The impact of glpQ2 gene on virulence in a Streptococcus pneumoniae serotype 19AST320 strain.

Infect Immun. 2014 Nov 24. pii: IAI.02357-14. [Epub ahead of print]

The impact of glpQ2 gene on virulence in a Streptococcus pneumoniae serotype 19AST320 strain.

Chuang YP1, Peng ZR2, Tseng SF3, Lin YC4, Sytwu HK2, Hsieh YC5.

Author information

Abstract

Glycerophosphodiester phosphodiesterase (GlpQ) metabolizes glycerophosphorylcholine from the lung epithelium to produce free choline, which is transformed into phosphorylcholine and presented on the surfaces of many respiratory pathogens. Two orthologs of glpQ genes are found in Streptococcus pneumoniae: glpQ with a membrane motif is widespread in pneumococci whereas glpQ2, which shares high similarity with glpQ in Haemophilus influenzae and Mycoplasma pneumoniae, is only present in S. pneumoniae serotype 3, 6B, 19A, and 19F strains. Recently, serotype 19A has emerged as an epidemiological etiology associated with invasive pneumococcal diseases. Thus, we investigated the pathophysiological role of glpQ2 in a serotype 19AST320 strain, which was the prevalent sequence type in 19A associated with severe pneumonia and invasive pneumococcal disease in pediatric patients. Mutations in glpQ2 reduced phosphorylcholine expression and the anchorage of choline-binding proteins to the pneumococcal surface during the exponential phase, where the mutants exhibited reduced autolysis and lower natural transformation abilities compared with the parent strain. The deletion of glpQ2 also decreased the adherence and cytotoxicity to human lung epithelial cell lines, whereas these functions were indistinguishable from the wild type in complementation strains. In a respiratory infection murine model, glpQ2 was important for nasopharynx and lung colonization. Furthermore, infection with a glpQ2 mutant decreased the severity of pneumonia compared with the parent strain and glpQ2 gene complementation restored the inflammation level. Therefore, glpQ2 enhances surface phosphorylcholine expression in S. pneumoniae 19AST320 during the exponential phase, which contributes to the severity of pneumonia by promoting adherence and host cell cytotoxicity.

Copyright © 2014, American Society for Microbiology. All Rights Reserved.

PMID: 25422269 [PubMed - as supplied by publisher]

Lethal co-infection of influenza virus and Streptococcus pneumoniae lowers antibody response to influenza virus in lung, and reduces germinal center B cells, T follicular helper cells and plasma cells in mediastinal lymph node.

J Virol. 2014 Nov 26. pii: JVI.02455-14. [Epub ahead of print]

Lethal co-infection of influenza virus and Streptococcus pneumoniae lowers antibody response to influenza virus in lung, and reduces germinal center B cells, T follicular helper cells and plasma cells in mediastinal lymph node.

Wu Y1, Tu W2, Lam KT1, Chow KH3, Ho PL3, Guan Y4, Malik Peiris JS4, Lau YL5.

Author information

Abstract

Secondary Streptococcus pneumoniae infection after influenza is a significant clinical complication resulting in morbidity and sometimes mortality. Prior influenza virus infection has been demonstrated to impair the macrophage and neutrophil response to the subsequent pneumococcal infection. In contrast, how the secondary pneumococcal infection after influenza can affect the adaptive immune response to the initial influenza virus infection is less well understood. Therefore, this study focuses on how secondary pneumococcal infection after influenza may impact on the humoral immune response to the initial influenza virus infection in a lethal co-infection mouse model. When compared to mice infected with influenza virus alone, mice co-infected with influenza virus followed by pneumococcus had significant body weight loss and 100% mortality. In the lung, lethal co-infection significantly increased virus titer, bacterial cell counts and decreased the level of virus specific IgG, IgM and IgA, as well as the number of B cells, CD4 T cells and plasma cells. In spleen, lethal co-infection significantly reduced the size and weight of spleen, as well as the B cells along the follicular developmental lineage. In mediastinal lymph nodes, lethal co-infection significantly decreased germinal center B cells, T follicular helper cells and plasma cells. Adoptive transfer of influenza virus-specific immune serum to co-infected mice improved survival, suggesting the protective functions of anti-influenza virus antibodies. In conclusion, co-infection reduced the B cell response to influenza virus. This study helps us to understand the modulation of B cell response to influenza virus during the lethal co-infection.

