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Keogh RA, Haeberle AL, Langouët-Astrié CJ, Kavanaugh JS, Schmidt EP, Moore GD, Horswill AR, Doran KS. Group B Streptococcus adaptation promotes survival in a hyperinflammatory diabetic wound environment. SCIENCE ADVANCES 2022; 8:eadd3221. [PMID: 36367946 PMCID: PMC9651866 DOI: 10.1126/sciadv.add3221] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 06/03/2022] [Accepted: 09/22/2022] [Indexed: 06/16/2023]
Abstract
Diabetic wounds have poor healing outcomes due to the presence of numerous pathogens and a dysregulated immune response. Group B Streptococcus (GBS) is commonly isolated from diabetic wound infections, but the mechanisms of GBS virulence during these infections have not been investigated. Here, we develop a murine model of GBS diabetic wound infection and, using dual RNA sequencing, demonstrate that GBS infection triggers an inflammatory response. GBS adapts to this hyperinflammatory environment by up-regulating virulence factors including those known to be regulated by the two-component system covRS, such as the surface protein pbsP, and the cyl operon, which is responsible for hemolysin/pigmentation production. We recover hyperpigmented/hemolytic GBS colonies from the murine diabetic wound, which we determined encode mutations in covR. We further demonstrate that GBS mutants in cylE and pbsP are attenuated in the diabetic wound. This foundational study provides insight into the pathogenesis of GBS diabetic wound infections.
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Affiliation(s)
- Rebecca A. Keogh
- Department of Immunology and Microbiology, University of Colorado Anschutz, Aurora, CO, USA
| | - Amanda L. Haeberle
- Department of Immunology and Microbiology, University of Colorado Anschutz, Aurora, CO, USA
| | | | - Jeffrey S. Kavanaugh
- Department of Immunology and Microbiology, University of Colorado Anschutz, Aurora, CO, USA
| | - Eric P. Schmidt
- Department of Medicine–Pulmonary Sciences and Critical Care, University of Colorado Anschutz, Aurora, CO, USA
| | - Garrett D. Moore
- Department of Orthopedics, University of Colorado, Anschutz Medical Campus, Aurora, CO, USA
| | - Alexander R. Horswill
- Department of Immunology and Microbiology, University of Colorado Anschutz, Aurora, CO, USA
- Department of Veterans Affairs Eastern Colorado Healthcare System, Aurora, CO, USA
| | - Kelly S. Doran
- Department of Immunology and Microbiology, University of Colorado Anschutz, Aurora, CO, USA
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2
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Keith MF, Gopalakrishna KP, Bhavana VH, Hillebrand GH, Elder JL, Megli CJ, Sadovsky Y, Hooven TA. Nitric Oxide Production and Effects in Group B Streptococcus Chorioamnionitis. Pathogens 2022; 11:1115. [PMID: 36297171 PMCID: PMC9608865 DOI: 10.3390/pathogens11101115] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2022] [Revised: 09/21/2022] [Accepted: 09/23/2022] [Indexed: 11/16/2022] Open
Abstract
Intrauterine infection, or chorioamnionitis, due to group B Streptococcus (GBS) is a common cause of miscarriage and preterm birth. To cause chorioamnionitis, GBS must bypass maternal-fetal innate immune defenses including nitric oxide (NO), a microbicidal gas produced by nitric oxide synthases (NOS). This study examined placental NO production and its role in host-pathogen interactions in GBS chorioamnionitis. In a murine model of ascending GBS chorioamnionitis, placental NOS isoform expression quantified by RT-qPCR revealed a four-fold expression increase in inducible NOS, no significant change in expression of endothelial NOS, and decreased expression of neuronal NOS. These NOS expression results were recapitulated ex vivo in freshly collected human placental samples that were co-incubated with GBS. Immunohistochemistry of wild type C57BL/6 murine placentas with GBS chorioamnionitis demonstrated diffuse inducible NOS expression with high-expression foci in the junctional zone and areas of abscess. Pregnancy outcomes between wild type and inducible NOS-deficient mice did not differ significantly although wild type dams had a trend toward more frequent preterm delivery. We also identified possible molecular mechanisms that GBS uses to survive in a NO-rich environment. In vitro exposure of GBS to NO resulted in dose-dependent growth inhibition that varied by serovar. RNA-seq on two GBS strains with distinct NO resistance phenotypes revealed that both GBS strains shared several detoxification pathways that were differentially expressed during NO exposure. These results demonstrate that the placental immune response to GBS chorioamnionitis includes induced NO production and indicate that GBS activates conserved stress pathways in response to NO exposure.
