scholarly journals Asymptomatic Carriage of Group A Streptococcus Is Associated with Elimination of Capsule Production

2014 ◽  
Vol 82 (9) ◽  
pp. 3958-3967 ◽  
Author(s):  
Anthony R. Flores ◽  
Brittany E. Jewell ◽  
Randall J. Olsen ◽  
Samuel A. Shelburne ◽  
Nahuel Fittipaldi ◽  
...  
Keyword(s):  
Pathogenic Bacteria ◽  
Group A Streptococcus ◽  
Ex Vivo ◽  
Human Subjects ◽  
Full Genome Sequencing ◽  
Isogenic Strain ◽  
Capsule Production ◽  
Key Factor ◽  
Group A

ABSTRACTHumans commonly carry pathogenic bacteria asymptomatically, but despite decades of study, the underlying molecular contributors remain poorly understood. Here, we show that a group A streptococcus carriage strain contains a frameshift mutation in thehasAgene resulting in loss of hyaluronic acid capsule biosynthesis. This mutation was repaired by allelic replacement, resulting in restoration of capsule production in the isogenic derivative strain. The “repaired” isogenic strain was significantly more virulent than the carriage strain in a mouse model of necrotizing fasciitis and had enhanced growthex vivoin human blood. Importantly, the repaired isogenic strain colonized the mouse oropharynx with significantly greater bacterial burden and had significantly reduced ability to internalize into cultured epithelial cells than the acapsular carriage strain. We conducted full-genome sequencing of 81 strains cultured serially from 19 epidemiologically unrelated human subjects and discovered the common theme that mutations negatively affecting capsule biosynthesis arisein vivoin thehasoperon. The significantly decreased capsule production is a key factor contributing to the molecular détente between pathogen and host. Our discoveries suggest a general model for bacterial pathogens in which mutations that downregulate or ablate virulence factor production contribute to carriage.

scholarly journals Natural Variation in the Promoter of the Gene Encoding the Mga Regulator Alters Host-Pathogen Interactions in Group A Streptococcus Carrier Strains

2013 ◽  
Vol 81 (11) ◽  
pp. 4128-4138 ◽  
Author(s):  
Anthony R. Flores ◽  
Randall J. Olsen ◽  
Andrea Wunsche ◽  
Muthiah Kumaraswami ◽  
Samuel A. Shelburne ◽  
...  
Keyword(s):  
Pathogenic Bacteria ◽  
Group A Streptococcus ◽  
Ex Vivo ◽  
Asymptomatic Carrier ◽  
Carrier State ◽  
Wild Type ◽  
Gene Encoding ◽  
Content Type ◽  
Group A

ABSTRACTHumans commonly carry pathogenic bacteria asymptomatically, but the molecular factors underlying microbial asymptomatic carriage are poorly understood. We previously reported that two epidemiologically unassociated serotype M3 group AStreptococcus(GAS) carrier strains had an identical 12-bp deletion in the promoter of the gene encoding Mga, a global positive gene regulator. Herein, we report on studies designed to test the hypothesis that the identified 12-bp deletion in themgapromoter alters GAS virulence, thereby potentially contributing to the asymptomatic carrier phenotype. Using allelic exchange, we introduced the variant promoter into a serotype M3 invasive strain and the wild-type promoter into an asymptomatic carrier strain. Compared to strains with the wild-typemgapromoter, we discovered that strains containing the promoter with the 12-bp deletion produced significantly fewermgaand Mga-regulated gene transcripts. Consistent with decreasedmgatranscripts, strains containing the variantmgapromoter were also significantly less virulent inin vivoandex vivomodels of GAS disease. Further, we provide evidence that the pleiotropic regulator protein CodY binds to themgapromoter and that the 12-bp deletion in themgapromoter reduces CodY-mediatedmgatranscription. We conclude that the naturally occurring 12-bp deletion in themgapromoter significantly alters the pathogen-host interaction of these asymptomatic carrier strains. Our findings provide new insight into the molecular basis of the carrier state of an important human pathogen.

scholarly journals Group A Streptococcus AdcR Regulon Participates in Bacterial Defense against Host-Mediated Zinc Sequestration and Contributes to Virulence

2020 ◽  
Vol 88 (8) ◽  
Author(s):  
Nishanth Makthal ◽  
Hackwon Do ◽  
Brian M. Wendel ◽  
Randall J. Olsen ◽  
John D. Helmann ◽  
...  
Keyword(s):  
Pathogenic Bacteria ◽  
Group A Streptococcus ◽  
Zn Deficiency ◽  
Direct Competition ◽  
Mutant Strains ◽  
Genes Encoding ◽  
Group A ◽  
Gas Interactions

