IgG4 Subclass-Specific Responses to Staphylococcus aureus Antigens Shed New Light on Host-Pathogen Interaction

IgG4 responses are considered indicative for long-term or repeated exposure to particular antigens. Therefore, studying IgG4-specific antibody responses againstStaphylococcus aureusmight generate new insights into the respective host-pathogen interactions and the microbial virulence factors involved. Using a bead-based flow cytometry assay, we determined total IgG (IgGt), IgG1, and IgG4 antibody responses to 40 differentS. aureusvirulence factors in sera from healthy persistent nasal carriers, healthy persistent noncarriers, and patients with various staphylococcal infections from three distinct countries. IgGt responses were detected against all tested antigens. These were mostly IgG1 responses. In contrast, IgG4 antibodies were detected to alpha-toxin, chemotaxis inhibitory protein ofS. aureus(CHIPS), exfoliative toxins A and B (ETA and -B), HlgB, IsdA, LukD, -E, -F, and -S, staphylococcal complement inhibitor (SCIN), staphylococcal enterotoxin C (SEC), staphylococcal superantigen-like proteins 1, 3, 5, and 9 (SSL1, -3, -5, and -9), and toxic shock syndrome toxin 1 (TSST-1) only. Large interpatient variability was observed, and the type of infection or geographical location did not reveal conserved patterns of response. As persistentS. aureuscarriers trended toward IgG4 responses to a larger number of antigens than persistent noncarriers, we also investigated sera from patients with epidermolysis bullosa (EB), a genetic blistering disease associated with highS. aureuscarriage rates. EB patients responded immunologically to significantly more antigens than noncarriers and trended toward even more responses than carriers. Altogether, we conclude that the IgG4 responses against a restricted panel of staphylococcal antigens consisting primarily of immune modulators and particular toxins indicate important roles for these virulence factors in staphylococcal pathogen-host interactions, such as chronicity of colonization and/or (subclinical) infections.

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Temporal and Racial Differences Associated with Atopic Dermatitis Staphylococcus aureus and Encoded Virulence Factors

mSphere ◽

10.1128/msphere.00295-16 ◽

2016 ◽

Vol 1 (6) ◽

Cited By ~ 9

Author(s):

Joseph A. Merriman ◽

Elizabeth A. Mueller ◽

Michael P. Cahill ◽

Lisa A. Beck ◽

Amy S. Paller ◽

...

Keyword(s):

Staphylococcus Aureus ◽

Atopic Dermatitis ◽

Gene Cluster ◽

Virulence Factors ◽

Toxic Shock Syndrome ◽

Enterotoxin Gene ◽

Toxic Shock ◽

Gene Encoding ◽

Content Type ◽

Toxic Shock Syndrome Toxin

ABSTRACT Monitoring pathogen emergence provides insight into how pathogens adapt in the human population. Secreted virulence factors, important contributors to infections, may differ in a manner dependent on the strain and host. Temporal changes of Staphylococcus aureus toxigenic potential, for example, in encoding toxic shock syndrome toxin 1 (TSST-1), contributed to an epidemic of TSS with significant health impact. This study monitored changes in atopic dermatitis (AD) S. aureus isolates and demonstrated both temporal and host infection differences according to host race based on secreted superantigen potential. The current temporal increase in enterotoxin gene cluster superantigen prevalence and lack of the gene encoding TSST-1 in AAs predict differences in infection types and presentations. Atopic dermatitis (AD) is an inflammatory skin condition strongly associated with Staphylococcus aureus colonization and infection. S. aureus strains shift in populations in ~10-year intervals depending on virulence factors. Shifts in S. aureus virulence factors may in part explain the racial differences observed in the levels of prevalence and severity of AD. AD S. aureus isolates collected from 2011 to 2014 (103 isolates) and in 2008 (100 isolates) were examined for the prevalence of genes encoding superantigens (SAgs). The strains from 2011 to 2014 were obtained from AD patients as a part of the National Institute of Allergy and Infectious Diseases (NIAID) Atopic Dermatitis Research Network (ADRN). The prevalence of SAg genes was investigated temporally and racially. The enterotoxin gene cluster (EGC) was more prevalent in the 2011–2014 AD isolates than in the 2008 AD isolates. The prevalences of virulence factor genes were similar in European American (EA) and Mexican American (MA) patients but differed in 6 of 22 SAg genes between EA and African American (AA) or MA and AA isolates; notably, AA isolates lacked tstH, the gene encoding toxic shock syndrome toxin 1 (TSST-1). The presence of tstH and sel-p (enterotoxin-like P) was associated with decreased clinical severity and increased blood eosinophils, respectively. The EGC is becoming more prevalent, consistent with the previously observed 10 years of cycling of S. aureus strains. Race-specific S. aureus selection may account for differences in virulence factor profiles. The lack of TSST-1-positive (TSST-1+) AD S. aureus in AA is consistent with the lack of AAs acquiring TSST-1-associated menstrual toxic shock syndrome (TSS). IMPORTANCE Monitoring pathogen emergence provides insight into how pathogens adapt in the human population. Secreted virulence factors, important contributors to infections, may differ in a manner dependent on the strain and host. Temporal changes of Staphylococcus aureus toxigenic potential, for example, in encoding toxic shock syndrome toxin 1 (TSST-1), contributed to an epidemic of TSS with significant health impact. This study monitored changes in atopic dermatitis (AD) S. aureus isolates and demonstrated both temporal and host infection differences according to host race based on secreted superantigen potential. The current temporal increase in enterotoxin gene cluster superantigen prevalence and lack of the gene encoding TSST-1 in AAs predict differences in infection types and presentations.

