1
|
Nygaard TK, Borgogna TR, Pallister KB, Predtechenskaya M, Burroughs OS, Gao A, Lubick EG, Voyich JM. The Relative Importance of Cytotoxins Produced by Methicillin-Resistant Staphylococcus aureus Strain USA300 for Causing Human PMN Destruction. Microorganisms 2024; 12:1782. [PMID: 39338457 PMCID: PMC11434515 DOI: 10.3390/microorganisms12091782] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2024] [Revised: 08/20/2024] [Accepted: 08/22/2024] [Indexed: 09/30/2024] Open
Abstract
Staphylococcus aureus (S. aureus) is a prominent Gram-positive bacterial pathogen that expresses numerous cytotoxins known to target human polymorphonuclear leukocytes (PMNs or neutrophils). These include leukocidin G/H (LukGH, also known as LukAB), the Panton-Valentine leukocidin (PVL), γ-hemolysin A/B (HlgAB), γ-hemolysin B/C (HlgBC), leukocidin E/D (LukED), α-hemolysin (Hla), and the phenol-soluble modulin-α peptides (PSMα). However, the relative contribution of each of these cytotoxins in causing human PMN lysis is not clear. In this study, we used a library of cytotoxin deletion mutants in the clinically relevant methicillin-resistant S. aureus (MRSA) isolate LAC (strain ST8:USA300) to determine the relative importance of each for causing human PMN lysis upon exposure to extracellular components as well as following phagocytosis. Using flow cytometry to examine plasma membrane permeability and assays quantifying lactose dehydrogenase release, we found that PVL was the dominant extracellular factor causing human PMN lysis produced by USA300. In contrast, LukGH was the most important cytotoxin causing human PMN lysis immediately following phagocytosis with contributions from the other bicomponent leukocidins only observed at later time points. These results not only clarify the relative importance of different USA300 cytotoxins for causing human PMN destruction but also demonstrate how two apparently redundant virulence factors play distinctive roles in promoting S. aureus pathogenesis.
Collapse
Affiliation(s)
- Tyler K Nygaard
- Department of Microbiology Cell Biology, Montana State University, Bozeman, MT 59718, USA
| | - Timothy R Borgogna
- Department of Microbiology Cell Biology, Montana State University, Bozeman, MT 59718, USA
| | - Kyler B Pallister
- Department of Microbiology Cell Biology, Montana State University, Bozeman, MT 59718, USA
| | - Maria Predtechenskaya
- Department of Microbiology Cell Biology, Montana State University, Bozeman, MT 59718, USA
| | - Owen S Burroughs
- Department of Microbiology Cell Biology, Montana State University, Bozeman, MT 59718, USA
| | - Annika Gao
- Department of Microbiology Cell Biology, Montana State University, Bozeman, MT 59718, USA
| | - Evan G Lubick
- Department of Microbiology Cell Biology, Montana State University, Bozeman, MT 59718, USA
| | - Jovanka M Voyich
- Department of Microbiology Cell Biology, Montana State University, Bozeman, MT 59718, USA
| |
Collapse
|
2
|
Lichota A, Gwozdzinski K, Kowalczyk E, Kowalczyk M, Sienkiewicz M. Contribution of staphylococcal virulence factors in the pathogenesis of thrombosis. Microbiol Res 2024; 283:127703. [PMID: 38537329 DOI: 10.1016/j.micres.2024.127703] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2023] [Revised: 03/20/2024] [Accepted: 03/20/2024] [Indexed: 04/17/2024]
Abstract
Staphylococci are responsible for many infections in humans, starting with skin and soft tissue infections and finishing with invasive diseases such as endocarditis, sepsis and pneumonia, which lead to high mortality. Patients with sepsis often demonstrate activated clotting pathways, decreased levels of anticoagulants, decreased fibrinolysis, activated endothelial surfaces and activated platelets. This results in disseminated intravascular coagulation and formation of a microthrombus, which can lead to a multiorgan failure. This review describes various staphylococcal virulence factors that contribute to vascular thrombosis, including deep vein thrombosis in infected patients. The article presents mechanisms of action of different factors released by bacteria in various host defense lines, which in turn can lead to formation of blood clots in the vessels.
Collapse
Affiliation(s)
- Anna Lichota
- Department of Pharmaceutical Microbiology and Microbiological Diagnostics, Medical University of Lodz, Lodz, Poland.
| | | | - Edward Kowalczyk
- Department of Pharmacology and Toxicology, Medical University of Lodz, Lodz, Poland
| | | | - Monika Sienkiewicz
- Department of Pharmaceutical Microbiology and Microbiological Diagnostics, Medical University of Lodz, Lodz, Poland
| |
Collapse
|
3
|
Zhu Z, Hu Z, Li S, Fang R, Ono HK, Hu DL. Molecular Characteristics and Pathogenicity of Staphylococcus aureus Exotoxins. Int J Mol Sci 2023; 25:395. [PMID: 38203566 PMCID: PMC10778951 DOI: 10.3390/ijms25010395] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2023] [Revised: 12/24/2023] [Accepted: 12/26/2023] [Indexed: 01/12/2024] Open
Abstract
Staphylococcus aureus stands as one of the most pervasive pathogens given its morbidity and mortality worldwide due to its roles as an infectious agent that causes a wide variety of diseases ranging from moderately severe skin infections to fatal pneumonia and sepsis. S. aureus produces a variety of exotoxins that serve as important virulence factors in S. aureus-related infectious diseases and food poisoning in both humans and animals. For example, staphylococcal enterotoxins (SEs) produced by S. aureus induce staphylococcal foodborne poisoning; toxic shock syndrome toxin-1 (TSST-1), as a typical superantigen, induces toxic shock syndrome; hemolysins induce cell damage in erythrocytes and leukocytes; and exfoliative toxin induces staphylococcal skin scalded syndrome. Recently, Panton-Valentine leucocidin, a cytotoxin produced by community-associated methicillin-resistant S. aureus (CA-MRSA), has been reported, and new types of SEs and staphylococcal enterotoxin-like toxins (SEls) were discovered and reported successively. This review addresses the progress of and novel insights into the molecular structure, biological activities, and pathogenicity of both the classic and the newly identified exotoxins produced by S. aureus.
Collapse
Affiliation(s)
- Zhihao Zhu
- Department of Zoonoses, Kitasato University School of Veterinary Medicine, Towada 034-8628, Japan; (Z.Z.); (Z.H.); (H.K.O.)
- College of Veterinary Medicine, Huazhong Agricultural University, Wuhan 430070, China;
| | - Zuo Hu
- Department of Zoonoses, Kitasato University School of Veterinary Medicine, Towada 034-8628, Japan; (Z.Z.); (Z.H.); (H.K.O.)
| | - Shaowen Li
- College of Veterinary Medicine, Huazhong Agricultural University, Wuhan 430070, China;
| | - Rendong Fang
- Joint International Research Laboratory of Animal Health and Animal Food Safety, College of Veterinary Medicine, Southwest University, Chongqing 400715, China;
| | - Hisaya K. Ono
- Department of Zoonoses, Kitasato University School of Veterinary Medicine, Towada 034-8628, Japan; (Z.Z.); (Z.H.); (H.K.O.)
| | - Dong-Liang Hu
- Department of Zoonoses, Kitasato University School of Veterinary Medicine, Towada 034-8628, Japan; (Z.Z.); (Z.H.); (H.K.O.)
| |
Collapse
|
4
|
Ilmain JK, Perelman SS, Panepinto MC, Irnov I, Coudray N, Samhadaneh N, Pironti A, Ueberheide B, Ekiert DC, Bhabha G, Torres VJ. Unlatching of the stem domains in the Staphylococcus aureus pore-forming leukocidin LukAB influences toxin oligomerization. J Biol Chem 2023; 299:105321. [PMID: 37802313 PMCID: PMC10665946 DOI: 10.1016/j.jbc.2023.105321] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2023] [Revised: 09/22/2023] [Accepted: 09/27/2023] [Indexed: 10/08/2023] Open
Abstract
Staphylococcus aureus (S. aureus) is a serious global pathogen that causes a diverse range of invasive diseases. S. aureus utilizes a family of pore-forming toxins, known as bi-component leukocidins, to evade the host immune response and promote infection. Among these is LukAB (leukocidin A/leukocidin B), a toxin that assembles into an octameric β-barrel pore in the target cell membrane, resulting in host cell death. The established cellular receptor for LukAB is CD11b of the Mac-1 complex. Here, we show that hydrogen voltage-gated channel 1 is also required for the cytotoxicity of all major LukAB variants. We demonstrate that while each receptor is sufficient to recruit LukAB to the plasma membrane, both receptors are required for maximal lytic activity. Why LukAB requires two receptors, and how each of these receptors contributes to pore-formation remains unknown. To begin to resolve this, we performed an alanine scanning mutagenesis screen to identify mutations that allow LukAB to maintain cytotoxicity without CD11b. We discovered 30 mutations primarily localized in the stem domains of LukA and LukB that enable LukAB to exhibit full cytotoxicity in the absence of CD11b. Using crosslinking, electron microscopy, and hydroxyl radical protein footprinting, we show these mutations increase the solvent accessibility of the stem domain, priming LukAB for oligomerization. Together, our data support a model in which CD11b binding unlatches the membrane penetrating stem domains of LukAB, and this change in flexibility promotes toxin oligomerization.
Collapse
Affiliation(s)
- Juliana K Ilmain
- Department of Microbiology, New York University Grossman School of Medicine, New York, New York, USA
| | - Sofya S Perelman
- Department of Microbiology, New York University Grossman School of Medicine, New York, New York, USA
| | - Maria C Panepinto
- Proteomics Laboratory, Division of Advanced Research Technologies, New York University Grossman School of Medicine, New York, New York, USA
| | - Irnov Irnov
- Department of Microbiology, New York University Grossman School of Medicine, New York, New York, USA
| | - Nicolas Coudray
- Applied Bioinformatics Laboratories, New York University Grossman School of Medicine, New York, New York, USA; Department of Cell Biology, New York University Grossman School of Medicine, New York, New York, USA
| | - Nora Samhadaneh
- Antimicrobial-Resistant Pathogens Program, New York University Langone Health, New York, New York, USA
| | - Alejandro Pironti
- Department of Microbiology, New York University Grossman School of Medicine, New York, New York, USA; Antimicrobial-Resistant Pathogens Program, New York University Langone Health, New York, New York, USA
| | - Beatrix Ueberheide
- Proteomics Laboratory, Division of Advanced Research Technologies, New York University Grossman School of Medicine, New York, New York, USA; Department of Biochemistry and Molecular Pharmacology, New York University Grossman School of Medicine, New York, New York, USA; Department of Neurology, Center for Cognitive Neurology, New York University Grossman School of Medicine, New York, New York, USA
| | - Damian C Ekiert
- Department of Microbiology, New York University Grossman School of Medicine, New York, New York, USA; Department of Cell Biology, New York University Grossman School of Medicine, New York, New York, USA; Antimicrobial-Resistant Pathogens Program, New York University Langone Health, New York, New York, USA
| | - Gira Bhabha
- Department of Cell Biology, New York University Grossman School of Medicine, New York, New York, USA; Antimicrobial-Resistant Pathogens Program, New York University Langone Health, New York, New York, USA
| | - Victor J Torres
- Department of Microbiology, New York University Grossman School of Medicine, New York, New York, USA; Department of Host-Microbe Interactions, St Jude Children's Research Hospital, Memphis, Tennessee, USA.
| |
Collapse
|
5
|
Staphylococcus lugdunensis Uses the Agr Regulatory System to Resist Killing by Host Innate Immune Effectors. Infect Immun 2022; 90:e0009922. [PMID: 36069592 PMCID: PMC9584346 DOI: 10.1128/iai.00099-22] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Coagulase-negative staphylococci (CoNS) are frequently commensal bacteria that rarely cause disease in mammals. Staphylococcus lugdunensis is an exceptional CoNS that causes disease in humans similar to virulent Staphylococcus aureus, but the factors that enhance the virulence of this bacterium remain ill defined. Here, we used random transposon insertion mutagenesis to identify the agr quorum sensing system as a regulator of hemolysins in S. lugdunensis. Using RNA sequencing (RNA-seq), we revealed that agr regulates dozens of genes, including hemolytic S. lugdunensis synergistic hemolysins (SLUSH) peptides and the protease lugdulysin. A murine bacteremia model was used to show that mice infected systemically with wild-type S. lugdunensis do not show overt signs of disease despite there being high numbers of bacteria in the livers and kidneys of mice. Moreover, proliferation of the agr mutant in these organs was no different from that of the wild-type strain, leaving the role of the SLUSH peptides and the metalloprotease lugdulysin in pathogenesis still unclear. Nonetheless, the tropism of S. lugdunensis for humans led us to investigate the role of virulence factors in other ways. We show that agr-regulated effectors, but not SLUSH or lugdulysin alone, are important for S. lugdunensis survival in whole human blood. Moreover, we demonstrate that Agr contributes to survival of S. lugdunensis during encounters with murine and primary human macrophages. These findings demonstrate that, in S. lugdunensis, Agr regulates expression of virulence factors and is required for resistance to host innate antimicrobial defenses. This study therefore provides insight into strategies that this Staphylococcus species uses to cause disease.