IMPORTANCE:

Secondary pneumococcal infection after influenza is an important clinical issue that often results in excess mortality. Since antibodies are key mediator of protection, this study aims to examine the antibody response to influenza virus, and demonstrated that lethal co-infection reduced the B cell response to influenza virus. This study helps to highlight the complexity of the modulation of B cell response in the context of co-infection.

Copyright © 2014, American Society for Microbiology. All Rights Reserved.

PMID: 25428873 [PubMed - as supplied by publisher]

Prevalence and characteristics of Streptococcus pneumoniae "putative serotype 6E" isolates from Asian countries.

Diagn Microbiol Infect Dis. 2014 Sep 6;80(4):334-337. doi: 10.1016/j.diagmicrobio.2014.08.017. [Epub ahead of print]

Prevalence and characteristics of Streptococcus pneumoniae "putative serotype 6E" isolates from Asian countries.

Baek JY1, Park IH2, So TM3, Lalitha MK4, Shimono N5, Yasin RM6, Carlos CC7, Perera J8, Thamlikitkul V9, Hsueh PR10, Van PH11, Shibl AM12, Song JH13, Ko KS14.

Author information

Abstract

The prevalence, antimicrobial susceptibility, and genotypes of Streptococcus pneumoniae "putative serotype 6E" isolates from Asian countries were investigated. A total of 244 S. pneumoniae serogroup 6 isolates obtained from 11 Asian countries were included in this study. Of the 244 serogroup 6 isolates, 101 (41.4%) were typed as "putative serotype 6E," followed by serotypes 6A, 6B, 6C, and 6D (27.0, 20.1, 5.7, and 5.7%, respectively). Multilocus sequence typing revealed that clonal complex (CC) 90, including ST90 and its variants, was the most prevalent clonal group of "putative serotype 6E" isolates (n = 63; 62.4%). CC146 and CC315 were also found frequently in some of the countries. Most of the "putative serotype 6E" isolates showed very high resistance rates against cefuroxime, erythromycin, azithromycin, clarithromycin, clindamycin, and trimethoprim/sulfamethoxazole, probably due to their highly resistant to antimicrobials clone, CC90. Our results indicate that "putative serotype 6E" is prevalent in Asian countries. The clonal dissemination of "putative serotype 6E" isolates was also identified.

Copyright © 2014 Elsevier Inc. All rights reserved.

KEYWORDS:

CC90; Pneumococci; Serogroup 6

PMID: 25439447 [PubMed - as supplied by publisher]

Natural transformation and genome evolution in Streptococcus pneumoniae.

Infect Genet Evol. 2014 Nov 4. pii: S1567-1348(14)00391-8. doi: 10.1016/j.meegid.2014.10.020. [Epub ahead of print]

Natural transformation and genome evolution in Streptococcus pneumoniae.

Straume D1, Stamsås GA1, Håvarstein LS2.

Author information

Abstract

Streptococcus pneumoniae is a frequent colonizer of the human nasopharynx that has the potential to cause severe infections such as pneumonia, bacteremia and meningitis. Despite considerable efforts to reduce the burden of pneumococcal disease, it continues to be a major public health problem. After the Second World War, antimicrobial therapy was introduced to fight pneumococcal infections, followed by the first effective vaccines more than half a century later. These clinical interventions generated a selection pressure that drove the evolution of vaccine-escape mutants and strains that were highly resistant against antibiotics. The remarkable ability of S. pneumoniae to acquire drug resistance and evade vaccine pressure is due to its recombination-mediated genetic plasticity. S. pneumoniae is competent for natural genetic transformation, a property that enables the pneumococcus to acquire new traits by taking up naked DNA from the environment and incorporating it into its genome through homologous recombination. In the present paper, we review current knowledge on pneumococcal transformation, and discuss how the pneumococcus uses this mechanism to adapt and survive under adverse and fluctuating conditions.

