, United Kingdom
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15
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Jen FEC, Seib KL, Tan A. Screening DNA Repeat Tracts of Phase Variable Genes by Fragment Analysis. METHODS IN MOLECULAR BIOLOGY (CLIFTON, N.J.) 2019; 1969:93-104. [PMID: 30877671 DOI: 10.1007/978-1-4939-9202-7_6] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
Fragment analysis (or fragment length analysis) is a PCR-based method which allows quantification of the size and proportion of a DNA repeat tract length of a phase-variable region. Primers are labeled with a fluorescent dye, the resulting amplicons are processed by capillary electrophoresis, and results are analyzed for amplicon size and proportion by associated software (such as Peakscanner). Here we describe the process of designing primers and controls to screen for the number of repeats in a polymeric tract of a phase-variable gene in Neisseria meningitidis (the DNA methyltransferase ModA is used as an example, but this method can be applied to other phase-variable genes).
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Affiliation(s)
- Freda E-C Jen
- Institute for Glycomics, Griffith University, Gold Coast, QLD, Australia
| | - Kate L Seib
- Institute for Glycomics, Griffith University, Gold Coast, QLD, Australia.
| | - Aimee Tan
- Institute for Glycomics, Griffith University, Gold Coast, QLD, Australia
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16
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Whole-Genome Sequencing for Characterization of Capsule Locus and Prediction of Serogroup of Invasive Meningococcal Isolates. J Clin Microbiol 2019; 57:JCM.01609-18. [PMID: 30567750 DOI: 10.1128/jcm.01609-18] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2018] [Accepted: 12/14/2018] [Indexed: 01/07/2023] Open
Abstract
Invasive meningococcal disease is mainly caused by Neisseria meningitidis serogroups A, B, C, X, W, and Y. The serogroup is typically determined by slide agglutination serogrouping (SASG) and real-time PCR (RT-PCR). We describe a whole-genome sequencing (WGS)-based method to characterize the capsule polysaccharide synthesis (cps) locus, classify N. meningitidis serogroups, and identify mechanisms for nongroupability using 453 isolates from a global strain collection. We identified novel genomic organizations within functional cps loci, consisting of insertion sequence (IS) elements in unique positions that did not disrupt the coding sequence. Genetic mutations (partial gene deletion, missing genes, IS insertion, internal stop, and phase-variable off) that led to nongroupability were identified. The results of WGS and SASG were in 91% to 100% agreement for all serogroups, while the results of WGS and RT-PCR showed 99% to 100% agreement. Among isolates determined to be nongroupable by WGS (31 of 453), the results of all three methods agreed 100% for those without a capsule polymerase gene. However, 61% (WGS versus SASG) and 36% (WGS versus RT-PCR) agreements were observed for the isolates, particularly those with phase variations or internal stops in cps loci, which warrant further characterization by additional tests. Our WGS-based serogrouping method provides comprehensive characterization of the N. meningitidis capsule, which is critical for meningococcal surveillance and outbreak investigations.
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17
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Genus-Wide Comparative Genomics Analysis of Neisseria to Identify New Genes Associated with Pathogenicity and Niche Adaptation of Neisseria Pathogens. Int J Genomics 2019; 2019:6015730. [PMID: 30775379 PMCID: PMC6350579 DOI: 10.1155/2019/6015730] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2018] [Revised: 10/06/2018] [Accepted: 10/09/2018] [Indexed: 12/15/2022] Open
Abstract
N. gonorrhoeae and N. meningitidis, the only two human pathogens of Neisseria, are closely related species. But the niches they survived in and their pathogenic characteristics are distinctly different. However, the genetic basis of these differences has not yet been fully elucidated. In this study, comparative genomics analysis was performed based on 15 N. gonorrhoeae, 75 N. meningitidis, and 7 nonpathogenic Neisseria genomes. Core-pangenome analysis found 1111 conserved gene families among them, and each of these species groups had opening pangenome. We found that 452, 78, and 319 gene families were unique in N. gonorrhoeae, N. meningitidis, and both of them, respectively. Those unique gene families were regarded as candidates that related to their pathogenicity and niche adaptation. The relationships among them have been partly verified by functional annotation analysis. But at least one-third genes for each gene set have not found the certain functional information. Simple sequence repeat (SSR), the basis of gene phase variation, was found abundant in the membrane or related genes of each unique gene set, which may facilitate their adaptation to variable host environments. Protein-protein interaction (PPI) analysis found at least five distinct PPI clusters in N. gonorrhoeae and four in N. meningitides, and 167 and 52 proteins with unknown function were contained within them, respectively.
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18
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Tzeng YL, Berman Z, Toh E, Bazan JA, Turner AN, Retchless AC, Wang X, Nelson DE, Stephens DS. Heteroresistance to the model antimicrobial peptide polymyxin B in the emerging Neisseria meningitidis lineage 11.2 urethritis clade: mutations in the pilMNOPQ operon. Mol Microbiol 2018; 111:254-268. [PMID: 30338585 DOI: 10.1111/mmi.14153] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 10/12/2018] [Indexed: 02/02/2023]
Abstract
Clusters of Neisseria meningitidis (Nm) urethritis among primarily heterosexual males in multiple US cities have been attributed to a unique non-encapsulated meningococcal clade (the US Nm urethritis clade, US_NmUC) within the hypervirulent clonal complex 11. Resistance to antimicrobial peptides (AMPs) is a key feature of urogenital pathogenesis of the closely related species, Neisseria gonorrhoeae. The US_NmUC isolates were found to be highly resistant to the model AMP, polymyxin B (PmB, MICs 64-256 µg ml-1 ). The isolates also demonstrated stable subpopulations of heteroresistant colonies that showed near total resistant to PmB (MICs 384-1024 µg ml-1 ) and colistin (MIC 256 µg ml-1 ) as well as enhanced LL-37 resistance. This is the first observation of heteroresistance in N. meningitidis. Consistent with previous findings, overall PmB resistance in US_NmUC isolates was due to active Mtr efflux and LptA-mediated lipid A modification. However, whole genome sequencing, variant analyses and directed mutagenesis revealed that the heteroresistance phenotypes and very high-level AMP resistance were the result of point mutations and IS1655 element movement in the pilMNOPQ operon, encoding the type IV pilin biogenesis apparatus. Cross-resistance to other classes of antibiotics was also observed in the heteroresistant colonies. High-level resistance to AMPs may contribute to the pathogenesis of US_NmUC.
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Affiliation(s)
- Yih-Ling Tzeng
- Division of Infectious Diseases, Department of Medicine, Emory University School of Medicine, Atlanta, GA, 30322, USA
| | - Zachary Berman
- Division of Infectious Diseases, Department of Medicine, Emory University School of Medicine, Atlanta, GA, 30322, USA
| | - Evelyn Toh
- Department of Microbiology and Immunology, Indiana University School of Medicine, Indianapolis, IN, 46202, USA
| | - Jose A Bazan
- Division of Infectious Diseases, Department of Internal Medicine, Ohio State University College of Medicine, Columbus, OH, 43210, USA.,Sexual Health Clinic, Columbus Public Health, Columbus, OH, 43210, USA
| | - Abigail Norris Turner
- Division of Infectious Diseases, Department of Internal Medicine, Ohio State University College of Medicine, Columbus, OH, 43210, USA
| | - Adam C Retchless
- Meningitis and Vaccine Preventable Diseases Branch, Centers for Disease Control and Prevention, Atlanta, GA, 30333, USA
| | - Xin Wang
- Meningitis and Vaccine Preventable Diseases Branch, Centers for Disease Control and Prevention, Atlanta, GA, 30333, USA
| | - David E Nelson
- Department of Microbiology and Immunology, Indiana University School of Medicine, Indianapolis, IN, 46202, USA
| | - David S Stephens
- Division of Infectious Diseases, Department of Medicine, Emory University School of Medicine, Atlanta, GA, 30322, USA.,Department of Microbiology and Immunology, Emory University School of Medicine, Atlanta, GA, 30322, USA
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19
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Callejas-Hernández F, Rastrojo A, Poveda C, Gironès N, Fresno M. Genomic assemblies of newly sequenced Trypanosoma cruzi strains reveal new genomic expansion and greater complexity. Sci Rep 2018; 8:14631. [PMID: 30279473 PMCID: PMC6168536 DOI: 10.1038/s41598-018-32877-2] [Citation(s) in RCA: 47] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2018] [Accepted: 09/13/2018] [Indexed: 12/19/2022] Open
Abstract
Chagas disease is a complex illness caused by the protozoan Trypanosoma cruzi displaying highly diverse clinical outcomes. In this sense, the genome sequence elucidation and comparison between strains may lead to disease understanding. Here, two new T. cruzi strains, have been sequenced, Y using Illumina and Bug2148 using PacBio, assembled, analyzed and compared with the T. cruzi annotated genomes available to date. The assembly stats from the new sequences show effective improvement of T. cruzi genome over the actual ones. Such as, the largest contig assembled (1.3 Mb in Bug2148) in de novo attempts and the highest mean assembly coverage (71X for Y). Our analysis reveals a new genomic expansion and greater complexity for those multi-copy gene families related to infection process and disease development, such as Trans-sialidases, Mucins and Mucin Associated Surface Proteins, among others. On one side, we demonstrate that multi-copy gene families are located near telomeric regions of the "chromosome-like" 1.3 Mb contig assembled of Bug2148, where they likely suffer high evolutive pressure. On the other hand, we identified several strain-specific single copy genes that might help to understand the differences in infectivity and physiology among strains. In summary, our results indicate that T. cruzi has a complex genomic architecture that may have promoted its evolution.