Collapse
|
6
|
Monecke S, Roberts MC, Braun SD, Diezel C, Müller E, Reinicke M, Linde J, Joshi PR, Paudel S, Acharya M, Chalise MK, Feßler AT, Hotzel H, Khanal L, Koju NP, Schwarz S, Kyes RC, Ehricht R. Sequence Analysis of Novel Staphylococcus aureus Lineages from Wild and Captive Macaques. Int J Mol Sci 2022; 23:11225. [PMID: 36232529 PMCID: PMC9570271 DOI: 10.3390/ijms231911225] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2022] [Revised: 09/16/2022] [Accepted: 09/19/2022] [Indexed: 11/24/2022] Open
Abstract
Staphylococcus aureus is a widespread and common opportunistic bacterium that can colonise or infect humans as well as a wide range of animals. There are a few studies of both methicillin-susceptible S. aureus (MSSA) and methicillin-resistant S. aureus (MRSA) isolated from monkeys, apes, and lemurs, indicating a presence of a number of poorly or unknown lineages of the pathogen. In order to obtain insight into staphylococcal diversity, we sequenced strains from wild and captive individuals of three macaque species (Macaca mulatta, M. assamensis, and M. sylvanus) using Nanopore and Illumina technologies. These strains were previously identified by microarray as poorly or unknown strains. Isolates of novel lineages ST4168, ST7687, ST7688, ST7689, ST7690, ST7691, ST7692, ST7693, ST7694, ST7695, ST7745, ST7746, ST7747, ST7748, ST7749, ST7750, ST7751, ST7752, ST7753, and ST7754 were sequenced and characterised for the first time. In addition, isolates belonging to ST2990, a lineage also observed in humans, and ST3268, a MRSA strain already known from macaques, were also included into the study. Mobile genetic elements, genomic islands, and carriage of prophages were analysed. There was no evidence for novel host-specific virulence factors. However, a conspicuously high rate of carriage of a pathogenicity island harbouring edinB and etD2/etE as well as a higher number of repeat units within the gene sasG (encoding an adhesion factor) than in human isolates were observed. None of the strains harboured the genes encoding Panton-Valentine leukocidin. In conclusion, wildlife including macaques may harbour an unappreciated diversity of S. aureus lineages that may be of clinical relevance for humans, livestock, or for wildlife conservation, given the declining state of many wildlife populations.
Collapse
Affiliation(s)
- Stefan Monecke
- Leibniz Institute of Photonic Technology (IPHT), 07745 Jena, Germany
- InfectoGnostics Research Campus, 07745 Jena, Germany
- Institute for Medical Microbiology and Virology, Dresden University Hospital, 01307 Dresden, Germany
| | - Marilyn C. Roberts
- Department of Environmental and Occupational Health, School of Public Health, University of Washington, Seattle, WA 98195, USA
| | - Sascha D. Braun
- Leibniz Institute of Photonic Technology (IPHT), 07745 Jena, Germany
- InfectoGnostics Research Campus, 07745 Jena, Germany
| | - Celia Diezel
- Leibniz Institute of Photonic Technology (IPHT), 07745 Jena, Germany
- InfectoGnostics Research Campus, 07745 Jena, Germany
| | - Elke Müller
- Leibniz Institute of Photonic Technology (IPHT), 07745 Jena, Germany
- InfectoGnostics Research Campus, 07745 Jena, Germany
| | - Martin Reinicke
- Leibniz Institute of Photonic Technology (IPHT), 07745 Jena, Germany
- InfectoGnostics Research Campus, 07745 Jena, Germany
| | - Jörg Linde
- Friedrich-Loeffler-Institut (Federal Research Institute for Animal Health), Institute of Bacterial Infections and Zoonoses, 07743 Jena, Germany
| | - Prabhu Raj Joshi
- Division of Biology, Kansas State University, Manhattan, KS 66506, USA
| | - Saroj Paudel
- Nepalese Farming Institute, Maitidevi, Kathmandu 44600, Nepal
| | - Mahesh Acharya
- Nepalese Farming Institute, Maitidevi, Kathmandu 44600, Nepal
| | - Mukesh K. Chalise
- Nepal Biodiversity Research Society, Central Department of Zoology, Tribhuvan University, Kirtipur, Kathmandu 44618, Nepal
| | - Andrea T. Feßler
- Institute of Microbiology and Epizootics, Freie Universität Berlin, 14163 Berlin, Germany
- Veterinary Centre for Resistance Research (TZR), Freie Universität Berlin, 14163 Berlin, Germany
| | - Helmut Hotzel
- Friedrich-Loeffler-Institut (Federal Research Institute for Animal Health), Institute of Bacterial Infections and Zoonoses, 07743 Jena, Germany
| | - Laxman Khanal
- Central Department of Zoology, Institute of Science and Technology, Tribhuvan University, Kathmandu 44618, Nepal
| | - Narayan P. Koju
- Center for Postgraduate Studies, Nepal Engineering College, Pokhara University, Lalitpur 33700, Nepal
- Department of Psychology, University of Washington, Seattle, WA 98195, USA
| | - Stefan Schwarz
- Institute of Microbiology and Epizootics, Freie Universität Berlin, 14163 Berlin, Germany
- Veterinary Centre for Resistance Research (TZR), Freie Universität Berlin, 14163 Berlin, Germany
| | - Randall C. Kyes
- Washington National Primate Research Center, Center for Global Field Study, Departments of Psychology, Global Health, Anthropology, University of Washington, Seattle, WA 98195, USA
| | - Ralf Ehricht
- Leibniz Institute of Photonic Technology (IPHT), 07745 Jena, Germany
- InfectoGnostics Research Campus, 07745 Jena, Germany
- Institute of Physical Chemistry, Friedrich-Schiller University, 07743 Jena, Germany
| |
Collapse
|
7
|
Staphylococcus aureus isolates from Eurasian Beavers (Castor fiber) carry a novel phage-borne bicomponent leukocidin related to the Panton-Valentine leukocidin. Sci Rep 2021; 11:24394. [PMID: 34937862 PMCID: PMC8695587 DOI: 10.1038/s41598-021-03823-6] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2021] [Accepted: 12/08/2021] [Indexed: 11/08/2022] Open
Abstract
Staphylococcus aureus can be a harmless coloniser, but it can also cause severe infections in humans, livestock and wildlife. Regarding the latter, only few studies have been performed and knowledge on virulence factors is insufficient. The aim of the present study was to study S. aureus isolates from deceased wild beavers (Castor fiber). Seventeen isolates from eleven beavers, found in Germany and Austria, were investigated. Antimicrobial and biocide susceptibility tests were performed. Isolates were characterised using S. aureus-specific DNA microarrays, spa typing and whole-genome sequencing. From two isolates, prophages were induced by mitomycin C and studied by transmission electron microscopy. Four isolates belonged to clonal complex (CC) 8, CC12, and CC398. Twelve isolates belonged to CC1956 and one isolate was CC49. The CC49 and CC1956 isolates carried distinct lukF/S genes related to the Panton-Valentine leukocidin (PVL) from human isolates of S. aureus. These genes were located on related, but not identical, Siphovirus prophages. The beavers, from which those isolates originated, suffered from abscesses, purulent organ lesions and necrotising pneumonia, i.e., clinical manifestations resembling symptoms of severe PVL-associated disease in humans. It might thus be assumed that the “Beaver Leukocidin (BVL, lukF/S-BV)”-positive strains are beaver-specific pathogens, and further studies on their clinical role as well as on a possible transmissibility to other species, including humans, are warranted.
Collapse
|
8
|
The cell envelope of Staphylococcus aureus selectively controls the sorting of virulence factors. Nat Commun 2021; 12:6193. [PMID: 34702812 PMCID: PMC8548510 DOI: 10.1038/s41467-021-26517-z] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2020] [Accepted: 10/05/2021] [Indexed: 11/08/2022] Open
Abstract
Staphylococcus aureus bi-component pore-forming leukocidins are secreted toxins that directly target and lyse immune cells. Intriguingly, one of the leukocidins, Leukocidin AB (LukAB), is found associated with the bacterial cell envelope in addition to secreted into the extracellular milieu. Here, we report that retention of LukAB on the bacterial cells provides S. aureus with a pre-synthesized active toxin that kills immune cells. On the bacteria, LukAB is distributed as discrete foci in two distinct compartments: membrane-proximal and surface-exposed. Through genetic screens, we show that a membrane lipid, lysyl-phosphatidylglycerol (LPG), and lipoteichoic acid (LTA) contribute to LukAB deposition and release. Furthermore, by studying non-covalently surface-bound proteins we discovered that the sorting of additional exoproteins, such as IsaB, Hel, ScaH, and Geh, are also controlled by LPG and LTA. Collectively, our study reveals a multistep secretion system that controls exoprotein storage and protein translocation across the S. aureus cell wall.
Collapse
|
9
|
Mondal AK, Chattopadhyay K. Structures and functions of the membrane-damaging pore-forming proteins. ADVANCES IN PROTEIN CHEMISTRY AND STRUCTURAL BIOLOGY 2021; 128:241-288. [PMID: 35034720 DOI: 10.1016/bs.apcsb.2021.07.001] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
Pore-forming proteins (PFPs) of the diverse life forms have emerged as the potent cell-killing entities owing to their specialized membrane-damaging properties. PFPs have the unique ability to perforate the plasma membranes of their target cells, and they exert this functionality by creating oligomeric pores in the membrane lipid bilayer. Pathogenic bacteria employ PFPs as toxins to execute their virulence mechanisms, whereas in the higher vertebrates PFPs are deployed as the part of the immune system and to generate inflammatory responses. PFPs are the unique dimorphic proteins that are generally synthesized as water-soluble molecules, and transform into membrane-inserted oligomeric pore assemblies upon interacting with the target membranes. In spite of sharing very little sequence similarity, PFPs from diverse organisms display incredible structural similarity. Yet, at the same time, structure-function mechanisms of the PFPs document remarkable versatility. Such notions establish PFPs as the fascinating model system to explore variety of unsolved issues pertaining to the structure-function paradigm of the proteins that interact and act in the membrane environment. In this article, we discuss our current understanding regarding the structural basis of the pore-forming functions of the diverse class of PFPs. We attempt to highlight the similarities and differences in their structures, membrane pore-formation mechanisms, and their implications for the various biological processes, ranging from the bacterial virulence mechanisms to the inflammatory immune response generation in the higher animals.