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Finding of Agr Phase Variants in Staphylococcus aureus

mBio ◽

10.1128/mbio.00796-19 ◽

2019 ◽

Vol 10 (4) ◽

Cited By ~ 3

Author(s):

Vishal Gor ◽

Aya J. Takemura ◽

Masami Nishitani ◽

Masato Higashide ◽

Veronica Medrano Romero ◽

...

Keyword(s):

Staphylococcus Aureus ◽

Virulence Factors ◽

Phase Variation ◽

Accessory Gene ◽

Content Type ◽

Accessory Gene Regulator ◽

Immune Mediated ◽

A Minor ◽

First Time ◽

Phase Variants

ABSTRACT Staphylococcus aureus is an important human pathogen whose success is largely attributed to its vast arsenal of virulence factors that facilitate its invasion into, and survival within, the human host. The expression of these virulence factors is controlled by the quorum sensing accessory gene regulator (Agr) system. However, a large proportion of clinical S. aureus isolates are consistently found to have a mutationally inactivated Agr system. These mutants have a survival advantage in the host but are considered irreversible mutants. Here we show, for the first time, that a fraction of Agr-negative mutants can revert their Agr activity. By serially passaging Agr-negative strains and screening for phenotypic reversion of hemolysis and subsequent sequencing, we identified two mutational events responsible for reversion: a genetic duplication plus inversion event and a poly(A) tract alteration. Additionally, we demonstrate that one clinical Agr-negative methicillin-resistant S. aureus (MRSA) isolate could reproducibly generate Agr-revertant colonies with a poly(A) tract genetic mechanism. We also show that these revertants activate their Agr system upon phagocytosis. We propose a model in which a minor fraction of Agr-negative S. aureus strains are phase variants that can revert their Agr activity and may act as a cryptic insurance strategy against host-mediated stress. IMPORTANCE Staphylococcus aureus is responsible for a broad range of infections. This pathogen has a vast arsenal of virulence factors at its disposal, but avirulent strains are frequently isolated as the cause of clinical infections. These isolates have a mutated agr locus and have been believed to have no evolutionary future. Here we show that a fraction of Agr-negative strains can repair their mutated agr locus with mechanisms resembling phase variation. The agr revertants sustain an Agr OFF state as long as they exist as a minority but can activate their Agr system upon phagocytosis. These revertant cells might function as a cryptic insurance strategy to survive immune-mediated host stress that arises during infection.