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Affiliation(s)
- Mary Frances Keith
- Department of Pediatrics, Vanderbilt University School of Medicine, Nashville, TN 37232, USA
| | | | | | - Gideon Hayden Hillebrand
- Department of Pediatrics, University of Pittsburgh School of Medicine, Pittsburgh, PA 15224, USA
| | - Jordan Lynn Elder
- Manual Hematology and Coagulation Department, The Cleveland Clinic, Cleveland, OH 44195, USA
| | - Christina Joann Megli
- Department of Obstetrics, Gynecology, and Reproductive Sciences, University of Pittsburgh School of Medicine, Pittsburgh, PA 15213, USA
- UPMC Magee-Womens Research Institute, Pittsburgh, PA 15213, USA
| | - Yoel Sadovsky
- Department of Obstetrics, Gynecology, and Reproductive Sciences, University of Pittsburgh School of Medicine, Pittsburgh, PA 15213, USA
- UPMC Magee-Womens Research Institute, Pittsburgh, PA 15213, USA
| | - Thomas Alexander Hooven
- Department of Pediatrics, University of Pittsburgh School of Medicine, Pittsburgh, PA 15224, USA
- UPMC Magee-Womens Research Institute, Pittsburgh, PA 15213, USA
- UPMC Children’s Hospital of Pittsburgh Richard King Mellon Institute for Pediatric Research, Pittsburgh, PA 15224, USA
- UPMC Children’s Hospital of Pittsburgh, 4401 Penn Ave. Rangos Research Building #8128, Pittsburgh, PA 15224, USA
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3
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Meehan M, Eogan M, McCallion N, Cunney R, Bray JE, Jolley KA, Unitt A, Maiden MCJ, Harrison OB, Drew RJ. Genomic epidemiology of group B streptococci spanning 10 years in an Irish maternity hospital, 2008-2017. J Infect 2021; 83:37-45. [PMID: 33862060 DOI: 10.1016/j.jinf.2021.04.003] [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] [Received: 02/07/2021] [Revised: 03/30/2021] [Accepted: 04/05/2021] [Indexed: 02/02/2023]
Abstract
OBJECTIVES The genomic epidemiology of group b streptococcal (GBS) isolates from the Rotunda maternity hospital, Dublin, 2008-2017, was investigated. METHODS Whole genome sequences of isolates (invasive, n = 114; non-invasive, n = 76) from infants and women were analysed using the PubMLST database (https://pubmlst.org/sagalactiae/). RESULTS Serotypes III (36%), Ia (18%), V (17%), II (11%) and Ib, (9%) and sequence types (ST) 17 (23%), ST-23 (14%), ST-1 (12%) and ST-19 (7%) were most common. Core genome MLST (cgMLST) differentiated isolates of the same ST, grouped STs into five lineages congruent with known clonal complexes and identified known mother-baby pairs and suspected linked infant cases. Clonal complex (CC) 17 accounted for 40% and 22% of infant and maternal invasive cases, respectively and 21% of non-invasive isolates. CC23 and CC19 were associated with maternal disease (30%) and carriage (24%), respectively. Erythromycin (26%) and clindamycin (18%) resistance increased over the study period and was associated with presence of the erm(B) gene (55%), CC1 (33%) and CC19 (24%). A multi-resistant integrative conjugative element incorporated in the PI-1 locus was detected in CC17, an ST-12 and ST-23 isolate confirming the global dissemination of this element. All isolates possessed one or more pilus islands. Genes encoding other potential protective proteins including Sip, C5a peptidase and Srr1 were present in 100%, 99.5% and 65.8% of isolates, respectively. The srr2 gene was unique to CC17. CONCLUSIONS The PubMLST.org website provides a valuable framework for genomic GBS surveillance to inform on local and global GBS epidemiology, preventive and control measures.
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Affiliation(s)
- Mary Meehan
- Irish Meningitis and Sepsis Reference Laboratory, Children's Health Ireland at Temple Street, Dublin, Ireland.
| | - Maeve Eogan
- Department of Obstetrics and Gynaecology, Rotunda Hospital, Dublin, Ireland
| | - Naomi McCallion
- Department of Neonatology, The Rotunda Hospital, Dublin, Ireland; Department of Paediatrics, The Royal College of Surgeons in Ireland, Dublin, Ireland
| | - Robert Cunney
- Irish Meningitis and Sepsis Reference Laboratory, Children's Health Ireland at Temple Street, Dublin, Ireland; Department of Clinical Microbiology, Royal College of Surgeons in Ireland, Dublin, Ireland
| | - James E Bray
- Department of Zoology, University of Oxford, Peter Medawar Building, Oxford OX1 3SY, UK
| | - Keith A Jolley
- Department of Zoology, University of Oxford, Peter Medawar Building, Oxford OX1 3SY, UK
| | - Anastasia Unitt
- Department of Zoology, University of Oxford, Peter Medawar Building, Oxford OX1 3SY, UK
| | - Martin C J Maiden
- Department of Zoology, University of Oxford, Peter Medawar Building, Oxford OX1 3SY, UK
| | - Odile B Harrison
- Department of Zoology, University of Oxford, Peter Medawar Building, Oxford OX1 3SY, UK
| | - Richard J Drew
- Irish Meningitis and Sepsis Reference Laboratory, Children's Health Ireland at Temple Street, Dublin, Ireland; Clinical Innovation Unit, Rotunda Hospital, Dublin, Ireland; Department of Clinical Microbiology, Royal College of Surgeons in Ireland, Dublin, Ireland
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4
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Dammann AN, Chamby AB, Catomeris AJ, Davidson KM, Tettelin H, van Pijkeren JP, Gopalakrishna KP, Keith MF, Elder JL, Ratner AJ, Hooven TA. Genome-Wide fitness analysis of group B Streptococcus in human amniotic fluid reveals a transcription factor that controls multiple virulence traits. PLoS Pathog 2021; 17:e1009116. [PMID: 33684178 PMCID: PMC7971860 DOI: 10.1371/journal.ppat.1009116] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2020] [Revised: 03/18/2021] [Accepted: 02/18/2021] [Indexed: 02/06/2023] Open
Abstract
Streptococcus agalactiae (group B Streptococcus; GBS) remains a dominant cause of serious neonatal infections. One aspect of GBS that renders it particularly virulent during the perinatal period is its ability to invade the chorioamniotic membranes and persist in amniotic fluid, which is nutritionally deplete and rich in fetal immunologic factors such as antimicrobial peptides. We used next-generation sequencing of transposon-genome junctions (Tn-seq) to identify five GBS genes that promote survival in the presence of human amniotic fluid. We confirmed our Tn-seq findings using a novel CRISPR inhibition (CRISPRi) gene expression knockdown system. This analysis showed that one gene, which encodes a GntR-class transcription factor that we named MrvR, conferred a significant fitness benefit to GBS in amniotic fluid. We generated an isogenic targeted deletion of the mrvR gene, which had a growth defect in amniotic fluid relative to the wild type parent strain. The mrvR deletion strain also showed a significant biofilm defect in vitro. Subsequent in vivo studies showed that while the mutant was able to cause persistent murine vaginal colonization, pregnant mice colonized with the mrvR deletion strain did not develop preterm labor despite consistent GBS invasion of the uterus and the fetoplacental units. In contrast, pregnant mice colonized with wild type GBS consistently deliver prematurely. In a sepsis model the mrvR deletion strain showed significantly decreased lethality. In order to better understand the mechanism by which this newly identified transcription factor controls GBS virulence, we performed RNA-seq on wild type and mrvR deletion GBS strains, which revealed that the transcription factor affects expression of a wide range of genes across the GBS chromosome. Nucleotide biosynthesis and salvage pathways were highly represented among the set of differentially expressed genes, suggesting that MrvR may be involved in regulating nucleotide availability. Group B Streptococcus (GBS) is a species of Gram-positive bacteria that often colonizes the healthy adult intestinal and reproductive tracts without causing serious symptoms. During pregnancy, however, GBS can invade the pregnant uterus, where it can cause infection of the placenta, fetal membranes, and fetus—a condition known as chorioamnionitis. Chorioamnionitis is associated with serious adverse pregnancy outcomes, including stillbirth, preterm labor, and severe infection of the newborn. GBS can survive in human amniotic fluid, which is low in bacterial nutrients and contains immune molecules that limit microbial persistence, and this ability likely contributes to GBS chorioamnionitis. This study is focused on a single GBS gene that encodes a genetic regulator we called MrvR, which we show is important for GBS resistance to human amniotic fluid. Using a series of genetic techniques combined with animal models of GBS colonization and infection, we show that MrvR also plays a key role in allowing GBS to invade the bloodstream and trigger the inflammatory responses that lead to preterm labor and stillbirth. The study concludes with a survey of other GBS genes whose activity is regulated by MrvR, which seems to be an important contributor to GBS virulence.
