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Mattos-Graner RO, Klein MI, Alves LA. The complement system as a key modulator of the oral microbiome in health and disease. Crit Rev Microbiol 2024; 50:138-167. [PMID: 36622855 DOI: 10.1080/1040841x.2022.2163614] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2022] [Revised: 12/22/2022] [Accepted: 12/23/2022] [Indexed: 01/10/2023]
Abstract
In this review, we address the interplay between the complement system and host microbiomes in health and disease, focussing on oral bacteria known to contribute to homeostasis or to promote dysbiosis associated with dental caries and periodontal diseases. Host proteins modulating complement activities in the oral environment and expression profiles of complement proteins in oral tissues were described. In addition, we highlight a sub-set of bacterial proteins involved in complement evasion and/or dysregulation previously characterized in pathogenic species (or strains), but further conserved among prototypical commensal species of the oral microbiome. Potential roles of these proteins in host-microbiome homeostasis and in the emergence of commensal strain lineages with increased virulence were also addressed. Finally, we provide examples of how commensal bacteria might exploit the complement system in competitive or cooperative interactions within the complex microbial communities of oral biofilms. These issues highlight the need for studies investigating the effects of the complement system on bacterial behaviour and competitiveness during their complex interactions within oral and extra-oral host sites.
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Affiliation(s)
- Renata O Mattos-Graner
- Department of Oral Diagnosis, Piracicaba Dental School, State University of Campinas (UNICAMP), Sao Paulo, Brazil
| | - Marlise I Klein
- Department of Oral Diagnosis, Piracicaba Dental School, State University of Campinas (UNICAMP), Sao Paulo, Brazil
| | - Lívia Araújo Alves
- Department of Oral Diagnosis, Piracicaba Dental School, State University of Campinas (UNICAMP), Sao Paulo, Brazil
- School of Dentistry, Cruzeiro do Sul University (UNICSUL), Sao Paulo, Brazil
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2
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Milly TA, Renshaw CP, Tal-Gan Y. Developing multispecies quorum-sensing modulators based on the Streptococcus mitis competence-stimulating peptide. J Biol Chem 2023; 299:105448. [PMID: 37951305 PMCID: PMC10714334 DOI: 10.1016/j.jbc.2023.105448] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2023] [Revised: 10/26/2023] [Accepted: 10/30/2023] [Indexed: 11/13/2023] Open
Abstract
Bacteria utilize quorum sensing (QS) to coordinate many group behaviors. As such, QS has attracted significant attention as a potential mean to attenuate bacterial infectivity without introducing selective pressure for resistance development. Streptococcus mitis, a human commensal, acts as a genetic diversity reservoir for Streptococcus pneumoniae, a prevalent human pathogen. S. mitis possesses a typical comABCDE competence regulon QS circuitry; however, the competence-stimulating peptide (CSP) responsible for QS activation and the regulatory role of the competence regulon QS circuitry in S. mitis are yet to be explored. We set out to delineate the competence regulon QS circuitry in S. mitis, including confirming the identity of the native CSP signal, evaluating the molecular mechanism that governs CSP interactions with histidine kinase receptor ComD leading to ComD activation, and defining the regulatory roles of the competence regulon QS circuitry in initiating various S. mitis phenotypes. Our analysis revealed important structure-activity relationship insights of the CSP signal and facilitated the development of novel CSP-based QS modulators. Our analysis also revealed the involvement of the competence regulon in modulating competence development and biofilm formation. Furthermore, our analysis revealed that the native S. mitis CSP signal can modulate QS response in S. pneumoniae. Capitalizing on this crosstalk, we developed a multispecies QS modulator that activates both the pneumococcus ComD receptors and the S. mitis ComD-2 receptor with high potencies. The novel scaffolds identified herein can be utilized to evaluate the effects temporal QS modulation has on S. mitis as it inhabits its natural niche.
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Affiliation(s)
- Tahmina A Milly
- Department of Chemistry, University of Nevada, Reno, Reno, Nevada, USA
| | - Clay P Renshaw
- Department of Chemistry, University of Nevada, Reno, Reno, Nevada, USA
| | - Yftah Tal-Gan
- Department of Chemistry, University of Nevada, Reno, Reno, Nevada, USA.
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3
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Brennan AA, Harrington A, Guo M, Renshaw CP, Tillett RL, Miura P, Tal-Gan Y. Investigating the Streptococcus sinensis competence regulon through a combination of transcriptome analysis and phenotypic evaluation. MICROBIOLOGY (READING, ENGLAND) 2022; 168. [PMID: 36282148 DOI: 10.1099/mic.0.001256] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
Streptococcus sinensis is a recently identified member of the Mitis group of streptococci. This species has been associated with infective endocarditis; however its mechanisms of pathogenesis and virulence are not fully understood. This study aimed to investigate the influence of the competence-stimulating peptide (CSP) and the competence regulon quorum-sensing circuitry (ComABCDE) on subsequent gene transcription and expression, as well as resultant phenotypes. In this study we confirmed the native CSP identity, ascertained when endogenous CSP was produced and completed a transcriptome-wide analysis of all genes following CSP exposure. RNA sequencing analysis revealed the upregulation of genes known to be associated with competence, biofilm formation and virulence. As such, a variety of phenotypic assays were utilized to assess the correlation between increased mRNA expression and potential phenotype response, ultimately gaining insight into the effects of CSP on both gene expression and developed phenotypes. The results indicated that the addition of exogenous CSP aided in competence development and successful transformation, yielding an average transformation efficiency comparable to that of other Mitis group streptococci. Additional studies are needed to further delineate the effects of CSP exposure on biofilm formation and virulence. Overall, this study provides novel information regarding S. sinensis and provides a substantial foundation on which this species and its role in disease pathogenesis can be further investigated.
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Affiliation(s)
- Alec A Brennan
- Department of Chemistry, University of Nevada, Reno, 1664 North Virginia Street, Reno, Nevada 89557, USA
| | - Anthony Harrington
- Department of Chemistry, University of Nevada, Reno, 1664 North Virginia Street, Reno, Nevada 89557, USA
| | - Mingzhe Guo
- Department of Chemistry, University of Nevada, Reno, 1664 North Virginia Street, Reno, Nevada 89557, USA
| | - Clay P Renshaw
- Department of Chemistry, University of Nevada, Reno, 1664 North Virginia Street, Reno, Nevada 89557, USA
| | - Richard L Tillett
- Nevada Center for Bioinformatics, University of Nevada, Reno, 1664 North Virginia Street, Reno, Nevada 89557, USA
| | - Pedro Miura
- Department of Biology, University of Nevada, Reno, 1664 North Virginia Street, Reno, Nevada 89557, USA
| | - Yftah Tal-Gan
- Department of Chemistry, University of Nevada, Reno, 1664 North Virginia Street, Reno, Nevada 89557, USA
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4
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Gil E, Noursadeghi M, Brown JS. Streptococcus pneumoniae interactions with the complement system. Front Cell Infect Microbiol 2022; 12:929483. [PMID: 35967850 PMCID: PMC9366601 DOI: 10.3389/fcimb.2022.929483] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2022] [Accepted: 07/08/2022] [Indexed: 11/21/2022] Open
Abstract
Host innate and adaptive immunity to infection with Streptococcus pneumoniae is critically dependent on the complement system, demonstrated by the high incidence of invasive S. pneumoniae infection in people with inherited deficiency of complement components. The complement system is activated by S. pneumoniae through multiple mechanisms. The classical complement pathway is activated by recognition of S. pneumoniae by C-reactive protein, serum amyloid P, C1q, SIGN-R1, or natural or acquired antibody. Some S. pneumoniae strains are also recognised by ficolins to activate the mannose binding lectin (MBL) activation pathway. Complement activation is then amplified by the alternative complement pathway, which can also be activated by S. pneumoniae directly. Complement activation results in covalent linkage of the opsonic complement factors C3b and iC3b to the S. pneumoniae surface which promote phagocytic clearance, along with complement-mediated immune adherence to erythrocytes, thereby protecting against septicaemia. The role of complement for mucosal immunity to S. pneumoniae is less clear. Given the major role of complement in controlling infection with S. pneumoniae, it is perhaps unsurprising that S. pneumoniae has evolved multiple mechanisms of complement evasion, including the capsule, multiple surface proteins, and the toxin pneumolysin. There is considerable variation between S. pneumoniae capsular serotypes and genotypes with regards to sensitivity to complement which correlates with ability to cause invasive infections. However, at present we only have a limited understanding of the main mechanisms causing variations in complement sensitivity between S. pneumoniae strains and to non-pathogenic streptococci.