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Interleukin-10 (IL-10) Produced by Mutant Toxic Shock Syndrome Toxin 1 Vaccine-Induced Memory T Cells Downregulates IL-17 Production and Abrogates the Protective Effect against Staphylococcus aureus Infection

Infection and Immunity ◽

10.1128/iai.00494-19 ◽

2019 ◽

Vol 87 (10) ◽

Author(s):

Kouji Narita ◽

Dong-Liang Hu ◽

Krisana Asano ◽

Akio Nakane

Keyword(s):

Staphylococcus Aureus ◽

T Cells ◽

Infectious Diseases ◽

Protective Effect ◽

Toxic Shock Syndrome ◽

Long Term Memory ◽

Toxic Shock ◽

Content Type ◽

Memory Phase ◽

Toxic Shock Syndrome Toxin

ABSTRACT Development of long-term memory is crucial for vaccine-induced adaptive immunity against infectious diseases such as Staphylococcus aureus infection. Toxic shock syndrome toxin 1 (TSST-1), one of the superantigens produced by S. aureus, is a possible vaccine candidate against infectious diseases caused by this pathogen. We previously reported that vaccination with less toxic mutant TSST-1 (mTSST-1) induced T helper 17 (Th17) cells and elicited interleukin-17A (IL-17A)-mediated protection against S. aureus infection 1 week after vaccination. In the present study, we investigated the host immune response induced by mTSST-1 vaccination in the memory phase, 12 weeks after the final vaccination. The protective effect and IL-17A production after vaccination with mTSST-1 were eliminated because of IL-10 production. In the presence of IL-10-neutralizing monoclonal antibody (mAb), IL-17A production was restored in culture supernatants of CD4+ T cells and macrophages sorted from the spleens of vaccinated mice. Vaccinated mice treated with anti-IL-10 mAb were protected against systemic S. aureus infection in the memory phase. From these results, it was suggested that IL-10 produced in the memory phase suppresses the IL-17A-dependent vaccine effect through downregulation of IL-17A production.

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The Innate Immune Modulators Staphylococcal Complement Inhibitor and Chemotaxis Inhibitory Protein of Staphylococcus aureus Are Located on β-Hemolysin-Converting Bacteriophages

Journal of Bacteriology ◽

10.1128/jb.188.4.1310-1315.2006 ◽

2006 ◽

Vol 188 (4) ◽

pp. 1310-1315 ◽

Cited By ~ 316

Author(s):

Willem J. B. van Wamel ◽

Suzan H. M. Rooijakkers ◽

Maartje Ruyken ◽

Kok P. M. van Kessel ◽

Jos A. G. van Strijp

Keyword(s):

Staphylococcus Aureus ◽

Mitomycin C ◽

Immune Evasion ◽

Innate Immune ◽

Complement Inhibitor ◽

Inhibitory Protein ◽

Immune Modulators ◽

Phage Dna ◽

Innate Immune Evasion ◽

Human Specific

ABSTRACT Two newly discovered immune modulators, chemotaxis inhibitory protein of Staphylococcus aureus (CHIPS) and staphylococcal complement inhibitor (SCIN), cluster on the conserved 3′ end of β-hemolysin (hlb)-converting bacteriophages (βC-φs). Since these βC-φs also carry the genes for the immune evasion molecules staphylokinase (sak) and enterotoxin A (sea), this 8-kb region at the 3′ end of βC-φ represents an innate immune evasion cluster (IEC). By PCR and Southern analyses of 85 clinical Staphylococcus aureus strains and 5 classical laboratory strains, we show that 90% of S. aureus strains carry a βC-φ with an IEC. Seven IEC variants were discovered, carrying different combinations of chp, sak, or sea (or sep), always in the same 5′-to-3′ orientation and on the 3′ end of a βC-φ. From most IEC variants we could isolate active bacteriophages by mitomycin C treatment, of which lysogens were generated in S. aureus R5 (broad phage host). All IEC-carrying bacteriophages integrated into hlb, as was measured by Southern blotting of R5 lysogens. Large quantities of the different bacteriophages were obtained by mitomycin C treatment of the lysogens, and bacteriophages were collected and used to reinfect all lysogenic R5 strains. In total, five lytic families were found. Furthermore, phage DNA was isolated and digested with EcoR1, revealing that one IEC variant can be found on different βI-φs. In conclusion, the four human-specific innate immune modulators SCIN, CHIPS, SAK, and SEA form an IEC that is easily transferred among S. aureus strains by a diverse group of β-hemolysin-converting bacteriophages.