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Affiliation(s)
- Allison N. Dammann
- Department of Pediatrics, New York University School of Medicine, New York, New York, United States of America
| | - Anna B. Chamby
- University of Vermont Larner College of Medicine, Burlington, Vermont, United States of America
| | - Andrew J. Catomeris
- Georgetown University School of Medicine, Washington, District of Columbia, United States of America
| | - Kyle M. Davidson
- Department of Pediatrics, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, United States of America
| | - Hervé Tettelin
- Department of Microbiology and Immunology, University of Maryland School of Medicine, Baltimore, Maryland, United States of America
- Institute for Genome Sciences, University of Maryland School of Medicine, Baltimore, Maryland, United States of America
| | - Jan-Peter van Pijkeren
- Department of Food Science, University of Wisconsin, Madison, Wisconsin, United States of America
| | - Kathyayini P. Gopalakrishna
- Department of Pediatrics, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, United States of America
| | - Mary F. Keith
- Department of Pediatrics, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, United States of America
| | - Jordan L. Elder
- Department of Pediatrics, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, United States of America
| | - Adam J. Ratner
- Department of Pediatrics, New York University School of Medicine, New York, New York, United States of America
- Department of Microbiology, New York University, New York, New York, United States of America
| | - Thomas A. Hooven
- Department of Pediatrics, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, United States of America
- Richard King Mellon Institute for Pediatric Research, UPMC Children’s Hospital of Pittsburgh, Pittsburgh, Pennsylvania, United States of America
- * E-mail:
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5
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Armistead B, Quach P, Snyder JM, Santana-Ufret V, Furuta A, Brokaw A, Rajagopal L. Hemolytic Membrane Vesicles of Group B Streptococcus Promote Infection. J Infect Dis 2020; 223:1488-1496. [PMID: 32861213 DOI: 10.1093/infdis/jiaa548] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2020] [Accepted: 08/25/2020] [Indexed: 01/12/2023] Open
Abstract
BACKGROUND Group B streptococci (GBS) are β-hemolytic, Gram-positive bacteria associated with fetal injury, preterm birth, spontaneous abortion, and neonatal infections. A key factor promoting GBS virulence is the β-hemolysin/cytolysin, a pigmented ornithine rhamnolipid (also known as granadaene) associated with the bacterial surface. METHODS A previous study indicated that GBS produce small structures known as membrane vesicles (MVs), which contain virulence-associated proteins. In this study, we show that GBS MVs are pigmented and hemolytic, indicating that granadaene is functionally active in MVs. RESULTS In addition, MVs from hyperhemolytic GBS induced greater cell death of neutrophils, T cells, and B cells compared with MVs from isogenic nonhemolytic GBS, implicating MVs as a potential mechanism for granadaene-mediated virulence. Finally, hemolytic MVs reduced oxidative killing of GBS and aggravated morbidity and mortality of neonatal mice infected with GBS. CONCLUSIONS These studies, taken together, reveal a novel mechanism by which GBS deploy a crucial virulence factor to promote bacterial dissemination and pathogenesis.
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Affiliation(s)
- Blair Armistead
- Department of Global Health, University of Washington, Seattle, Washington, USA.,Center for Global Infectious Disease Research, Seattle Children's Research Institute, Seattle, Washington, USA
| | - Phoenicia Quach
- Center for Global Infectious Disease Research, Seattle Children's Research Institute, Seattle, Washington, USA
| | - Jessica M Snyder
- Department of Comparative Medicine, University of Washington School of Medicine, Seattle, Washington, USA
| | - Verónica Santana-Ufret
- Center for Global Infectious Disease Research, Seattle Children's Research Institute, Seattle, Washington, USA
| | - Anna Furuta
- Department of Global Health, University of Washington, Seattle, Washington, USA.,Center for Global Infectious Disease Research, Seattle Children's Research Institute, Seattle, Washington, USA
| | - Alyssa Brokaw
- Department of Global Health, University of Washington, Seattle, Washington, USA.,Center for Global Infectious Disease Research, Seattle Children's Research Institute, Seattle, Washington, USA
| | - Lakshmi Rajagopal
- Department of Global Health, University of Washington, Seattle, Washington, USA.,Center for Global Infectious Disease Research, Seattle Children's Research Institute, Seattle, Washington, USA.,Department of Pediatrics, University of Washington School of Medicine, Seattle, Washington, USA
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6
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Lipid analogs reveal features critical for hemolysis and diminish granadaene mediated Group B Streptococcus infection. Nat Commun 2020; 11:1502. [PMID: 32198389 PMCID: PMC7083881 DOI: 10.1038/s41467-020-15282-0] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2019] [Accepted: 02/27/2020] [Indexed: 12/17/2022] Open
Abstract
Although certain microbial lipids are toxins, the structural features important for cytotoxicity remain unknown. Increased functional understanding is essential for developing therapeutics against toxic microbial lipids. Group B Streptococci (GBS) are bacteria associated with preterm births, stillbirths, and severe infections in neonates and adults. GBS produce a pigmented, cytotoxic lipid, known as granadaene. Despite its importance to all manifestations of GBS disease, studies towards understanding granadaene’s toxic activity are hindered by its instability and insolubility in purified form. Here, we report the synthesis and screening of lipid derivatives inspired by granadaene, which reveal features central to toxin function, namely the polyene chain length. Furthermore, we show that vaccination with a non-toxic synthetic analog confers the production of antibodies that inhibit granadaene-mediated hemolysis ex vivo and diminish GBS infection in vivo. This work provides unique structural and functional insight into granadaene and a strategy to mitigate GBS infection, which will be relevant to other toxic lipids encoded by human pathogens. Granadaene, produced by Group B Streptococcus (GBS), is a long polyene lipid involved in cellular toxicity and hemolytic activity. Here, the authors synthesize and characterize granadaene-like compounds and show that a non-toxic analog diminishes GBS infection in mice when incorporated into a vaccine formulation.