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Affiliation(s)
- Eliza Gil
- Division of Infection and Immunity, University College London, London, United Kingdom
- *Correspondence: Eliza Gil,
| | - Mahdad Noursadeghi
- Division of Infection and Immunity, University College London, London, United Kingdom
| | - Jeremy S. Brown
- Division of Medicine, University College London, London, United Kingdom
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5
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Menghani SV, Cutcliffe MP, Sanchez-Rosario Y, Pok C, Watson A, Neubert MJ, Ochoa K, Wu HJJ, Johnson MDL. N, N-Dimethyldithiocarbamate Elicits Pneumococcal Hypersensitivity to Copper and Macrophage-Mediated Clearance. Infect Immun 2022; 90:e0059721. [PMID: 35311543 PMCID: PMC9022595 DOI: 10.1128/iai.00597-21] [Citation(s) in RCA: 1] [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: 11/02/2021] [Accepted: 02/12/2022] [Indexed: 12/26/2022] Open
Abstract
Streptococcus pneumoniae is a Gram-positive, encapsulated bacterium that is a significant cause of disease burden in pediatric and elderly populations. The rise in unencapsulated disease-causing strains and antimicrobial resistance in S. pneumoniae has increased the need for developing new antimicrobial strategies. Recent work by our laboratory has identified N,N-dimethyldithiocarbamate (DMDC) as a copper-dependent antimicrobial against bacterial, fungal, and parasitic pathogens. As a bactericidal antibiotic against S. pneumoniae, DMDC's ability to work as a copper-dependent antibiotic and its ability to work in vivo warranted further investigation. Here, our group studied the mechanisms of action of DMDC under various medium and excess-metal conditions and investigated DMDC's interactions with the innate immune system in vitro and in vivo. Of note, we found that DMDC plus copper significantly increased the internal copper concentration, hydrogen peroxide stress, nitric oxide stress, and the in vitro macrophage killing efficiency and decreased capsule. Furthermore, we found that in vivo DMDC treatment increased the quantity of innate immune cells in the lung during infection. Taken together, this study provides mechanistic insights regarding DMDC's activity as an antibiotic at the host-pathogen interface.
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Affiliation(s)
- Sanjay V. Menghani
- Department of Immunobiology, University of Arizona College of Medicine—Tucson, Tucson, Arizona, USA
- Medical Scientist Training M.D.-Ph.D. Program (MSTP), University of Arizona College of Medicine—Tucson, Tucson, Arizona, USA
| | - Madeline P. Cutcliffe
- Department of Immunobiology, University of Arizona College of Medicine—Tucson, Tucson, Arizona, USA
| | - Yamil Sanchez-Rosario
- Department of Immunobiology, University of Arizona College of Medicine—Tucson, Tucson, Arizona, USA
| | - Chansorena Pok
- Department of Immunobiology, University of Arizona College of Medicine—Tucson, Tucson, Arizona, USA
| | - Alison Watson
- Department of Immunobiology, University of Arizona College of Medicine—Tucson, Tucson, Arizona, USA
| | - Miranda J. Neubert
- Department of Immunobiology, University of Arizona College of Medicine—Tucson, Tucson, Arizona, USA
| | - Klariza Ochoa
- Department of Immunobiology, University of Arizona College of Medicine—Tucson, Tucson, Arizona, USA
| | - Hsin-Jung Joyce Wu
- Department of Immunobiology, University of Arizona College of Medicine—Tucson, Tucson, Arizona, USA
- Arizona Arthritis Center, University of Arizona College of Medicine—Tucson, Tucson, Arizona, USA
| | - Michael D. L. Johnson
- Department of Immunobiology, University of Arizona College of Medicine—Tucson, Tucson, Arizona, USA
- Valley Fever Center for Excellence, University of Arizona College of Medicine—Tucson, Tucson, Arizona, USA
- BIO5 Institute, University of Arizona College of Medicine—Tucson, Tucson, Arizona, USA
- Asthma and Airway Disease Research Center, University of Arizona College of Medicine—Tucson, Tucson, Arizona, USA
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6
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Hames RG, Jasiunaite Z, Wanford JJ, Carreno D, Chung WY, Dennison AR, Oggioni MR. Analyzing Macrophage Infection at the Organ Level. Methods Mol Biol 2021; 2414:405-431. [PMID: 34784049 DOI: 10.1007/978-1-0716-1900-1_22] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/11/2023]
Abstract
Classical in vivo infection models are oftentimes associated with speculation due to the many physiological factors that are unseen or not accounted for when analyzing experimental outputs, especially when solely utilizing the classic approach of tissue-derived colony-forming unit (CFU) enumeration. To better understand the steps and natural progression of bacterial infection, the pathophysiology of individual organs with which the bacteria interact in their natural course of infection must be considered. In this case, it is not only important to isolate organs as much as possible from additional physiological processes, but to also consider the dynamics of the bacteria at the cellular level within these organs of interest. Here, we describe in detail two models, ex vivo porcine liver and spleen coperfusion and a murine infection model, and the numerous associated experimental outputs produced by these models that can be taken and used together to investigate the pathogen-host interactions within tissues in depth.
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Affiliation(s)
- Ryan G Hames
- Department of Genetics and Genome Biology, University of Leicester, Leicester, UK
| | - Zydrune Jasiunaite
- Department of Genetics and Genome Biology, University of Leicester, Leicester, UK
| | - Joseph J Wanford
- Department of Genetics and Genome Biology, University of Leicester, Leicester, UK
| | - David Carreno
- Department of Genetics and Genome Biology, University of Leicester, Leicester, UK
| | - Wen Y Chung
- Department of Hepatobiliary and Pancreatic Surgery, University Hospitals of Leicester, Leicester, UK
| | - Ashley R Dennison
- Department of Hepatobiliary and Pancreatic Surgery, University Hospitals of Leicester, Leicester, UK
| | - Marco R Oggioni
- Department of Genetics and Genome Biology, University of Leicester, Leicester, UK. .,Department of Pharmacy and Biotechnology, University of Bologna, Bologna, Italy.
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7
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Marshall H, José RJ, Kilian M, Petersen FC, Brown JS. Effects of Expression of Streptococcus pneumoniae PspC on the Ability of Streptococcus mitis to Evade Complement-Mediated Immunity. Front Microbiol 2021; 12:773877. [PMID: 34880844 PMCID: PMC8646030 DOI: 10.3389/fmicb.2021.773877] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2021] [Accepted: 11/01/2021] [Indexed: 11/13/2022] Open
Abstract
Streptococcus pneumoniae and Streptococcus mitis are genetically closely related and both frequently colonise the naso-oropharynx, yet S. pneumoniae is a common cause of invasive infections whereas S. mitis is only weakly pathogenic. We hypothesise that sensitivity to innate immunity may underlie these differences in virulence phenotype. We compared the sensitivity of S. pneumoniae and S. mitis strains to complement-mediated immunity, demonstrating S. mitis strains were susceptible to complement-mediated opsonophagocytosis. S. pneumoniae resistance to complement is partially dependent on binding of the complement regulator Factor H by the surface protein PspC. However, S. mitis was unable to bind factor H. The S. pneumoniae TIGR4 strain pspC was expressed in the S. mitis SK142 strain to create a S. mitis pspC+ strain. Immunoblots demonstrated the S. mitis pspC+ strain expressed PspC, and flow cytometry confirmed this resulted in Factor H binding to S. mitis, reduced susceptibility to complement and improved survival in whole human blood compared to the wild-type S. mitis strain. However, in mouse models the S. mitis pspC+ strain remained unable to establish persistent infection. Unlike S. pneumoniae strains, culture in serum or blood did not support increased CFU of the S. mitis strains. These results suggest S. mitis is highly sensitive to opsonisation with complement partially due to an inability to bind Factor H, but even when complement sensitivity was reduced by expression of pspC, poor growth in physiological fluid limited the virulence of S. mitis in mice.