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Structure-Based Functional Characterization of Repressor of Toxin (Rot), a Central Regulator of Staphylococcus aureus Virulence

Journal of Bacteriology ◽

10.1128/jb.02317-14 ◽

2014 ◽

Vol 197 (1) ◽

pp. 188-200 ◽

Cited By ~ 10

Author(s):

April Killikelly ◽

Meredith A. Benson ◽

Elizabeth A. Ohneck ◽

Jared M. Sampson ◽

Jean Jakoncic ◽

...

Keyword(s):

Staphylococcus Aureus ◽

Dna Binding ◽

Virulence Factors ◽

Regulatory Networks ◽

Functional Characterization ◽

Site Directed Mutagenesis ◽

Binding Motif ◽

Content Type ◽

Specific Effects ◽

Target Promoters

Staphylococcus aureusis responsible for a large number of diverse infections worldwide. In order to support its pathogenic lifestyle,S. aureushas to regulate the expression of virulence factors in a coordinated fashion. One of the central regulators of theS. aureusvirulence regulatory networks is the transcription factor repressor of toxin (Rot). Rot plays a key role in regulatingS. aureusvirulence through activation or repression of promoters that control expression of a large number of critical virulence factors. However, the mechanism by which Rot mediates gene regulation has remained elusive. Here, we have determined the crystal structure of Rot and used this information to probe the contribution made by specific residues to Rot function. Rot was found to form a dimer, with each monomer harboring a winged helix-turn-helix (WHTH) DNA-binding motif. Despite an overall acidic pI, the asymmetric electrostatic charge profile suggests that Rot can orient the WHTH domain to bind DNA. Structure-based site-directed mutagenesis studies demonstrated that R91, at the tip of the wing, plays an important role in DNA binding, likely through interaction with the minor groove. We also found that Y66, predicted to bind within the major groove, contributes to Rot interaction with target promoters. Evaluation of Rot binding to different activated and repressed promoters revealed that certain mutations on Rot exhibit promoter-specific effects, suggesting for the first time that Rot differentially interacts with target promoters. This work provides insight into a precise mechanism by which Rot controls virulence factor regulation inS. aureus.

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Impact of Currently Marketed Tampons and Menstrual Cups onStaphylococcus aureusGrowth and Toxic Shock Syndrome Toxin 1 ProductionIn Vitro

Applied and Environmental Microbiology ◽

10.1128/aem.00351-18 ◽

2018 ◽

Vol 84 (12) ◽

pp. e00351-18 ◽

Cited By ~ 12

Author(s):

Louis Nonfoux ◽

Myriam Chiaruzzi ◽

Cédric Badiou ◽

Jessica Baude ◽

Anne Tristan ◽

...

Keyword(s):

Staphylococcus Aureus ◽

Toxic Shock Syndrome ◽

Severe Disease ◽

Toxin Production ◽

Toxic Shock ◽

Content Type ◽

Physiological Conditions ◽

Simple Protocol ◽

Toxic Shock Syndrome Toxin ◽

The Impact

ABSTRACTFifteen currently marketed intravaginal protection products (11 types of tampon and 4 types of menstrual cup) were tested by the modified tampon sac method to determine their effect onStaphylococcus aureusgrowth and toxic shock syndrome toxin 1 (TSST-1) production. Most tampons reducedS. aureusgrowth and TSST-1 production, with differences based on brand and composition, and the level ofS. aureusgrowth was higher in destructured than in unaltered tampons. We observed higher levels ofS. aureusgrowth and toxin production in menstrual cups than in tampons, potentially due to the additional air introduced into the bag by cups, with differences based on cup composition and size.IMPORTANCEMenstrual toxic shock syndrome is a rare but severe disease. It occurs in healthy women vaginally colonized byStaphylococcus aureusproducing toxic shock syndrome toxin 1 using intravaginal protection, such as tampons or menstrual cups. Intravaginal protection induces TSS by the collection of catamenial products, which act as a growth medium forS. aureus. Previous studies evaluated the impact of tampon composition onS. aureusproducing toxic shock syndrome toxin 1, but they are not recent and did not include menstrual cups. This study demonstrates that highly reproducible results forS. aureusgrowth and TSST-1 production can be obtained by using a simple protocol that reproduces the physiological conditions of tampon and cup usage as closely as possible, providing recommendations for tampon or cup use to both manufacturers and consumers. Notably, our results do not show that menstrual cups are safer than tampons and suggest that they require similar precautions.