ABSTRACT Colonization by pathogenic bacteria depends on their ability to overcome host nutritional defenses and acquire nutrients. The human pathogen group A streptococcus (GAS) encounters the host defense factor calprotectin (CP) during infection. CP inhibits GAS growth in vitro by imposing zinc (Zn) limitation. However, GAS counterstrategies to combat CP-mediated Zn limitation and the in vivo relevance of CP-GAS interactions to bacterial pathogenesis remain unknown. Here, we report that GAS upregulates the AdcR regulon in response to CP-mediated Zn limitation. The AdcR regulon includes genes encoding Zn import (adcABC), Zn sparing (rpsN.2), and Zn scavenging systems (adcAII, phtD, and phtY). Each gene in the AdcR regulon contributes to GAS Zn acquisition and CP resistance. The ΔadcC and ΔrpsN.2 mutant strains were the most susceptible to CP, whereas the ΔadcA, ΔadcAII, and ΔphtD mutant strains displayed less CP sensitivity during growth in vitro. However, the ΔphtY mutant strain did not display an increased CP sensitivity. The varied sensitivity of the mutant strains to CP-mediated Zn limitation suggests distinct roles for individual AdcR regulon genes in GAS Zn acquisition. GAS upregulates the AdcR regulon during necrotizing fasciitis infection in WT mice but not in S100a9−/− mice lacking CP. This suggests that CP induces Zn deficiency in the host. Finally, consistent with the in vitro results, several of the AdcR regulon genes are critical for GAS virulence in WT mice, whereas they are dispensable for virulence in S100a9−/− mice, indicating the direct competition for Zn between CP and proteins encoded by the GAS AdcR regulon during infection.

scholarly journals Genome-wide analysis of in vivo CcpA binding with and without its key co-factor HPr in the major human pathogen group A Streptococcus

2020 ◽  
Author(s):  
Sruti DebRoy ◽  
Victor Aliaga Tobar ◽  
Gabriel Galvez ◽  
Srishtee Arora ◽  
Xiaowen Liang ◽  
...  
Keyword(s):  
Dna Binding ◽  
Pathogenic Bacteria ◽  
Group A Streptococcus ◽  
Protein A ◽  
Data Availability ◽  
Human Pathogen ◽  
Transcript Levels ◽  
Catabolite Control Protein A ◽  
Group A

SummaryCatabolite control protein A (CcpA) is a master regulator of carbon source utilization and contributes to the virulence of numerous medically important Gram-positive bacteria. Most functional assessments of CcpA, including interaction with its key co-factor HPr, have been performed in non-pathogenic bacteria. In this study we aimed to identify the in vivo DNA binding profile of CcpA and assess the extent to which HPr is required for CcpA-mediated regulation and DNA binding in the major human pathogen group A Streptococcus (GAS). Using a combination RNAseq/ChIPseq approach, we found that CcpA affects transcript levels of 514 of 1667 GAS genes (31%) whereas direct DNA binding was identified for 105 GAS genes. Three of the directly regulated genes encode the key GAS virulence factors Streptolysin S, PrtS (IL-8 degrading proteinase), and SpeB (cysteine protease). Mutating CcpA Val301 to Ala (strain 2221-CcpA-V301A) abolished interaction between CcpA and HPr and impacted the transcript levels of 205 genes (40%) in the total CcpA regulon. By ChIPseq analysis, CcpAV301A bound to DNA from 74% of genes bound by wild-type CcpA, but generally with lower affinity. These data delineate the direct CcpA regulon and clarify the HPr-dependent and independent activities of CcpA in a key pathogenic bacterium.Data sharing and data availabilityThe data that support the findings of this study are available from the corresponding author upon reasonable request.

scholarly journals Signaling by a Conserved Quorum Sensing Pathway Contributes to GrowthEx Vivoand Oropharyngeal Colonization of Human Pathogen Group A Streptococcus

2018 ◽  
Vol 86 (5) ◽  
Author(s):  
Nishanth Makthal ◽  
Hackwon Do ◽  
Arica R. VanderWal ◽  
Randall J. Olsen ◽  
James M. Musser ◽  
...  
Keyword(s):  
Quorum Sensing ◽  
Signaling Pathway ◽  
Group A Streptococcus ◽  
Ex Vivo ◽  
Human Saliva ◽  
Distinct Pattern ◽  
Human Pathogen ◽  
Bacterial Gene ◽  
Group A