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Affiliation(s)
- Francisco Callejas-Hernández
- Centro de Biología Molecular Severo Ochoa, Consejo Superior de Investigaciones Científicas, Universidad Autónoma de Madrid, Cantoblanco, Madrid, Spain
| | - Alberto Rastrojo
- Centro de Biología Molecular Severo Ochoa, Consejo Superior de Investigaciones Científicas, Universidad Autónoma de Madrid, Cantoblanco, Madrid, Spain
| | - Cristina Poveda
- Centro de Biología Molecular Severo Ochoa, Consejo Superior de Investigaciones Científicas, Universidad Autónoma de Madrid, Cantoblanco, Madrid, Spain
| | - Núria Gironès
- Centro de Biología Molecular Severo Ochoa, Consejo Superior de Investigaciones Científicas, Universidad Autónoma de Madrid, Cantoblanco, Madrid, Spain.
- Instituto Sanitario de Investigación Princesa, Madrid, Spain.
| | - Manuel Fresno
- Centro de Biología Molecular Severo Ochoa, Consejo Superior de Investigaciones Científicas, Universidad Autónoma de Madrid, Cantoblanco, Madrid, Spain.
- Instituto Sanitario de Investigación Princesa, Madrid, Spain.
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20
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Siena E, Bodini M, Medini D. Interplay Between Virulence and Variability Factors as a Potential Driver of Invasive Meningococcal Disease. Comput Struct Biotechnol J 2018; 16:61-69. [PMID: 29686800 PMCID: PMC5910500 DOI: 10.1016/j.csbj.2018.02.002] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2017] [Revised: 01/29/2018] [Accepted: 02/11/2018] [Indexed: 01/09/2023] Open
Abstract
Neisseria meningitidis (Nm) is frequently found in the upper respiratory tract of the human population. Despite its prevalence as a commensal organism, Nm can occasionally invade the pharyngeal mucosal epithelium causing septicemia and life-threatening disease. A number of studies have tried to identify factors that are responsible for the onset of a virulent phenotype. Despite this however, we still miss clear causative elements. Several factors have been identified to be associated to an increased susceptibility to meningococcal disease in humans. None of them, however, could unambiguously discriminate healthy carrier from infected individuals. Similarly, comparative studies of virulent and apathogenic strains failed to identify virulence factors that could explain the emergence of the pathogenic phenotype. In line with this, a recent study of within host evolution found that Nm accumulates genomic changes during the asymptomatic carriage phase and that these are likely to contribute to the shift to a pathogenic phenotype. These results suggest that the presence of virulence factors in the meningococcal genome is not a sufficient condition for developing virulent traits, but is rather the ability to promote phenotypic variation, through the stochastic assortment of the repertoire of such factors, which could explain the occasional and unpredictable onset of IMD. Here, we present a series of argumentations supporting the hypothesis that invasive meningococcal disease comes as a result of the coexistence of bacterial virulence and variability factors in a plot that can be further complicated by additional latent factors, like host pre-existing immune status and genetic predisposition.
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21
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Pannekoek Y, Huis In 't Veld R, Schipper K, Bovenkerk S, Kramer G, Speijer D, van der Ende A. Regulation of Neisseria meningitidis cytochrome bc1 components by NrrF, a Fur-controlled small noncoding RNA. FEBS Open Bio 2017; 7:1302-1315. [PMID: 28904860 PMCID: PMC5586341 DOI: 10.1002/2211-5463.12266] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2017] [Revised: 06/27/2017] [Accepted: 06/28/2017] [Indexed: 12/23/2022] Open
Abstract
NrrF is a small regulatory RNA of the human pathogen Neisseria meningitidis. NrrF was previously shown to repress succinate dehydrogenase (sdhCDAB) under control of the ferric uptake regulator (Fur). Here, we provide evidence that cytochrome bc1 , encoded by the polycistronic mRNA petABC, is a NrrF target as well. We demonstrated differential expression of cytochrome bc1 comparing wild-type meningococci and meningococci expressing NrrF when sufficient iron is available. Using a gfp-reporter system monitoring translational control and target recognition of sRNA in Escherichia coli, we show that interaction between NrrF and the 5' untranslated region of the petABC mRNA results in its repression. The NrrF region essential for repression of petABC was identified by site-directed mutagenesis and is fully conserved among meningococci. Our results provide further insights into the mechanism by which Fur controls essential components of the N. meningitidis respiratory chain. Adaptation of cytochrome bc1 complex component levels upon iron limitation is post-transcriptionally regulated via the small regulatory RNA NrrF.
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Affiliation(s)
- Yvonne Pannekoek
- Department of Medical Microbiology Center for Infection and Immunity Amsterdam (CINIMA) Academic Medical Center The Netherlands
| | - Robert Huis In 't Veld
- Department of Medical Microbiology Center for Infection and Immunity Amsterdam (CINIMA) Academic Medical Center The Netherlands
| | - Kim Schipper
- Department of Medical Microbiology Center for Infection and Immunity Amsterdam (CINIMA) Academic Medical Center The Netherlands
| | - Sandra Bovenkerk
- Department of Medical Microbiology Center for Infection and Immunity Amsterdam (CINIMA) Academic Medical Center The Netherlands
| | - Gertjan Kramer
- Department of Medical Biochemistry Academic Medical Center Amsterdam The Netherlands.,Present address: Genome Biology Unit EMBL Heidelberg Heidelberg Germany
| | - Dave Speijer
- Department of Medical Biochemistry Academic Medical Center Amsterdam The Netherlands
| | - Arie van der Ende
- Department of Medical Microbiology Center for Infection and Immunity Amsterdam (CINIMA) Academic Medical Center The Netherlands
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22
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Seib KL, Jen FEC, Scott AL, Tan A, Jennings MP. Phase variation of DNA methyltransferases and the regulation of virulence and immune evasion in the pathogenic Neisseria. Pathog Dis 2017; 75:3966716. [DOI: 10.1093/femspd/ftx080] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2017] [Accepted: 07/13/2017] [Indexed: 01/31/2023] Open
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23
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Huis In 't Veld RAG, Kramer G, van der Ende A, Speijer D, Pannekoek Y. The Hfq regulon of Neisseria meningitidis. FEBS Open Bio 2017; 7:777-788. [PMID: 28593133 PMCID: PMC5458458 DOI: 10.1002/2211-5463.12218] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2016] [Revised: 02/07/2017] [Accepted: 03/09/2017] [Indexed: 01/09/2023] Open
Abstract
The conserved RNA‐binding protein, Hfq, has multiple regulatory roles within the prokaryotic cell, including promoting stable duplex formation between small RNAs and mRNAs, and thus hfq deletion mutants have pleiotropic phenotypes. Previous proteome and transcriptome studies of Neisseria meningitidis have generated limited insight into differential gene expression due to Hfq loss. In this study, reversed‐phase liquid chromatography combined with data‐independent alternate scanning mass spectrometry (LC‐MSE) was utilized for rapid high‐resolution quantitative proteomic analysis to further elucidate the differentially expressed proteome of a meningococcal hfq deletion mutant. Whole‐cell lysates of N. meningitidis serogroup B H44/76 wild‐type (wt) and H44/76Δhfq (Δhfq) grown in liquid growth medium were subjected to tryptic digestion. The resulting peptide mixtures were separated by liquid chromatography (LC) prior to analysis by mass spectrometry (MSE). Differential expression was analyzed by Student's t‐test with control for false discovery rate (FDR). Reliable quantitation of relative expression comparing wt and Δhfq was achieved with 506 proteins (20%). Upon FDR control at q ≤ 0.05, 48 up‐ and 59 downregulated proteins were identified. From these, 81 were identified as novel Hfq‐regulated candidates, while 15 proteins were previously found by SDS/PAGE/MS and 24 with microarray analyses. Thus, using LC‐MSE we have expanded the repertoire of Hfq‐regulated proteins. In conjunction with previous studies, a comprehensive network of Hfq‐regulated proteins was constructed and differentially expressed proteins were found to be involved in a large variety of cellular processes. The results and comparisons with other gram‐negative model systems, suggest still unidentified sRNA analogs in N. meningitidis.