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Production of Staphylococcal Complement Inhibitor (SCIN) and Other Immune Modulators during the Early Stages ofStaphylococcus aureusBiofilm Formation in a Mammalian Cell Culture Medium

Infection and Immunity ◽

10.1128/iai.00352-18 ◽

2018 ◽

Vol 86 (8) ◽

Cited By ~ 3

Author(s):

Andi R. Sultan ◽

Jasper W. Swierstra ◽

Nicole A. Lemmens-den Toom ◽

Susan V. Snijders ◽

Silvie Hansenová Maňásková ◽

...

Keyword(s):

Biofilm Formation ◽

Innate Immune ◽

Formyl Peptide Receptor ◽

Complement Inhibitor ◽

Inhibitory Protein ◽

Content Type ◽

Immune Modulators ◽

Early Stages

ABSTRACTImmune modulators are known to be produced by matured biofilms and during different stages of planktonic growth ofStaphylococcus aureus. Little is known about immune modulator production during the early stages of biofilm formation, thus raising the following question: how doesS. aureusprotect itself from the innate immune responses at these stages? Therefore, we determined the production of the following immune modulators: chemotaxis inhibitory protein of staphylococci (CHIPS); staphylococcal complement inhibitor (SCIN); formyl peptide receptor-like 1 inhibitor; gamma-hemolysin component B; leukocidins D, E, and S; staphylococcal superantigen-like proteins 1, 3, 5, and 9; and staphylococcal enterotoxin A. Production was determined duringin vitrobiofilm formation in Iscove's modified Dulbecco's medium at different time points using a competitive Luminex assay and mass spectrometry. Both methods demonstrated the production of the immune modulators SCIN and CHIPS during the early stages of biofilm formation. The green fluorescence protein promoter fusion technology confirmedscn(SCIN) and, to a lesser extent,chp(CHIPS) transcription during the early stages of biofilm formation. Furthermore, we found that SCIN could inhibit human complement activation induced by early biofilms, indicating thatS. aureusis able to modulate the innate immune system already during the early stages of biofilm formationin vitro. These results form a stepping stone toward elucidating the role of immune modulators in the establishment of biofilmsin vivoand present opportunities to develop preventive strategies.

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Staphylococcus aureus Arsenal To Conquer the Lower Respiratory Tract

mSphere ◽

10.1128/msphere.00059-21 ◽

2021 ◽

Vol 6 (3) ◽

Author(s):

Mariane Pivard ◽

Karen Moreau ◽

François Vandenesch

Keyword(s):

Staphylococcus Aureus ◽

Respiratory Tract ◽

Virulence Factors ◽

Lower Respiratory Tract ◽

Defense Mechanisms ◽

Future Research ◽

Epithelial Barrier ◽

Content Type ◽

Wide Range ◽

The Impact

ABSTRACT Staphylococcus aureus is both a commensal and a pathogenic bacterium for humans. Its ability to induce severe infections is based on a wide range of virulence factors. S. aureus community-acquired pneumonia (SA-CAP) is rare and severe, and the contribution of certain virulence factors in this disease has been recognized over the past 2 decades. First, the factors involved in metabolism adaptation are crucial for S. aureus survival in the lower respiratory tract, and toxins and enzymes are required for it to cross the pulmonary epithelial barrier. S. aureus subsequently faces host defense mechanisms, including the epithelial barrier, but most importantly the immune system. Here, again, S. aureus uses myriad virulence factors to successfully escape from the host’s defenses and takes advantage of them. The impact of S. aureus virulence, combined with the collateral damage caused by an overwhelming immune response, leads to severe tissue damage and adverse clinical outcomes. In this review, we summarize step by step all of the S. aureus factors implicated in CAP and described to date, and we provide an outlook for future research.