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7
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Armistead B, Whidbey C, Iyer LM, Herrero-Foncubierta P, Quach P, Haidour A, Aravind L, Cuerva JM, Jaspan HB, Rajagopal L. The cyl Genes Reveal the Biosynthetic and Evolutionary Origins of the Group B Streptococcus Hemolytic Lipid, Granadaene. Front Microbiol 2020; 10:3123. [PMID: 32038561 PMCID: PMC6985545 DOI: 10.3389/fmicb.2019.03123] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2019] [Accepted: 12/24/2019] [Indexed: 01/31/2023] Open
Abstract
Group B Streptococcus (GBS) is a β-hemolytic, Gram-positive bacterium that commonly colonizes the female lower genital tract and is associated with fetal injury, preterm birth, spontaneous abortion, and neonatal infections. A major factor promoting GBS virulence is the β-hemolysin/cytolysin, which is cytotoxic to several host cells. We recently showed that the ornithine rhamnolipid pigment, Granadaene, produced by the gene products of the cyl operon, is hemolytic. Here, we demonstrate that heterologous expression of the GBS cyl operon conferred hemolysis, pigmentation, and cytoxicity to Lactococcus lactis, a model non-hemolytic Gram-positive bacterium. Similarly, pigment purified from L. lactis is hemolytic, cytolytic, and identical in structure to Granadaene extracted from GBS, indicating the cyl operon is sufficient for Granadaene production in a heterologous host. Using a systematic survey of phyletic patterns and contextual associations of the cyl genes, we identify homologs of the cyl operon in physiologically diverse Gram-positive bacteria and propose undescribed functions of cyl gene products. Together, these findings bring greater understanding to the biosynthesis and evolutionary foundations of a key GBS virulence factor and suggest that such potentially toxic lipids may be encoded by other bacteria.
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Affiliation(s)
- Blair Armistead
- Department of Global Health, University of Washington, Seattle, WA, United States.,Center for Global Infectious Disease Research, Seattle Children's Research Institute, Seattle, WA, United States
| | - Christopher Whidbey
- Department of Global Health, University of Washington, Seattle, WA, United States.,Center for Global Infectious Disease Research, Seattle Children's Research Institute, Seattle, WA, United States
| | - Lakshminarayan M Iyer
- Computational Biology Branch, National Center for Biotechnology Information, National Institutes of Health, Bethesda, MD, United States
| | | | - Phoenicia Quach
- Center for Global Infectious Disease Research, Seattle Children's Research Institute, Seattle, WA, United States
| | - Ali Haidour
- Department of Organic Chemistry, University of Granada, Granada, Spain
| | - L Aravind
- Computational Biology Branch, National Center for Biotechnology Information, National Institutes of Health, Bethesda, MD, United States
| | | | - Heather B Jaspan
- Department of Global Health, University of Washington, Seattle, WA, United States.,Center for Global Infectious Disease Research, Seattle Children's Research Institute, Seattle, WA, United States.,Department of Pediatrics, University of Washington School of Medicine, Seattle, WA, United States.,Department of Pathology, Institute of Infectious Disease and Molecular Medicine, University of Cape Town, Cape Town, South Africa
| | - Lakshmi Rajagopal
- Department of Global Health, University of Washington, Seattle, WA, United States.,Center for Global Infectious Disease Research, Seattle Children's Research Institute, Seattle, WA, United States.,Department of Pediatrics, University of Washington School of Medicine, Seattle, WA, United States
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8
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Siemens N, Oehmcke-Hecht S, Hoßmann J, Skorka SB, Nijhuis RHT, Ruppen C, Skrede S, Rohde M, Schultz D, Lalk M, Itzek A, Pieper DH, van den Bout CJ, Claas ECJ, Kuijper EJ, Mauritz R, Sendi P, Wunderink HF, Norrby-Teglund A. Prothrombotic and Proinflammatory Activities of the β-Hemolytic Group B Streptococcal Pigment. J Innate Immun 2019; 12:291-303. [PMID: 31743913 DOI: 10.1159/000504002] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2019] [Accepted: 10/06/2019] [Indexed: 12/29/2022] Open
Abstract
A prominent feature of severe streptococcal infections is the profound inflammatory response that contributes to systemic toxicity. In sepsis the dysregulated host response involves both immunological and nonimmunological pathways. Here, we report a fatal case of an immunocompetent healthy female presenting with toxic shock and purpura fulminans caused by group B streptococcus (GBS; serotype III, CC19). The strain (LUMC16) was pigmented and hyperhemolytic. Stimulation of human primary cells with hyperhemolytic LUMC16 and STSS/NF-HH strains and pigment toxin resulted in a release of proinflammatory mediators, including tumor necrosis factor, interleukin (IL)-1β, and IL-6. In addition, LUMC16 induced blood clotting and showed factor XII activity on its surface, which was linked to the presence of the pigment. The expression of pigment was not linked to a mutation within the CovR/S region. In conclusion, our study shows that the hemolytic lipid toxin contributes to the ability of GBS to cause systemic hyperinflammation and interferes with the coagulation system.