Collapse
Affiliation(s)
- Anish Kumar Mondal
- Department of Biological Sciences, Indian Institute of Science Education and Research Mohali, Mohali, Punjab, India
| | - Kausik Chattopadhyay
- Department of Biological Sciences, Indian Institute of Science Education and Research Mohali, Mohali, Punjab, India.
| |
Collapse
|
10
|
Development of combination vaccine conferring optimal protection against six pore-forming toxins of Staphylococcus aureus. Infect Immun 2021; 89:e0034221. [PMID: 34227839 DOI: 10.1128/iai.00342-21] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
In Gram-positive pathogen Staphylococcus aureus, pore-forming toxins (PFTs) such as leukocidins and hemolysins play prominent roles in staphylococcal pathogenesis by killing host immune cells and red blood cells (RBCs). However, it remains unknown which combination of toxin antigens would induce the broadest protective immune response against those toxins. In this study, by targeting six major staphylococcal PFTs (i.e., HlgAB, HlgCB, LukAB, LukED, LukSF-PV, and Hla), we generated ten recombinant toxins or toxin-subunits, three toxoids, and their rabbit antibodies. Using the cytolytic assay for RBCs and polymorphonuclear cells (PMNs), we determined the best combination of toxin antibodies conferring the broadest protection against those staphylococcal PFTs. Although anti-HlgA IgG (HlgA-IgG) showed low cross-reactivity to other toxin components, it was essential to protect rabbit and human RBCs and human PMNs. For the protection of rabbit RBCs, HlaH35L toxoid-IgG was also required, whereas, for human PMNs, LukS-IgG and LukAE323AB-IgG were essential too. When the toxin/toxoid antigens HlgA, LukS-PV, HlaH35L, and LukAE323AB were used to immunize rabbits, they increased rabbit survival; however, they did not block staphylococcal abscess formation in kidneys. Based on these results, we proposed that the combination of HlgA, LukS, HlaH35L, and LukAE323AB is the optimal vaccine component to protect human RBCs and PMNs from staphylococcal PFTs. We also concluded that a successful S. aureus vaccine requires not only those toxin antigens but also other antigens that can induce immune response blocking staphylococcal colonization.
Collapse
|
11
|
Perelman SS, James DBA, Boguslawski KM, Nelson CW, Ilmain JK, Zwack EE, Prescott RA, Mohamed A, Tam K, Chan R, Narechania A, Pawline MB, Vozhilla N, Moustafa AM, Kim SY, Dittmann M, Ekiert DC, Bhabha G, Shopsin B, Planet PJ, Koralov SB, Torres VJ. Genetic variation of staphylococcal LukAB toxin determines receptor tropism. Nat Microbiol 2021; 6:731-745. [PMID: 33875847 PMCID: PMC8597016 DOI: 10.1038/s41564-021-00890-3] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2020] [Accepted: 03/11/2021] [Indexed: 02/02/2023]
Abstract
Staphylococcus aureus has evolved into diverse lineages, known as clonal complexes (CCs), which exhibit differences in the coding sequences of core virulence factors. Whether these alterations affect functionality is poorly understood. Here, we studied the highly polymorphic pore-forming toxin LukAB. We discovered that the LukAB toxin variants produced by S. aureus CC30 and CC45 kill human phagocytes regardless of whether CD11b, the previously established LukAB receptor, is present, and instead target the human hydrogen voltage-gated channel 1 (HVCN1). Biochemical studies identified the domain within human HVCN1 that drives LukAB species specificity, enabling the generation of humanized HVCN1 mice with enhanced susceptibility to CC30 LukAB and to bloodstream infection caused by CC30 S. aureus strains. Together, this work advances our understanding of an important S. aureus toxin and underscores the importance of considering genetic variation in characterizing virulence factors and understanding the tug of war between pathogens and the host.
Collapse
Affiliation(s)
- Sofya S Perelman
- Department of Microbiology, New York University Grossman School of Medicine, New York, NY, USA
| | - David B A James
- Department of Microbiology, New York University Grossman School of Medicine, New York, NY, USA
| | - Kristina M Boguslawski
- Department of Microbiology, New York University Grossman School of Medicine, New York, NY, USA
| | - Chase W Nelson
- Institute for Comparative Genomics, American Museum of Natural History, New York, NY, USA
- Biodiversity Research Center, Academia Sinica, Taipei, Taiwan
| | - Juliana K Ilmain
- Department of Microbiology, New York University Grossman School of Medicine, New York, NY, USA
| | - Erin E Zwack
- Department of Microbiology, New York University Grossman School of Medicine, New York, NY, USA
| | - Rachel A Prescott
- Department of Microbiology, New York University Grossman School of Medicine, New York, NY, USA
| | - Adil Mohamed
- Department of Microbiology, New York University Grossman School of Medicine, New York, NY, USA
| | - Kayan Tam
- Department of Microbiology, New York University Grossman School of Medicine, New York, NY, USA
| | - Rita Chan
- Department of Microbiology, New York University Grossman School of Medicine, New York, NY, USA
| | - Apurva Narechania
- Institute for Comparative Genomics, American Museum of Natural History, New York, NY, USA
| | - Miranda B Pawline
- Department of Microbiology, New York University Grossman School of Medicine, New York, NY, USA
- Department of Medicine, Division of Infectious Diseases, New York University Grossman School of Medicine, New York, NY, USA
| | - Nikollaq Vozhilla
- Department of Microbiology, New York University Grossman School of Medicine, New York, NY, USA
| | - Ahmed M Moustafa
- Department of Pediatrics, Children's Hospital of Philadelphia, Philadelphia, PA, USA
| | - Sang Y Kim
- Department of Pathology, New York University Grossman School of Medicine, New York, NY, USA
- Office of Collaborative Sciences, NYU Grossman School of Medicine, New York, NY, USA
| | - Meike Dittmann
- Department of Microbiology, New York University Grossman School of Medicine, New York, NY, USA
| | - Damian C Ekiert
- Department of Microbiology, New York University Grossman School of Medicine, New York, NY, USA
- Skirball Institute of Biomolecular Medicine and Department of Cell Biology, New York University Grossman School of Medicine, New York, NY, USA
| | - Gira Bhabha
- Skirball Institute of Biomolecular Medicine and Department of Cell Biology, New York University Grossman School of Medicine, New York, NY, USA
| | - Bo Shopsin
- Department of Microbiology, New York University Grossman School of Medicine, New York, NY, USA
- Department of Medicine, Division of Infectious Diseases, New York University Grossman School of Medicine, New York, NY, USA
| | - Paul J Planet
- Institute for Comparative Genomics, American Museum of Natural History, New York, NY, USA
- Department of Pediatrics, Children's Hospital of Philadelphia, Philadelphia, PA, USA
- Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - Sergei B Koralov
- Department of Pathology, New York University Grossman School of Medicine, New York, NY, USA
| | - Victor J Torres
- Department of Microbiology, New York University Grossman School of Medicine, New York, NY, USA.
| |
Collapse
|
12
|
Fernandez J, Sanders H, Henn J, Wilson JM, Malone D, Buoninfante A, Willms M, Chan R, DuMont AL, McLahan C, Grubb K, Romanello A, van den Dobbelsteen G, Torres VJ, Poolman JT. Vaccination with Detoxified Leukocidin AB Reduces Bacterial Load in a Staphylococcus aureus Minipig Deep Surgical Wound Infection Model. J Infect Dis 2021; 225:1460-1470. [PMID: 33895843 PMCID: PMC9016470 DOI: 10.1093/infdis/jiab219] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2021] [Accepted: 04/19/2021] [Indexed: 12/15/2022] Open
Abstract
Vaccines against Staphylococcus aureus have eluded researchers for >3 decades while the burden of staphylococcal diseases has increased. Early vaccine attempts mainly used rodents to characterize preclinical efficacy, and all subsequently failed in human clinical efficacy trials. More recently, leukocidin AB (LukAB) has gained interest as a vaccine antigen. We developed a minipig deep surgical wound infection model offering 3 independent efficacy readouts: bacterial load at the superficial and at the deep-seated surgical site, and dissemination of bacteria. Due to similarities with humans, minipigs are an attractive option to study novel vaccine candidates. With this model, we characterized the efficacy of a LukAB toxoid as vaccine candidate. Compared to control animals, a 3-log reduction of bacteria at the deep-seated surgical site was observed in LukAB-treated minipigs and dissemination of bacteria was dramatically reduced. Therefore, LukAB toxoids may be a useful addition to S. aureus vaccines and warrant further study.
Collapse
Affiliation(s)
| | - H Sanders
- Janssen Vaccines & Prevention B.V., Leiden, The Netherlands
| | - J Henn
- Bacterial Vaccines, Spring House, PA, USA
| | | | - D Malone
- Bacterial Vaccines, Spring House, PA, USA
| | - A Buoninfante
- Janssen Vaccines & Prevention B.V., Leiden, The Netherlands
| | - M Willms
- Bacterial Vaccines, Spring House, PA, USA
| | - R Chan
- Department of Microbiology, New York University Grossman School of Medicine, New York, NY, USA
| | - A L DuMont
- Department of Microbiology, New York University Grossman School of Medicine, New York, NY, USA
| | - C McLahan
- In Vivo Sciences, Spring House, PA, USA
| | - K Grubb
- Bacterial Vaccines, Spring House, PA, USA
| | | | | | - V J Torres
- Department of Microbiology, New York University Grossman School of Medicine, New York, NY, USA
| | - J T Poolman
- Janssen Vaccines & Prevention B.V., Leiden, The Netherlands
| |
Collapse
|
13
|
Li Y, Li Y, Mengist HM, Shi C, Zhang C, Wang B, Li T, Huang Y, Xu Y, Jin T. Structural Basis of the Pore-Forming Toxin/Membrane Interaction. Toxins (Basel) 2021; 13:toxins13020128. [PMID: 33572271 PMCID: PMC7914777 DOI: 10.3390/toxins13020128] [Citation(s) in RCA: 21] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2020] [Revised: 01/13/2021] [Accepted: 02/02/2021] [Indexed: 12/14/2022] Open
Abstract
With the rapid growth of antibiotic-resistant bacteria, it is urgent to develop alternative therapeutic strategies. Pore-forming toxins (PFTs) belong to the largest family of virulence factors of many pathogenic bacteria and constitute the most characterized classes of pore-forming proteins (PFPs). Recent studies revealed the structural basis of several PFTs, both as soluble monomers, and transmembrane oligomers. Upon interacting with host cells, the soluble monomer of bacterial PFTs assembles into transmembrane oligomeric complexes that insert into membranes and affect target cell-membrane permeability, leading to diverse cellular responses and outcomes. Herein we have reviewed the structural basis of pore formation and interaction of PFTs with the host cell membrane, which could add valuable contributions in comprehensive understanding of PFTs and searching for novel therapeutic strategies targeting PFTs and interaction with host receptors in the fight of bacterial antibiotic-resistance.
Collapse
Affiliation(s)
- Yajuan Li
- Department of Clinical Laboratory, the First Affiliated Hospital of Anhui Medical University, Hefei 230022, China; (Y.L.); (C.S.); (B.W.); (T.L.); (Y.H.)
| | - Yuelong Li
- Hefei National Laboratory for Physical Sciences at Microscale, Laboratory of Structural Immunology, CAS Key Laboratory of Innate Immunity and Chronic Disease, Division of Life Sciences and Medicine, School of Basic Medical Sciences, University of Science and Technology of China, Hefei 230027, China; (Y.L.); (H.M.M.); (C.Z.)
| | - Hylemariam Mihiretie Mengist
- Hefei National Laboratory for Physical Sciences at Microscale, Laboratory of Structural Immunology, CAS Key Laboratory of Innate Immunity and Chronic Disease, Division of Life Sciences and Medicine, School of Basic Medical Sciences, University of Science and Technology of China, Hefei 230027, China; (Y.L.); (H.M.M.); (C.Z.)
| | - Cuixiao Shi
- Department of Clinical Laboratory, the First Affiliated Hospital of Anhui Medical University, Hefei 230022, China; (Y.L.); (C.S.); (B.W.); (T.L.); (Y.H.)
| | - Caiying Zhang
- Hefei National Laboratory for Physical Sciences at Microscale, Laboratory of Structural Immunology, CAS Key Laboratory of Innate Immunity and Chronic Disease, Division of Life Sciences and Medicine, School of Basic Medical Sciences, University of Science and Technology of China, Hefei 230027, China; (Y.L.); (H.M.M.); (C.Z.)
| | - Bo Wang
- Department of Clinical Laboratory, the First Affiliated Hospital of Anhui Medical University, Hefei 230022, China; (Y.L.); (C.S.); (B.W.); (T.L.); (Y.H.)
| | - Tingting Li
- Department of Clinical Laboratory, the First Affiliated Hospital of Anhui Medical University, Hefei 230022, China; (Y.L.); (C.S.); (B.W.); (T.L.); (Y.H.)
| | - Ying Huang
- Department of Clinical Laboratory, the First Affiliated Hospital of Anhui Medical University, Hefei 230022, China; (Y.L.); (C.S.); (B.W.); (T.L.); (Y.H.)
| | - Yuanhong Xu
- Department of Clinical Laboratory, the First Affiliated Hospital of Anhui Medical University, Hefei 230022, China; (Y.L.); (C.S.); (B.W.); (T.L.); (Y.H.)