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Affiliation(s)
- Robert A G Huis In 't Veld
- Department of Medical Microbiology Center of Infection and Immunity Amsterdam (CINIMA) Academic Medical Center Amsterdam The Netherlands
| | - Gertjan Kramer
- Clinical Proteomics Facility Department of Medical Biochemistry Academic Medical Center Amsterdam The Netherlands.,Present address: Genome Biology Unit EMBL Heidelberg Heidelberg Germany
| | - Arie van der Ende
- Department of Medical Microbiology Center of Infection and Immunity Amsterdam (CINIMA) Academic Medical Center Amsterdam The Netherlands.,Reference Laboratory for Bacterial Meningitis Department of Medical Microbiology Academic Medical Center Amsterdam The Netherlands
| | - Dave Speijer
- Clinical Proteomics Facility Department of Medical Biochemistry Academic Medical Center Amsterdam The Netherlands
| | - Yvonne Pannekoek
- Department of Medical Microbiology Center of Infection and Immunity Amsterdam (CINIMA) Academic Medical Center Amsterdam The Netherlands
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24
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Pérez-Ortega J, Rodríguez A, Ribes E, Tommassen J, Arenas J. Interstrain Cooperation in Meningococcal Biofilms: Role of Autotransporters NalP and AutA. Front Microbiol 2017; 8:434. [PMID: 28382026 PMCID: PMC5360712 DOI: 10.3389/fmicb.2017.00434] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2016] [Accepted: 03/02/2017] [Indexed: 12/18/2022] Open
Abstract
Neisseria meningitidis (Nm) and Neisseria lactamica (Nl) are commensal bacteria that live in the human nasopharynx, where they form microcolonies. In contrast to Nl, Nm occasionally causes blood and/or meningitis infection with often fatal consequences. Here, we studied interactions between neisserial strains during biofilm formation. Fluorescent strains were engineered and analyzed for growth in single- and dual-strain biofilms with confocal laser-scanning microscopy. Different strains of diverse Neisseria species formed microcolonies of different sizes and morphologies. Pair-wise combinations of two invasive Nm strains and one Nm carrier isolate showed that these strains can coexist in spite of the fact that they produce toxins to combat congeners. This lack of competition was even observed when the biofilms were formed under nutrient limitation and can be explained by the observation that the separate microcolonies within mixed biofilms are mostly lineage specific. However, these microcolonies showed different levels of interaction. The coexistence of two strains was also observed in mixed biofilms of Nm and Nl strains. Inactivation of the autotransporter NalP, which prevents the release of the heparin-binding antigen NHBA and the α-peptide of IgA protease from the cell surface, and/or the production of autotransporter AutA increased interactions between microcolonies, as evidenced by close contacts between microcolonies on the substratum. Qualitative and quantitative analysis revealed an altered spatial distribution of each strain in mixed biofilms with consequences for the biomass, biofilm architecture and bacterial viability depending on the synthesis of NalP and AutA, the expression of which is prone to phase variation. Being in a consortium resulted in some cases in commensalism and cooperative behavior, which promoted attachment to the substratum or increased survival, possibly as result of the shared use of the biofilm matrix. We hypothesize that Nm strains can cooperate during host colonization, but, possibly, the different capacities of the microcolonies of each strain to resist the host's defenses limits the long-term coexistence of strains in the host.
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Affiliation(s)
- Jesús Pérez-Ortega
- Section Molecular Microbiology, Department of Biology, Utrecht University Utrecht, Netherlands
| | - Antonio Rodríguez
- Section Molecular Microbiology, Department of Biology, Utrecht University Utrecht, Netherlands
| | - Eduardo Ribes
- Section Molecular Microbiology, Department of Biology, Utrecht University Utrecht, Netherlands
| | - Jan Tommassen
- Section Molecular Microbiology, Department of Biology, Utrecht University Utrecht, Netherlands
| | - Jesús Arenas
- Section Molecular Microbiology, Department of Biology, Utrecht University Utrecht, Netherlands
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25
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Klughammer J, Dittrich M, Blom J, Mitesser V, Vogel U, Frosch M, Goesmann A, Müller T, Schoen C. Comparative Genome Sequencing Reveals Within-Host Genetic Changes in Neisseria meningitidis during Invasive Disease. PLoS One 2017; 12:e0169892. [PMID: 28081260 PMCID: PMC5231331 DOI: 10.1371/journal.pone.0169892] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2016] [Accepted: 12/22/2016] [Indexed: 11/29/2022] Open
Abstract
Some members of the physiological human microbiome occasionally cause life-threatening disease even in immunocompetent individuals. A prime example of such a commensal pathogen is Neisseria meningitidis, which normally resides in the human nasopharynx but is also a leading cause of sepsis and epidemic meningitis. Using N. meningitidis as model organism, we tested the hypothesis that virulence of commensal pathogens is a consequence of within host evolution and selection of invasive variants due to mutations at contingency genes, a mechanism called phase variation. In line with the hypothesis that phase variation evolved as an adaptation to colonize diverse hosts, computational comparisons of all 27 to date completely sequenced and annotated meningococcal genomes retrieved from public databases showed that contingency genes are indeed enriched for genes involved in host interactions. To assess within-host genetic changes in meningococci, we further used ultra-deep whole-genome sequencing of throat-blood strain pairs isolated from four patients suffering from invasive meningococcal disease. We detected up to three mutations per strain pair, affecting predominantly contingency genes involved in type IV pilus biogenesis. However, there was not a single (set) of mutation(s) that could invariably be found in all four pairs of strains. Phenotypic assays further showed that these genetic changes were generally not associated with increased serum resistance, higher fitness in human blood ex vivo or differences in the interaction with human epithelial and endothelial cells in vitro. In conclusion, we hypothesize that virulence of meningococci results from accidental emergence of invasive variants during carriage and without within host evolution of invasive phenotypes during disease progression in vivo.
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Affiliation(s)
- Johanna Klughammer
- CeMM Research Center for Molecular Medicine of the Austrian Academy of Sciences, Vienna, Austria
- Institute for Hygiene and Microbiology, University of Würzburg, Würzburg, Germany
| | - Marcus Dittrich
- Department of Bioinformatics, Biocenter, University of Würzburg, Würzburg, Germany
- Institute of Human Genetics, Biocenter, University of Würzburg, Würzburg, Germany
| | - Jochen Blom
- Institute for Bioinformatics and Systems Biology, Justus Liebig University Giessen, Giessen, Germany
| | - Vera Mitesser
- Institute for Hygiene and Microbiology, University of Würzburg, Würzburg, Germany
| | - Ulrich Vogel
- Institute for Hygiene and Microbiology, University of Würzburg, Würzburg, Germany
- Research Center for Infectious Diseases, University of Würzburg, Würzburg, Germany
- German Reference Laboratory for Meningococci and Haemophilus influenzae, Institute for Hygiene and Microbiology, University of Würzburg, Würzburg, Germany
| | - Matthias Frosch
- Institute for Hygiene and Microbiology, University of Würzburg, Würzburg, Germany
- Research Center for Infectious Diseases, University of Würzburg, Würzburg, Germany
- German Reference Laboratory for Meningococci and Haemophilus influenzae, Institute for Hygiene and Microbiology, University of Würzburg, Würzburg, Germany
| | - Alexander Goesmann
- Institute for Bioinformatics and Systems Biology, Justus Liebig University Giessen, Giessen, Germany
| | - Tobias Müller
- Department of Bioinformatics, Biocenter, University of Würzburg, Würzburg, Germany
| | - Christoph Schoen
- Institute for Hygiene and Microbiology, University of Würzburg, Würzburg, Germany
- Research Center for Infectious Diseases, University of Würzburg, Würzburg, Germany
- * E-mail:
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26
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Tan A, Atack JM, Jennings MP, Seib KL. The Capricious Nature of Bacterial Pathogens: Phasevarions and Vaccine Development. Front Immunol 2016; 7:586. [PMID: 28018352 PMCID: PMC5149525 DOI: 10.3389/fimmu.2016.00586] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2016] [Accepted: 11/28/2016] [Indexed: 12/11/2022] Open
Abstract
Infectious diseases are a leading cause of morbidity and mortality worldwide, and vaccines are one of the most successful and cost-effective tools for disease prevention. One of the key considerations for rational vaccine development is the selection of appropriate antigens. Antigens must induce a protective immune response, and this response should be directed to stably expressed antigens so the target microbe can always be recognized by the immune system. Antigens with variable expression, due to environmental signals or phase variation (i.e., high frequency, random switching of expression), are not ideal vaccine candidates because variable expression could lead to immune evasion. Phase variation is often mediated by the presence of highly mutagenic simple tandem DNA repeats, and genes containing such sequences can be easily identified, and their use as vaccine antigens reconsidered. Recent research has identified phase variably expressed DNA methyltransferases that act as global epigenetic regulators. These phase-variable regulons, known as phasevarions, are associated with altered virulence phenotypes and/or expression of vaccine candidates. As such, genes encoding candidate vaccine antigens that have no obvious mechanism of phase variation may be subject to indirect, epigenetic control as part of a phasevarion. Bioinformatic and experimental studies are required to elucidate the distribution and mechanism of action of these DNA methyltransferases, and most importantly, whether they mediate epigenetic regulation of potential and current vaccine candidates. This process is essential to define the stably expressed antigen target profile of bacterial pathogens and thereby facilitate efficient, rational selection of vaccine antigens.