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Affiliation(s)
- Helina Marshall
- Centre for Inflammation and Tissue Repair, UCL Respiratory, Department of Medicine, Royal Free and University College Medical School, University College London, London, United Kingdom.,Wellcome-Wolfson Institute for Experimental Medicine, Queen's University Belfast, Belfast, United Kingdom
| | - Ricardo J José
- Centre for Inflammation and Tissue Repair, UCL Respiratory, Department of Medicine, Royal Free and University College Medical School, University College London, London, United Kingdom
| | - Mogens Kilian
- Department of Biomedicine, Faculty of Health, Aarhus University, Aarhus, Denmark
| | - Fernanda C Petersen
- Department of Oral Biology, Faculty of Dentistry, University of Oslo, Oslo, Norway
| | - Jeremy S Brown
- Centre for Inflammation and Tissue Repair, UCL Respiratory, Department of Medicine, Royal Free and University College Medical School, University College London, London, United Kingdom
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8
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Jakubovics NS, Goodman SD, Mashburn-Warren L, Stafford GP, Cieplik F. The dental plaque biofilm matrix. Periodontol 2000 2021; 86:32-56. [PMID: 33690911 PMCID: PMC9413593 DOI: 10.1111/prd.12361] [Citation(s) in RCA: 136] [Impact Index Per Article: 45.3] [Reference Citation Analysis] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Affiliation(s)
| | - Steven D Goodman
- Center for Microbial Pathogenesis, The Abigail Wexner Research Institute at Nationwide Children's Hospital, The Ohio State University College of Medicine, Columbus, Ohio, USA
| | - Lauren Mashburn-Warren
- Center for Microbial Pathogenesis, The Abigail Wexner Research Institute at Nationwide Children's Hospital, The Ohio State University College of Medicine, Columbus, Ohio, USA
| | - Graham P Stafford
- Integrated Biosciences, School of Clinical Dentistry, University of Sheffield, Sheffield, UK
| | - Fabian Cieplik
- Department of Conservative Dentistry and Periodontology, University Hospital Regensburg, Regensburg, Germany
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9
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Zhou K, Xiao T, David S, Wang Q, Zhou Y, Guo L, Aanensen D, Holt KE, Thomson NR, Grundmann H, Shen P, Xiao Y. Novel Subclone of Carbapenem-Resistant Klebsiella pneumoniae Sequence Type 11 with Enhanced Virulence and Transmissibility, China. Emerg Infect Dis 2021; 26:289-297. [PMID: 31961299 PMCID: PMC6986851 DOI: 10.3201/eid2602.190594] [Citation(s) in RCA: 110] [Impact Index Per Article: 36.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
We aimed to clarify the epidemiologic and clinical importance of evolutionary events that occurred in carbapenem-resistant Klebsiella pneumoniae (CRKP). We collected 203 CRKP causing bloodstream infections in a tertiary hospital in China during 2013-2017. We detected a subclonal shift in the dominant clone sequence type (ST) 11 CRKP in which the previously prevalent capsular loci (KL) 47 had been replaced by KL64 since 2016. Patients infected with ST11-KL64 CRKP had a significantly higher 30-day mortality rate than other CRKP-infected patients. Enhanced virulence was further evidenced by phenotypic tests. Phylogenetic reconstruction demonstrated that ST11-KL64 is derived from an ST11-KL47-like ancestor through recombination. We identified a pLVPK-like virulence plasmid carrying rmpA and peg-344 in ST11-KL64 exclusively from 2016 onward. The pLVPK-like-positive ST11-KL64 isolates exhibited enhanced environmental survival. Retrospective screening of a national collection identified ST11-KL64 in multiple regions. Targeted surveillance of this high-risk CRKP clone is urgently needed.
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10
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Marshall H, Aguayo S, Kilian M, Petersen F, Bozec L, Brown J. In Vivo Relationship between the Nano-Biomechanical Properties of Streptococcal Polysaccharide Capsules and Virulence Phenotype. ACS NANO 2020; 14:1070-1083. [PMID: 31854972 DOI: 10.1021/acsnano.9b08631] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
In common with many bacterial pathogens, Streptococcus pneumoniae has a polysaccharide capsule which facilitates immune evasion and determines virulence. Recent data have shown that the closely related Streptococcus mitis also expresses polysaccharide capsules including those with an identical chemical structure to S. pneumoniae capsular serotypes. We utilized atomic force microscopy (AFM) techniques to investigate the biophysical properties of S. mitis and S. pneumoniae strains expressing the same capsular serotypes that might relate to differences in virulence potential. When comparing S. mitis and S. pneumoniae strains with identical capsule serotypes, S. mitis strains were susceptible to neutrophil killing, and electron microscopy and AFM demonstrated significant morphological differences. Force-volume mapping using AFM showed distinct force-curve profiles for the center and edge areas of encapsulated streptococcal strains. This "edge effect" was not observed in unencapsulated bacteria and therefore was a direct representation of the mechanical properties of the bacterial capsule. When two strains of S. mitis and S. pneumoniae expressed an identical capsular serotype, they presented similar biomechanical characteristics. This infers a potential relationship between capsule biochemistry and nanomechanics, independent of bacterial strain. Overall, this study demonstrates that it is possible to investigate reproducibly the mechanistic, structural, and mechanical properties of both the capsule and the body of individual living bacterial cells and relate the data to virulence phenotypes. We have demonstrated that using nanomechanics to investigate individual bacterial cells we can now begin to identify the surface properties bacterial pathogens require to avoid host-mediated immunity.
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Affiliation(s)
- Helina Marshall
- Centre for Inflammation and Tissue Repair, Department of Medicine, Royal Free and University College Medical School , Rayne Institute , London WC1E 6JF , United Kingdom
- School of Biological Sciences , Queen's University Belfast , Belfast BT7 1NN , United Kingdom
| | - Sebastian Aguayo
- Biomaterials and Tissue Engineering, Eastman Dental Institute , University College London , London WC1E 6BT , United Kingdom
- School of Dentistry, Faculty of Medicine , Pontificia Universidad Catolica de Chile , Santiago , Chile
| | - Mogens Kilian
- Department of Biomedicine, Faculty of Health , Aarhus University , Aarhus 8000 , Denmark
| | - Fernanda Petersen
- Faculty of Dentistry, Institute of Oral Biology , University of Oslo , Oslo 0315 , Norway
| | - Laurent Bozec
- Biomaterials and Tissue Engineering, Eastman Dental Institute , University College London , London WC1E 6BT , United Kingdom
- Faculty of Dentistry , University of Toronto , Toronto , Ontario M5G 1G6 , Canada
| | - Jeremy Brown
- Centre for Inflammation and Tissue Repair, Department of Medicine, Royal Free and University College Medical School , Rayne Institute , London WC1E 6JF , United Kingdom
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11
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Harth-Chu EN, Alves LA, Theobaldo JD, Salomão MF, Höfling JF, King WF, Smith DJ, Mattos-Graner RO. PcsB Expression Diversity Influences on Streptococcus mitis Phenotypes Associated With Host Persistence and Virulence. Front Microbiol 2019; 10:2567. [PMID: 31798545 PMCID: PMC6861525 DOI: 10.3389/fmicb.2019.02567] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2019] [Accepted: 10/23/2019] [Indexed: 12/31/2022] Open
Abstract
S. mitis is an abundant member of the commensal microbiota of the oral cavity and pharynx, which has the potential to promote systemic infections. By analyzing a collection of S. mitis strains isolated from the oral cavity at commensal states or from systemic infections (blood strains), we established that S. mitis ubiquitously express the surface immunodominant protein, PcsB (also called GbpB), required for binding to sucrose-derived exopolysaccharides (EPS). Immuno dot blot assays with anti-PcsB antibodies and RT-qPCR transcription analyses revealed strain-specific profiles of PcsB production associated with diversity in pcsB transcriptional activities. Additionally, blood strains showed significantly higher levels of PcsB expression compared to commensal isolates. Because Streptococcus mutans co-colonizes S. mitis dental biofilms, and secretes glucosyltransferases (GtfB/C/D) for the synthesis of highly insoluble EPS from sucrose, profiles of S. mitis binding to EPS, biofilm formation and evasion of the complement system were assessed in sucrose-containing BHI medium supplemented or not with filter-sterilized S. mutans culture supernatants. These analyses showed significant S. mitis binding to EPS and biofilm formation in the presence of S. mutans supernatants supplemented with sucrose, compared to BHI or BHI-sucrose medium. In addition, these phenotypes were abolished if strains were grown in culture supernatants of a gtfBCD-defective S. mutans mutant. Importantly, GtfB/C/D-associated phenotypes were enhanced in high PcsB-expressing strains, compared to low PcsB producers. Increased PcsB expression was further correlated with increased resistance to deposition of C3b/iC3b of the complement system after exposure to human serum, when strains were previously grown in the presence of S. mutans supernatants. Finally, analyses of PcsB polymorphisms and bioinformatic prediction of epitopes with significant binding to MHC class II alleles revealed that blood isolates harbor PcsB polymorphisms in its functionally conserved CHAP-domain, suggesting antigenic variation. These findings reveal important roles of PcsB in S. mitis-host interactions under commensal and pathogenic states, highlighting the need for studies to elucidate mechanisms regulating PcsB expression in this species.