- Correspondence: (Y.X.); (T.J.); Tel.: +86-13505694447 (Y.X.); +86-17605607323 (T.J.)
| | - Tengchuan Jin
- Hefei National Laboratory for Physical Sciences at Microscale, Laboratory of Structural Immunology, CAS Key Laboratory of Innate Immunity and Chronic Disease, Division of Life Sciences and Medicine, School of Basic Medical Sciences, University of Science and Technology of China, Hefei 230027, China; (Y.L.); (H.M.M.); (C.Z.)
- Correspondence: (Y.X.); (T.J.); Tel.: +86-13505694447 (Y.X.); +86-17605607323 (T.J.)
| |
Collapse
|
14
|
Bosch ME, Bertrand BP, Heim CE, Alqarzaee AA, Chaudhari SS, Aldrich AL, Fey PD, Thomas VC, Kielian T. Staphylococcus aureus ATP Synthase Promotes Biofilm Persistence by Influencing Innate Immunity. mBio 2020; 11:e01581-20. [PMID: 32900803 PMCID: PMC7482063 DOI: 10.1128/mbio.01581-20] [Citation(s) in RCA: 25] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2020] [Accepted: 08/08/2020] [Indexed: 12/20/2022] Open
Abstract
Staphylococcus aureus is a major cause of prosthetic joint infection (PJI), which is characterized by biofilm formation. S. aureus biofilm skews the host immune response toward an anti-inflammatory profile by the increased recruitment of myeloid-derived suppressor cells (MDSCs) that attenuate macrophage proinflammatory activity, leading to chronic infection. A screen of the Nebraska Transposon Mutant Library identified several hits in the ATP synthase operon that elicited a heightened inflammatory response in macrophages and MDSCs, including atpA, which encodes the alpha subunit of ATP synthase. An atpA transposon mutant (ΔatpA) had altered growth kinetics under both planktonic and biofilm conditions, along with a diffuse biofilm architecture that was permissive for leukocyte infiltration, as observed by confocal laser scanning microscopy. Coculture of MDSCs and macrophages with ΔatpA biofilm elicited significant increases in the proinflammatory cytokines interleukin 12p70 (IL-12p70), tumor necrosis factor alpha (TNF-α), and IL-6. This was attributed to increased leukocyte survival resulting from less toxin and protease production by ΔatpA biofilm as determined by liquid chromatography with tandem mass spectrometry (LC-MS/MS). The enhanced inflammatory response elicited by ΔatpA biofilm was cell lysis-dependent since it was negated by polyanethole sodium sulfanate treatment or deletion of the major autolysin, Atl. In a mouse model of PJI, ΔatpA-infected mice had decreased MDSCs concomitant with increased monocyte/macrophage infiltrates and proinflammatory cytokine production, which resulted in biofilm clearance. These studies identify S. aureus ATP synthase as an important factor in influencing the immune response during biofilm-associated infection and bacterial persistence.IMPORTANCE Medical device-associated biofilm infections are a therapeutic challenge based on their antibiotic tolerance and ability to evade immune-mediated clearance. The virulence determinants responsible for bacterial biofilm to induce a maladaptive immune response remain largely unknown. This study identified a critical role for S. aureus ATP synthase in influencing the host immune response to biofilm infection. An S. aureus ATP synthase alpha subunit mutant (ΔatpA) elicited heightened proinflammatory cytokine production by leukocytes in vitro and in vivo, which coincided with improved biofilm clearance in a mouse model of prosthetic joint infection. The ability of S. aureus ΔatpA to augment host proinflammatory responses was cell lysis-dependent, as inhibition of bacterial lysis by polyanethole sodium sulfanate or a ΔatpAΔatl biofilm did not elicit heightened cytokine production. These studies reveal a critical role for AtpA in shaping the host immune response to S. aureus biofilm.
Collapse
Affiliation(s)
- Megan E Bosch
- Department of Pathology and Microbiology, University of Nebraska Medical Center, Omaha, Nebraska, USA
| | - Blake P Bertrand
- Department of Pathology and Microbiology, University of Nebraska Medical Center, Omaha, Nebraska, USA
| | - Cortney E Heim
- Department of Pathology and Microbiology, University of Nebraska Medical Center, Omaha, Nebraska, USA
| | - Abdulelah A Alqarzaee
- Department of Pathology and Microbiology, University of Nebraska Medical Center, Omaha, Nebraska, USA
| | - Sujata S Chaudhari
- Department of Pathology and Microbiology, University of Nebraska Medical Center, Omaha, Nebraska, USA
| | - Amy L Aldrich
- Department of Pathology and Microbiology, University of Nebraska Medical Center, Omaha, Nebraska, USA
| | - Paul D Fey
- Department of Pathology and Microbiology, University of Nebraska Medical Center, Omaha, Nebraska, USA
| | - Vinai C Thomas
- Department of Pathology and Microbiology, University of Nebraska Medical Center, Omaha, Nebraska, USA
| | - Tammy Kielian
- Department of Pathology and Microbiology, University of Nebraska Medical Center, Omaha, Nebraska, USA
| |
Collapse
|
15
|
Liu J, Kozhaya L, Torres VJ, Unutmaz D, Lu M. Structure-based discovery of a small-molecule inhibitor of methicillin-resistant Staphylococcus aureus virulence. J Biol Chem 2020; 295:5944-5959. [PMID: 32179646 PMCID: PMC7196633 DOI: 10.1074/jbc.ra120.012697] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2020] [Revised: 03/06/2020] [Indexed: 01/07/2023] Open
Abstract
The rapid emergence and dissemination of methicillin-resistant Staphylococcus aureus (MRSA) strains poses a major threat to public health. MRSA possesses an arsenal of secreted host-damaging virulence factors that mediate pathogenicity and blunt immune defenses. Panton-Valentine leukocidin (PVL) and α-toxin are exotoxins that create lytic pores in the host cell membrane. They are recognized as being important for the development of invasive MRSA infections and are thus potential targets for antivirulence therapies. Here, we report the high-resolution X-ray crystal structures of both PVL and α-toxin in their soluble, monomeric, and oligomeric membrane-inserted pore states in complex with n-tetradecylphosphocholine (C14PC). The structures revealed two evolutionarily conserved phosphatidylcholine-binding mechanisms and their roles in modulating host cell attachment, oligomer assembly, and membrane perforation. Moreover, we demonstrate that the soluble C14PC compound protects primary human immune cells in vitro against cytolysis by PVL and α-toxin and hence may serve as the basis for the development of an antivirulence agent for managing MRSA infections.
Collapse
Affiliation(s)
- Jie Liu
- Public Health Research Institute, Department of Microbiology, Biochemistry, and Molecular Genetics, New Jersey Medical School, Rutgers University, Newark, New Jersey 07103
| | - Lina Kozhaya
- Jackson Laboratory for Genomic Medicine, Farmington, Connecticut 06032
| | - Victor J. Torres
- Department of Microbiology, New York University School of Medicine, New York, New York 10016
| | - Derya Unutmaz
- Jackson Laboratory for Genomic Medicine, Farmington, Connecticut 06032
| | - Min Lu
- Public Health Research Institute, Department of Microbiology, Biochemistry, and Molecular Genetics, New Jersey Medical School, Rutgers University, Newark, New Jersey 07103, To whom correspondence should be addressed:
Public Health Research Institute, Dept. of Microbiology, Biochemistry, and Molecular Genetics, New Jersey Medical School, Newark, NJ 07103. Tel.:
973-854-3260; E-mail:
| |
Collapse
|
16
|
Unbiased Identification of Immunogenic Staphylococcus aureus Leukotoxin B-Cell Epitopes. Infect Immun 2020; 88:IAI.00785-19. [PMID: 32014894 DOI: 10.1128/iai.00785-19] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2019] [Accepted: 01/26/2020] [Indexed: 12/26/2022] Open
Abstract
Unbiased identification of individual immunogenic B-cell epitopes in major antigens of a pathogen remains a technology challenge for vaccine discovery. We therefore developed a platform for rapid phage display screening of deep recombinant libraries consisting of as few as one major pathogen antigen. Using the bicomponent pore-forming leukocidin (Luk) exotoxins of the major pathogen Staphylococcus aureus as a prototype, we randomly fragmented and separately ligated the hemolysin gamma A (HlgA) and LukS genes into a custom-built phage display system, termed pComb-Opti8. Deep sequence analysis of barcoded amplimers of the HlgA and LukS gene fragment libraries demonstrated that biopannng against a cross-reactive anti-Luk monoclonal antibody (MAb) recovered convergent molecular clones with short overlapping homologous sequences. We thereby identified an 11-amino-acid sequence that is highly conserved in four Luk toxin subunits and is ubiquitous in representation within S. aureus clinical isolates. The isolated 11-amino-acid peptide probe was predicted to retain the native three-dimensional (3D) conformation seen within the Luk holotoxin. Indeed, this peptide was recognized by the selecting anti-Luk MAb, and, using mutated peptides, we showed that a particular amino acid side chain was essential for these interactions. Furthermore, murine immunization with this peptide elicited IgG responses that were highly reactive with both the autologous synthetic peptide and the full-length Luk toxin homologues. Thus, using a gene fragment- and phage display-based pipeline, we have identified and validated immunogenic B-cell epitopes that are cross-reactive between members of the pore-forming leukocidin family. This approach could be harnessed to identify novel epitopes for a much-needed S. aureus-protective subunit vaccine.
Collapse
|
17
|
Chan R, Buckley PT, O'Malley A, Sause WE, Alonzo F, Lubkin A, Boguslawski KM, Payne A, Fernandez J, Strohl WR, Whitaker B, Lynch AS, Torres VJ. Identification of biologic agents to neutralize the bicomponent leukocidins of Staphylococcus aureus. Sci Transl Med 2020; 11:11/475/eaat0882. [PMID: 30651319 DOI: 10.1126/scitranslmed.aat0882] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2017] [Revised: 01/22/2018] [Accepted: 12/17/2018] [Indexed: 12/12/2022]
Abstract
A key aspect underlying the severity of infections caused by Staphylococcus aureus is the abundance of virulence factors that the pathogen uses to thwart critical components of the human immune response. One such mechanism involves the destruction of host immune cells by cytolytic toxins secreted by S. aureus, including five bicomponent leukocidins: PVL, HlgAB, HlgCB, LukED, and LukAB. Purified leukocidins can lyse immune cells ex vivo, and systemic injections of purified LukED or HlgAB can acutely kill mice. Here, we describe the generation and characterization of centyrins that bind S. aureus leukocidins with high affinity and protect primary human immune cells from toxin-mediated cytolysis. Centyrins are small protein scaffolds derived from the fibronectin type III-binding domain of the human protein tenascin-C. Although centyrins are potent in tissue culture assays, their short serum half-lives limit their efficacies in vivo. By extending the serum half-lives of centyrins through their fusion to an albumin-binding consensus domain, we demonstrate the in vivo efficacy of these biologics in a murine intoxication model and in models of both prophylactic and therapeutic treatment of live S. aureus systemic infections. These biologics that target S. aureus virulence factors have potential for treating and preventing serious staphylococcal infections.