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De Novo Purine Biosynthesis Is Required for Intracellular Growth of Staphylococcus aureus and for the Hypervirulence Phenotype of a purR Mutant

Infection and Immunity ◽

10.1128/iai.00104-20 ◽

2020 ◽

Vol 88 (5) ◽

Cited By ~ 1

Author(s):

Mariya I. Goncheva ◽

Ronald S. Flannagan ◽

David E. Heinrichs

Keyword(s):

Staphylococcus Aureus ◽

Virulence Factors ◽

Metabolic Regulation ◽

De Novo ◽

Purine Biosynthesis ◽

Mammalian Host ◽

Cell Binding ◽

Intracellular Growth ◽

Content Type ◽

De Novo Purine Biosynthesis

ABSTRACT Staphylococcus aureus is a noted human and animal pathogen. Despite decades of research on this important bacterium, there are still many unanswered questions regarding the pathogenic mechanisms it uses to infect the mammalian host. This can be attributed to it possessing a plethora of virulence factors and complex virulence factor and metabolic regulation. PurR, the purine biosynthesis regulator, was recently also shown to regulate virulence factors in S. aureus, and mutations in purR result in derepression of fibronectin binding proteins (FnBPs) and extracellular toxins, required for a so-called hypervirulent phenotype. Here, we show that hypervirulent strains containing purR mutations can be attenuated with the addition of purine biosynthesis mutations, implicating the necessity for de novo purine biosynthesis in this phenotype and indicating that S. aureus in the mammalian host experiences purine limitation. Using cell culture, we showed that while purR mutants are not altered in epithelial cell binding, compared to that of wild-type (WT) S. aureus, purR mutants have enhanced invasion of these nonprofessional phagocytes, consistent with the requirement of FnBPs for invasion of these cells. This correlates with purR mutants having increased transcription of fnb genes, resulting in higher levels of surface-exposed FnBPs to promote invasion. These data provide important contributions to our understanding of how the pathogenesis of S. aureus is affected by sensing of purine levels during infection of the mammalian host.

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Characterization of Methicillin-Resistant Staphylococcus aureus Isolates from Food and Food Products of Poultry Origin in Germany

Applied and Environmental Microbiology ◽

10.1128/aem.00561-11 ◽

2011 ◽

Vol 77 (20) ◽

pp. 7151-7157 ◽

Cited By ~ 134

Author(s):

Andrea T. Feßler ◽

Kristina Kadlec ◽

Melanie Hassel ◽

Tomasz Hauschild ◽

Christopher Eidam ◽

...

Keyword(s):

Staphylococcus Aureus ◽

Meat Products ◽

Poultry Meat ◽

The Novel ◽

Methicillin Resistant ◽

Content Type ◽

Turkey Meat ◽

Poultry Products ◽

Type Iv ◽

Toxic Shock Syndrome Toxin

ABSTRACTDuring a survey of fresh chicken and turkey meat as well as chicken and turkey meat products for the presence of methicillin-resistantStaphylococcus aureus(MRSA) isolates in Germany, 32 (37.2%) of 86 samples were MRSA positive. Twenty-eight of these MRSA isolates belonged to clonal complex 398 (CC398), which is widespread among food-producing animals. These CC398 isolates carried SCCmecelements of type IV or V and exhibitedspatype t011, t034, t899, t2346 or t6574 and either the knowndrutypes dt2b, dt6j, dt10a, dt10q, dt11a, dt11v, and dt11ab or the noveldrutypes dt6m, dt10as, and dt10at. In addition, two MRSA sequence type 9 (ST9) isolates with a type IV SCCmeccassette,spatype t1430, anddrutype dt10a as well as single MRSA ST5 and ST1791 isolates with a type III SCCmeccassette,spatype t002, anddrutype dt9v were identified. All but two isolates were classified as multiresistant. A wide variety of resistance phenotypes and genotypes were detected. All isolates were negative for the major virulence factors, such as Panton-Valentine leukocidin, toxic shock syndrome toxin 1, or exfoliative toxins. In contrast to the MRSA CC398 isolates, the four ST9, ST5, or ST1791 isolates harbored theegcgene cluster for enterotoxin G, I, M, N, O, and U genes. Although the relevance of contamination of fresh poultry meat or poultry products with MRSA is currently unclear, the presence of multiresistant and, in part, enterotoxigenic MRSA emphasizes the need for further studies to elucidate possible health hazards for consumers.

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