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Affiliation(s)
- Erika N Harth-Chu
- Department of Oral Diagnosis, Piracicaba Dental School, UNICAMP, Piracicaba, Brazil
| | - Lívia A Alves
- Department of Oral Diagnosis, Piracicaba Dental School, UNICAMP, Piracicaba, Brazil
| | - Jéssica D Theobaldo
- Department of Oral Diagnosis, Piracicaba Dental School, UNICAMP, Piracicaba, Brazil
| | - Mariana F Salomão
- Department of Oral Diagnosis, Piracicaba Dental School, UNICAMP, Piracicaba, Brazil
| | - José F Höfling
- Department of Oral Diagnosis, Piracicaba Dental School, UNICAMP, Piracicaba, Brazil
| | - William F King
- Department of Immunology and Infectious Disease, The Forsyth Institute, Cambridge, MA, United States
| | - Daniel J Smith
- Department of Immunology and Infectious Disease, The Forsyth Institute, Cambridge, MA, United States
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12
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Periselneris J, Ercoli G, Pollard T, Chimalapati S, Camberlein E, Szylar G, Hyams C, Tomlinson G, Petersen FC, Floto RA, Noursadeghi M, Brown JS. Relative Contributions of Extracellular and Internalized Bacteria to Early Macrophage Proinflammatory Responses to Streptococcus pneumoniae. mBio 2019; 10:e02144-19. [PMID: 31551336 PMCID: PMC6759765 DOI: 10.1128/mbio.02144-19] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2019] [Accepted: 08/15/2019] [Indexed: 02/06/2023] Open
Abstract
Both intracellular immune sensing and extracellular innate immune sensing have been implicated in initiating macrophage proinflammatory cytokine responses to Streptococcus pneumoniae The S. pneumoniae capsule, a major virulence determinant, prevents phagocytosis, and we hypothesized that this would reduce activation of host innate inflammatory responses by preventing activation of intracellular proinflammatory signaling pathways. We investigated this hypothesis in human monocyte-derived macrophages stimulated with encapsulated or isogenic unencapsulated mutant S. pneumoniae Unexpectedly, despite strongly inhibiting bacterial internalization, the capsule resulted in enhanced inflammatory cytokine production by macrophages infected with S. pneumoniae Experiments using purified capsule material and a Streptococcus mitis mutant expressing an S. pneumoniae serotype 4 capsule indicated these differences required whole bacteria and were not due to proinflammatory effects of the capsule itself. Transcriptional profiling demonstrated relatively few differences in macrophage gene expression profiles between infections with encapsulated S. pneumoniae and those with unencapsulated S. pneumoniae, largely limited to reduced expression of proinflammatory genes in response to unencapsulated bacteria, predicted to be due to reduced activation of the NF-κB family of transcription factors. Blocking S. pneumoniae internalization using cytochalasin D had minimal effects on the inflammatory response to S. pneumoniae Experiments using murine macrophages indicated that the affected genes were dependent on Toll-like receptor 2 (TLR2) activation, although not through direct stimulation of TLR2 by capsule polysaccharide. Our data demonstrate that the early macrophage proinflammatory response to S. pneumoniae is mainly dependent on extracellular bacteria and reveal an unexpected proinflammatory effect of encapsulated S. pneumoniae that could contribute to disease pathogenesis.IMPORTANCE Multiple extra- and intracellular innate immune receptors have been identified that recognize Streptococcus pneumoniae, but the relative contributions of intra- versus extracellular bacteria to the inflammatory response were unknown. We have shown that intracellular S. pneumoniae contributes surprisingly little to the inflammatory responses, with production of important proinflammatory cytokines largely dependent on extracellular bacteria. Furthermore, although we expected the S. pneumoniae polysaccharide capsule to block activation of the host immune system by reducing bacterial internalization and therefore activation of intracellular innate immune receptors, there was an increased inflammatory response to encapsulated compared to unencapsulated bacteria, which is likely to contribute to disease pathogenesis.
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Affiliation(s)
- Jimstan Periselneris
- Centre for Inflammation and Tissue Repair, UCL Respiratory, Division of Medicine, University College Medical School, Rayne Institute, London, United Kingdom
| | - Giuseppe Ercoli
- Centre for Inflammation and Tissue Repair, UCL Respiratory, Division of Medicine, University College Medical School, Rayne Institute, London, United Kingdom
| | - Tracey Pollard
- Centre for Inflammation and Tissue Repair, UCL Respiratory, Division of Medicine, University College Medical School, Rayne Institute, London, United Kingdom
| | - Suneeta Chimalapati
- Centre for Inflammation and Tissue Repair, UCL Respiratory, Division of Medicine, University College Medical School, Rayne Institute, London, United Kingdom
| | - Emilie Camberlein
- Centre for Inflammation and Tissue Repair, UCL Respiratory, Division of Medicine, University College Medical School, Rayne Institute, London, United Kingdom
| | - Gabriella Szylar
- Centre for Inflammation and Tissue Repair, UCL Respiratory, Division of Medicine, University College Medical School, Rayne Institute, London, United Kingdom
| | - Catherine Hyams
- Centre for Inflammation and Tissue Repair, UCL Respiratory, Division of Medicine, University College Medical School, Rayne Institute, London, United Kingdom
| | - Gillian Tomlinson
- Division of Infection and Immunity, University College London, London, United Kingdom
| | - Fernanda C Petersen
- Department of Oral Biology, Faculty of Dentistry, University of Oslo, Oslo, Norway
| | - R Andres Floto
- Molecular Immunity Unit, Department of Medicine, University of Cambridge, MRC Laboratory of Molecular Biology, Cambridge, United Kingdom
| | - Mahdad Noursadeghi
- Division of Infection and Immunity, University College London, London, United Kingdom
| | - Jeremy S Brown
- Centre for Inflammation and Tissue Repair, UCL Respiratory, Division of Medicine, University College Medical School, Rayne Institute, London, United Kingdom
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13
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Alves LA, de Carli TR, Harth-Chu EN, Mariano FS, Höfling JF, Stipp RN, Mattos-Graner RO. Oral streptococci show diversity in resistance to complement immunity. J Med Microbiol 2019; 68:600-608. [PMID: 30843785 DOI: 10.1099/jmm.0.000955] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
PURPOSE Mechanisms underlying systemic infections by oral species of Mitis (Streptococcus mitis, Streptococcus oralis) and Sanguinis (Streptococcus gordonii, Streptococcus sanguinis) commensal streptococci are poorly understood. This study investigates profiles of susceptibility to complement-mediated host immunity in representative strains of these four species, which were isolated from oral sites or from the bloodstream. METHODOLOGY Deposition of complement opsonins (C3b/iC3b), and surface binding to C-reactive protein (CRP) and to IgG antibodies were quantified by flow cytometry in 34 strains treated with human serum (HS), and compared to rates of opsonophagocytosis by human PMN mediated by complement (CR1/3) and/or IgG Fc (FcγRII/III) receptors. RESULTS S. sanguinis strains showed reduced susceptibility to complement opsonization and low binding to CRP and to IgG compared to other species. Surface levels of C3b/iC3b in S. sanguinis strains were 4.5- and 7.8-fold lower than that observed in S. gordonii and Mitis strains, respectively. Diversity in C3b/iC3b deposition was evident among Mitis species, in which C3b/iC3b deposition was significantly associated with CR/FcγR-dependent opsonophagocytosis by PMN (P<0.05). Importantly, S. gordonii and Mitis group strains isolated from systemic infections showed resistance to complement opsonization when compared to oral isolates of the respective species (P<0.05). CONCLUSIONS This study establishes species-specific profiles of susceptibility to complement immunity in Mitis and Sanguinis streptococci, and indicates that strains associated with systemic infections have increased capacity to evade complement immunity. These findings highlight the need for studies identifying molecular functions involved in complement evasion in oral streptococci.