Collapse
Affiliation(s)
- Rita Chan
- Department of Microbiology, New York University School of Medicine, Alexandria Center for Life Science, 430 East 29th Street, New York, NY 10016, USA
| | - Peter T Buckley
- Janssen Research & Development, 1400 McKean Road, Spring House, PA, 19477, USA
| | - Aidan O'Malley
- Department of Microbiology, New York University School of Medicine, Alexandria Center for Life Science, 430 East 29th Street, New York, NY 10016, USA
| | - William E Sause
- Department of Microbiology, New York University School of Medicine, Alexandria Center for Life Science, 430 East 29th Street, New York, NY 10016, USA
| | - Francis Alonzo
- Department of Microbiology, New York University School of Medicine, Alexandria Center for Life Science, 430 East 29th Street, New York, NY 10016, USA
| | - Ashira Lubkin
- Department of Microbiology, New York University School of Medicine, Alexandria Center for Life Science, 430 East 29th Street, New York, NY 10016, USA
| | - Kristina M Boguslawski
- Department of Microbiology, New York University School of Medicine, Alexandria Center for Life Science, 430 East 29th Street, New York, NY 10016, USA
| | - Angela Payne
- Janssen Research & Development, 1400 McKean Road, Spring House, PA, 19477, USA
| | - Jeffrey Fernandez
- Janssen Research & Development, 1400 McKean Road, Spring House, PA, 19477, USA
| | - William R Strohl
- Janssen Research & Development, 1400 McKean Road, Spring House, PA, 19477, USA
| | - Brian Whitaker
- Janssen Research & Development, 1400 McKean Road, Spring House, PA, 19477, USA
| | - Anthony Simon Lynch
- Janssen Research & Development, 1400 McKean Road, Spring House, PA, 19477, USA.
| | - Victor J Torres
- Department of Microbiology, New York University School of Medicine, Alexandria Center for Life Science, 430 East 29th Street, New York, NY 10016, USA.
| |
Collapse
|
18
|
Molecular mechanism of leukocidin GH-integrin CD11b/CD18 recognition and species specificity. Proc Natl Acad Sci U S A 2019; 117:317-327. [PMID: 31852826 PMCID: PMC6955338 DOI: 10.1073/pnas.1913690116] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
Staphylococcus aureus is one of the most virulent bacterial pathogens and, in particular, has the richest repertoire of cytotoxins: A single bacterium can secrete 6 different β-barrel pore-forming toxins, with different cell type and species specificities. Each toxin engages specific receptors on target cells, but the role the receptor plays in the pore-formation process is poorly understood. Here, we determine the crystal structures of a very potent S. aureus leukocidin (LukGH) in complex with its receptor (CD11b) from a sensitive (human) and an insensitive (murine) host, and track the receptor involvement in different steps on the pore-formation pathway. These results advance the knowledge of receptor-mediated leukocidin pore formation and open ways for antileukocidin and anti-S. aureus approaches. Host–pathogen interactions are central to understanding microbial pathogenesis. The staphylococcal pore-forming cytotoxins hijack important immune molecules but little is known about the underlying molecular mechanisms of cytotoxin–receptor interaction and host specificity. Here we report the structures of a staphylococcal pore-forming cytotoxin, leukocidin GH (LukGH), in complex with its receptor (the α-I domain of complement receptor 3, CD11b-I), both for the human and murine homologs. We observe 2 binding interfaces, on the LukG and the LukH protomers, and show that human CD11b-I induces LukGH oligomerization in solution. LukGH binds murine CD11b-I weakly and is inactive toward murine neutrophils. Using a LukGH variant engineered to bind mouse CD11b-I, we demonstrate that cytolytic activity does not only require binding but also receptor-dependent oligomerization. Our studies provide an unprecedented insight into bicomponent leukocidin–host receptor interaction, enabling the development of antitoxin approaches and improved animal models to explore these approaches.
Collapse
|
19
|
Rational Design of Toxoid Vaccine Candidates for Staphylococcus aureus Leukocidin AB (LukAB). Toxins (Basel) 2019; 11:toxins11060339. [PMID: 31207937 PMCID: PMC6628420 DOI: 10.3390/toxins11060339] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2019] [Revised: 06/10/2019] [Accepted: 06/12/2019] [Indexed: 11/16/2022] Open
Abstract
Staphylococcus aureus (SA) infections cause high mortality and morbidity in humans. Being central to its pathogenesis, S. aureus thwarts the host defense by secreting a myriad of virulence factors, including bicomponent, pore-forming leukotoxins. While all vaccine development efforts that aimed at achieving opsonophagocytic killing have failed, targeting virulence by toxoid vaccines represents a novel approach to preventing mortality and morbidity that are caused by SA. The recently discovered leukotoxin LukAB kills human phagocytes and monocytes and it is present in all known S. aureus clinical isolates. While using a structure-guided approach, we generated a library of mutations that targeted functional domains within the LukAB heterodimer to identify attenuated toxoids as potential vaccine candidates. The mutants were evaluated based on expression, solubility, yield, biophysical properties, cytotoxicity, and immunogenicity, and several fully attenuated LukAB toxoids that were capable of eliciting high neutralizing antibody titers were identified. Rabbit polyclonal antibodies against the lead toxoid candidate provided potent neutralization of LukAB. While the neutralization of LukAB alone was not sufficient to fully suppress leukotoxicity in supernatants of S. aureus USA300 isolates, a combination of antibodies against LukAB, α-toxin, and Panton-Valentine leukocidin completely neutralized the cytotoxicity of these strains. These data strongly support the inclusion of LukAB toxoids in a multivalent toxoid vaccine for the prevention of S. aureus disease.
Collapse
|
20
|
The Role of Streptococcal and Staphylococcal Exotoxins and Proteases in Human Necrotizing Soft Tissue Infections. Toxins (Basel) 2019; 11:toxins11060332. [PMID: 31212697 PMCID: PMC6628391 DOI: 10.3390/toxins11060332] [Citation(s) in RCA: 25] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2019] [Revised: 06/04/2019] [Accepted: 06/10/2019] [Indexed: 12/31/2022] Open
Abstract
Necrotizing soft tissue infections (NSTIs) are critical clinical conditions characterized by extensive necrosis of any layer of the soft tissue and systemic toxicity. Group A streptococci (GAS) and Staphylococcus aureus are two major pathogens associated with monomicrobial NSTIs. In the tissue environment, both Gram-positive bacteria secrete a variety of molecules, including pore-forming exotoxins, superantigens, and proteases with cytolytic and immunomodulatory functions. The present review summarizes the current knowledge about streptococcal and staphylococcal toxins in NSTIs with a special focus on their contribution to disease progression, tissue pathology, and immune evasion strategies.
Collapse
|
21
|
Tam K, Torres VJ. Staphylococcus aureus Secreted Toxins and Extracellular Enzymes. Microbiol Spectr 2019; 7:10.1128/microbiolspec.GPP3-0039-2018. [PMID: 30873936 PMCID: PMC6422052 DOI: 10.1128/microbiolspec.gpp3-0039-2018] [Citation(s) in RCA: 201] [Impact Index Per Article: 40.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2018] [Indexed: 02/06/2023] Open
Abstract
Staphylococcus aureus is a formidable pathogen capable of causing infections in different sites of the body in a variety of vertebrate animals, including humans and livestock. A major contribution to the success of S. aureus as a pathogen is the plethora of virulence factors that manipulate the host's innate and adaptive immune responses. Many of these immune modulating virulence factors are secreted toxins, cofactors for activating host zymogens, and exoenzymes. Secreted toxins such as pore-forming toxins and superantigens are highly inflammatory and can cause leukocyte cell death by cytolysis and clonal deletion, respectively. Coagulases and staphylokinases are cofactors that hijack the host's coagulation system. Exoenzymes, including nucleases and proteases, cleave and inactivate various immune defense and surveillance molecules, such as complement factors, antimicrobial peptides, and surface receptors that are important for leukocyte chemotaxis. Additionally, some of these secreted toxins and exoenzymes can cause disruption of endothelial and epithelial barriers through cell lysis and cleavage of junction proteins. A unique feature when examining the repertoire of S. aureus secreted virulence factors is the apparent functional redundancy exhibited by the majority of the toxins and exoenzymes. However, closer examination of each virulence factor revealed that each has unique properties that have important functional consequences. This chapter provides a brief overview of our current understanding of the major secreted virulence factors critical for S. aureus pathogenesis.
Collapse
Affiliation(s)
- Kayan Tam
- Department of Microbiology, New York University School of Medicine, Alexandria Center for Life Science, New York, NY 10016
| | - Victor J Torres
- Department of Microbiology, New York University School of Medicine, Alexandria Center for Life Science, New York, NY 10016
| |
Collapse
|
22
|
Adaptation of the Staphylococcus aureus leukocidin LukGH for the rabbit host by protein engineering. Biochem J 2019; 476:275-292. [PMID: 30559327 DOI: 10.1042/bcj20180691] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2018] [Revised: 12/12/2018] [Accepted: 12/14/2018] [Indexed: 02/07/2023]
Abstract
Host defense against Staphylococcus aureus greatly depends on bacterial clearance by phagocytic cells. LukGH (or LukAB) is the most potent staphylococcal leukocidin towards human phagocytes in vitro, but its role in pathogenesis is obscured by the lack of suitable small animal models because LukGH has limited or no cytotoxicity towards rodent and rabbit compared with human polymorphonuclear cells (PMNs) likely due to an impaired interaction with its cellular receptor, CD11b. We aimed at adapting LukGH for the rabbit host by improving binding to the rabbit homolog of CD11b, specifically its I-domain (CD11b-I). Targeted amino acid substitutions were introduced into the LukH polypeptide to map its receptor interaction site(s). We found that the binding affinity of LukGH variants to the human and rabbit CD11b-I correlated well with their PMN cytotoxicity. Importantly, we identified LukGH variants with significantly improved cytotoxicity towards rabbit PMNs, when expressed recombinantly (10-15-fold) or by engineered S. aureus strains. These findings support the development of small animal models of S. aureus infection with the potential for demonstrating the importance of LukGH in pathogenesis.
Collapse
|
23
|
Darisipudi MN, Nordengrün M, Bröker BM, Péton V. Messing with the Sentinels-The Interaction of Staphylococcus aureus with Dendritic Cells. Microorganisms 2018; 6:microorganisms6030087. [PMID: 30111706 PMCID: PMC6163568 DOI: 10.3390/microorganisms6030087] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2018] [Revised: 08/12/2018] [Accepted: 08/14/2018] [Indexed: 12/14/2022] Open
Abstract
Staphylococcus aureus (S. aureus) is a dangerous pathogen as well as a frequent colonizer, threatening human health worldwide. Protection against S. aureus infection is challenging, as the bacteria have sophisticated strategies to escape the host immune response. To maintain equilibrium with S. aureus, both innate and adaptive immune effector mechanisms are required. Dendritic cells (DCs) are critical players at the interface between the two arms of the immune system, indispensable for inducing specific T cell responses. In this review, we highlight the importance of DCs in mounting innate as well as adaptive immune responses against S. aureus with emphasis on their role in S. aureus-induced respiratory diseases. We also review what is known about mechanisms that S. aureus has adopted to evade DCs or manipulate these cells to its advantage.
Collapse
Affiliation(s)
- Murthy N Darisipudi
- Department of Immunology, University Medicine Greifswald, Ferdinand-Sauerbruch-Straße DZ7, D-17475 Greifswald, Germany.
| | - Maria Nordengrün
- Department of Immunology, University Medicine Greifswald, Ferdinand-Sauerbruch-Straße DZ7, D-17475 Greifswald, Germany.
| | - Barbara M Bröker
- Department of Immunology, University Medicine Greifswald, Ferdinand-Sauerbruch-Straße DZ7, D-17475 Greifswald, Germany.
| | - Vincent Péton
- Department of Immunology, University Medicine Greifswald, Ferdinand-Sauerbruch-Straße DZ7, D-17475 Greifswald, Germany.
| |
Collapse
|
24
|
Staphylococcus aureus Toxins and Their Molecular Activity in Infectious Diseases. Toxins (Basel) 2018; 10:toxins10060252. [PMID: 29921792 PMCID: PMC6024779 DOI: 10.3390/toxins10060252] [Citation(s) in RCA: 234] [Impact Index Per Article: 39.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2018] [Revised: 06/14/2018] [Accepted: 06/15/2018] [Indexed: 12/04/2022] Open
Abstract
Staphylococcus aureus is a microorganism resident in the skin and nasal membranes with a dreadful pathogenic potential to cause a variety of community and hospital-acquired infections. The frequency of these infections is increasing and their treatment is becoming more difficult. The ability of S. aureus to form biofilms and the emergence of multidrug-resistant strains are the main reasons determining the challenge in dealing with these infections. S. aureus' infectious capacity and its success as a pathogen is related to the expression of virulence factors, among which the production of a wide variety of toxins is highlighted. For this reason, a better understanding of S. aureus toxins is needed to enable the development of new strategies to reduce their production and consequently improve therapeutic approaches. This review focuses on understanding the toxin-based pathogenesis of S. aureus and their role on infectious diseases.