Copyright © 2014 Elsevier B.V. All rights reserved.

KEYWORDS:

Fratricide; Genome evolution; Natural genetic transformation; Penicillin resistance; Streptococcus pneumoniae

PMID: 25445643 [PubMed - as supplied by publisher]

Identification of Proteins in Streptococcus pneumoniae by Reverse Vaccinology and Genetic Diversity of These Proteins in Clinical Isolates.

Appl Biochem Biotechnol. 2014 Dec 2. [Epub ahead of print]

Identification of Proteins in Streptococcus pneumoniae by Reverse Vaccinology and Genetic Diversity of These Proteins in Clinical Isolates.

Argondizzo AP1, da Mota FF, Pestana CP, Reis JN, de Miranda AB, Galler R, Medeiros MA.

Author information

Abstract

Streptococcus pneumoniae is a major cause of morbidity and mortality worldwide. Virulence-associated proteins common and conserved among all capsular types now represent the best strategy to combat pneumococcal infections. Our aim was to identify conserved targets in pneumococci that showed positive prediction for lipoprotein and extracellular subcellular location using bioinformatics programs and verify the distribution and the degree of conservation of these targets in pneumococci. These targets can be considered potential vaccine candidate to be evaluated in the future. A set of 13 targets were analyzed and confirmed the presence in all pneumococci tested. These 13 genes were highly conserved showing around >96 % of amino acid and nucleotide identity, but they were also present and show high identity in the closely related species Streptococcus mitis, Streptococcus oralis, and Streptococcus pseudopneumoniae. S. oralis clusters away from S. pneumoniae, while S. pseudopneumoniae and S. mitis cluster closer. The divergence between the selected targets was too small to be observed consistently in phylogenetic groups between the analyzed genomes of S. pneumoniae. The proteins analyzed fulfill two of the initial criteria of a vaccine candidate: targets are present in a variety of different pneumococci strains including different serotypes and are conserved among the samples evaluated.

PMID: 25448632 [PubMed - as supplied by publisher]

Endocytosis of Streptococcus pneumoniae via the polymeric immunoglobulin receptor of epithelial cells relies on clathrin and caveolin dependent mechanisms.

Int J Med Microbiol. 2014 Nov;304(8):1233-46. doi: 10.1016/j.ijmm.2014.10.001. Epub 2014 Oct 14.

Endocytosis of Streptococcus pneumoniae via the polymeric immunoglobulin receptor of epithelial cells relies on clathrin and caveolin dependent mechanisms.

Asmat TM1, Agarwal V2, Saleh M3, Hammerschmidt S4.

Author information

Abstract

Colonization of Streptococcus pneumoniae (pneumococci) is a prerequisite for bacterial dissemination and their capability to enter the bloodstream. Pneumococci have evolved various successful strategies to colonize the mucosal epithelial barrier of humans. A pivotal mechanism of host cell invasion implicated with invasive diseases is promoted by the interaction of pneumococcal PspC with the polymeric Ig-receptor (pIgR). However, the mechanism(s) of pneumococcal endocytosis and the intracellular route of pneumococci upon uptake by the PspC-pIgR-interaction are not known. Here, we demonstrate by using a combination of pharmacological inhibitors and genetics interference approaches the involvement of active dynamin-dependent caveolae and clathrin-coated vesicles for pneumococcal uptake via the PspC-pIgR mechanism. Depleting cholesterol from host cell membranes and disruption of lipid microdomains impaired pneumococcal internalization. Moreover, chemical inhibition of clathrin or functional inactivation of dynamin, caveolae or clathrin by RNA interference significantly affected pneumococcal internalization suggesting that clathrin-mediated endocytosis (CME) and caveolae are involved in the bacterial uptake process. Confocal fluorescence microscopy of pIgR-expressing epithelial cells infected with pneumococci or heterologous Lactococcus lactis expressing PspC demonstrated bacterial co-localization with fluorescent-tagged clathrin and early as well as recycling or late endosomal markers such as Lamp1, Rab5, Rab4, and Rab7, respectively. In conclusion these data suggest that PspC-promoted uptake is mediated by both CME and caveolae. After endocytosis pneumococci are routed via the endocytic pathway into early endosomes and are then sorted into recycling or late endosomes, which can result in pneumococcal killing in phagolysosomes or transcytosis via recycling endosomes.