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Affiliation(s)
- Lívia A Alves
- Department of Oral Diagnosis, Piracicaba Dental School - State University of Campinas, Piracicaba, SP, Brazil
| | - Thaís R de Carli
- Department of Oral Diagnosis, Piracicaba Dental School - State University of Campinas, Piracicaba, SP, Brazil
| | - Erika N Harth-Chu
- Department of Oral Diagnosis, Piracicaba Dental School - State University of Campinas, Piracicaba, SP, Brazil
| | - Flávia S Mariano
- Department of Oral Diagnosis, Piracicaba Dental School - State University of Campinas, Piracicaba, SP, Brazil
| | - José F Höfling
- Department of Oral Diagnosis, Piracicaba Dental School - State University of Campinas, Piracicaba, SP, Brazil
| | - Rafael N Stipp
- Department of Oral Diagnosis, Piracicaba Dental School - State University of Campinas, Piracicaba, SP, Brazil
| | - Renata O Mattos-Graner
- Department of Oral Diagnosis, Piracicaba Dental School - State University of Campinas, Piracicaba, SP, Brazil
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14
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Intranasal Immunization with the Commensal Streptococcus mitis Confers Protective Immunity against Pneumococcal Lung Infection. Appl Environ Microbiol 2019; 85:AEM.02235-18. [PMID: 30683742 DOI: 10.1128/aem.02235-18] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2018] [Accepted: 01/02/2019] [Indexed: 02/04/2023] Open
Abstract
Streptococcus pneumoniae is a bacterial pathogen that causes various diseases of public health concern worldwide. Current pneumococcal vaccines target the capsular polysaccharide surrounding the cells. However, only up to 13 of more than 90 pneumococcal capsular serotypes are represented in the current conjugate vaccines. In this study, we used two experimental approaches to evaluate the potential of Streptococcus mitis, a commensal that exhibits immune cross-reactivity with S. pneumoniae, to confer protective immunity to S. pneumoniae lung infection in mice. First, we assessed the immune response and protective effect of wild-type S. mitis against lung infection by S. pneumoniae strains D39 (serotype 2) and TIGR4 (serotype 4). Second, we examined the ability of an S. mitis mutant expressing the S. pneumoniae type 4 capsule (S. mitis TIGR4cps) to elicit focused protection against S. pneumoniae TIGR4. Our results showed that intranasal immunization of mice with S. mitis produced significantly higher levels of serum IgG and IgA antibodies reactive to both S. mitis and S. pneumoniae, as well as enhanced production of interleukin 17A (IL-17A), but not gamma interferon (IFN-γ) and IL-4, compared with control mice. The immunization resulted in a reduced bacterial load in respiratory tissues following lung infection with S. pneumoniae TIGR4 or D39 compared with control mice. With S. mitis TIGR4cps, protection upon challenge with S. pneumoniae TIGR4 was superior. Thus, these findings show the potential of S. mitis to elicit natural serotype-independent protection against two pneumococcal serotypes and to provide the benefits of the well-recognized protective effect of capsule-targeting vaccines.IMPORTANCE Streptococcus pneumoniae causes various diseases worldwide. Current pneumococcal vaccines protect against a limited number of more than 90 pneumococcal serotypes, accentuating the urgent need to develop novel prophylactic strategies. S. pneumoniae and the commensal Streptococcus mitis share immunogenic characteristics that make S. mitis an attractive vaccine candidate against S. pneumoniae In this study, we evaluated the potential of S. mitis and its mutant expressing pneumococcal capsule type 4 (S. mitis TIGR4cps) to induce protection against S. pneumoniae lung infection in mice. Our findings show that intranasal vaccination with S. mitis protects against S. pneumoniae strains D39 (serotype 2) and TIGR4 (serotype 4) in a serotype-independent fashion, which is associated with enhanced antibody and T cell responses. Furthermore, S. mitis TIGR4cps conferred additional protection against S. pneumoniae TIGR4, but not against D39. The findings highlight the potential of S. mitis to generate protection that combines both serotype-independent and serotype-specific responses.
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15
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Streptococcus mitis Expressing Pneumococcal Serotype 1 Capsule. Sci Rep 2018; 8:17959. [PMID: 30568178 PMCID: PMC6299277 DOI: 10.1038/s41598-018-35921-3] [Citation(s) in RCA: 30] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2018] [Accepted: 11/08/2018] [Indexed: 01/22/2023] Open
Abstract
Streptococcus pneumoniae's polysaccharide capsule is an important virulence factor; vaccine-induced immunity to specific capsular polysaccharide effectively prevents disease. Serotype 1 S. pneumoniae is rarely found in healthy persons, but is highly invasive and a common cause of meningitis outbreaks and invasive disease outside of the United States. Here we show that genes for polysaccharide capsule similar to those expressed by pneumococci were commonly detected by polymerase chain reaction among upper respiratory tract samples from older US adults not carrying pneumococci. Serotype 1-specific genes were predominantly detected. In five oropharyngeal samples tested, serotype 1 gene belonging to S. mitis expressed capsules immunologically indistinct from pneumococcal capsules. Whole genome sequencing revealed three distinct S. mitis clones, each representing a cps1 operon highly similar to the pneumococcal cps1 reference operon. These findings raise important questions about the contribution of commensal streptococci to natural immunity against pneumococci, a leading cause of mortality worldwide.
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16
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A recombinant conjugated pneumococcal vaccine that protects against murine infections with a similar efficacy to Prevnar-13. NPJ Vaccines 2018; 3:53. [PMID: 30393571 PMCID: PMC6208403 DOI: 10.1038/s41541-018-0090-4] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2018] [Accepted: 10/08/2018] [Indexed: 11/09/2022] Open
Abstract
The pneumococcal conjugate vaccine (PCV) strongly protects against vaccine serotypes, but the rapid expansion of non-vaccine serotype disease and the vaccine's high expense has reduced its overall impact. We have developed Protein Glycan Coupling Technology (PGCT) as a flexible methodology for making low-cost polysaccharide/protein glycoconjugates recombinantly in Escherichia coli. We have used PGCT to make a recombinant PCV containing serotype 4 capsular polysaccharide linked to the Streptococcus pneumoniae proteins NanA, PiuA, and Sp0148. The introduction of the Campylobacter jejuni UDP-glucose 4-epimerase gene GalE (gne) into E. coli improved the yield of the resulting glycoprotein. PGCT glycoconjugate vaccination generated strong antibody responses in mice to both the capsule and the carrier protein antigens, with the PiuA/capsule glycoconjugate inducing similar anti-capsular antibody responses as the commercial PCV Prevnar-13. Antibody responses to PGCT glycoconjugates opsonised S. pneumoniae and Streptococcus mitis expressing the serotype 4 capsule and promoted neutrophil phagocytosis of S. pneumoniae to a similar level as antisera generated by vaccination with Prevnar-13. Vaccination with the PGCT glycoconjugates protected mice against meningitis and septicaemia with the same efficacy as vaccination with Prevnar-13. In addition, vaccination with the protein antigen components from PGCT glycoconjugates alone provided partial protection against septicaemia and colonisation. These data demonstrate that a vaccine made by PGCT is as effective as Prevnar-13, identifies PiuA as a carrier protein for glycoconjugate vaccines, and demonstrates that linking capsular antigen to S. pneumoniae protein antigens has additional protective benefits that could provide a degree of serotype-independent immunity.