Collapse
|
25
|
Affiliation(s)
- Isaac P Thomsen
- a Department of Pediatrics , Division of Pediatric Infectious Diseases and the Vanderbilt Vaccine Research Program, Vanderbilt University Medical Center , Nashville , Tennessee , USA
| |
Collapse
|
26
|
Wood JB, Jones LS, Soper NR, Xu M, Torres VJ, Buddy Creech C, Thomsen IP. Serologic Detection of Antibodies Targeting the Leukocidin LukAB Strongly Predicts Staphylococcus aureus in Children With Invasive Infection. J Pediatric Infect Dis Soc 2018. [PMID: 29538707 PMCID: PMC6510946 DOI: 10.1093/jpids/piy017] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
BACKGROUND Staphylococcus aureus is among the most commonly identified causes of invasive bacterial infection in children; however, reliable results from cultures of sterile-site samples often cannot be obtained, which necessitates prescription of a broad empiric antimicrobial agent(s). Children with invasive S aureus infection rapidly generate high antibody titers to the cytotoxin LukAB; therefore, the aim of this study was to assess the diagnostic utility of an anti-LukAB antibody assay for children with musculoskeletal infection (MSKI). METHODS We conducted a 2-year prospective study of all eligible children admitted to Vanderbilt Children's Hospital with an MSKI. Acute and convalescent sera were obtained, and antibodies that target LukAB were measured by an enzyme-linked immunosorbent assay. RESULTS Forty-two children were enrolled. The median concentrations of LukAB antibodies for children with S aureus infection were 130.3 U/mL in the acute phase and 455 U/mL in the convalescent phase (P < .001). The median concentrations of LukAB antibodies in children with a non-S aureus MSKI were 8.6 U/mL in the acute phase and 9.7 U/mL in the convalescent phase. The assay discriminated between S aureus and non-S aureus infection with areas under the receiver operating characteristic curve of 0.81 (95% confidence interval, 0.67-0.95; P < .001) and 0.95 (95% confidence interval, 0.86-1; P < .001) for samples tested in the acute and follow-up periods, respectively. With no false-negative results, the assay accurately ruled out S aureus in samples obtained during the convalescent phase. CONCLUSION Culture-independent diagnostics have the potential to improve care by narrowing antimicrobial therapy on the basis of the likelihood of S aureus infection. The results of this proof-of-concept study suggest that a LukAB serologic assay might be useful in the diagnosis of invasive bacterial infections, and larger-scale validation studies are warranted.
Collapse
Affiliation(s)
- James B Wood
- Division of Pediatric Infectious Diseases, Department of Pediatrics, Nashville, Tennessee,Correspondence: J. B. Wood, Vanderbilt University Medical Center, Division of Pediatric Infectious Diseases, 1161 21st Ave South, D-7235 MCN, Nashville, TN 37232 ()
| | - Lauren S Jones
- Division of Pediatric Infectious Diseases, Department of Pediatrics, Nashville, Tennessee
| | - Nicole R Soper
- Division of Pediatric Infectious Diseases, Department of Pediatrics, Nashville, Tennessee
| | - Meng Xu
- Department of Biostatistics, Vanderbilt University School of Medicine, Nashville, Tennessee
| | - Victor J Torres
- Department of Microbiology, New York University School of Medicine, New York
| | - C Buddy Creech
- Division of Pediatric Infectious Diseases, Department of Pediatrics, Nashville, Tennessee
| | - Isaac P Thomsen
- Division of Pediatric Infectious Diseases, Department of Pediatrics, Nashville, Tennessee
| |
Collapse
|
27
|
Staphylococcus aureus produces pain through pore-forming toxins and neuronal TRPV1 that is silenced by QX-314. Nat Commun 2018; 9:37. [PMID: 29295977 PMCID: PMC5750211 DOI: 10.1038/s41467-017-02448-6] [Citation(s) in RCA: 104] [Impact Index Per Article: 17.3] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2017] [Accepted: 11/30/2017] [Indexed: 12/22/2022] Open
Abstract
The hallmark of many bacterial infections is pain. The underlying mechanisms of pain during live pathogen invasion are not well understood. Here, we elucidate key molecular mechanisms of pain produced during live methicillin-resistant Staphylococcus aureus (MRSA) infection. We show that spontaneous pain is dependent on the virulence determinant agr and bacterial pore-forming toxins (PFTs). The cation channel, TRPV1, mediated heat hyperalgesia as a distinct pain modality. Three classes of PFTs-alpha-hemolysin (Hla), phenol-soluble modulins (PSMs), and the leukocidin HlgAB-directly induced neuronal firing and produced spontaneous pain. From these mechanisms, we hypothesized that pores formed in neurons would allow entry of the membrane-impermeable sodium channel blocker QX-314 into nociceptors to silence pain during infection. QX-314 induced immediate and long-lasting blockade of pain caused by MRSA infection, significantly more than lidocaine or ibuprofen, two widely used clinical analgesic treatments.
Collapse
|
28
|
After the deluge: mining Staphylococcus aureus genomic data for clinical associations and host-pathogen interactions. Curr Opin Microbiol 2017; 41:43-50. [PMID: 29197673 DOI: 10.1016/j.mib.2017.11.014] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2017] [Revised: 11/04/2017] [Accepted: 11/16/2017] [Indexed: 01/31/2023]
Abstract
The genome of Staphylococcus aureus has rapidly become one the most frequently sequenced among bacteria, with more than 40000 genome sequences uploaded to public databases. Computational resources required for analysis and quality assessment have lagged behind accumulation of sequence data. Improved analytic pipelines, in combination with the development of customized S. aureus reference databases, can be used to inform S. aureus biology and potentially predict clinical outcome. Here, we review the currently available data about S. aureus genome in public databases, and discuss their potential utility for understanding S. aureus evolution. Also discussed are ways to overcome challenges to the application of whole-genome sequencing data for prevention and management of S. aureus disease.
Collapse
|
29
|
Gillman AN, Breshears LM, Kistler CK, Finnegan PM, Torres VJ, Schlievert PM, Peterson ML. Epidermal Growth Factor Receptor Signaling Enhances the Proinflammatory Effects of Staphylococcus aureus Gamma-Toxin on the Mucosa. Toxins (Basel) 2017; 9:toxins9070202. [PMID: 28657583 PMCID: PMC5535149 DOI: 10.3390/toxins9070202] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2016] [Revised: 06/02/2017] [Accepted: 06/09/2017] [Indexed: 12/27/2022] Open
Abstract
Staphylococcus aureus (S. aureus) produces many different exotoxins including the gamma-toxins, HlgAB and HlgCB. Gamma-toxins form pores in both leukocyte and erythrocyte membranes, resulting in cell lysis. The genes encoding gamma-toxins are present in most strains of S. aureus, and are commonly expressed in clinical isolates recovered from menstrual Toxic Shock Syndrome (mTSS) patients. This study set out to investigate the cytotoxic and proinflammatory effects of gamma-toxins on vaginal epithelial surfaces. We found that both HlgAB and HlgCB were cytotoxic to cultured human vaginal epithelial cells (HVECs) and induced cytokine production at sub-cytotoxic doses. Cytokine production induced by gamma-toxin treatment of HVECs was found to involve epidermal growth factor receptor (EGFR) signaling and mediated by shedding of EGFR ligands from the cell surface. The gamma-toxin subunits displayed differential binding to HVECs (HlgA 93%, HlgB 97% and HlgC 28%) with both components (HlgAB or HlgCB) required for maximum detectable binding and significant stimulation of cytokine production. In studies using full thickness ex vivo porcine vaginal mucosa, HlgAB or HlgCB stimulated a dose-dependent cytokine response, which was reduced significantly by inhibition of EGFR signaling. The effects of gamma-toxins on porcine vaginal tissue and cultured HVECs were validated using ex vivo human ectocervical tissue. Collectively, these studies have identified the EGFR-signaling pathway as a key component in gamma-toxin-induced proinflammatory changes at epithelial surfaces and highlight a potential therapeutic target to diminish toxigenic effects of S. aureus infections.
Collapse
Affiliation(s)
- Aaron N Gillman
- Department of Pharmacy, University of Tromsø, Tromsø 9019, Troms, Norway.
- Department of Experimental and Clinical Pharmacology, University of Minnesota, Minneapolis, MN 55455, USA.
| | - Laura M Breshears
- Department of Experimental and Clinical Pharmacology, University of Minnesota, Minneapolis, MN 55455, USA.
| | | | | | - Victor J Torres
- Department of Microbiology, New York University School of Medicine, New York, NY 10016, USA.
| | - Patrick M Schlievert
- Department of Microbiology, University of Iowa Carver College of Medicine, Iowa City, IA 52242, USA.
| | - Marnie L Peterson
- Department of Experimental and Clinical Pharmacology, University of Minnesota, Minneapolis, MN 55455, USA.
- Extherid Biosciences, LLC., Jackson, WY 83001, USA.
- School of Pharmacy, University of Wyoming, Laramie, WY 82071, USA.
| |
Collapse
|
30
|
Seilie ES, Bubeck Wardenburg J. Staphylococcus aureus pore-forming toxins: The interface of pathogen and host complexity. Semin Cell Dev Biol 2017; 72:101-116. [PMID: 28445785 DOI: 10.1016/j.semcdb.2017.04.003] [Citation(s) in RCA: 140] [Impact Index Per Article: 20.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2016] [Revised: 03/22/2017] [Accepted: 04/18/2017] [Indexed: 12/20/2022]
Abstract
Staphylococcus aureus is a prominent human pathogen capable of infecting a variety of host species and tissue sites. This versatility stems from the pathogen's ability to secrete diverse host-damaging virulence factors. Among these factors, the S. aureus pore-forming toxins (PFTs) α-toxin and the bicomponent leukocidins, have garnered much attention for their ability to lyse cells at low concentrations and modulate disease severity. Although many of these toxins were discovered nearly a century ago, their host cell specificities have only been elucidated over the past five to six years, starting with the discovery of the eukaryotic receptor for α-toxin and rapidly followed by identification of the leukocidin receptors. The identification of these receptors has revealed the species- and cell type-specificity of toxin binding, and provided insight into non-lytic effects of PFT intoxication that contribute to disease pathogenesis.
Collapse
Affiliation(s)
- E Sachiko Seilie
- Department of Pediatrics, The University of Chicago, Chicago, IL 60637, United States; Department of Microbiology, The University of Chicago, Chicago, IL 60637, United States
| | | |
Collapse
|
31
|
Spaan AN, van Strijp JAG, Torres VJ. Leukocidins: staphylococcal bi-component pore-forming toxins find their receptors. Nat Rev Microbiol 2017; 15:435-447. [PMID: 28420883 DOI: 10.1038/nrmicro.2017.27] [Citation(s) in RCA: 225] [Impact Index Per Article: 32.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
Staphylococcus aureus is a major bacterial pathogen that causes disease worldwide. The emergence of strains that are resistant to commonly used antibiotics and the failure of vaccine development have resulted in a renewed interest in the pathophysiology of this bacterium. Staphylococcal leukocidins are a family of bi-component pore-forming toxins that are important virulence factors. During the past five years, cellular receptors have been identified for all of the bi-component leukocidins. The identification of the leukocidin receptors explains the cellular tropism and species specificity that is exhibited by these toxins, which has important biological consequences. In this Review, we summarize the recent discoveries that have reignited interest in these toxins and provide an outlook for future research.
