scholarly journals Sweet revenge - Streptococcus pyogenes showcases first example of immune evasion through specific IgG glycan hydrolysis

2019 ◽  
Author(s):  
Andreas Naegeli ◽  
Eleni Bratanis ◽  
Christofer Karlsson ◽  
Oonagh Shannon ◽  
Raja Kalluru ◽  
...  
Keyword(s):  
Streptococcus Pyogenes ◽  
Immune Evasion ◽  
Vaccine Development ◽  
Group A Streptococcus ◽  
Model Systems ◽  
Invasive Infection ◽  
Invasive Infections ◽  
Set Up

AbstractStreptococcus pyogenes (Group A streptococcus, GAS) is an important human pathogen responsible for a wide variety of diseases from uncomplicated tonsillitis to life-threatening invasive infections. GAS secretes EndoS, an endoglycosidase able to specifically cleave the conserved N-glycan on human 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 were able to characterize the effects of EndoS on host IgG glycosylation during the course of natural infections in human patients. We found substantial IgG glycan hydrolysis locally at site of infection as well as systemically in the most severe cases. Using these findings we were able to set up appropriate model systems to demonstrate decreased resistance to phagocytic killing of GAS lacking EndoS in vitro, as well as decreased virulence in a mouse model of invasive infection. This study represents the first described example of specific bacterial IgG glycan hydrolysis during infection and highlights the importance of IgG glycan hydrolysis for streptococcal pathogenesis. We thereby offer new insights into the mechanism of immune evasion employed by this pathogen with clear implications for treatment of severe GAS infections and future efforts at vaccine development.

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 The Transcriptional Regulator CpsY Is Important for Innate Immune Evasion in Streptococcus pyogenes

2016 ◽  
Vol 85 (3) ◽  
Author(s):  
Luis A. Vega ◽  
Kayla M. Valdes ◽  
Ganesh S. Sundar ◽  
Ashton T. Belew ◽  
Emrul Islam ◽  
...  
Keyword(s):  
Streptococcus Pyogenes ◽  
Immune Evasion ◽  
Immune Cell ◽  
Group A Streptococcus ◽  
Transcriptional Regulator ◽  
Innate Immune ◽  
Content Type ◽  
Human Host

ABSTRACTAs an exclusively human pathogen,Streptococcus pyogenes(the group A streptococcus [GAS]) has specifically adapted to evade host innate immunity and survive in multiple tissue niches, including blood. GAS can overcome the metabolic constraints of the blood environment and expresses various immunomodulatory factors necessary for survival and immune cell resistance. Here we present our investigation of one such factor, the predicted LysR family transcriptional regulator CpsY. The encoding gene,cpsY, was initially identified as being required for GAS survival in a transposon-site hybridization (TraSH) screen in whole human blood. CpsY is homologous with transcriptional regulators ofStreptococcus mutans(MetR),Streptococcus iniae(CpsY), andStreptococcus agalactiae(MtaR) that regulate methionine transport, amino acid metabolism, resistance to neutrophil-mediated killing, and survivalin vivo. Our investigation indicated that CpsY is involved in GAS resistance to innate immune cells of its human host. However, GAS CpsY does not manifest thein vitrophenotypes of its homologs in other streptococcal species. GAS CpsY appears to regulate a small set of genes that is markedly different from the regulons of its homologs. The differential expression of these genes depends on the growth medium, and CpsY modestly influences their expression. The GAS CpsY regulon includes known virulence factors (mntE,speB,spd,nga[spn],prtS[SpyCEP], andsse) and cell surface-associated factors of GAS (emm1,mur1.2,sibA[cdhA], andM5005_Spy0500). Intriguingly, the loss of CpsY in GAS does not result in virulence defects in murine models of infection, suggesting that CpsY function in immune evasion is specific to the human host.

scholarly journals AR-12 Has a Bactericidal Activity and a Synergistic Effect with Gentamicin against Group A Streptococcus

2021 ◽  
Vol 22 (21) ◽  
pp. 11617
Author(s):  
Nina Tsao ◽  
Ya-Chu Chang ◽  
Sung-Yuan Hsieh ◽  
Tang-Chi Li ◽  
Ching-Chen Chiu ◽  
...  
Keyword(s):  
Toxic Shock Syndrome ◽  
Group A Streptococcus ◽  
Streptococcal Toxic Shock Syndrome ◽  
Invasive Infection ◽  
Toxic Shock ◽  
Spherical Structures ◽  
Group A ◽  
Bacteria And Fungi