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Affiliation(s)
- Aimee Tan
- Institute for Glycomics, Griffith University , Gold Coast, QLD , Australia
| | - John M Atack
- Institute for Glycomics, Griffith University , Gold Coast, QLD , Australia
| | - Michael P Jennings
- Institute for Glycomics, Griffith University , Gold Coast, QLD , Australia
| | - Kate L Seib
- Institute for Glycomics, Griffith University , Gold Coast, QLD , Australia
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27
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Arenas J, Paganelli FL, Rodríguez-Castaño P, Cano-Crespo S, van der Ende A, van Putten JPM, Tommassen J. Expression of the Gene for Autotransporter AutB of Neisseria meningitidis Affects Biofilm Formation and Epithelial Transmigration. Front Cell Infect Microbiol 2016; 6:162. [PMID: 27921012 PMCID: PMC5118866 DOI: 10.3389/fcimb.2016.00162] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2016] [Accepted: 11/07/2016] [Indexed: 11/15/2022] Open
Abstract
Neisseria meningitidis is a Gram-negative bacterium that resides as a commensal in the upper respiratory tract of humans, but occasionally, it invades the host and causes sepsis and/or meningitis. The bacterium can produce eight autotransporters, seven of which have been studied to some detail. The remaining one, AutB, has not been characterized yet. Here, we show that the autB gene is broadly distributed among pathogenic Neisseria spp. The gene is intact in most meningococcal strains. However, its expression is prone to phase variation due to slipped-strand mispairing at AAGC repeats located within the DNA encoding the signal sequence and is switched off in the vast majority of these strains. Moreover, various genetic disruptions prevent autB expression in most of the strains in which the gene is in phase indicating a strong selection against AutB synthesis. We observed that autB is expressed in two of the strains examined and that AutB is secreted and exposed at the cell surface. Functionality assays revealed that AutB synthesis promotes biofilm formation and delays the passage of epithelial cell layers in vitro. We hypothesize that this autotransporter is produced during the colonization process only in specific niches to facilitate microcolony formation, but its synthesis is switched off probably to evade the immune system and facilitate human tissue invasion.
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Affiliation(s)
- Jesús Arenas
- Department of Molecular Microbiology and Institute of Biomembranes, Utrecht University Utrecht, Netherlands
| | - Fernanda L Paganelli
- Department of Medical Microbiology, University Medical Center Utrecht Utrecht, Netherlands
| | - Patricia Rodríguez-Castaño
- Department of Molecular Microbiology and Institute of Biomembranes, Utrecht University Utrecht, Netherlands
| | - Sara Cano-Crespo
- Department of Molecular Microbiology and Institute of Biomembranes, Utrecht University Utrecht, Netherlands
| | - Arie van der Ende
- Department of Medical Microbiology, Academic Medical Center Amsterdam, Netherlands
| | - Jos P M van Putten
- Department of Infectious Diseases and Immunology, Faculty of Veterinary Medicine, Utrecht University Utrecht, Netherlands
| | - Jan Tommassen
- Department of Molecular Microbiology and Institute of Biomembranes, Utrecht University Utrecht, Netherlands
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Siena E, D’Aurizio R, Riley D, Tettelin H, Guidotti S, Torricelli G, Moxon ER, Medini D. In-silico prediction and deep-DNA sequencing validation indicate phase variation in 115 Neisseria meningitidis genes. BMC Genomics 2016; 17:843. [PMID: 27793092 PMCID: PMC5084427 DOI: 10.1186/s12864-016-3185-1] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2016] [Accepted: 10/22/2016] [Indexed: 01/25/2023] Open
Abstract
BACKGROUND The Neisseria meningitidis (Nm) chromosome shows a high abundance of simple sequence DNA repeats (SSRs) that undergo stochastic, reversible mutations at high frequency. This mechanism is reflected in an extensive phenotypic diversity that facilitates Nm adaptation to dynamic environmental changes. To date, phase-variable phenotypes mediated by SSRs variation have been experimentally confirmed for 26 Nm genes. RESULTS Here we present a population-scale comparative genomic analysis that identified 277 genes and classified them into 52 strong, 60 moderate and 165 weak candidates for phase variation. Deep-coverage DNA sequencing of single colonies grown overnight under non-selective conditions confirmed the presence of high-frequency, stochastic variation in 115 of them, providing circumstantial evidence for their phase variability. We confirmed previous observations of a predominance of variable SSRs within genes for components located on the cell surface or DNA metabolism. However, in addition we identified an unexpectedly broad spectrum of other metabolic functions, and most of the variable SSRs were predicted to induce phenotypic changes by modulating gene expression at a transcriptional level or by producing different protein isoforms rather than mediating on/off translational switching through frameshifts. Investigation of the evolutionary history of SSR contingency loci revealed that these loci were inherited from a Nm ancestor, evolved independently within Nm, or were acquired by Nm through lateral DNA exchange. CONCLUSIONS Overall, our results have identified a broader and qualitatively different phenotypic diversification of SSRs-mediated stochastic variation than previously documented, including its impact on central Nm metabolism.
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Affiliation(s)
| | - Romina D’Aurizio
- GSK Vaccines, 53100 Siena, Italy
- Present address: Institute of Informatics and Telematics and Institute of Clinical Physiology, National Research Council, 56124 Pisa, Italy
| | - David Riley
- Institute for Genome Sciences, University of Maryland School of Medicine, Baltimore, MD 21201 USA
- Present address: Personal Genome Disgnostics inc., Baltimore, MD 21224 USA
| | - Hervé Tettelin
- Institute for Genome Sciences, University of Maryland School of Medicine, Baltimore, MD 21201 USA
| | | | | | - E. Richard Moxon
- Medical Sciences Division, Weatherall Institute of Molecular Medicine, John Radcliffe Hospital, Oxford, OX3 9DS UK
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29
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Scholz CFP, Brüggemann H, Lomholt HB, Tettelin H, Kilian M. Genome stability of Propionibacterium acnes: a comprehensive study of indels and homopolymeric tracts. Sci Rep 2016; 6:20662. [PMID: 26857276 PMCID: PMC4746626 DOI: 10.1038/srep20662] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2015] [Accepted: 01/11/2016] [Indexed: 01/06/2023] Open
Abstract
We present a species-wide comparative analysis of 90 genomes of Propionibacterium acnes that represent the known diversity of the species. Our results are augmented by six high-quality genomes and a manual investigation of all gene-sized indels found in the strains. Overall, the order of genes is conserved throughout the species. A public sybil database for easy comparative analysis of the 90 genomes was established. The analysis of indels revealed a total of 66 loci of non-core genes that correlate with phylogenetic clades. No gene was strain-specific in agreement with our conclusion that the P. acnes pan-genome is closed. An exhaustive search for homopolymeric tracts (HPTs) identified a total of 54 variable-length HPTs almost exclusively of guanine/cytosines located between genes or affecting the reading frame of genes. The repeat variation was consistent with phylogenetic clades suggesting slow accumulation over time rather than active modification. By transcriptome analysis we demonstrate how an HPT variation can affect the gene expression levels. Selected cases of both indels and HPTs are described. The catalogued data and the public P. acnes Sybil database provide a solid foundation for generating hypotheses and facilitate comparative genetic analyses in future P. acnes research.