Collapse
Affiliation(s)
- András N Spaan
- Department of Medical Microbiology, University Medical Center Utrecht, Heidelberglaan 100, 3584CX Utrecht, The Netherlands
| | - Jos A G van Strijp
- Department of Medical Microbiology, University Medical Center Utrecht, Heidelberglaan 100, 3584CX Utrecht, The Netherlands
| | - Victor J Torres
- Department of Microbiology, New York University School of Medicine, 430 East 29th Street, 10016 New York, USA
| |
Collapse
|
32
|
Thomsen IP, Sapparapu G, James DBA, Cassat JE, Nagarsheth M, Kose N, Putnam N, Boguslawski KM, Jones LS, Wood JB, Creech CB, Torres VJ, Crowe JE. Monoclonal Antibodies Against the Staphylococcus aureus Bicomponent Leukotoxin AB Isolated Following Invasive Human Infection Reveal Diverse Binding and Modes of Action. J Infect Dis 2017; 215:1124-1131. [PMID: 28186295 PMCID: PMC5426380 DOI: 10.1093/infdis/jix071] [Citation(s) in RCA: 63] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2016] [Accepted: 01/30/2017] [Indexed: 12/15/2022] Open
Abstract
The 2-component leukotoxin LukAB is critical for Staphylococcus aureus targeting and killing of human neutrophils ex vivo and is produced in the setting of human infection. We report 3 LukAB-specific human monoclonal antibodies (mAbs) with distinct mechanisms of toxin neutralization and in vivo efficacy. Three hybridomas secreting mAbs with anti-LukAB activity (designated SA-13, -15, and -17) were generated from B cells obtained from a 12-year-old boy with S. aureus osteomyelitis. Each of the 3 mAbs neutralized LukAB-mediated neutrophil toxicity, exhibited differing levels of potency, recognized different antigenic sites on the toxin, and displayed at least 2 distinct mechanisms for cytotoxic inhibition. SA-15 bound exclusively to the dimeric form of the toxin, suggesting that human B cells recognize epitopes on the dimerized form of LukAB during natural infection. Both SA-13 and SA-17 bound the LukA monomer and the LukAB dimer. Although all 3 mAbs potently neutralized cytotoxicity, only SA-15 and SA-17 significantly inhibited toxin association with the cell surface. Treatment with a 1:1 mixture of mAbs SA-15 and SA-17 resulted in significantly lower bacterial colony counts in heart, liver, and kidneys in a murine model of S. aureus sepsis. These data describe the isolation of diverse and efficacious antitoxin mAbs.
Collapse
Affiliation(s)
| | | | - David B A James
- Department of Microbiology, New York University School of Medicine, New York, New York
| | - James E Cassat
- Department of Pediatrics
- Department of Pathology, Microbiology and Immunology, Vanderbilt University Medical Center, Nashville, Tennessee ; and
| | | | | | - Nicole Putnam
- Department of Pathology, Microbiology and Immunology, Vanderbilt University Medical Center, Nashville, Tennessee; and
| | | | | | | | | | - Victor J Torres
- Department of Microbiology, New York University School of Medicine, New York, New York
| | - James E Crowe
- Department of Pediatrics
- Vanderbilt Vaccine Center, and
- Department of Pathology, Microbiology and Immunology, Vanderbilt University Medical Center, Nashville, Tennessee ; and
| |
Collapse
|
33
|
Janesch P, Rouha H, Weber S, Malafa S, Gross K, Maierhofer B, Badarau A, Visram ZC, Stulik L, Nagy E. Selective sensitization of human neutrophils to LukGH mediated cytotoxicity by Staphylococcus aureus and IL-8. J Infect 2017; 74:473-483. [PMID: 28237625 DOI: 10.1016/j.jinf.2017.02.004] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2016] [Revised: 02/14/2017] [Accepted: 02/17/2017] [Indexed: 01/03/2023]
Abstract
OBJECTIVES Staphylococcus aureus produces up to five bi-component leukocidins - LukSF-PV, gamma-hemolysins AB and CB, LukGH (LukAB) and LukED - to evade innate immunity by lysing phagocytic cells. Species specificity of these leukocidins limits the relevance of animal models, therefore we assessed their individual contribution using human neutrophils. METHODS Human polymorphonuclear leukocytes (PMNs) were activated with stimuli relevant during bacterial infections and sensitivity to recombinant leukocidins was measured in cell-viability assays. Leukocidin receptor expression was quantified by flow cytometry. RESULTS We observed greatly variable sensitivities of different PMN preparations towards LukGH. Activation of PMNs by lipopolysaccharide (LPS) or S. aureus culture supernatant (CS) lacking all leukocidins resulted in higher surface expression of CD11b, the LukGH receptor, and greatly enhanced the sensitivity towards LukGH, eliminating the variability observed with unstimulated cells. In contrast, CS induced a decrease in sensitivity of PMNs to the other four leukocidins and reduced surface staining for their cognate receptors (CXCR1, CXCR2, C5aR, C5L2). Delta-toxin and peptidoglycan mimicked the effect of CS. Moreover, IL-8, an important cytokine in neutrophil activation, also selectively increased LukGH sensitivity. Deletion of lukGH, but not other leukocidin genes, prevented PMN killing upon infection with USA300 CA-MRSA. CONCLUSION Inflammatory signals enhance the susceptibility of human PMNs to lysis by LukGH rendering this toxin dominant among the S. aureus leukocidins in vitro.
Collapse
|
34
|
Ahn D, Prince A. Host-Pathogen Interface: Progress in Understanding the Pathogenesis of Infection Due to Multidrug-Resistant Bacteria in the Intensive Care Unit. J Infect Dis 2017; 215:S1-S8. [PMID: 28375516 PMCID: PMC5853223 DOI: 10.1093/infdis/jiw405] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
The diverse responses of critically ill patients to infection with multi-drug resistant (MDR) bacteria are determined by many complex factors. These include the nature of the immune response activated by specific organisms. Properties unique to each organism such as adherence proteins, microvesicle formation, toxin production and the propensity to form biofilms are important factors in pathogenesis. Equally important is the variability in the host immune response, whether due to genetic or iatrogenic factors, including the presence of major comorbidities, treatment with immunomodulatory therapy and disruption of the microbiome. Future approaches in treating infections caused by MDR bacteria will be heavily influenced by a precision medicine approach, with rapid diagnostic techniques of both bacterial and host factors and high throughput screening of novel therapeutics becoming the mainstay of treatment.
Collapse
Affiliation(s)
- Danielle Ahn
- Department of Pediatrics, Columbia University Medical Center, New York
| | - Alice Prince
- Department of Pediatrics, Columbia University Medical Center, New York
| |
Collapse
|
35
|
Chapman JR, Balasubramanian D, Tam K, Askenazi M, Copin R, Shopsin B, Torres VJ, Ueberheide BM. Using Quantitative Spectrometry to Understand the Influence of Genetics and Nutritional Perturbations On the Virulence Potential of Staphylococcus aureus. Mol Cell Proteomics 2017; 16:S15-S28. [PMID: 28196877 DOI: 10.1074/mcp.o116.065581] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2016] [Revised: 02/12/2017] [Indexed: 01/03/2023] Open
Abstract
Staphylococcus aureus (Sa) is the leading cause of a variety of bacterial infections ranging from superficial skin infections to invasive and life threatening diseases such as septic bacteremia, necrotizing pneumonia, and endocarditis. The success of Sa as a human pathogen is contributed to its ability to adapt to different environments by changing expression, production, or secretion of virulence factors. Although Sa immune evasion is well-studied, the regulation of virulence factors under different nutrient and growth conditions is still not well understood. Here, we used label-free quantitative mass spectrometry to quantify and compare the Sa exoproteins (i.e. exoproteomes) of master regulator mutants or established reference strains. Different environmental conditions were addressed by growing the bacteria in rich or minimal media at different phases of growth. We observed clear differences in the composition of the exoproteomes depending on the genetic background or growth conditions. The relative abundance of cytotoxins determined in our study correlated well with differences in cytotoxicity measured by lysis of human neutrophils. Our findings demonstrate that label-free quantitative mass spectrometry is a versatile tool for predicting the virulence of bacterial strains and highlights the importance of the experimental design for in vitro studies. Furthermore, the results indicate that label-free proteomics can be used to cluster isolates into groups with similar virulence properties, highlighting the power of label-free quantitative mass spectrometry to distinguish Sa strains.
Collapse
Affiliation(s)
| | | | | | | | - Richard Copin
- §Department of Microbiology.,‖Department of Medicine
| | - Bo Shopsin
- §Department of Microbiology.,‖Department of Medicine
| | | | - Beatrix M Ueberheide
- From the ‡Proteomics Laboratory, .,**Department of Biochemistry and Molecular Pharmacology, New York University School of Medicine, New York, New York 10016
| |
Collapse
|
36
|
Structure and Function of the Two-Component Cytotoxins of Staphylococcus aureus - Learnings for Designing Novel Therapeutics. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2017; 966:15-35. [PMID: 28455832 DOI: 10.1007/5584_2016_200] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Staphylococcus aureus can produce up to five different bi-component cytotoxins: two gamma-hemolysins HlgAB and HlgCB, and leukocidins SF-PV (Panton Valentine leukocidin), ED (LukED) and GH (LukGH, also called LukAB). Their major function in S. aureus pathogenesis is to evade innate immunity by attacking phagocytic cells and to support bacterial growth by lysing red blood cells. The five cytotoxins display different levels of amino acid sequence conservation (30-82%), but all form a remarkably similar beta-barrel type pore structure (greatly resembling the mono-component toxin alpha-hemolysin) that inserts into the target cell membrane leading to necrotic cell death. This review provides an overview of the culmination of decades of research on the structure of these toxins, their unique sequence and structural features that helps to explain the observed functional differences, such as toxin potency towards different cell types and species, receptor specificity and formation of functional non-cognate toxin pairs. The vast knowledge accumulated in this field supports novel approaches and the design of therapeutics targeting these cytotoxins to tame virulence and fight S. aureus infections.
Collapse
|
37
|
Staphylococcus aureus Leukocidin LukED and HIV-1 gp120 Target Different Sequence Determinants on CCR5. mBio 2016; 7:mBio.02024-16. [PMID: 27965453 PMCID: PMC5156306 DOI: 10.1128/mbio.02024-16] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023] Open
Abstract
Leukocidin ED (LukED) is a bicomponent pore-forming toxin produced by Staphylococcus aureus that lyses host cells by targeting the chemokine receptors CC chemokine receptor type 5 (CCR5), CXCR1, CXCR2, and DARC. In addition to its role as a receptor for LukED, CCR5 is the major coreceptor for primary isolates of human immunodeficiency virus type 1 (HIV-1) and has been extensively studied. To compare how LukED and HIV-1 target CCR5, we analyzed their respective abilities to use CCR5/CCR2b chimeras to mediate cytotoxicity and virus entry. These analyses showed that the second and third extracellular loops (ECL) of CCR5 are necessary and sufficient for LukED to target the receptor and promote cell lysis. In contrast, the second ECL of CCR5 is necessary but not sufficient for HIV-1 infectivity. The analysis of CCR5 point mutations showed that glycine-163 is critical for HIV-1 infectivity, while arginine-274 and aspartic acid-276 are critical for LukED cytotoxicity. Point mutations in ECL2 diminished both HIV-1 infectivity and LukED cytotoxicity. Treatment of cells with LukED did not interfere with CCR5-tropic HIV-1 infectivity, demonstrating that LukED and the viral envelope glycoprotein use nonoverlapping sites on CCR5. Analysis of point mutations in LukE showed that amino acids 64 to 69 in the rim domain are required for CCR5 targeting and cytotoxicity. Taking the results together, this study identified the molecular basis by which LukED targets CCR5, highlighting the divergent molecular interactions evolved by HIV-1 and LukED to interact with CCR5. The bicomponent pore-forming toxins are thought to play a vital role in the success of Staphylococcus aureus as a mammalian pathogen. One of the leukocidins, LukED, is necessary and sufficient for lethality in mice. At the molecular level, LukED causes cell lysis through binding to specific cellular receptors. CCR5 is one of the receptors targeted by LukED and is the major coreceptor for CCR5-tropic HIV-1. While the molecular interaction of CCR5 and HIV-1 is well characterized, the means by which LukED interacts with CCR5 is less clear. In this study, we demonstrated that receptor specificity is conferred through unique interactions between key domains on CCR5 and LukE. Although HIV-1 and LukED target the same receptor, our data demonstrated that they interact with CCR5 differently, highlighting the molecular complexity of host-pathogen interactions.