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Affiliation(s)
- Nikolai Siemens
- Center for Infectious Medicine, Department of Medicine Huddinge, Karolinska Institutet, Karolinska University Hospital, Huddinge, Sweden, .,Center for Functional Genomics of Microbes, Department of Molecular Genetics and Infection Biology, University of Greifswald, Greifswald, Germany,
| | - Sonja Oehmcke-Hecht
- Institute of Medical Microbiology, Virology, and Hygiene, University Medicine Rostock, Rostock, Germany
| | - Jörn Hoßmann
- Microbial Interactions and Processes, Helmholtz Centre for Infection Research - HZI, Braunschweig, Germany
| | - Sebastian B Skorka
- Center for Functional Genomics of Microbes, Department of Molecular Genetics and Infection Biology, University of Greifswald, Greifswald, Germany
| | - Roel H T Nijhuis
- Department of Medical Microbiology, Leiden University Medical Center, Leiden, The Netherlands.,Department of Medical Microbiology and Medical Immunology, Meander Medical Center, Amersfoort, The Netherlands
| | - Corinne Ruppen
- Institute for Infectious Diseases, University of Bern, Bern, Switzerland
| | - Steinar Skrede
- Department of Medicine, Haukeland University Hospital, Bergen, Norway.,Department of Clinical Science, University of Bergen, Bergen, Norway
| | - Manfred Rohde
- Central Facility for Microscopy, Helmholtz Centre for Infection Research - HZI, Braunschweig, Germany
| | - Daniel Schultz
- Institute of Biochemistry, University of Greifswald, Greifswald, Germany
| | - Michael Lalk
- Institute of Biochemistry, University of Greifswald, Greifswald, Germany
| | - Andreas Itzek
- Microbial Interactions and Processes, Helmholtz Centre for Infection Research - HZI, Braunschweig, Germany
| | - Dietmar H Pieper
- Microbial Interactions and Processes, Helmholtz Centre for Infection Research - HZI, Braunschweig, Germany
| | | | - Eric C J Claas
- Department of Medical Microbiology, Leiden University Medical Center, Leiden, The Netherlands
| | - Ed J Kuijper
- Department of Medical Microbiology, Leiden University Medical Center, Leiden, The Netherlands
| | - Robert Mauritz
- Department of Intensive Care Medicine, Leiden University Medical Center, Leiden, The Netherlands
| | - Parham Sendi
- Institute for Infectious Diseases, University of Bern, Bern, Switzerland
| | - Herman F Wunderink
- Department of Medical Microbiology, Leiden University Medical Center, Leiden, The Netherlands.,Department of Medical Microbiology, University Medical Center Utrecht, Utrecht, The Netherlands
| | - Anna Norrby-Teglund
- Center for Infectious Medicine, Department of Medicine Huddinge, Karolinska Institutet, Karolinska University Hospital, Huddinge, Sweden
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9
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Patras KA, Derieux J, Al-Bassam MM, Adiletta N, Vrbanac A, Lapek JD, Zengler K, Gonzalez DJ, Nizet V. Group B Streptococcus Biofilm Regulatory Protein A Contributes to Bacterial Physiology and Innate Immune Resistance. J Infect Dis 2019; 218:1641-1652. [PMID: 29868829 DOI: 10.1093/infdis/jiy341] [Citation(s) in RCA: 34] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2018] [Accepted: 06/02/2018] [Indexed: 12/18/2022] Open
Abstract
Background Streptococcus agalactiae (group B Streptococcus [GBS]) asymptomatically colonizes approximately 20% of adults; however, GBS causes severe disease in susceptible populations, including newborns, pregnant women, and elderly individuals. In shifting between commensal and pathogenic states, GBS reveals multiple mechanisms of virulence factor control. Here we describe a GBS protein that we named "biofilm regulatory protein A" (BrpA) on the basis of its homology with BrpA from Streptococcus mutans. Methods We coupled phenotypic assays, RNA sequencing, human neutrophil and whole-blood killing assays, and murine infection models to investigate the contribution of BrpA to GBS physiology and virulence. Results Sequence analysis identified BrpA as a LytR-CpsA-Psr enzyme. Targeted mutagenesis yielded a GBS mutant (ΔbrpA) with normal ultrastructural morphology but a 6-fold increase in chain length, a biofilm defect, and decreased acid tolerance. GBS ΔbrpA stimulated increased neutrophil reactive oxygen species and proved more susceptible to human and murine blood and neutrophil killing. Notably, the wild-type parent outcompeted ΔbrpA GBS in murine sepsis and vaginal colonization models. RNA sequencing of ΔbrpA uncovered multiple differences from the wild-type parent, including pathways of cell wall synthesis and cellular metabolism. Conclusions We propose that BrpA is an important virulence regulator and potential target for design of novel antibacterial therapeutics against GBS.
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Affiliation(s)
- Kathryn A Patras
- Division of Host-Microbe Systems and Therapeutics, Department of Pediatrics, University of California-San Diego, La Jolla
| | - Jaclyn Derieux
- Division of Host-Microbe Systems and Therapeutics, Department of Pediatrics, University of California-San Diego, La Jolla
| | - Mahmoud M Al-Bassam
- Division of Host-Microbe Systems and Therapeutics, Department of Pediatrics, University of California-San Diego, La Jolla
| | - Nichole Adiletta
- Division of Host-Microbe Systems and Therapeutics, Department of Pediatrics, University of California-San Diego, La Jolla
| | - Alison Vrbanac
- Division of Host-Microbe Systems and Therapeutics, Department of Pediatrics, University of California-San Diego, La Jolla
| | - John D Lapek
- Department of Pharmacology, School of Medicine, University of California-San Diego, La Jolla.,Skaggs School of Pharmacy and Pharmaceutical Sciences, University of California-San Diego, La Jolla
| | - Karsten Zengler
- Division of Host-Microbe Systems and Therapeutics, Department of Pediatrics, University of California-San Diego, La Jolla
| | - David J Gonzalez
- Department of Pharmacology, School of Medicine, University of California-San Diego, La Jolla.,Skaggs School of Pharmacy and Pharmaceutical Sciences, University of California-San Diego, La Jolla
| | - Victor Nizet
- Division of Host-Microbe Systems and Therapeutics, Department of Pediatrics, University of California-San Diego, La Jolla.,Skaggs School of Pharmacy and Pharmaceutical Sciences, University of California-San Diego, La Jolla
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10
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Gendrin C, Merillat S, Vornhagen J, Coleman M, Armistead B, Ngo L, Aggarwal A, Quach P, Berrigan J, Rajagopal L. Diminished Capsule Exacerbates Virulence, Blood-Brain Barrier Penetration, Intracellular Persistence, and Antibiotic Evasion of Hyperhemolytic Group B Streptococci. J Infect Dis 2019; 217:1128-1138. [PMID: 29301010 DOI: 10.1093/infdis/jix684] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2017] [Accepted: 12/28/2017] [Indexed: 12/21/2022] Open
Abstract
Group B streptococci (GBS) are encapsulated, β-hemolytic bacteria that are a common cause of infections in human newborns and certain adults. Two factors important for GBS virulence are the sialic acid capsular polysaccharide that promotes immune evasion and the hemolytic pigment that induces host cell cytotoxcity. These virulence factors are often oppositely regulated by the CovR/CovS two-component system. Clinical GBS strains exhibiting hyperhemolysis and low capsule due to pathoadaptive covR/S mutations have been isolated from patients. Given the importance of capsule to GBS virulence, we predicted that a decrease or loss of capsule would attenuate the virulence of covR/S mutants. Surprisingly, hyperhemolytic GBS with low or no capsule exhibit increased virulence, intracellular persistence, and blood-brain barrier penetration, which was independent of a Trojan horse mechanism of barrier penetration. Additionally, intracellular persistence enabled both hemolytic and hyperhemolytic GBS to evade antibiotics routinely used to treat these infections. The finding that diminished capsule expression promotes GBS virulence, intracellular persistence, and antibiotic evasion has important implications for sustained antibiotic therapy and efficacy of capsule-based vaccines.