ABSTRACTBacterial virulence factor production is a highly coordinated process. The temporal pattern of bacterial gene expression varies in different host anatomic sites to overcome niche-specific challenges. The human pathogen group A streptococcus (GAS) produces a potent secreted protease, SpeB, that is crucial for pathogenesis. Recently, we discovered that a quorum sensing pathway comprised of a leaderless short peptide, SpeB-inducing peptide (SIP), and a cytosolic global regulator, RopB, controlsspeBexpression in concert with bacterial population density. The SIP signaling pathway is activein vivoand contributes significantly to GAS invasive infections. In the current study, we investigated the role of the SIP signaling pathway in GAS-host interactions during oropharyngeal colonization. The SIP signaling pathway is functional during growthex vivoin human saliva. SIP-mediatedspeBexpression plays a crucial role in GAS colonization of the mouse oropharynx. GAS employs a distinct pattern of SpeB production during growthex vivoin saliva that includes a transient burst ofspeBexpression during early stages of growth coupled with sustained levels of secreted SpeB protein. SpeB production aids GAS survival by degrading LL37, an abundant human antimicrobial peptide. We found that SIP signaling occurs during growth in human bloodex vivo. Moreover, the SIP signaling pathway is critical for GAS survival in blood. SIP-dependentspeBregulation is functional in strains of diverseemmtypes, indicating that SIP signaling is a conserved virulence regulatory mechanism. Our discoveries have implications for future translational studies.

scholarly journals Defects in ex vivo and in vivo growth and sensitivity to osmotic stress of group A Streptococcus caused by interruption of response regulator gene vicR

Microbiology ◽  
2006 ◽  
Vol 152 (4) ◽  
pp. 967-978 ◽  
Author(s):  
Mengyao Liu ◽  
Tracey S. Hanks ◽  
Jinlian Zhang ◽  
Michael J. McClure ◽  
Daniel W. Siemsen ◽  
...  
Keyword(s):  
Cell Wall ◽  
Osmotic Stress ◽  
Microarray Analysis ◽  
Deletion Mutant ◽  
Group A Streptococcus ◽  
Ex Vivo ◽  
Regulatory System ◽  
Phosphotransferase System ◽  
Group A

The regulator VicR of the two-component regulatory system VicRK is essential in several Gram-positive bacteria. However, the authors were able to generate an unconditional vicR insertional mutant of group A Streptococcus. This mutant grew well in rich media but not in non-immune human blood and serum, had attenuated virulence, and was unstable in mice. Complementation of the mutant with vicR expressed in trans restored its phenotype to wild-type. A vicK deletion mutant had a phenotype similar to that of the vicR mutant. Phagocytosis and killing of the vicR mutant were normal, suggesting that VicRK does not regulate processes involved in evasion of host defence. Microarray analysis showed that vicR inactivation down-regulated the transcription of 13 genes, including putative cell wall hydrolase gene pcsB and spy1058–1060, which encode a putative phosphotransferase system enzyme II for carbohydrate transport, and upregulated the expression of five genes, including spy0183 and spy0184, which encode an osmoprotectant transporter OpuA. Consistent with microarray analysis, the vicR mutant took up more of the osmoprotectants betaine and proline and was sensitive to osmotic stress, indicating that vicR inactivation induced osmotic stress and increased susceptibility to osmotic pressure. Additionally, a spy1060 deletion mutant also displayed attenuated virulence. These results suggest that VicRK regulates processes involved in cell wall metabolism, nutrient uptake, and osmotic protection.

scholarly journals Genome‐wide analysis of in vivo CcpA binding with and without its key co‐factor HPr in the major human pathogen group A Streptococcus

2020 ◽  
Author(s):  
Sruti DebRoy ◽  
Victor Aliaga‐Tobar ◽  
Gabriel Galvez ◽  
Srishtee Arora ◽  
Xiaowen Liang ◽  
...  
Keyword(s):  
Group A Streptococcus ◽  
Human Pathogen ◽  
Genome Wide Analysis ◽  
Genome Wide ◽  
Group A

scholarly journals SpyAD, a Moonlighting Protein of Group A Streptococcus Contributing to Bacterial Division and Host Cell Adhesion

2014 ◽  
Vol 82 (7) ◽  
pp. 2890-2901 ◽  
Author(s):  
Marilena Gallotta ◽  
Giovanni Gancitano ◽  
Giampiero Pietrocola ◽  
Marirosa Mora ◽  
Alfredo Pezzicoli ◽  
...  
Keyword(s):  
Cell Division ◽  
Mammalian Cells ◽  
Group A Streptococcus ◽  
Host Cells ◽  
Knockout Mutant ◽  
Content Type ◽  
Moonlighting Protein ◽  
Group A