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Affiliation(s)
| | | | | | - Hervé Tettelin
- Institute for Genome Sciences, University of Maryland School of Medicine, USA
| | - Mogens Kilian
- Department of Biomedicine, Aarhus University, Denmark
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30
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Scully IL, Swanson K, Green L, Jansen KU, Anderson AS. Anti-infective vaccination in the 21st century—new horizons for personal and public health. Curr Opin Microbiol 2015; 27:96-102. [DOI: 10.1016/j.mib.2015.07.006] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2015] [Accepted: 07/10/2015] [Indexed: 12/17/2022]
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31
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Gasparini R, Panatto D, Bragazzi NL, Lai PL, Bechini A, Levi M, Durando P, Amicizia D. How the Knowledge of Interactions between Meningococcus and the Human Immune System Has Been Used to Prepare Effective Neisseria meningitidis Vaccines. J Immunol Res 2015; 2015:189153. [PMID: 26351643 PMCID: PMC4553322 DOI: 10.1155/2015/189153] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2015] [Accepted: 06/09/2015] [Indexed: 01/17/2023] Open
Abstract
In the last decades, tremendous advancement in dissecting the mechanisms of pathogenicity of Neisseria meningitidis at a molecular level has been achieved, exploiting converging approaches of different disciplines, ranging from pathology to microbiology, immunology, and omics sciences (such as genomics and proteomics). Here, we review the molecular biology of the infectious agent and, in particular, its interactions with the immune system, focusing on both the innate and the adaptive responses. Meningococci exploit different mechanisms and complex machineries in order to subvert the immune system and to avoid being killed. Capsular polysaccharide and lipooligosaccharide glycan composition, in particular, play a major role in circumventing immune response. The understanding of these mechanisms has opened new horizons in the field of vaccinology. Nowadays different licensed meningococcal vaccines are available and used: conjugate meningococcal C vaccines, tetravalent conjugate vaccines, an affordable conjugate vaccine against the N. menigitidis serogroup A, and universal vaccines based on multiple antigens each one with a different and peculiar function against meningococcal group B strains.
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Affiliation(s)
- R. Gasparini
- Department of Health Sciences, University of Genoa, Via Pastore 1, 16132 Genoa, Italy
| | - D. Panatto
- Department of Health Sciences, University of Genoa, Via Pastore 1, 16132 Genoa, Italy
| | - N. L. Bragazzi
- Department of Health Sciences, University of Genoa, Via Pastore 1, 16132 Genoa, Italy
| | - P. L. Lai
- Department of Health Sciences, University of Genoa, Via Pastore 1, 16132 Genoa, Italy
| | - A. Bechini
- Department of Health Sciences, University of Florence, Viale G.B. Morgagni 48, 50134 Florence, Italy
| | - M. Levi
- Department of Health Sciences, University of Florence, Viale G.B. Morgagni 48, 50134 Florence, Italy
| | - P. Durando
- Department of Health Sciences, University of Genoa, Via Pastore 1, 16132 Genoa, Italy
| | - D. Amicizia
- Department of Health Sciences, University of Genoa, Via Pastore 1, 16132 Genoa, Italy
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32
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A biphasic epigenetic switch controls immunoevasion, virulence and niche adaptation in non-typeable Haemophilus influenzae. Nat Commun 2015. [PMID: 26215614 PMCID: PMC4525171 DOI: 10.1038/ncomms8828] [Citation(s) in RCA: 87] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Non-typeable Haemophilus influenzae contains an N6-adenine DNA-methyltransferase (ModA) that is subject to phase-variable expression (random ON/OFF switching). Five modA alleles, modA2, modA4, modA5, modA9 and modA10, account for over two-thirds of clinical otitis media isolates surveyed. Here, we use single molecule, real-time (SMRT) methylome analysis to identify the DNA-recognition motifs for all five of these modA alleles. Phase variation of these alleles regulates multiple proteins including vaccine candidates, and key virulence phenotypes such as antibiotic resistance (modA2, modA5, modA10), biofilm formation (modA2) and immunoevasion (modA4). Analyses of a modA2 strain in the chinchilla model of otitis media show a clear selection for ON switching of modA2 in the middle ear. Our results indicate that a biphasic epigenetic switch can control bacterial virulence, immunoevasion and niche adaptation in an animal model system. Non-typeable Haemophilus influenzae, which causes ear and lung infections, has a DNA methyltransferase encoded by alternative alleles that are subject to random ON/OFF switching. Here, Atack et al. show that this epigenetic switch controls the expression of key proteins involved in virulence.
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33
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Giacani L, Brandt SL, Ke W, Reid TB, Molini BJ, Iverson-Cabral S, Ciccarese G, Drago F, Lukehart SA, Centurion-Lara A. Transcription of TP0126, Treponema pallidum putative OmpW homolog, is regulated by the length of a homopolymeric guanosine repeat. Infect Immun 2015; 83:2275-89. [PMID: 25802057 PMCID: PMC4432754 DOI: 10.1128/iai.00360-15] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2015] [Accepted: 03/17/2015] [Indexed: 12/12/2022] Open
Abstract
An effective mechanism for introduction of phenotypic diversity within a bacterial population exploits changes in the length of repetitive DNA elements located within gene promoters. This phenomenon, known as phase variation, causes rapid activation or silencing of gene expression and fosters bacterial adaptation to new or changing environments. Phase variation often occurs in surface-exposed proteins, and in Treponema pallidum subsp. pallidum, the syphilis agent, it was reported to affect transcription of three putative outer membrane protein (OMP)-encoding genes. When the T. pallidum subsp. pallidum Nichols strain genome was initially annotated, the TP0126 open reading frame was predicted to include a poly(G) tract and did not appear to have a predicted signal sequence that might suggest the possibility of its being an OMP. Here we show that the initial annotation was incorrect, that this poly(G) is instead located within the TP0126 promoter, and that it varies in length in vivo during experimental syphilis. Additionally, we show that TP0126 transcription is affected by changes in the poly(G) length consistent with regulation by phase variation. In silico analysis of the TP0126 open reading frame based on the experimentally identified transcriptional start site shortens this hypothetical protein by 69 amino acids, reveals a predicted cleavable signal peptide, and suggests structural homology with the OmpW family of porins. Circular dichroism of recombinant TP0126 supports structural homology to OmpW. Together with the evidence that TP0126 is fully conserved among T. pallidum subspecies and strains, these data suggest an important role for TP0126 in T. pallidum biology and syphilis pathogenesis.
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Affiliation(s)
- Lorenzo Giacani
- Department of Medicine, Division of Allergy and Infectious Diseases, University of Washington, Seattle, Washington, USA Department of Global Health, University of Washington, Seattle, Washington, USA
| | - Stephanie L Brandt
- Department of Medicine, Division of Allergy and Infectious Diseases, University of Washington, Seattle, Washington, USA
| | - Wujian Ke
- Department of Medicine, Division of Allergy and Infectious Diseases, University of Washington, Seattle, Washington, USA Graduate School, Southern Medical University, Guangzhou, People's Republic of China, and Division of STD, Guangdong Provincial Center for STI & Skin Diseases Control and Prevention, Guangzhou, People's Republic of China
| | - Tara B Reid
- Department of Medicine, Division of Allergy and Infectious Diseases, University of Washington, Seattle, Washington, USA
| | - Barbara J Molini
- Department of Medicine, Division of Allergy and Infectious Diseases, University of Washington, Seattle, Washington, USA
| | - Stefanie Iverson-Cabral
- Department of Medicine, Division of Allergy and Infectious Diseases, University of Washington, Seattle, Washington, USA
| | - Giulia Ciccarese
- Department of Dermatology, IRCCS Azienda Universitaria Ospedaliera San Martino-IST, Genoa, Italy
| | - Francesco Drago
- Department of Dermatology, IRCCS Azienda Universitaria Ospedaliera San Martino-IST, Genoa, Italy
| | - Sheila A Lukehart
- Department of Medicine, Division of Allergy and Infectious Diseases, University of Washington, Seattle, Washington, USA Department of Global Health, University of Washington, Seattle, Washington, USA
| | - Arturo Centurion-Lara
- Department of Medicine, Division of Allergy and Infectious Diseases, University of Washington, Seattle, Washington, USA
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Mutations in pneumococcal cpsE generated via in vitro serial passaging reveal a potential mechanism of reduced encapsulation utilized by a conjunctival isolate. J Bacteriol 2015; 197:1781-91. [PMID: 25777672 DOI: 10.1128/jb.02602-14] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2014] [Accepted: 03/05/2015] [Indexed: 12/27/2022] Open
Abstract
UNLABELLED The polysaccharide capsule of Streptococcus pneumoniae is required for nasopharyngeal colonization and for invasive disease in the lungs, blood, and meninges. In contrast, the vast majority of conjunctival isolates are acapsular. The first serotype-specific gene in the capsule operon, cpsE, encodes the initiating glycosyltransferase and is one of the few serotype-specific genes that can tolerate null mutations. This report characterizes a spontaneously arising TIGR4 mutant exhibiting a reduced capsule, caused by a 6-nucleotide duplication in cpsE which results in duplication of Ala and Ile at positions 45 and 46. This strain (AI45dup) possessed more exposed phosphorylcholine and was hypersusceptible to C3 complement deposition compared to the wild type. Accordingly, the mutant was significantly better at forming abiotic biofilms and binding epithelial cells in vitro but was avirulent in a sepsis model. In vitro serial passaging of the wild-type strain failed to reproduce the AI45dup mutation but instead led to a variety of mutants with reduced capsule harboring single nucleotide polymorphisms (SNPs) in cpsE. A single passage in the sepsis model after high-dose inoculation readily yielded revertants of AI45dup with restored wild-type capsule level, but the majority of SNP alleles of cpsE could not revert, suppress, or bypass. Analysis of cpsE in conjunctival isolates revealed a strain with a single missense mutation at amino acid position 377, which was responsible for reduced encapsulation. This study supports the hypothesis that spontaneous, nonreverting mutations in cpsE serve as a form of adaptive mutation by providing a selective advantage to S. pneumoniae in niches where expression of capsule is detrimental. IMPORTANCE While the capsule of Streptococcus pneumoniae is required for colonization and invasive disease, most conjunctival isolates are acapsular by virtue of deletion of the entire capsular operon. We show that spontaneous acapsular mutants isolated in vitro harbor mostly nonrevertible single nucleotide polymorphism (SNP) null mutations in cpsE, encoding the initiating glycosyltransferase. From a small collection of acapsular conjunctival isolates, we identified one strain with a complete capsular operon but containing a SNP in cpsE that we show is responsible for the acapsular phenotype. We propose that acapsular conjunctival isolates may arise initially from such nonreverting SNP null mutations in cpsE, which can be followed later by deletion of portions or all of the cps operon.