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Affiliation(s)
- Claire Gendrin
- Department of Pediatrics, University of Washington.,Center for Global Infections Disease Research, Seattle Children's Research Institute
| | - Sean Merillat
- Center for Global Infections Disease Research, Seattle Children's Research Institute
| | - Jay Vornhagen
- Department of Pediatrics, University of Washington.,Center for Global Infections Disease Research, Seattle Children's Research Institute.,Department of Global Health, University of Washington, Seattle
| | - Michelle Coleman
- Department of Pediatrics, University of Washington.,Center for Global Infections Disease Research, Seattle Children's Research Institute
| | - Blair Armistead
- Department of Pediatrics, University of Washington.,Center for Global Infections Disease Research, Seattle Children's Research Institute.,Department of Global Health, University of Washington, Seattle
| | - Lisa Ngo
- Center for Global Infections Disease Research, Seattle Children's Research Institute
| | - Anjali Aggarwal
- Center for Global Infections Disease Research, Seattle Children's Research Institute
| | - Phoenicia Quach
- Center for Global Infections Disease Research, Seattle Children's Research Institute
| | - Jacob Berrigan
- Center for Global Infections Disease Research, Seattle Children's Research Institute
| | - Lakshmi Rajagopal
- Department of Pediatrics, University of Washington.,Center for Global Infections Disease Research, Seattle Children's Research Institute.,Department of Global Health, University of Washington, Seattle
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11
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Armistead B, Oler E, Adams Waldorf K, Rajagopal L. The Double Life of Group B Streptococcus: Asymptomatic Colonizer and Potent Pathogen. J Mol Biol 2019; 431:2914-2931. [PMID: 30711542 DOI: 10.1016/j.jmb.2019.01.035] [Citation(s) in RCA: 69] [Impact Index Per Article: 13.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2018] [Revised: 01/22/2019] [Accepted: 01/23/2019] [Indexed: 12/22/2022]
Abstract
Group B streptococcus (GBS) is a β-hemolytic gram-positive bacterium that colonizes the lower genital tract of approximately 18% of women globally as an asymptomatic member of the gastrointestinal and/or vaginal flora. If established in other host niches, however, GBS is highly pathogenic. During pregnancy, ascending GBS infection from the vagina to the intrauterine space is associated with preterm birth, stillbirth, and fetal injury. In addition, vertical transmission of GBS during or after birth results in life-threatening neonatal infections, including pneumonia, sepsis, and meningitis. Although the mechanisms by which GBS traffics from the lower genital tract to vulnerable host niches are not well understood, recent advances have revealed that many of the same bacterial factors that promote asymptomatic vaginal carriage also facilitate dissemination and virulence. Furthermore, highly pathogenic GBS strains have acquired unique factors that enhance survival in invasive niches. Several host factors also exist that either subdue GBS upon vaginal colonization or alternatively permit invasive infection. This review summarizes the GBS and host factors involved in GBS's state as both an asymptomatic colonizer and an invasive pathogen. Gaining a better understanding of these mechanisms is key to overcoming the challenges associated with vaccine development and identification of novel strategies to mitigate GBS virulence.
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Affiliation(s)
- Blair Armistead
- Department of Global Health, University of Washington, Seattle 98195, WA, USA; Center for Global Infectious Disease Research, Seattle Children's Research Institute, Seattle 98101, WA, USA
| | - Elizabeth Oler
- Department of Obstetrics and Gynecology, University of Washington School of Medicine, Seattle 98195, WA, USA
| | - Kristina Adams Waldorf
- Department of Global Health, University of Washington, Seattle 98195, WA, USA; Department of Obstetrics and Gynecology, University of Washington School of Medicine, Seattle 98195, WA, USA; Center for Innate Immunity and Immune Disease, University of Washington, Seattle 98109, WA, USA; Sahlgrenska Academy, Gothenburg University, Gothenburg 413 90, Sweden
| | - Lakshmi Rajagopal
- Department of Global Health, University of Washington, Seattle 98195, WA, USA; Center for Global Infectious Disease Research, Seattle Children's Research Institute, Seattle 98101, WA, USA; Department of Pediatrics, University of Washington School of Medicine, Seattle 98195, WA, USA.
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12
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Phenotypic and molecular analysis of nontypeable Group B streptococci: identification of cps2a and hybrid cps2a/cps5 Group B streptococcal capsule gene clusters. Emerg Microbes Infect 2018; 7:137. [PMID: 30087323 PMCID: PMC6081472 DOI: 10.1038/s41426-018-0138-6] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2018] [Revised: 05/11/2018] [Accepted: 06/23/2018] [Indexed: 11/08/2022]
Abstract
The Group B streptococcus (GBS) can express a capsular polysaccharide (CPS). There are ten recognized CPSs (Ia, Ib, and II-IX). A GBS isolate is considered nontypeable (NT) when CPS cannot be identified as one of ten types. Two groups of GBS NT isolates were studied, isolates without surface sialic acid (sia(-)) and isolates with surface sialic acid (sia(+)). The first objective was to characterize NT sia(-) isolates that failed CPS identification by an immunodiffusion antisera typing assay and a RT-PCR capsule typing assay. NT sia(-) isolates were characterized by assaying phenotypic changes and identifying covR/S mutations that may potentially have a role in the altered phenotypes. The second objective was to characterize NT sia(+) isolates that failed to identify as one of the ten CPS types by an immundiffusion antisera-based typing assay and a RT-PCR capsule typing assay yet expressed capsule. Fifteen NT sia(-) isolates displayed increased β hemolysis/orange pigmentation, decreased CAMP activity, inability to form biofilm, and susceptibility to phagocytosis by human blood. DNA sequence analysis of the covR/S genes in the sia(-) isolates found mutations in 14 of 15 isolates assayed. These mutations in the covR/S genes may potentially contribute to lack of expression of phenotypic traits assayed in vitro. For the three NT sia(+) isolates, whole-genome sequence analyses identified two isolates with cps gene clusters identical to the recently described and uncommon CPSIIa type. The third isolate possessed a hybrid cluster containing cps genes for both CPSIIa and CPSV suggesting recombination between these two gene clusters.