Streptococcus pyogenes (group A Streptococcus (GAS) is an important human pathogen that can cause severe invasive infection, such as necrotizing fasciitis and streptococcal toxic shock syndrome. The mortality rate of streptococcal toxic shock syndrome ranges from 20% to 50% in spite of antibiotics administration. AR-12, a pyrazole derivative, has been reported to inhibit the infection of viruses, intracellular bacteria, and fungi. In this report, we evaluated the bactericidal activities and mechanisms of AR-12 on GAS infection. Our in vitro results showed that AR-12 dose-dependently reduced the GAS growth, and 2.5 μg/mL of AR-12 significantly killed GAS within 2 h. AR-12 caused a remarkable reduction in nucleic acid and protein content of GAS. The expression of heat shock protein DnaK and streptococcal exotoxins was also inhibited by AR-12. Surveys of the GAS architecture by scanning electron microscopy revealed that AR-12-treated GAS displayed incomplete septa and micro-spherical structures protruding out of cell walls. Moreover, the combination of AR-12 and gentamicin had a synergistic antibacterial activity against GAS replication for both in vitro and in vivo infection. Taken together, these novel findings obtained in this study may provide a new therapeutic strategy for invasive GAS infection.

scholarly journals Characterization of an Extracellular Virulence FactorMade by Group A Streptococcus with Homology to theListeria monocytogenes Internalin Family ofProteins

2003 ◽  
Vol 71 (12) ◽  
pp. 7043-7052 ◽  
Author(s):  
Sean D. Reid ◽  
Alison G. Montgomery ◽  
Jovanka M. Voyich ◽  
Frank R. DeLeo ◽  
Benfang Lei ◽  
...  
Keyword(s):  
Protein Interactions ◽  
Group A Streptococcus ◽  
Shigella Flexneri ◽  
Immunoblot Analysis ◽  
Invasive Infections ◽  
Isogenic Mutant Strain ◽  
Group A ◽  
And Function

ABSTRACT Leucine-rich repeats (LRR) characterize a diverse array of proteins and function to provide a versatile framework for protein-protein interactions. Importantly, each of the bacterial LRR proteins that have been well described, including those of Listeria monocytogenes, Yersinia pestis, and Shigella flexneri, have been implicated in virulence. Here we describe an 87.4-kDa group A Streptococcus (GAS) protein (designated Slr, for streptococcal leucine-rich) containing 10 1/2 sequential units of a 22-amino-acid C-terminal LRR homologous to the LRR of the L. monocytogenes internalin family of proteins. In addition to the LRR domain, slr encodes a gram-positive signal secretion sequence characteristic of a lipoprotein and a putative N-terminal domain with a repeated histidine triad motif (HxxHxH). Real-time reverse transcriptase PCR assays indicated that slr is transcribed abundantly in vitro in the exponential phase of growth. Flow cytometry confirmed that Slr was attached to the GAS cell surface. Western immunoblot analysis of sera obtained from 80 patients with invasive infections, noninvasive soft tissue infections, pharyngitis, and rheumatic fever indicated that Slr is produced in vivo. An isogenic mutant strain lacking slr was significantly less virulent in an intraperitoneal mouse model of GAS infection and was significantly more susceptible to phagocytosis by human polymorphonuclear leukocytes. These studies characterize the first GAS LRR protein as an extracellular virulence factor that contributes to pathogenesis and may participate in evasion of the innate host defense.

scholarly journals Noroviruses—The State of the Art, Nearly Fifty Years after Their Initial Discovery

Viruses ◽  
2021 ◽  
Vol 13 (8) ◽  
pp. 1541
Author(s):  
Louisa F. Ludwig-Begall ◽  
Axel Mauroy ◽  
Etienne Thiry
Keyword(s):  
Vaccine Development ◽  
Analytical Techniques ◽  
Model Systems ◽  
Viral Gastroenteritis ◽  
Viral Reservoirs ◽  
Viral Egress ◽  
Trial Testing ◽  
Direct Acting

Human noroviruses are recognised as the major global cause of viral gastroenteritis. Here, we provide an overview of notable advances in norovirus research and provide a short recap of the novel model systems to which much of the recent progress is owed. Significant advances include an updated classification system, the description of alternative virus-like protein morphologies and capsid dynamics, and the further elucidation of the functions and roles of various viral proteins. Important milestones include new insights into cell tropism, host and microbial attachment factors and receptors, interactions with the cellular translational apparatus, and viral egress from cells. Noroviruses have been detected in previously unrecognised hosts and detection itself is facilitated by improved analytical techniques. New potential transmission routes and/or viral reservoirs have been proposed. Recent in vivo and in vitro findings have added to the understanding of host immunity in response to norovirus infection, and vaccine development has progressed to preclinical and even clinical trial testing. Ongoing development of therapeutics includes promising direct-acting small molecules and host-factor drugs.

scholarly journals First Streptococcus pyogenes Signature-Tagged Mutagenesis Screen Identifies Novel Virulence Determinants

2009 ◽  
Vol 77 (5) ◽  
pp. 1854-1865 ◽  
Author(s):  
Anne E. Kizy ◽  
Melody N. Neely
Keyword(s):  
Streptococcus Pyogenes ◽  
Large Scale ◽  
Virulence Genes ◽  
Insertion Site ◽  
Disease Model ◽  
Invasive Infection ◽  
Virulence Determinants ◽  
Infectious Disease Model