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35
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Neisseria gonorrhoeae MutS affects pilin antigenic variation through mismatch correction and not by pilE guanine quartet binding. J Bacteriol 2015; 197:1828-38. [PMID: 25777677 DOI: 10.1128/jb.02594-14] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2014] [Accepted: 03/08/2015] [Indexed: 11/20/2022] Open
Abstract
UNLABELLED Many pathogens use homologous recombination to vary surface antigens to avoid immune surveillance. Neisseria gonorrhoeae achieves this in part by changing the properties of its surface pili in a process called pilin antigenic variation (AV). Pilin AV occurs by high-frequency gene conversion reactions that transfer silent pilS sequences into the expressed pilE locus and requires the formation of an upstream guanine quartet (G4) DNA structure to initiate this process. The MutS and MutL proteins of the mismatch correction (MMC) system act to correct mismatches after replication and prevent homeologous (i.e., partially homologous) recombination, but MutS orthologs can also bind to G4 structures. A previous study showed that mutation of MutS resulted in a 3-fold increase in pilin AV, which could be due to the loss of MutS antirecombination properties or loss of G4 binding. We tested two site-directed separation-of-function MutS mutants that are both predicted to bind to G4s but are not able to perform MMC. Pilus phase variation assays and DNA sequence analysis of pilE variants produced in these mutants showed that all three mutS mutants and a mutL mutant had similar increased frequencies of pilin AV. Moreover, the mutS mutants all showed similar increased levels of pilin AV-dependent synthetic lethality. These results show that antirecombination by MMC is the reason for the effect that MutS has on pilin AV and is not due to pilE G4 binding by MutS. IMPORTANCE Neisseria gonorrhoeae continually changes its outer surface proteins to avoid recognition by the immune system. N. gonorrhoeae alters the antigenicity of the pilus by directed recombination between partially homologous pilin copies in a process that requires a guanine quartet (G4) structure. The MutS protein of the mismatch correction (MMC) system prevents recombination between partially homologous sequences and can also bind to G4s. We confirmed that loss of MMC increases the frequency of pilin antigenic variation and that two MutS mutants that are predicted to separate the two different functions of MutS inhibit pilin variation similarly to a complete-loss-of-function mutant, suggesting that interaction of MutS with the G4 structure is not a major factor in this process.
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36
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Atack JM, Winter LE, Jurcisek JA, Bakaletz LO, Barenkamp SJ, Jennings MP. Selection and Counterselection of Hia Expression Reveals a Key Role for Phase-Variable Expression of Hia in Infection Caused by Nontypeable Haemophilus influenzae. J Infect Dis 2015; 212:645-53. [PMID: 25712964 DOI: 10.1093/infdis/jiv103] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2015] [Accepted: 02/13/2015] [Indexed: 11/12/2022] Open
Abstract
Hia is a major adhesin of nontypeable Haemophilus influenzae (NTHi) and has long been investigated as a vaccine candidate. Here we show that Hia phase variation is controlled by changes in the length of a polythymidine tract located in the hia promoter. Studies of an invasive clinical isolate (strain R2866) show that strains expressing high Hia levels are more efficiently killed by opsonophagocytosis. An opsonophagocytic assay was used to select for a subpopulation of variants that expressed a low level of Hia, which facilitated their escape from killing by anti-Hia antisera. Conversely, a subpopulation of variants expressing a high level of Hia was selected for during passaging through Chang cells. In both cases, phase variation of Hia expression corresponded directly with discrete modal changes in polythymidine tract length. In the chinchilla model of NTHi infection, we observed consistent selection for high Hia expression upon nasopharyngeal colonization, confirming the key role of phase-variable expression of Hia within a specific niche in vivo.
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Affiliation(s)
- John M Atack
- Institute for Glycomics, Griffith University, Gold Coast, Australia
| | - Linda E Winter
- Department of Pediatrics, Saint Louis University School of Medicine Pediatric Research Institute, Cardinal Glennon Children's Medical Center, Saint Louis, Missouri
| | - Joseph A Jurcisek
- Center for Microbial Pathogenesis, The Research Institute at Nationwide Children's Hospital and The Ohio State University College of Medicine, Columbus
| | - Lauren O Bakaletz
- Center for Microbial Pathogenesis, The Research Institute at Nationwide Children's Hospital and The Ohio State University College of Medicine, Columbus
| | - Stephen J Barenkamp
- Department of Pediatrics, Saint Louis University School of Medicine Pediatric Research Institute, Cardinal Glennon Children's Medical Center, Saint Louis, Missouri
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37
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Goldberg A, Fridman O, Ronin I, Balaban NQ. Systematic identification and quantification of phase variation in commensal and pathogenic Escherichia coli. Genome Med 2014; 6:112. [PMID: 25530806 PMCID: PMC4272514 DOI: 10.1186/s13073-014-0112-4] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2014] [Accepted: 11/14/2014] [Indexed: 11/10/2022] Open
Abstract
Bacteria have been shown to generate constant genetic variation in a process termed phase variation. We present a tool based on whole genome sequencing that allows detection and quantification of coexisting genotypes mediated by genomic inversions in bacterial cultures. We tested our method on widely used strains of Escherichia coli, and detected stable and reproducible phase variation in several invertible loci. These are shown here to be responsible for maintaining constant variation in populations grown from a single colony. Applying this tool on other bacterial strains can shed light on how pathogens adjust to hostile environments by diversifying their genomes.
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Affiliation(s)
- Amir Goldberg
- Racah Institute of Physics and the Sudarsky Center for Computational Biology, The Hebrew University, Edmond J. Safra Campus, Jerusalem, 91904 Israel
| | - Ofer Fridman
- Racah Institute of Physics and the Sudarsky Center for Computational Biology, The Hebrew University, Edmond J. Safra Campus, Jerusalem, 91904 Israel
| | - Irine Ronin
- Racah Institute of Physics and the Sudarsky Center for Computational Biology, The Hebrew University, Edmond J. Safra Campus, Jerusalem, 91904 Israel
| | - Nathalie Q Balaban
- Racah Institute of Physics and the Sudarsky Center for Computational Biology, The Hebrew University, Edmond J. Safra Campus, Jerusalem, 91904 Israel
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Abstract
Neisseria gonorrhoeae and Neisseria meningitidis are closely related organisms that cause the sexually transmitted infection gonorrhea and serious bacterial meningitis and septicemia, respectively. Both species possess multiple mechanisms to alter the expression of surface-exposed proteins through the processes of phase and antigenic variation. This potential for wide variability in surface-exposed structures allows the organisms to always have subpopulations of divergent antigenic types to avoid immune surveillance and to contribute to functional variation. Additionally, the Neisseria are naturally competent for DNA transformation, which is their main means of genetic exchange. Although bacteriophages and plasmids are present in this genus, they are not as effective as DNA transformation for horizontal genetic exchange. There are barriers to genetic transfer, such as restriction-modification systems and CRISPR loci, that limit particular types of exchange. These host-restricted pathogens illustrate the rich complexity of genetics that can help define the similarities and differences of closely related organisms.