Copyright © 2014 Elsevier GmbH. All rights reserved.

KEYWORDS:

Adherence; Caveolin; Clathrin; Dynamin; Endocytosis; Polymeric Ig receptor; PspC; Rab; Streptococcus pneumoniae

PMID: 25455218 [PubMed - in process]

• 
  

Structural determination of Streptococcus pneumoniae repeat units in serotype 41A and 41F capsular polysaccharides to probe gene functions in the corresponding capsular biosynthetic loci.

Carbohydr Res. 2014 Dec 5;400:26-32. doi: 10.1016/j.carres.2014.08.017. Epub 2014 Sep 16.

Structural determination of Streptococcus pneumoniae repeat units in serotype 41A and 41F capsular polysaccharides to probe gene functions in the corresponding capsular biosynthetic loci.

Petersen BO1, Skovsted IC2, Paulsen BS3, Redondo AR2, Meier S4.

Author information

Abstract

We report the repeating unit structures of the native capsular polysaccharides of Streptococcus pneumoniae serotypes 41A and 41F. Structural determinations yielded six carbohydrate units in the doubly branched repeating unit to give the following structure for serotype 41A: The structure determinations were motivated (1) by an ambition to help close the remaining gaps in S. pneumoniae capsular polysaccharide structures, and (2) by the attempt to derive functional annotations of carbohydrate active enzymes in the biosynthesis of bacterial polysaccharides from the determined structures. An activity present in 41F but not 41A is identified as an acetyltransferase acting on the rhamnopyranosyl sidechain E. The genes encoding the formation of the six glycosidic bonds in serogroup 41 were determined from the capsular polysaccharide structures of serotype 41A, 41F, and genetically related serotypes, in conjunction with corresponding genomic information and computational homology searches. In combination with complementary information, NMR spectroscopy considerably simplifies the functional annotation of carbohydrate active enzymes in the biosynthesis of bacterial polysaccharides.

Copyright © 2014 Elsevier Ltd. All rights reserved.

KEYWORDS:

Biosynthetic loci; Capsular polysaccharide; NMR; Serotype 41A; Streptococcus pneumoniae

PMID: 25457607 [PubMed - in process]

Increase in Fitness of Streptococcus pneumoniae is Associated with the Severity of Necrotizing Pneumonia.

Pediatr Infect Dis J. 2014 Dec 3. [Epub ahead of print]

Increase in Fitness of Streptococcus pneumoniae is Associated with the Severity of Necrotizing Pneumonia.

Hsieh YC1, Chi H, Chang KY, Lai SH, Mu JJ, Wong KS, Liu CC, Huang YC, Lin HC, Chang LY, Huang YC, Huang LM; for The Taiwan Pediatric Infectious Diseases Alliance.

Author information

Abstract

BACKGROUND::

The incidence of necrotizing pneumococcal pneumonia has increased during the past two decades. We hypothothesized that increased pneumococcal load or augmented inflammatory cytokine production might lead to destructive pneumococcal lung disease.