ABSTRACTGroup A streptococcus (GAS) is a human pathogen causing a wide repertoire of mild and severe diseases for which no vaccine is yet available. We recently reported the identification of three protein antigens that in combination conferred wide protection against GAS infection in mice. Here we focused our attention on the characterization of one of these three antigens, Spy0269, a highly conserved, surface-exposed, and immunogenic protein of unknown function. Deletion of thespy0269gene in a GAS M1 isolate resulted in very long bacterial chains, which is indicative of an impaired capacity of the knockout mutant to properly divide. Confocal microscopy and immunoprecipitation experiments demonstrated that the protein was mainly localized at the cell septum and could interactin vitrowith the cell division protein FtsZ, leading us to hypothesize that Spy0269 is a member of the GAS divisome machinery. Predicted structural domains and sequence homologies with known streptococcal adhesins suggested that this antigen could also play a role in mediating GAS interaction with host cells. This hypothesis was confirmed by showing that recombinant Spy0269 could bind to mammalian epithelial cellsin vitroand thatLactococcus lactisexpressing Spy0269 on its cell surface could adhere to mammalian cellsin vitroand to mice nasal mucosain vivo. On the basis of these data, we believe that Spy0269 is involved both in bacterial cell division and in adhesion to host cells and we propose to rename this multifunctional moonlighting protein as SpyAD (StreptococcuspyogenesAdhesion andDivision protein).

Invasive M1T1 group A Streptococcus undergoes a phase-shift in vivo to prevent proteolytic degradation of multiple virulence factors by SpeB

2003 ◽  
Vol 51 (1) ◽  
pp. 123-134 ◽  
Author(s):  
Ramy K. Aziz ◽  
Michael J. Pabst ◽  
Arthur Jeng ◽  
Rita Kansal ◽  
Donald. E. Low ◽  
...  
Keyword(s):  
Phase Shift ◽  
Virulence Factors ◽  
Group A Streptococcus ◽  
Proteolytic Degradation ◽  
Group A

scholarly journals Streptococcus pyogenes evades adaptive immunity through specific IgG glycan hydrolysis

2019 ◽  
Vol 216 (7) ◽  
pp. 1615-1629 ◽  
Author(s):  
Andreas Naegeli ◽  
Eleni Bratanis ◽  
Christofer Karlsson ◽  
Oonagh Shannon ◽  
Raja Kalluru ◽  
...  
Keyword(s):  
Streptococcus Pyogenes ◽  
Vaccine Development ◽  
Group A Streptococcus ◽  
Invasive Infection ◽  
Invasive Infections ◽  
Life Threatening ◽  
Group A ◽  
Specific Igg

Streptococcus pyogenes (Group A streptococcus; GAS) is a human pathogen causing diseases from uncomplicated tonsillitis to life-threatening invasive infections. GAS secretes EndoS, an endoglycosidase that specifically cleaves the conserved N-glycan on IgG antibodies. In vitro, removal of this glycan impairs IgG effector functions, but its relevance to GAS infection in vivo is unclear. Using targeted mass spectrometry, we characterized the effects of EndoS on host IgG glycosylation during the course of infections in humans. Substantial IgG glycan hydrolysis occurred at the site of infection and systemically in the severe cases. We demonstrated decreased resistance to phagocytic killing of GAS lacking EndoS in vitro and decreased virulence in a mouse model of invasive infection. This is the first described example of specific bacterial IgG glycan hydrolysis during infection and thereby verifies the hypothesis that EndoS modifies antibodies in vivo. This mechanisms of immune evasion could have implications for treatment of severe GAS infections and for future efforts at vaccine development.

scholarly journals Identification of Group A Streptococcus Antigenic Determinants Upregulated In Vivo

2005 ◽  
Vol 73 (9) ◽  
pp. 6026-6038 ◽  
Author(s):  
Kowthar Y. Salim ◽  
Dennis G. Cvitkovitch ◽  
Peter Chang ◽  
Darrin J. Bast ◽  
Martin Handfield ◽  
...  
Keyword(s):  
Murine Model ◽  
Vibrio Vulnificus ◽  
Group A Streptococcus ◽  
Hypothetical Protein ◽  
Invasive Disease ◽  
Antigenic Determinants ◽  
Expression Library ◽  
Group A

ABSTRACT Group A Streptococcus (GAS) causes a range of diseases in humans, from mild noninvasive infections to severe invasive infections. The molecular basis for the varying severity of disease remains unclear. We identified genes expressed during invasive disease using in vivo-induced antigen technology (IVIAT), applied for the first time in a gram-positive organism. Convalescent-phase sera from patients with invasive disease were pooled, adsorbed against antigens derived from in vitro-grown GAS, and used to screen a GAS genomic expression library. A murine model of invasive GAS disease was included as an additional source of sera for screening. Sequencing DNA inserts from clones reactive with both human and mouse sera indicated 16 open reading frames with homology to genes involved in metabolic activity to genes of unknown function. Of these, seven genes were assessed for their differential expression by quantitative real-time PCR both in vivo, utilizing a murine model of invasive GAS disease, and in vitro at different time points of growth. Three gene products—a putative penicillin-binding protein 1A, a putative lipoprotein, and a conserved hypothetical protein homologous to a putative translation initiation inhibitor in Vibrio vulnificus—were upregulated in vivo, suggesting that these genes play a role during invasive disease.

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