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Affiliation(s)
- Ella Rotman
- Department of Microbiology-Immunology, Northwestern University Feinberg School of Medicine, Chicago, Illinois 60611; ,
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Arenas J, Cano S, Nijland R, van Dongen V, Rutten L, van der Ende A, Tommassen J. The meningococcal autotransporter AutA is implicated in autoaggregation and biofilm formation. Environ Microbiol 2014; 17:1321-37. [PMID: 25059714 DOI: 10.1111/1462-2920.12581] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2013] [Accepted: 07/22/2014] [Indexed: 11/29/2022]
Abstract
Autotransporters (ATs) are proteins secreted by Gram-negative bacteria that often play a role in virulence. Eight different ATs have been identified in Neisseria meningitidis, but only six of them have been characterized. AutA is one of the remaining ATs. Its expression remains controversial. Here, we show that the autA gene is present in many neisserial species, but its expression is often disrupted by various genetic features; however, it is expressed in certain strains of N. meningitidis. By sequencing the autA gene in large panels of disease isolates and Western blot analysis, we demonstrated that AutA expression is prone to phase variation at AAGC nucleotide repeats located within the DNA encoding the signal sequence. AutA is not secreted into the extracellular medium, but remains associated with the bacterial cell surface. We further demonstrate that AutA expression induces autoaggregation in a process that, dependent on the particular strain, may require extracellular DNA (eDNA). This property influences the organization of bacterial communities like lattices and biofilms. In vitro assays evidenced that AutA is a self-associating AT that binds DNA. We suggest that AutA-mediated autoaggregation might be particularly important for colonization and persistence of the pathogen in the nasopharynx of the host.
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Affiliation(s)
- Jesús Arenas
- Department of Molecular Microbiology and Institute of Biomembranes, Utrecht University, Paudalaan 8, Utrecht, 3584 CH, The Netherlands
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40
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Kilian M, Riley DR, Jensen A, Brüggemann H, Tettelin H. Parallel evolution of Streptococcus pneumoniae and Streptococcus mitis to pathogenic and mutualistic lifestyles. mBio 2014; 5:e01490-14. [PMID: 25053789 PMCID: PMC4120201 DOI: 10.1128/mbio.01490-14] [Citation(s) in RCA: 93] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2014] [Accepted: 06/27/2014] [Indexed: 11/20/2022] Open
Abstract
The bacterium Streptococcus pneumoniae is one of the leading causes of fatal infections affecting humans. Intriguingly, phylogenetic analysis shows that the species constitutes one evolutionary lineage in a cluster of the otherwise commensal Streptococcus mitis strains, with which humans live in harmony. In a comparative analysis of 35 genomes, including phylogenetic analyses of all predicted genes, we have shown that the pathogenic pneumococcus has evolved into a master of genomic flexibility while lineages that evolved into the nonpathogenic S. mitis secured harmonious coexistence with their host by stabilizing an approximately 15%-reduced genome devoid of many virulence genes. Our data further provide evidence that interspecies gene transfer between S. pneumoniae and S. mitis occurs in a unidirectional manner, i.e., from S. mitis to S. pneumoniae. Import of genes from S. mitis and other mitis, anginosus, and salivarius group streptococci ensured allelic replacements and antigenic diversification and has been driving the evolution of the remarkable structural diversity of capsular polysaccharides of S. pneumoniae. Our study explains how the unique structural diversity of the pneumococcal capsule emerged and conceivably will continue to increase and reveals a striking example of the fragile border between the commensal and pathogenic lifestyles. While genomic plasticity enabling quick adaptation to environmental stress is a necessity for the pathogenic streptococci, the commensal lifestyle benefits from stability. Importance: One of the leading causes of fatal infections affecting humans, Streptococcus pneumoniae, and the commensal Streptococcus mitis are closely related obligate symbionts associated with hominids. Faced with a shortage of accessible hosts, the two opposing lifestyles evolved in parallel. We have shown that the nonpathogenic S. mitis secured harmonious coexistence with its host by stabilizing a reduced genome devoid of many virulence genes. Meanwhile, the pathogenic pneumococcus evolved into a master of genomic flexibility and imports genes from S. mitis and other related streptococci. This process ensured antigenic diversification and has been driving the evolution of the remarkable structural diversity of capsular polysaccharides of S. pneumoniae, which conceivably will continue to increase and present a challenge to disease prevention.
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Affiliation(s)
- Mogens Kilian
- Department of Biomedicine, Faculty of Health, Aarhus University, Aarhus, Denmark
| | - David R Riley
- Department of Microbiology and Immunology, Institute for Genome Sciences, University of Maryland School of Medicine, Baltimore, Maryland, USA
| | - Anders Jensen
- Department of Biomedicine, Faculty of Health, Aarhus University, Aarhus, Denmark
| | - Holger Brüggemann
- Department of Biomedicine, Faculty of Health, Aarhus University, Aarhus, Denmark
| | - Hervé Tettelin
- Department of Microbiology and Immunology, Institute for Genome Sciences, University of Maryland School of Medicine, Baltimore, Maryland, USA
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Alfsnes K, Raynaud X, Tønjum T, Ambur OH. Mathematical and live meningococcal models for simple sequence repeat dynamics - coherent predictions and observations. PLoS One 2014; 9:e101637. [PMID: 24999629 PMCID: PMC4085013 DOI: 10.1371/journal.pone.0101637] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2014] [Accepted: 06/10/2014] [Indexed: 11/18/2022] Open
Abstract
Evolvability by means of simple sequence repeat (SSR) instability is a feature under the constant influence of opposing selective pressures to expand and compress the repeat tract and is mechanistically influenced by factors that affect genetic instability. In addition to direct selection for protein expression and structural integrity, other factors that influence tract length evolution were studied. The genetic instability of SSRs that switch the expression of antibiotic resistance ON and OFF was modelled mathematically and monitored in a panel of live meningococcal strains. The mathematical model showed that the SSR length of a theoretical locus in an evolving population may be shaped by direct selection of expression status (ON or OFF), tract length dependent (α) and tract length independent factors (β). According to the model an increase in α drives the evolution towards shorter tracts. An increase in β drives the evolution towards a normal distribution of tract lengths given that an upper and a lower limit are set. Insertion and deletion biases were shown to skew allelic distributions in both directions. The meningococcal SSR model was tested in vivo by monitoring the frequency of spectinomycin resistance OFF→ON switching in a designed locus. The instability of a comprehensive panel of the homopolymeric SSRs, constituted of a range of 5-13 guanine nucleotides, was monitored in wildtype and mismatch repair deficient backgrounds. Both the repeat length itself and mismatch repair deficiency were shown to influence the genetic instability of the homopolymeric tracts. A possible insertion bias was observed in tracts ≤G10. Finally, an inverse correlation between the number of tract-encoded amino acids and growth in the presence of ON-selection illustrated a limitation to SSR expansion in an essential gene associated with the designed model locus and the protein function mediating antibiotic resistance.
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Affiliation(s)
- Kristian Alfsnes
- Department of Microbiology, University of Oslo, Oslo, Norway
- Department of Microbiology, Oslo University Hospital (Rikshospitalet), Oslo, Norway
| | - Xavier Raynaud
- Department of Mathematics, University of Oslo, Oslo, Norway
| | - Tone Tønjum
- Department of Microbiology, University of Oslo, Oslo, Norway
- Department of Microbiology, Oslo University Hospital (Rikshospitalet), Oslo, Norway
| | - Ole Herman Ambur
- Department of Microbiology, University of Oslo, Oslo, Norway
- Department of Microbiology, Oslo University Hospital (Rikshospitalet), Oslo, Norway
- Department of Microbiology and Infection Control, Akershus University Hospital, Lørenskog, Norway
- * E-mail:
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42
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Phase variation mediates reductions in expression of surface proteins during persistent meningococcal carriage. Infect Immun 2014; 82:2472-84. [PMID: 24686058 DOI: 10.1128/iai.01521-14] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Asymptomatic and persistent colonization of the upper respiratory tract by Neisseria meningitidis occurs despite elicitation of adaptive immune responses against surface antigens. A putative mechanism for facilitating host persistence of this bacterial commensal and pathogen is alterations in expression of surface antigens by simple sequence repeat (SSR)-mediated phase variation. We investigated how often phase variation occurs during persistent carriage by analyzing the SSRs of eight loci in multiple isolates from 21 carriers representative of 1 to 6 months carriage. Alterations in repeat number were detected by a GeneScan analysis and occurred at 0.06 mutations/gene/month of carriage. The expression states were determined by Western blotting and two genes, fetA and nadA, exhibited trends toward low expression states. A critical finding from our unique examination of combinatorial expression states, "phasotypes," was for significant reductions in expression of multiple phase-variable surface proteins during persistent carriage of some strains. The immune responses in these carriers were examined by measuring variant-specific PorA IgG antibodies, capsular group Y IgG antibodies and serum bactericidal activity in concomitant serum samples. Persistent carriage was associated with high levels of specific IgG antibodies and serum bactericidal activity while recent strain acquisition correlated with a significant induction of antibodies. We conclude that phase-variable genes are driven into lower expression states during long-term persistent meningococcal carriage, in part due to continuous exposure to antibody-mediated selection, suggesting localized hypermutation has evolved to facilitate host persistence.