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17
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Wyllie AL, Pannekoek Y, Bovenkerk S, van Engelsdorp Gastelaars J, Ferwerda B, van de Beek D, Sanders EAM, Trzciński K, van der Ende A. Sequencing of the variable region of rpsB to discriminate between Streptococcus pneumoniae and other streptococcal species. Open Biol 2018; 7:rsob.170074. [PMID: 28931649 PMCID: PMC5627049 DOI: 10.1098/rsob.170074] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2017] [Accepted: 08/11/2017] [Indexed: 01/08/2023] Open
Abstract
The vast majority of streptococci colonizing the human upper respiratory tract are commensals, only sporadically implicated in disease. Of these, the most pathogenic is Mitis group member, Streptococcus pneumoniae Phenotypic and genetic similarities between streptococci can cause difficulties in species identification. Using ribosomal S2-gene sequences extracted from whole-genome sequences published from 501 streptococci, we developed a method to identify streptococcal species. We validated this method on non-pneumococcal isolates cultured from cases of severe streptococcal disease (n = 101) and from carriage (n = 103), and on non-typeable pneumococci from asymptomatic individuals (n = 17) and on whole-genome sequences of 1157 pneumococcal isolates from meningitis in the Netherlands. Following this, we tested 221 streptococcal isolates in molecular assays originally assumed specific for S. pneumoniae, targeting cpsA, lytA, piaB, ply, Spn9802, zmpC and capsule-type-specific genes. Cluster analysis of S2-sequences showed grouping according to species in line with published phylogenies of streptococcal core genomes. S2-typing convincingly distinguished pneumococci from non-pneumococcal species (99.2% sensitivity, 100% specificity). Molecular assays targeting regions of lytA and piaB were 100% specific for S. pneumoniae, whereas assays targeting cpsA, ply, Spn9802, zmpC and selected serotype-specific assays (but not capsular sequence typing) showed a lack of specificity. False positive results were over-represented in species associated with carriage, although no particular confounding signal was unique for carriage isolates.
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Affiliation(s)
- Anne L Wyllie
- Department of Paediatric Immunology and Infectious Diseases, Wilhelmina Children's Hospital, University Medical Center Utrecht, Utrecht, the Netherlands
| | - Yvonne Pannekoek
- Department of Medical Microbiology, Academic Medical Center, Amsterdam, the Netherlands
| | - Sandra Bovenkerk
- Department of Medical Microbiology, Academic Medical Center, Amsterdam, the Netherlands
| | - Jody van Engelsdorp Gastelaars
- Department of Paediatric Immunology and Infectious Diseases, Wilhelmina Children's Hospital, University Medical Center Utrecht, Utrecht, the Netherlands
| | - Bart Ferwerda
- Department of Neurology, Academic Medical Center, Amsterdam Neuroscience, Amsterdam, the Netherlands
| | - Diederik van de Beek
- Department of Neurology, Academic Medical Center, Amsterdam Neuroscience, Amsterdam, the Netherlands
| | - Elisabeth A M Sanders
- Department of Paediatric Immunology and Infectious Diseases, Wilhelmina Children's Hospital, University Medical Center Utrecht, Utrecht, the Netherlands.,Centre for Infectious Disease Control, National Institute for Public Health and the Environment (RIVM), Bilthoven, the Netherlands
| | - Krzysztof Trzciński
- Department of Paediatric Immunology and Infectious Diseases, Wilhelmina Children's Hospital, University Medical Center Utrecht, Utrecht, the Netherlands
| | - Arie van der Ende
- Department of Medical Microbiology, Academic Medical Center, Amsterdam, the Netherlands.,The Netherlands Reference Laboratory for Bacterial Meningitis, Academic Medical Center, Amsterdam, the Netherlands
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18
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Di Giulio M, Di Valerio V, Bosco D, Marsich E, Cataldi A, Cellini L, Sancilio S. Molecular mechanisms driving Streptococcus mitis entry into human gingival fibroblasts in presence of chitlac-nAg and saliva. JOURNAL OF MATERIALS SCIENCE. MATERIALS IN MEDICINE 2018; 29:36. [PMID: 29556803 DOI: 10.1007/s10856-018-6040-x] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/21/2017] [Accepted: 03/05/2018] [Indexed: 06/08/2023]
Abstract
The molecular mechanisms leading to Streptococcus mitis capability of entering oral cells were investigated in a co-culture of S. mitis and Human Gingival Fibroblasts (HGFs) in the presence of saliva. An innovative colloidal solution based on silver nanoparticles (Chitlac-nAg), a promising device for daily oral care, was added to the experimental system in order to study the effects of silver on the bacterial overgrowth and ability to enter non-phagocytic eukaryotic cells. The entry of bacteria into the eukaryotic cells is mediated by a signalling pathway involving FAK, integrin β1, and the two cytoskeleton proteins vinculin and F-actin, and down-regulated by the presence of saliva both at 3 and 48 h of culture, whereas Chitlac-n Ag exposure seems to influence, by incrementing it, the number of bacteria entering the fibroblasts only at 48 h. The formation of fibrillary extrusion from HGFs and the co-localization of bacteria and silver nanoparticles within the fibroblast vacuoles were also recorded. After longer experimental times (72 and 96 h), the number of S. mitis chains inside gingival cells is reduced, mainly in presence of saliva. The results suggest an escape of bacteria from fibroblasts to restore the microbial balance of the oral cavity.
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Affiliation(s)
- M Di Giulio
- Department of Pharmacy, G. d'Annunzio" University, Chieti-Pescara, Italy
| | - V Di Valerio
- Department of Medicine and Ageing Sciences, "G. d'Annunzio" University, Chieti-Pescara, Italy
| | - D Bosco
- Genetic Molecular Institute of CNR, Unit of Chieti, "G. d'Annunzio" University, Chieti-Pescara, Italy
| | - E Marsich
- Department of Medical, Surgical and Health Sciences, University of Trieste, Trieste, Italy
| | - A Cataldi
- Department of Pharmacy, G. d'Annunzio" University, Chieti-Pescara, Italy
| | - L Cellini
- Department of Pharmacy, G. d'Annunzio" University, Chieti-Pescara, Italy
| | - S Sancilio
- Department of Pharmacy, G. d'Annunzio" University, Chieti-Pescara, Italy.
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19
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Engen SA, Schreurs O, Petersen F, Blix IJS, Baekkevold ES, Schenck K. The Regulatory Role of the Oral Commensal Streptococcus mitis on Human Monocytes. Scand J Immunol 2017; 87:80-87. [PMID: 29194752 DOI: 10.1111/sji.12636] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2017] [Accepted: 11/25/2017] [Indexed: 01/15/2023]
Abstract
Streptococcus mitis colonizes all niches of the human oral cavity from early infancy and throughout life. Monocytes patrol blood vessels, lymphoid and non-lymphoid tissues and migrate into infected tissue where they participate in the inflammatory cascade and immune regulation. Here, we studied the effect of S. mitis on monocytes. Transcriptome analysis of monocytes exposed to S. mitis (SmMo) revealed increased transcription of chemotactic factors (CCL2, CCL3, CCL20, CXCL1, CXCL2) and cytokines (IL1A, IL1B, IL6, IL23, IL36G, TNF), indicating that S. mitis may trigger recruitment of leucocytes and initiate inflammation. Increased transcription in SmMo of IL1B, IL6 and IL23 indicated that S. mitis may participate in the induction of Th17 responses and agreed with our earlier findings of S. mitis-mediated memory Th17 reactivity. Furthermore, S. mitis inhibited tetanus toxoid-specific CD4 T cell proliferation. This can be due to the increased secretion of IL-10 and expression of PD-L1 that was observed in SmMo. PGE2 can modulate IL-10 and PD-L1 expression, concomitant with that of CCR7, IL-12 and IL-23 that also were changed. This, along with increased SmMo transcription of PTGS2 (COX2) and PTGER4 (EP4), pointed to a role of PGE2. Measurement of PGE2 secretion by SmMo showed indeed a marked increase, and chemical inhibition of PGE2 production lowered the PD-L1 expression on SmMo. In conclusion, our findings show that S. mitis may trigger immune modulation by recruiting immune cells to the site of infection, while at the same time dampening the severity of the response through expression of IL-10, PGE2 and PD-L1.