METHODS::

This study enrolled prospectively 0-18 year-old children with a diagnosis of community-acquired pneumonia with pleural effusion admitted to 6 medical centers during March 2010 to April 2012. Children were diagnosed with pneumococcal empyema if the pleural fluid tested positive for quantitative pneumococcal (lytA) detection by real-time polymerase chain reaction (RT-PCR). Pneumococcal empyema cases were further divided into four groups according to necrosis severity: 0) non-necrosis, 1) mild necrosis, 2) cavitation, and 3) bronchopleural fistula (BPF). Nasopharyngeal and pleural pneumococcal load, as well as proinflammatory cytokines (TNF-α, IL-1β, IL-6, IL-8), Th1-(IL-2, IFN-γ), Th2-(IL-4, IL-10), and Th17-cytokines (IL-17) in the pleural fluid were measured.

RESULTS::

Serotypes 19A and 3 accounted for 69.4% and 12.5% (respectively) of 72 cases of pneumococcal empyema. Pleural pneumococcal load was significantly higher in serotypes 19A and 3 infection than for other strains causing infection (P=0.006). There was a correlation between nasopharyngeal and pleural pneumococcal load (ρ=0.35; P=0.05). In multivariate ordinal logistic regression analysis, pleural pneumococcal load (adjusted odds ratio [aOR], 1.79; 95% confidence interval [CI], 1.03-3.06), and IL-8 (aOR, 2.64; 95% CI, 1.21-5.75) were independent factors associated with the severity of lung necrosis.

CONCLUSIONS::

Evolution of S. pneumoniae toward increased fitness in their interaction with host and exaggerated IL-8 expression may be responsible for the increase of necrotizing pneumococcal pneumonia.

PMID: 25461475 [PubMed - as supplied by publisher]

MapZ marks the division sites and positions FtsZ rings in Streptococcus pneumoniae.

Nature. 2014 Nov 26. doi: 10.1038/nature13966. [Epub ahead of print]

MapZ marks the division sites and positions FtsZ rings in Streptococcus pneumoniae.

Fleurie A1, Lesterlin C2, Manuse S1, Zhao C1, Cluzel C3, Lavergne JP1, Franz-Wachtel M4, Macek B4, Combet C1, Kuru E5, VanNieuwenhze MS5, Brun YV5, Sherratt D2, Grangeasse C1.

Author information

Abstract

In every living organism, cell division requires accurate identification of the division site and placement of the division machinery. In bacteria, this process is traditionally considered to begin with the polymerization of the highly conserved tubulin-like protein FtsZ into a ring that locates precisely at mid-cell. Over the past decades, several systems have been reported to regulate the spatiotemporal assembly and placement of the FtsZ ring. However, the human pathogen Streptococcus pneumoniae, in common with many other organisms, is devoid of these canonical systems and the mechanisms of positioning the division machinery remain unknown. Here we characterize a novel factor that locates at the division site before FtsZ and guides septum positioning in pneumococcus. Mid-cell-anchored protein Z (MapZ) forms ring structures at the cell equator and moves apart as the cell elongates, therefore behaving as a permanent beacon of division sites. MapZ then positions the FtsZ ring through direct protein-protein interactions. MapZ-mediated control differs from previously described systems mostly on the basis of negative regulation of FtsZ assembly. Furthermore, MapZ is an endogenous target of the Ser/Thr kinase StkP, which was recently shown to have a central role in cytokinesis and morphogenesis of S. pneumoniae. We show that both phosphorylated and non-phosphorylated forms of MapZ are required for proper Z-ring formation and dynamics. Altogether, this work uncovers a new mechanism for bacterial cell division that is regulated by phosphorylation and illustrates that nature has evolved a diversity of cell division mechanisms adapted to the different bacterial clades.

PMID: 25470041 [PubMed - as supplied by publisher]

The Role of Macrophages in the Innate Immune Response to Streptococcus pneumoniae and Staphylococcus aureus: Mechanisms and Contrasts.

Adv Microb Physiol. 2014;65:125-202. doi: 10.1016/bs.ampbs.2014.08.004. Epub 2014 Nov 4.

The Role of Macrophages in the Innate Immune Response to Streptococcus pneumoniae and Staphylococcus aureus: Mechanisms and Contrasts.

Cole J1, Aberdein J1, Jubrail J1, Dockrell DH2.