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13
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The Streptococcus agalactiae Stringent Response Enhances Virulence and Persistence in Human Blood. Infect Immun 2017; 86:IAI.00612-17. [PMID: 29109175 PMCID: PMC5736797 DOI: 10.1128/iai.00612-17] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2017] [Accepted: 10/30/2017] [Indexed: 12/13/2022] Open
Abstract
Streptococcus agalactiae (group B Streptococcus [GBS]) causes serious infections in neonates. We previously reported a transposon sequencing (Tn-seq) system for performing genomewide assessment of gene fitness in GBS. In order to identify molecular mechanisms required for GBS to transition from a mucosal commensal lifestyle to bloodstream invasion, we performed Tn-seq on GBS strain A909 with human whole blood. Our analysis identified 16 genes conditionally essential for GBS survival in blood, of which 75% were members of the capsular polysaccharide (cps) operon. Among the non-cps genes identified as conditionally essential was relA, which encodes an enzyme whose activity is central to the bacterial stringent response—a conserved adaptation to environmental stress. We used blood coincubation studies of targeted knockout strains to confirm the expected growth defects of GBS deficient in capsule or stringent response activation. Unexpectedly, we found that the relA knockout strains demonstrated decreased expression of β-hemolysin/cytolysin, an important cytotoxin implicated in facilitating GBS invasion. Furthermore, chemical activation of the stringent response with serine hydroxamate increased β-hemolysin/cytolysin expression. To establish a mechanism by which the stringent response leads to increased cytotoxicity, we performed transcriptome sequencing (RNA-seq) on two GBS strains grown under stringent response or control conditions. This revealed a conserved decrease in the expression of genes in the arginine deiminase pathway during stringent response activation. Through coincubation with supplemental arginine and the arginine antagonist canavanine, we show that arginine availability is a determinant of GBS cytotoxicity and that the pathway between stringent response activation and increased virulence is arginine dependent.
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14
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Harrell MI, Burnside K, Whidbey C, Vornhagen J, Adams Waldorf KM, Rajagopal L. Exploring the Pregnant Guinea Pig as a Model for Group B Streptococcus Intrauterine Infection. ACTA ACUST UNITED AC 2017; 2. [PMID: 29034376 PMCID: PMC5635843 DOI: 10.4172/2576-1420.1000109] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
Infection of the amniotic cavity remains a major cause of preterm birth, stillbirth, fetal injury and early onset, fulminant infections in newborns. Currently, there are no effective therapies to prevent in utero infection and consequent co-morbidities. This is in part due to the lack of feasible and appropriate animal models to understand mechanisms that lead to in utero infections. Use of mouse and rat models do not fully recapitulate human pregnancy, while pregnant nonhuman primate models are limited by ethical considerations, technical constraints, and cost. Given these limitations, the guinea pig is an attractive animal model for studying pregnancy infections, particularly as the placental structure is quite similar to the human placenta. Here, we describe our studies that explored the pregnant guinea pig as a model to study in utero Group B Streptococci (GBS) infections. We observed that intrauterine inoculation of wild type GBS in pregnant guinea pigs resulted in bacterial invasion and dissemination to the placenta, amniotic fluid and fetal organs. Also, hyperhemolytic GBS such as those lacking the hemolysin repressor CovR/S showed increased dissemination into the amniotic fluid and fetal organs such as the fetal lung and brain. These results are similar to those observed in mouse and non-human primate models of in utero infection, and support use of the guinea pig as a model for studying GBS infections in pregnancy.
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Affiliation(s)
- Maria I Harrell
- Department of Pediatrics, University of Washington and Seattle Children's Research Institute, Seattle, Washington, United States of America
| | - Kellie Burnside
- Department of Pediatrics, University of Washington and Seattle Children's Research Institute, Seattle, Washington, United States of America
| | - Christopher Whidbey
- Department of Pediatrics, University of Washington and Seattle Children's Research Institute, Seattle, Washington, United States of America.,Department of Global Health, University of Washington, Seattle, Washington, United States of America
| | - Jay Vornhagen
- Department of Pediatrics, University of Washington and Seattle Children's Research Institute, Seattle, Washington, United States of America.,Department of Global Health, University of Washington, Seattle, Washington, United States of America
| | - Kristina M Adams Waldorf
- Department of Global Health, University of Washington, Seattle, Washington, United States of America.,Department of Obstetrics and Gynecology, School of Medicine, University of Washington, Seattle, Washington, United States of America
| | - Lakshmi Rajagopal
- Department of Pediatrics, University of Washington and Seattle Children's Research Institute, Seattle, Washington, United States of America.,Department of Global Health, University of Washington, Seattle, Washington, United States of America
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15
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Whole-Genome Comparison Uncovers Genomic Mutations between Group B Streptococci Sampled from Infected Newborns and Their Mothers. J Bacteriol 2015; 197:3354-66. [PMID: 26283765 DOI: 10.1128/jb.00429-15] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2015] [Accepted: 08/05/2015] [Indexed: 12/30/2022] Open
Abstract
UNLABELLED Streptococcus agalactiae (group B Streptococcus or GBS), a commensal of the human gut and genitourinary tract, is a leading cause of neonatal infections, in which vertical transmission from mother to child remains the most frequent route of contamination. Here, we investigated whether the progression of GBS from carriage to disease is associated with genomic adaptation. Whole-genome comparison of 47 GBS samples from 19 mother-child pairs uncovered 21 single nucleotide polymorphisms (SNPs) and seven insertions/deletions. Of the SNPs detected, 16 appear to have been fixed in the population sampled whereas five mutations were found to be polymorphic. In the infant strains, 14 mutations were detected, including two independently fixed variants affecting the covRS locus, which is known to encode a major regulatory system of virulence. A one-nucleotide insertion was also identified in the promoter region of the highly immunogenic surface protein Rib gene. Gene expression analysis after incubation in human blood showed that these mutations influenced the expression of virulence-associated genes. Additional identification of three mutated strains in the mothers' milk raised the possibility of the newborns also being a source of contamination for their mothers. Overall, our work showed that GBS strains in carriage and disease scenarios might undergo adaptive changes following colonization. The types and locations of the mutations found, together with the experimental results showing their phenotypic impact, suggest that those in a context of infection were positively selected during the transition of GBS from commensal to pathogen, contributing to an increased capacity to cause disease. IMPORTANCE Group B Streptococcus (GBS) is a major pathogen responsible for neonatal infections. Considering that its colonization of healthy adults is mostly asymptomatic, the mechanisms behind its switch from a commensal to an invasive state are largely unknown. In this work, we compared the genomic profile of GBS samples causing infections in newborns with that of the GBS colonizing their mothers. Multiple mutations were detected, namely, within key virulence factors, including the response regulator CovR and surface protein Rib, potentially affecting the pathogenesis of GBS. Their overall impact was supported by differences in the expression of virulence-associated genes in human blood. Our results suggest that during GBS's progression to disease, particular variants are positively selected, contributing to the ability of this bacterium to infect its host.