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Affiliation(s)
- S A Engen
- Department of Oral Biology, Faculty of Dentistry, University of Oslo, Oslo, Norway
| | - O Schreurs
- Department of Oral Biology, Faculty of Dentistry, University of Oslo, Oslo, Norway
| | - F Petersen
- Department of Oral Biology, Faculty of Dentistry, University of Oslo, Oslo, Norway
| | - I J S Blix
- Department of Oral Biology, Faculty of Dentistry, University of Oslo, Oslo, Norway.,Department of Periodontology, Faculty of Dentistry, University of Oslo, Oslo, Norway
| | - E S Baekkevold
- Department of Oral Biology, Faculty of Dentistry, University of Oslo, Oslo, Norway.,Department of Pathology, Centre for Immune Regulation, University of Oslo and Oslo University Hospital - Rikshospitalet, Oslo, Norway
| | - K Schenck
- Department of Oral Biology, Faculty of Dentistry, University of Oslo, Oslo, Norway
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20
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A Quorum-Sensing System That Regulates Streptococcus pneumoniae Biofilm Formation and Surface Polysaccharide Production. mSphere 2017; 2:mSphere00324-17. [PMID: 28932816 PMCID: PMC5597970 DOI: 10.1128/msphere.00324-17] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2017] [Accepted: 07/31/2017] [Indexed: 12/13/2022] Open
Abstract
Quorum sensing regulates bacterial social behaviors by production, secretion, and sensing of pheromones. In this study, we characterized a new quorum-sensing system of the Rgg/SHP class in S. pneumoniae D39. The system was found to directly induce the expression of a single gene cluster comprising the gene for the SHP pheromone and genes with putative functions in capsule synthesis. Capsule size, as measured by dextran exclusion, was increased by SHP exposure in R36A, an unencapsulated derivative of D39. In the encapsulated parent strain, overexpression of the gene cluster increased capsule size, supporting the role of Rgg/SHP in the synthesis of surface polysaccharides. Further, we found that biofilm formation on epithelial cells was reduced by overexpression of the system and increased in a mutant with an rgg deletion. Placing surface polysaccharide expression under quorum-sensing regulation may enable S. pneumoniae to tune interactions with the host and other bacteria in accordance with environmental and cell density conditions. Despite vaccines, Streptococcus pneumoniae kills more than a million people yearly. Thus, understanding how pneumococci transition from commensals to pathogens is particularly relevant. Quorum sensing regulates collective behaviors and thus represents a potential driver of commensal-to-pathogen transitions. Rgg/small hydrophobic peptide (SHP) quorum-sensing systems are widespread in streptococci, yet they remain largely uncharacterized in S. pneumoniae. Using directional transcriptome sequencing, we show that the S. pneumoniae D39 Rgg0939/SHP system induces the transcription of a single gene cluster including shp and capsule gene homologs. Capsule size measurements determined by fluorescein isothiocyanate-dextran exclusion allowed assignment of the system to the regulation of surface polysaccharide expression. We found that the SHP pheromone induced exopolysaccharide expression in R36A, an unencapsulated derivative of D39. In the encapsulated parent strain, overexpression of the Rgg system resulted in a mutant with increased capsule size. In line with previous studies showing that capsule expression is inversely associated with biofilm formation, we found that biofilm formed on lung epithelial cells was decreased in the overexpression strain and increased in an rgg deletion mutant. Although no significant differences were observed between D39 and the rgg deletion mutant in a mouse model of lung infection, in competitive assays, overexpression reduced fitness. This is the first study to reveal a quorum-sensing system in streptococci that regulates exopolysaccharide synthesis from a site distinct from the original capsule locus. IMPORTANCE Quorum sensing regulates bacterial social behaviors by production, secretion, and sensing of pheromones. In this study, we characterized a new quorum-sensing system of the Rgg/SHP class in S. pneumoniae D39. The system was found to directly induce the expression of a single gene cluster comprising the gene for the SHP pheromone and genes with putative functions in capsule synthesis. Capsule size, as measured by dextran exclusion, was increased by SHP exposure in R36A, an unencapsulated derivative of D39. In the encapsulated parent strain, overexpression of the gene cluster increased capsule size, supporting the role of Rgg/SHP in the synthesis of surface polysaccharides. Further, we found that biofilm formation on epithelial cells was reduced by overexpression of the system and increased in a mutant with an rgg deletion. Placing surface polysaccharide expression under quorum-sensing regulation may enable S. pneumoniae to tune interactions with the host and other bacteria in accordance with environmental and cell density conditions.
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21
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Rasmussen LH, Højholt K, Dargis R, Christensen JJ, Skovgaard O, Justesen US, Rosenvinge FS, Moser C, Lukjancenko O, Rasmussen S, Nielsen XC. In silico assessment of virulence factors in strains of Streptococcus oralis and Streptococcus mitis isolated from patients with Infective Endocarditis. J Med Microbiol 2017; 66:1316-1323. [PMID: 28874232 DOI: 10.1099/jmm.0.000573] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
Abstract
Purpose. Streptococcus oralis and Streptococcus mitis belong to the Mitis group, which are mostly commensals in the human oral cavity. Even though S. oralis and S. mitis are oral commensals, they can be opportunistic pathogens causing infective endocarditis. A recent taxonomic re-evaluation of the Mitis group has embedded the species Streptococcus tigurinus and Streptococcus dentisani into the species S. oralis as subspecies. In this study, the distribution of virulence factors that contribute to bacterial immune evasion, colonization and adhesion was assessed in clinical strains of S. oralis (subsp. oralis, subsp. tigurinus and subsp. dentisani) and S. mitis. Methodology. Forty clinical S. oralis (subsp. oralis, subsp. dentisani and subsp. tigurinus) and S. mitis genomes were annotated with the pipeline PanFunPro and aligned against the VFDB database for assessment of virulence factors.Results/Key findings. Three homologues of pavA, psaA and lmb, encoding adhesion proteins, were present in all strains. Seven homologues of nanA, nanB, ply, lytA, lytB, lytC and iga, of importance regarding survival in blood and modulation of the human immune system, were variously present in the genomes. Few S. oralis subspecies specific differences were observed. iga homologues were identified in S. oralis subsp. oralis, whereas lytA homologues were identified in S. oralis subsp. oralis and subsp. tigurinus. Conclusion. Differences in the presence of virulence factors among the three S. oralis subspecies were observed. The virulence gene profiles of the 40 S. mitis and S. oralis (subsp. oralis, subsp. dentisani and subsp. tigurinus) contribute with important new knowledge regarding these species and new subspecies.