Author information

Abstract

Macrophages are critical mediators of innate immune responses against bacteria. The Gram-positive bacteria Streptococcus pneumoniae and Staphylococcus aureus express a range of virulence factors, which challenge macrophages' immune competence. We review how macrophages respond to this challenge. Macrophages employ a range of strategies to phagocytose and kill each pathogen. When the macrophages capacity to clear bacteria is overwhelmed macrophages play important roles in orchestrating the inflammatory response through pattern recognition receptor-mediated responses. Macrophages also ensure the inflammatory response is tightly constrained, to avoid tissue damage, and play an important role in downregulating the inflammatory response once initial bacterial replication is controlled.

© 2014 Elsevier Ltd All rights reserved.

KEYWORDS:

Activation; Antimicrobicidal mechanisms; Macrophages; Pattern recognition receptors; Phagocytosis; Phagolysosomes; Staphylococcus aureus; Streptococcus pneumoniae

PMID: 25476766 [PubMed - in process]

Global phylogenomic analysis of nonencapsulated Streptococcus pneumoniae reveals a deep-branching classic lineage that is distinct from multiple sporadic lineages.

Genome Biol Evol. 2014 Dec 4. pii: evu263. [Epub ahead of print]

Global phylogenomic analysis of nonencapsulated Streptococcus pneumoniae reveals a deep-branching classic lineage that is distinct from multiple sporadic lineages.

Hilty M1, Wüthrich D2, Salter SJ3, Engel H4, Campbell S4, Sá-Leão R5, de Lencastre H6, Hermans P7, Sadowy E8, Turner P9, Chewapreecha C10, Diggle M11, Pluschke G12, McGee L13, Eser OK14, Low DE15, Smith-Vaughan H16, Endimiani A4, Küffer M4, Dupasquier M17, Beaudoing E17, Weber J17, Bruggmann R2, Hanage WP18, Parkhill J3, Hathaway LJ4, Mühlemann K19, Bentley SD20.

Author information

Abstract

The surrounding capsule of Streptococcus pneumoniae has been identified as a major virulence factor and is targeted by pneumococcal conjugate vaccines (PCV). However, nonencapsulated Streptococcus pneumoniae (Non-Ec-Sp) have also been isolated globally, mainly in carriage studies. It is unknown if Non-Ec-Sp evolve sporadically, if they have high antibiotic non-susceptiblity rates and a unique, specific gene content. Here, whole genome sequencing of 131 Non-Ec-Sp isolates sourced from 17 different locations around the world was performed. Results revealed a deep-branching classic lineage that is distinct from multiple sporadic lineages. The sporadic lineages clustered with a previously sequenced, global collection of encapsulated S. pneumoniae (Ec-Sp) isolates while the classic lineage is comprised mainly of the frequently identified multi-locus sequences types ST344 (n=39) and ST448 (n=40). All ST344 and nine ST448 isolates had high non-susceptiblity rates to β-lactams and other antimicrobials. Analysis of the accessory genome reveals that the classic Non-Ec-Sp contained an increased number of mobile elements, than Ec-Sp and sporadic Non-Ec-Sp. Performing adherence assays to human epithelial cells for selected classic and sporadic Non-Ec-Sp revealed that the presence of a integrative conjugative element (ICE) results in increased adherence to human epithelial cells (P=0.005). In contrast, sporadic Non-Ec-Sp lacking the ICE had greater growth in vitro possibly resulting in improved fitness. In conclusion, Non-Ec-Sp isolates from the classic lineage have evolved separately. They have spread globally, are well adapted to nasopharyngeal carriage and are able to coexist with Ec-Sp. Due to continued use of pneumococcal conjugate vaccines, Non-Ec-Sp may become more prevalent.

© The Author(s) 2014. Published by Oxford University Press on behalf of the Society for Molecular Biology and Evolution.

KEYWORDS:

Pneumococcal isolates; antibiotic non-susceptibility; comparative genomics; integrative conjugative elements (ICEs); whole genome sequencing

PMID: 25480686 [PubMed - as supplied by publisher]