ABSTRACT The virulence of bacterial pathogens is a complex process that requires the dynamic expression of many genes for the pathogens to invade and circumvent host defenses, as well as to proliferate in vivo. In this study, we employed a large-scale screen, signature-tagged mutagenesis (STM), to identify Streptococcus pyogenes virulence genes important for pathogenesis within the host. Approximately 1,200 STM mutants were created and screened using the zebrafish infectious disease model. The transposon insertion site was identified for 29 of the 150 mutants that were considered attenuated for virulence. Previously reported streptococcal virulence genes, such as mga, hasA, amrA, smeZ, and two genes in the sil locus, were identified, confirming the utility of the model for revealing genes important for virulence. Multiple genes not previously implicated in virulence were also identified, including genes encoding putative transporters, hypothetical cytosolic proteins, and macrolide efflux pumps. The STM mutant strains display various levels of attenuation, and multiple separate insertions were identified in either the same gene or the same locus, suggesting that these factors are important for this type of acute, invasive infection. We further examined two such genes, silB and silC of a putative quorum-sensing regulon, and determined that they are significant virulence factors in our model of necrotizing fasciitis. sil locus promoter expression was examined under various in vitro conditions, as well as in zebrafish tissues, and was found to be differentially induced. This study was a unique investigation of S. pyogenes factors required for successful invasive infection.

scholarly journals Structural Conservation, Variability, and Immunogenicity of the T6 Backbone Pilin of Serotype M6 Streptococcus pyogenes

2014 ◽  
Vol 82 (7) ◽  
pp. 2949-2957 ◽  
Author(s):  
Paul G. Young ◽  
Nicole J. Moreland ◽  
Jacelyn M. Loh ◽  
Anita Bell ◽  
Polly Atatoa Carr ◽  
...  
Keyword(s):  
Rheumatic Fever ◽  
Streptococcus Pyogenes ◽  
Acute Rheumatic Fever ◽  
Vaccine Development ◽  
Group A Streptococcus ◽  
T Antigen ◽  
Gram Positive ◽  
Content Type ◽  
Future Design

ABSTRACTGroup A streptococcus (GAS;Streptococcus pyogenes) is a Gram-positive human pathogen that causes a broad range of diseases ranging from acute pharyngitis to the poststreptococcal sequelae of acute rheumatic fever. GAS pili are highly diverse, long protein polymers that extend from the cell surface. They have multiple roles in infection and are promising candidates for vaccine development. This study describes the structure of the T6 backbone pilin (BP; Lancefield T-antigen) from the important M6 serotype. The structure reveals a modular arrangement of three tandem immunoglobulin-like domains, two with internal isopeptide bonds. The T6 pilin lysine, essential for polymerization, is located in a novel VAKS motif that is structurally homologous to the canonical YPKN pilin lysine in other three- and four-domain Gram-positive pilins. The T6 structure also highlights a conserved pilin core whose surface is decorated with highly variable loops and extensions. Comparison to other Gram-positive BPs shows that many of the largest variable extensions are found in conserved locations. Studies with sera from patients diagnosed with GAS-associated acute rheumatic fever showed that each of the three T6 domains, and the largest of the variable extensions (V8), are targeted by IgG during infectionin vivo. Although the GAS BP show large variations in size and sequence, the modular nature of the pilus proteins revealed by the T6 structure may aid the future design of a pilus-based vaccine.

Rapid, Refined, and Robust Method for Expression, Purification, and Characterization of Recombinant Human Amyloid-beta M1-42

2019 ◽  
Author(s):  
Priya Prakash ◽  
Travis Lantz ◽  
Krupal P. Jethava ◽  
Gaurav Chopra
Keyword(s):  
Amyloid Beta ◽  
Western Blots ◽  
Force Microscopy ◽  
E Coli ◽  
Atomic Force ◽  
Set Up ◽  
Short Time

Amyloid plaques found in the brains of Alzheimer’s disease (AD) patients primarily consists of amyloid beta 1-42 (Ab42). Commercially, Ab42 is synthetized using peptide synthesizers. We describe a robust methodology for expression of recombinant human Ab(M1-42) in Rosetta(DE3)pLysS and BL21(DE3)pLysS competent E. coli with refined and rapid analytical purification techniques. The peptide is isolated and purified from the transformed cells using an optimized set-up for reverse-phase HPLC protocol, using commonly available C18 columns, yielding high amounts of peptide (~15-20 mg per 1 L culture) in a short time. The recombinant Ab(M1-42) forms characteristic aggregates similar to synthetic Ab42 aggregates as verified by western blots and atomic force microscopy to warrant future biological use. Our rapid, refined, and robust technique to purify human Ab(M1-42) can be used to synthesize chemical probes for several downstream in vitro and in vivo assays to facilitate AD research.

In Vitro and In Vivo Model Systems for the Study of Allergic and Inflammatory Disorders in Man

CHEST Journal ◽  
1985 ◽  
Vol 87 (5) ◽  
pp. 162S-164S ◽  
Author(s):  
Stephen P. Peters ◽  
Robert M. Naclerio ◽  
Alkis Togias ◽  
Robert P. Schleimer ◽  
Donald W. MacGlashan ◽  
...  
Keyword(s):  
Model Systems ◽  
In Vivo Model ◽  
Inflammatory Disorders
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