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Affiliation(s)
- Louise H Rasmussen
- Department of Clinical Microbiology, Slagelse Hospital, Ingemannsvej 46, 4200 Slagelse, Denmark.,Department of Science and Environment, Roskilde University, Universitetsvej 1, 4000 Roskilde, Denmark
| | - Katrine Højholt
- Department of Clinical Microbiology, Slagelse Hospital, Ingemannsvej 46, 4200 Slagelse, Denmark.,Center for Biological Sequence Analysis, Department of Systems Biology, Technical University of Denmark, Kemitorvet, Building 208, 2800 Kgs Lyngby, Denmark
| | - Rimtas Dargis
- Department of Clinical Microbiology, Slagelse Hospital, Ingemannsvej 46, 4200 Slagelse, Denmark
| | - Jens Jørgen Christensen
- Department of Clinical Microbiology, Slagelse Hospital, Ingemannsvej 46, 4200 Slagelse, Denmark.,Department of Clinical Medicine, University of Copenhagen, Blegdamsvej 3B, 2200 Copenhagen N, Denmark
| | - Ole Skovgaard
- Department of Science and Environment, Roskilde University, Universitetsvej 1, 4000 Roskilde, Denmark
| | - Ulrik S Justesen
- Department of Clinical Microbiology, Odense University Hospital, J. B. Winsløws Vej 21, 2, 5000 Odense C, Denmark.,Department of Clinical Microbiology, Rigshospitalet, University Hospital of Copenhagen, Blegdamsvej 9, 2100 Copenhagen Ø, Denmark
| | - Flemming S Rosenvinge
- Department of Clinical Microbiology, Vejle Hospital, Kabbeltoft 25, 7100 Vejle, Denmark
| | - Claus Moser
- Department of Clinical Microbiology, Rigshospitalet, University Hospital of Copenhagen, Blegdamsvej 9, 2100 Copenhagen Ø, Denmark
| | - Oksana Lukjancenko
- National Food Institute, Technical University of Denmark, Søltofts plads, Building 221, 2800 Kgs Lyngby, Denmark
| | - Simon Rasmussen
- Center for Biological Sequence Analysis, Department of Systems Biology, Technical University of Denmark, Kemitorvet, Building 208, 2800 Kgs Lyngby, Denmark
| | - Xiaohui C Nielsen
- Department of Clinical Microbiology, Slagelse Hospital, Ingemannsvej 46, 4200 Slagelse, Denmark
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Naturally Acquired Human Immunity to Pneumococcus Is Dependent on Antibody to Protein Antigens. PLoS Pathog 2017; 13:e1006137. [PMID: 28135322 PMCID: PMC5279798 DOI: 10.1371/journal.ppat.1006137] [Citation(s) in RCA: 66] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2016] [Accepted: 12/17/2016] [Indexed: 12/31/2022] Open
Abstract
Naturally acquired immunity against invasive pneumococcal disease (IPD) is thought to be dependent on anti-capsular antibody. However nasopharyngeal colonisation by Streptococcus pneumoniae also induces antibody to protein antigens that could be protective. We have used human intravenous immunoglobulin preparation (IVIG), representing natural IgG responses to S. pneumoniae, to identify the classes of antigens that are functionally relevant for immunity to IPD. IgG in IVIG recognised capsular antigen and multiple S. pneumoniae protein antigens, with highly conserved patterns between different geographical sources of pooled human IgG. Incubation of S. pneumoniae in IVIG resulted in IgG binding to the bacteria, formation of bacterial aggregates, and enhanced phagocytosis even for unencapsulated S. pneumoniae strains, demonstrating the capsule was unlikely to be the dominant protective antigen. IgG binding to S. pneumoniae incubated in IVIG was reduced after partial chemical or genetic removal of bacterial surface proteins, and increased against a Streptococcus mitis strain expressing the S. pneumoniae protein PspC. In contrast, depletion of type-specific capsular antibody from IVIG did not affect IgG binding, opsonophagocytosis, or protection by passive vaccination against IPD in murine models. These results demonstrate that naturally acquired protection against IPD largely depends on antibody to protein antigens rather than the capsule. Streptococcus pneumoniae is a major global killer. Invasive pneumococcal disease (IPD) is the most severe form of infection. Surprisingly, the natural mechanisms of immunity to IPD in healthy individuals are unclear. The success of vaccines stimulating anti-capsular antibodies have led to the belief that the same mechanism lies behind natural protection. Using studies with pooled human immunoglobulin, we demonstrate that this is not the case and instead IgG recognising the bacterial surface proteins appears to have the dominant functional role. This finding supports efforts towards protein antigen-based vaccines, and opens the possibility of stratifying potential risk for individuals of IPD.
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Capsular Polysaccharide Expression in Commensal Streptococcus Species: Genetic and Antigenic Similarities to Streptococcus pneumoniae. mBio 2016; 7:mBio.01844-16. [PMID: 27935839 PMCID: PMC5111408 DOI: 10.1128/mbio.01844-16] [Citation(s) in RCA: 64] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
Abstract
Expression of a capsular polysaccharide is considered a hallmark of most invasive species of bacteria, including Streptococcus pneumoniae, in which the capsule is among the principal virulence factors and is the basis for successful vaccines. Consequently, it was previously assumed that capsule production distinguishes S. pneumoniae from closely related commensals of the mitis group streptococci. Based on antigenic and genetic analyses of 187 mitis group streptococci, including 90 recognized serotypes of S. pneumoniae, we demonstrated capsule production by the Wzy/Wzx pathway in 74% of 66 S. mitis strains and in virtually all tested strains of S. oralis (subspecies oralis, dentisani, and tigurinus) and S. infantis. Additional analyses of genomes of S. cristatus, S. parasanguinis, S. australis, S. sanguinis, S. gordonii, S. anginosus, S. intermedius, and S. constellatus revealed complete capsular biosynthesis (cps) loci in all strains tested. Truncated cps loci were detected in three strains of S. pseudopneumoniae, in 26% of S. mitis strains, and in a single S. oralis strain. The level of sequence identities of cps locus genes confirmed that the structural polymorphism of capsular polysaccharides in S. pneumoniae evolved by import of cps fragments from commensal Streptococcus species, resulting in a mosaic of genes of different origins. The demonstrated antigenic identity of at least eight of the numerous capsular polysaccharide structures expressed by commensal streptococci with recognized serotypes of S. pneumoniae raises concerns about potential misidentifications in addition to important questions concerning the consequences for vaccination and host-parasite relationships both for the commensals and for the pathogen. Expression of a capsular polysaccharide is among the principal virulence factors of Streptococcus pneumoniae and is the basis for successful vaccines against infections caused by this important pathogen. Contrasting with previous assumptions, this study showed that expression of capsular polysaccharides by the same genetic mechanisms is a general property of closely related species of streptococci that form a significant part of our commensal microbiota. The demonstrated antigenic identity of many capsular polysaccharides expressed by commensal streptococci and S. pneumoniae raises important questions concerning the consequences for vaccination and host-parasite relationships both for the commensals and the pathogen.
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Streptococcus iniae cpsG alters capsular carbohydrate composition and is a cause of serotype switching in vaccinated fish. Vet Microbiol 2016; 193:116-24. [DOI: 10.1016/j.vetmic.2016.08.011] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2016] [Revised: 08/12/2016] [Accepted: 08/16/2016] [Indexed: 11/21/2022]
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Salvadori G, Junges R, Morrison DA, Petersen FC. Overcoming the Barrier of Low Efficiency during Genetic Transformation of Streptococcus mitis. Front Microbiol 2016; 7:1009. [PMID: 27458432 PMCID: PMC4932118 DOI: 10.3389/fmicb.2016.01009] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2016] [Accepted: 06/14/2016] [Indexed: 01/31/2023] Open
Abstract
Objective:Streptococcus mitis is a predominant oral colonizer, but difficulties in genetic manipulation of this species have hampered our understanding of the mechanisms it uses for colonization of oral surfaces. The aim of this study was to reveal optimal conditions for natural genetic transformation in S. mitis and illustrate its application in direct genome editing. Methods: Luciferase reporter assays were used to assess gene expression of the alternative sigma factor (σX) in combination with natural transformation experiments to evaluate the efficiency by which S. mitis activates the competence system and incorporates exogenous DNA. Optimal amounts and sources of donor DNA (chromosomal, amplicon, or replicative plasmid), concentrations of synthetic competence-stimulating peptide, and transformation media were assessed. Results: A semi-defined medium showed much improved results for response to the competence stimulating peptide when compared to rich media. The use of a donor amplicon with large homology flanking regions also provided higher transformation rates. Overall, an increase of transformation efficiencies from 0.001% or less to over 30% was achieved with the developed protocol. We further describe the construction of a markerless mutant based on this high efficiency strategy. Conclusion: We optimized competence development in S. mitis, by use of semi-defined medium and appropriate concentrations of synthetic competence factor. Combined with the use of a large amplicon of donor DNA, this method allowed easy and direct editing of the S. mitis genome, broadening the spectrum of possible downstream applications of natural transformation in this species.
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Affiliation(s)
- Gabriela Salvadori
- Department of Oral Biology, Faculty of Dentistry, University of Oslo Oslo, Norway
| | - Roger Junges
- Department of Oral Biology, Faculty of Dentistry, University of Oslo Oslo, Norway
| | - Donald A Morrison
- Department of Biological Sciences, College of Liberal Arts and Sciences, University of Illinois at Chicago Chicago, IL, USA
| | - Fernanda C Petersen
- Department of Oral Biology, Faculty of Dentistry, University of Oslo Oslo, Norway
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Rukke H, Engen S, Schenck K, Petersen F. Capsule expression inStreptococcus mitismodulates interaction with oral keratinocytes and alters susceptibility to human antimicrobial peptides. Mol Oral Microbiol 2015; 31:302-13. [DOI: 10.1111/omi.12123] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 08/04/2015] [Indexed: 12/21/2022]
Affiliation(s)
- H.V. Rukke
- Department of Oral Biology; Faculty of Dentistry; University of Oslo; Norway
| | - S.A. Engen
- Department of Oral Biology; Faculty of Dentistry; University of Oslo; Norway
| | - K. Schenck
- Department of Oral Biology; Faculty of Dentistry; University of Oslo; Norway
| | - F.C. Petersen
- Department of Oral Biology; Faculty of Dentistry; University of Oslo; Norway
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