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16
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Vasilyeva A, Santos Sanches I, Florindo C, Dmitriev A. Natural Mutations in Streptococcus agalactiae Resulting in Abrogation of β Antigen Production. PLoS One 2015; 10:e0128426. [PMID: 26047354 PMCID: PMC4457541 DOI: 10.1371/journal.pone.0128426] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2014] [Accepted: 04/27/2015] [Indexed: 11/18/2022] Open
Abstract
Streptococcus agalactiae genome encodes 21 two-component systems (TCS) and a variety of regulatory proteins in order to control gene expression. One of the TCS, BgrRS, comprising the BgrR DNA-binding regulatory protein and BgrS sensor histidine kinase, was discovered within a putative virulence island. BgrRS influences cell metabolism and positively control the expression of bac gene, coding for β antigen at transcriptional level. Inactivation of bgrR abrogated bac gene expression and increased virulence properties of S. agalactiae. In this study, a total of 140 strains were screened for the presence of bac gene, and the TCS bgrR and bgrS genes. A total of 53 strains carried the bac, bgrR and bgrS genes. Most of them (48 strains) expressed β antigen, while five strains did not express β antigen. Three strains, in which bac gene sequence was intact, while bgrR and/or bgrS genes had mutations, and expression of β antigen was absent, were complemented with a constructed plasmid pBgrRS(P) encoding functionally active bgrR and bgrS gene alleles. This procedure restored expression of β antigen indicating the crucial regulatory role of TCS BgrRS. The complemented strain A49V/BgrRS demonstrated attenuated virulence in intraperitoneal mice model of S. agalactiae infection compared to parental strain A49V. In conclusion we showed that disruption of β antigen expression is associated with: i) insertion of ISSa4 upstream the bac gene just after the ribosomal binding site; ii) point mutation G342A resulting a stop codon TGA within the bac gene and a truncated form of β antigen; iii) single deletion (G) in position 439 of the bgrR gene resulting in a frameshift and the loss of DNA-binding domain of the BgrR protein, and iv) single base substitutions in bgrR and bgrS genes causing single amino acid substitutions in BgrR (Arg187Lys) and BgrS (Arg252Gln). The fact that BgrRS negatively controls virulent properties of S. agalactiae gives a novel clue for understanding of S. agalactiae adaptation to the human.
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Affiliation(s)
- Anastasia Vasilyeva
- Department of Molecular Microbiology, Institute of Experimental Medicine, Saint-Petersburg, Russia
| | - Ilda Santos Sanches
- Department of Life Sciences, Centro de Recursos Microbiológicos (CREM) and Research Unit on Applied Molecular Biosciences (UCIBIO, REQUIMTE), Faculdade de Ciências e Tecnologia, Universidade Nova de Lisboa, Caparica, Portugal
- * E-mail:
| | - Carlos Florindo
- Department of Infectious Diseases, National Institute of Health, Lisbon, Portugal
| | - Alexander Dmitriev
- Department of Molecular Microbiology, Institute of Experimental Medicine, Saint-Petersburg, Russia
- Department of Fundamental Problems of Medicine and Medical Technologies, Saint-Petersburg State University, Saint-Petersburg, Russia
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17
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De Gregorio PR, Juárez Tomás MS, Leccese Terraf MC, Nader-Macías MEF. Preventive effect of Lactobacillus reuteri CRL1324 on Group B Streptococcus vaginal colonization in an experimental mouse model. J Appl Microbiol 2015; 118:1034-47. [PMID: 25786121 DOI: 10.1111/jam.12739] [Citation(s) in RCA: 40] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2014] [Revised: 12/01/2014] [Accepted: 12/18/2014] [Indexed: 11/28/2022]
Abstract
AIMS To assess the preventive effect of different intravaginal (i.va.) doses of Lactobacillus reuteri CRL1324 against vaginal colonization by Group B Streptococcus (GBS) in a murine experimental model. METHODS AND RESULTS The major virulence factors of four vaginal GBS clinical isolates were determined to select the most virulent strain and set up a murine model of streptococcal vaginal colonization. Later, the effect of four and seven doses of 10(8) viable cells of Lact. reuteri CRL1324 i.va. administered, prior to the GBS challenge was studied. Seven doses of lactobacilli were able to significantly reduce the number of viable GBS cells, while four doses showed no preventive effect. Both doses reduced the leucocyte influx induced by GBS. Seven doses caused a slight increase in the Lact. reuteri CRL1324 vaginal colonization compared with four doses and reduced murine vaginal pH compared to control mice. CONCLUSIONS Lactobacillus reuteri CRL1324 evidenced a preventive effect on GBS vaginal colonization in an experimental mouse model. SIGNIFICANCE AND IMPACTS OF THE STUDY Maternal GBS colonization is one of the most important risk factors for developing disease in newborns. Lactobacillus reuteri CRL1324 could be considered as a new biological agent to reduce infections caused by this micro-organism.
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Affiliation(s)
- P R De Gregorio
- Centro de Referencia para Lactobacilos (CERELA)-CONICET, San Miguel de Tucumán, Tucumán, Argentina
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