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43
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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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Mudunuri SB, Patnana S, Nagarajaram HA. MICdb3.0: a comprehensive resource of microsatellite repeats from prokaryotic genomes. DATABASE-THE JOURNAL OF BIOLOGICAL DATABASES AND CURATION 2014; 2014:bau005. [PMID: 24536078 PMCID: PMC3926409 DOI: 10.1093/database/bau005] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
The MICdb is a comprehensive relational database of perfect microsatellites extracted from completely sequenced and annotated genomes of bacteria and archaea. The current version MICdb3.0 is an updated and revised version of MICdb2.0. As compared with the previous version MICdb2.0, the current release is significantly improved in terms of much larger coverage of genomes, improved presentation of queried results, user-friendly administration module to manage Simple Sequence Repeat (SSR) data such as addition of new genomes, deletion of obsolete data, etc., and also removal of certain features deemed to be redundant. The new web-interface to the database called Microsatellite Analysis Server (MICAS) version 3.0 has been improved by the addition of powerful high-quality visualization tools to view the query results in the form of pie charts and bar graphs. All the query results and graphs can be exported in different formats so that the users can use them for further analysis. MICAS3.0 is also equipped with a unique genome comparison module using which users can do pair-wise comparison of genomes with regard to their microsatellite distribution. The advanced search module can be used to filter the repeats based on certain criteria such as filtering repeats of a particular motif/repeat size, extracting repeats of coding/non-coding regions, sort repeats, etc. The MICdb database has, therefore, been made portable to be administered by a person with the necessary administrative privileges. The MICdb3.0 database and analysis server can be accessed for free from www.cdfd.org.in/micas. Database URL:http://www.cdfd.org.in/micas
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Affiliation(s)
- Suresh B Mudunuri
- Department of Computer Science & Engineering, Grandhi Varalakshmi Venkatarao Institute of Technology, Bhimavaram, Andhra Pradesh 534 207, India, Training & Delivery Department, TalentSprint Educational Services, IIIT Campus, Hyderabad, Andhra Pradesh 500 032, India and Laboratory of Computational Biology, Centre for DNA Fingerprinting & Diagnostics, Hyderabad, Andhra Pradesh 500 001, India
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45
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Bai X, Borrow R. Genetic shifts ofNeisseria meningitidisserogroup B antigens and the quest for a broadly cross-protective vaccine. Expert Rev Vaccines 2014; 9:1203-17. [DOI: 10.1586/erv.10.116] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
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46
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Feavers I. Choosing isolates for the evaluation of meningococcal protein vaccines. Expert Rev Vaccines 2014; 8:1461-3. [DOI: 10.1586/erv.09.104] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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47
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Neisseria meningitidis NalP cleaves human complement C3, facilitating degradation of C3b and survival in human serum. Proc Natl Acad Sci U S A 2013; 111:427-32. [PMID: 24367091 DOI: 10.1073/pnas.1321556111] [Citation(s) in RCA: 55] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
The complement system is a crucial component of the innate immune response against invading bacterial pathogens. The human pathogen Neisseria meningitidis (Nm) is known to possess several mechanisms to evade the complement system, including binding to complement inhibitors. In this study, we describe an additional mechanism used by Nm to evade the complement system and survive in human blood. Using an isogenic NalP deletion mutant and NalP complementing strains, we show that the autotransporter protease NalP cleaves C3, the central component of the complement cascade. The cleavage occurs 4 aa upstream from the natural C3 cleavage site and produces shorter C3a-like and longer C3b-like fragments. The C3b-like fragment is degraded in the presence of the complement regulators (factors H and I), and this degradation results in lower deposition of C3b on the bacterial surface. We conclude that NalP is an important factor to increase the survival of Nm in human serum.
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48
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Chagnot C, Zorgani MA, Astruc T, Desvaux M. Proteinaceous determinants of surface colonization in bacteria: bacterial adhesion and biofilm formation from a protein secretion perspective. Front Microbiol 2013; 4:303. [PMID: 24133488 PMCID: PMC3796261 DOI: 10.3389/fmicb.2013.00303] [Citation(s) in RCA: 128] [Impact Index Per Article: 11.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2013] [Accepted: 09/22/2013] [Indexed: 01/30/2023] Open
Abstract
Bacterial colonization of biotic or abiotic surfaces results from two quite distinct physiological processes, namely bacterial adhesion and biofilm formation. Broadly speaking, a biofilm is defined as the sessile development of microbial cells. Biofilm formation arises following bacterial adhesion but not all single bacterial cells adhering reversibly or irreversibly engage inexorably into a sessile mode of growth. Among molecular determinants promoting bacterial colonization, surface proteins are the most functionally diverse active components. To be present on the bacterial cell surface, though, a protein must be secreted in the first place. Considering the close association of secreted proteins with their cognate secretion systems, the secretome (which refers both to the secretion systems and their protein substrates) is a key concept to apprehend the protein secretion and related physiological functions. The protein secretion systems are here considered in light of the differences in the cell-envelope architecture between diderm-LPS (archetypal Gram-negative), monoderm (archetypal Gram-positive) and diderm-mycolate (archetypal acid-fast) bacteria. Besides, their cognate secreted proteins engaged in the bacterial colonization process are regarded from single protein to supramolecular protein structure as well as the non-classical protein secretion. This state-of-the-art on the complement of the secretome (the secretion systems and their cognate effectors) involved in the surface colonization process in diderm-LPS and monoderm bacteria paves the way for future research directions in the field.
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Affiliation(s)
- Caroline Chagnot
- UR454 Microbiologie, INRA Saint-Genès Champanelle, France ; UR370 Qualité des Produits Animaux, INRA Saint-Genès Champanelle, France
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49
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Arenas J, Schipper K, van Ulsen P, van der Ende A, Tommassen J. Domain exchange at the 3' end of the gene encoding the fratricide meningococcal two-partner secretion protein A. BMC Genomics 2013; 14:622. [PMID: 24034852 PMCID: PMC3848433 DOI: 10.1186/1471-2164-14-622] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2013] [Accepted: 09/13/2013] [Indexed: 02/01/2023] Open
Abstract
Background Two-partner secretion systems in Gram-negative bacteria consist of an outer membrane protein TpsB that mediates the secretion of a cognate TpsA protein into the extracellular milieu. TpsA proteins have diverse, often virulence-related functions, and some of them inhibit the growth of related bacteria. In Neisseria meningitidis, several functions have been attributed to the TpsA proteins. Downstream of the tpsB and tpsA genes, several shorter tpsA-related gene cassettes, called tpsC, are located interspersed with intervening open-reading frames (IORFs). It has been suggested that the tpsC cassettes may recombine with the tpsA gene as a mechanism of antigenic variation. Here, we investigated (i) whether TpsA of N. meningitidis also has growth-inhibitory properties, (ii) whether tpsC cassettes recombine with the tpsA gene, and (iii) what the consequences of such recombination events might be. Results We demonstrate that meningococcal TpsA has growth-inhibitory properties and that the IORF located immediately downstream of tpsA confers immunity to the producing strain. Although bioinformatics analysis suggests that recombination between tpsC cassettes and tpsA occurs, detailed analysis of the tpsA gene in a large collection of disease isolates of three clonal complexes revealed that the frequency is very low and cannot be a mechanism of antigenic variation. However, recombination affected growth inhibition. In vitro experiments revealed that recombination can be mediated through acquirement of tpsC cassettes from the environment and it identified the regions involved in the recombination. Conclusions Meningococcal TpsA has growth-inhibitory properties. Recombination between tpsA and tpsC cassettes occurs in vivo but is rare and has consequences for growth inhibition. A recombination model is proposed and we propose that the main goal of recombination is the collection of new IORFs for protection against a variety of TpsA proteins.
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Affiliation(s)
- Jesús Arenas
- Department of Molecular Microbiology, Utrecht University, Padualaan 8, Utrecht 3584 CH, The Netherlands.
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50
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Del Tordello E, Serruto D. Functional genomics studies of the human pathogen Neisseria meningitidis. Brief Funct Genomics 2013; 12:328-40. [PMID: 23723380 DOI: 10.1093/bfgp/elt018] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Neisseria meningitidis is a strictly human pathogen and is one of the major causes of septicemia and meningitis worldwide. Functional genomics approaches have been extensively applied to study how N. meningitidis adapts to grow and survive in different human niches encountered during the infection. DNA microarrays performed in in vitro and ex vivo conditions have revealed changes in the transcriptome profiles of N. meningitidis upon interaction with human cells and after incubation in human serum and blood. Mutagenesis studies allowed detecting mutants in genes crucial for N. meningitidis colonization and systemic infection. The analysis of N. meningitidis genomes has been also successful in the identification of vaccine candidates used to develop an effective protein-based vaccine. The application of all these approaches revealed the potential to identify new virulence factors and vaccine candidates and to assign functions to previously uncharacterized genes providing new insights in the biology and pathogenesis of N. meningitidis.
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