Collapse
|
38
|
Badarau A, Rouha H, Malafa S, Battles MB, Walker L, Nielson N, Dolezilkova I, Teubenbacher A, Banerjee S, Maierhofer B, Weber S, Stulik L, Logan DT, Welin M, Mirkina I, Pleban C, Zauner G, Gross K, Jägerhofer M, Magyarics Z, Nagy E. Context matters: The importance of dimerization-induced conformation of the LukGH leukocidin of Staphylococcus aureus for the generation of neutralizing antibodies. MAbs 2016; 8:1347-1360. [PMID: 27467113 PMCID: PMC5058624 DOI: 10.1080/19420862.2016.1215791] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
LukGH (LukAB) is a potent leukocidin of Staphylococcus aureus that lyses human phagocytic cells and is thought to contribute to immune evasion. Unlike the other bi-component leukocidins of S. aureus, LukGH forms a heterodimer before binding to its receptor, CD11b expressed on professional phagocytic cells, and displays significant sequence variation. We employed a high diversity human IgG1 library presented on yeast cells to discover monoclonal antibodies (mAbs) neutralizing the cytolytic activity of LukGH. Recombinant LukG and LukH monomers or a LukGH dimer were used as capture antigens in the library selections. We found that mAbs identified with LukG or LukH as bait had no or very low toxin neutralization potency. In contrast, LukGH dimer-selected antibodies proved to be highly potent, and several mAbs were able to neutralize even the most divergent LukGH variants. Based on biolayer interferometry and mesoscale discovery, the high affinity antibody binding site on the LukGH complex was absent on the individual monomers, suggesting that it was generated upon formation of the LukG-LukH dimer. X-ray crystallography analysis of the complex between the LukGH dimer and the antigen-binding fragment of a very potent mAb (PDB code 5K59) indicated that the epitope is located in the predicted cell binding region (rim domain) of LukGH. The corresponding IgG inhibited the binding of LukGH dimer to target cells. Our data suggest that knowledge of the native conformation of target molecules is essential to generate high affinity and functional mAbs.
Collapse
Affiliation(s)
- Adriana Badarau
- a Arsanis Biosciences , Campus Vienna Biocenter, Vienna , Austria
| | - Harald Rouha
- a Arsanis Biosciences , Campus Vienna Biocenter, Vienna , Austria
| | - Stefan Malafa
- a Arsanis Biosciences , Campus Vienna Biocenter, Vienna , Austria
| | | | | | | | | | | | - Srijib Banerjee
- a Arsanis Biosciences , Campus Vienna Biocenter, Vienna , Austria
| | | | - Susanne Weber
- a Arsanis Biosciences , Campus Vienna Biocenter, Vienna , Austria
| | - Lukas Stulik
- a Arsanis Biosciences , Campus Vienna Biocenter, Vienna , Austria
| | - Derek T Logan
- c SARomics Biostructures AB , Medicon Village, Lund , Sweden
| | - Martin Welin
- c SARomics Biostructures AB , Medicon Village, Lund , Sweden
| | - Irina Mirkina
- a Arsanis Biosciences , Campus Vienna Biocenter, Vienna , Austria
| | - Clara Pleban
- a Arsanis Biosciences , Campus Vienna Biocenter, Vienna , Austria
| | - Gerhild Zauner
- a Arsanis Biosciences , Campus Vienna Biocenter, Vienna , Austria
| | - Karin Gross
- a Arsanis Biosciences , Campus Vienna Biocenter, Vienna , Austria
| | | | - Zoltán Magyarics
- a Arsanis Biosciences , Campus Vienna Biocenter, Vienna , Austria
| | - Eszter Nagy
- a Arsanis Biosciences , Campus Vienna Biocenter, Vienna , Austria
| |
Collapse
|
39
|
Münzenmayer L, Geiger T, Daiber E, Schulte B, Autenrieth SE, Fraunholz M, Wolz C. Influence of Sae-regulated and Agr-regulated factors on the escape of Staphylococcus aureus from human macrophages. Cell Microbiol 2016; 18:1172-83. [PMID: 26895738 DOI: 10.1111/cmi.12577] [Citation(s) in RCA: 57] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2015] [Revised: 01/12/2016] [Accepted: 01/26/2016] [Indexed: 02/03/2023]
Abstract
Although Staphylococcus aureus is not a classical intracellular pathogen, it can survive within phagocytes and many other cell types. However, the pathogen is also able to escape from cells by mechanisms that are only partially understood. We analysed a series of isogenic S. aureus mutants of the USA300 derivative JE2 for their capacity to destroy human macrophages from within. Intracellular S. aureus JE2 caused severe cell damage in human macrophages and could efficiently escape from within the cells. To obtain this full escape phenotype including an intermittent residency in the cytoplasm, the combined action of the regulatory systems Sae and Agr is required. Mutants in Sae or mutants deficient in the Sae target genes lukAB and pvl remained in high numbers within the macrophages causing reduced cell damage. Mutants in the regulatory system Agr or in the Agr target gene psmα were largely similar to wild-type bacteria concerning cell damage and escape efficiency. However, these strains were rarely detectable in the cytoplasm, emphasizing the role of phenol-soluble modulins (PSMs) for phagosomal escape. Thus, Sae-regulated toxins largely determine damage and escape from within macrophages, whereas PSMs are mainly responsible for the escape from the phagosome into the cytoplasm. Damage of macrophages induced by intracellular bacteria was linked neither to activation of apoptosis-related caspase 3, 7 or 8 nor to NLRP3-dependent inflammasome activation.
Collapse
Affiliation(s)
- Lisa Münzenmayer
- Interfaculty Institute of Microbiology and Infection Medicine, University of Tübingen, Tübingen, Germany
| | - Tobias Geiger
- Interfaculty Institute of Microbiology and Infection Medicine, University of Tübingen, Tübingen, Germany.,School of Medicine, Section of Microbial Pathogenesis Boyer Center for Molecular Medicine Yale University, New Haven, CT, 06536, USA
| | - Ellen Daiber
- Interfaculty Institute of Microbiology and Infection Medicine, University of Tübingen, Tübingen, Germany
| | - Berit Schulte
- Interfaculty Institute of Microbiology and Infection Medicine, University of Tübingen, Tübingen, Germany
| | - Stella E Autenrieth
- Department of Internal Medicine II, University of Tübingen, Tübingen, Germany
| | - Martin Fraunholz
- Department of Microbiology, Biocenter, University of Würzburg, Würzburg, Germany
| | - Christiane Wolz
- Interfaculty Institute of Microbiology and Infection Medicine, University of Tübingen, Tübingen, Germany
| |
Collapse
|
40
|
Reyes-Robles T, Lubkin A, Alonzo F, Lacy DB, Torres VJ. Exploiting dominant-negative toxins to combat Staphylococcus aureus pathogenesis. EMBO Rep 2016; 17:428-40. [PMID: 26882549 DOI: 10.15252/embr.201540994] [Citation(s) in RCA: 35] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2015] [Accepted: 01/05/2016] [Indexed: 12/12/2022] Open
Abstract
Staphylococcus aureus (S. aureus) is a human pathogen that relies on the subversion of host phagocytes to support its pathogenic lifestyle. S. aureus strains can produce up to five beta-barrel, bi-component, pore-forming leukocidins that target and kill host phagocytes. Thus, preventing immune cell killing by these toxins is likely to boost host immunity. Here, we describe the identification of glycine-rich motifs within the membrane-penetrating stem domains of the leukocidin subunits that are critical for killing primary human neutrophils. Remarkably, leukocidins lacking these glycine-rich motifs exhibit dominant-negative inhibitory effects toward their wild-type toxin counterparts as well as other leukocidins. Biochemical and cellular assays revealed that these dominant-negative toxins work by forming mixed complexes that are impaired in pore formation. The dominant-negative leukocidins inhibited S. aureus cytotoxicity toward primary human neutrophils, protected mice from lethal challenge by wild-type leukocidin, and reduced bacterial burden in a murine model of bloodstream infection. Thus, we describe the first example of staphylococcal bi-component dominant-negative toxins and their potential as novel therapeutics to combat S. aureus infection.
Collapse
Affiliation(s)
- Tamara Reyes-Robles
- Department of Microbiology, New York University School of Medicine, New York, NY, USA
| | - Ashira Lubkin
- Department of Microbiology, New York University School of Medicine, New York, NY, USA
| | - Francis Alonzo
- Department of Microbiology, New York University School of Medicine, New York, NY, USA
| | - D Borden Lacy
- Department of Pathology, Microbiology and Immunology, Vanderbilt University School of Medicine, Nashville, TN, USA
| | - Victor J Torres
- Department of Microbiology, New York University School of Medicine, New York, NY, USA
| |
Collapse
|
41
|
Reyes-Robles T, Torres VJ. Staphylococcus aureus Pore-Forming Toxins. Curr Top Microbiol Immunol 2016; 409:121-144. [PMID: 27406190 DOI: 10.1007/82_2016_16] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
Staphylococcus aureus (S. aureus) is a formidable foe equipped with an armamentarium of virulence factors to thwart host defenses and establish a successful infection. Among these virulence factors, S. aureus produces several potent secreted proteins that act as cytotoxins, predominant among them the beta-barrel pore-forming toxins. These toxins play several roles in pathogenesis, including disruption of cellular adherens junctions at epithelial barriers, alteration of intracellular signaling events, modulation of host immune responses, and killing of eukaryotic immune and non-immune cells. This chapter provides an updated overview on the S. aureus beta-barrel pore-forming cytotoxins, the identification of toxin receptors on host cells, and their roles in pathogenesis.
Collapse
Affiliation(s)
- Tamara Reyes-Robles
- Department of Microbiology, Microbial Pathogenesis Program, New York University School of Medicine, 522 First Avenue, Smilow Research Building, Room 1010, New York, NY, 10016, USA
| | - Victor J Torres
- Department of Microbiology, Microbial Pathogenesis Program, New York University School of Medicine, 522 First Avenue, Smilow Research Building, Room 1010, New York, NY, 10016, USA.
| |
Collapse
|
42
|
Sause WE, Buckley PT, Strohl WR, Lynch AS, Torres VJ. Antibody-Based Biologics and Their Promise to Combat Staphylococcus aureus Infections. Trends Pharmacol Sci 2015; 37:231-241. [PMID: 26719219 DOI: 10.1016/j.tips.2015.11.008] [Citation(s) in RCA: 66] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2015] [Revised: 11/18/2015] [Accepted: 11/19/2015] [Indexed: 11/26/2022]
Abstract
The growing incidence of serious infections mediated by methicillin-resistant Staphylococcus aureus (MRSA) strains poses a significant risk to public health. This risk is exacerbated by a prolonged void in the discovery and development of truly novel antibiotics and the absence of a vaccine. These gaps have created renewed interest in the use of biologics in the prevention and treatment of serious staphylococcal infections. In this review, we focus on efforts towards the discovery and development of antibody-based biologic agents and their potential as clinical agents in the management of serious S. aureus infections. Recent promising data for monoclonal antibodies (mAbs) targeting anthrax and Ebola highlight the potential of antibody-based biologics as therapeutic agents for serious infections.
Collapse
Affiliation(s)
- William E Sause
- Department of Microbiology, New York University School of Medicine, New York, NY 10016, USA
| | - Peter T Buckley
- Janssen Research & Development LLC, 1400 McKean Road, Spring House, PA 19477, USA
| | - William R Strohl
- Janssen Research & Development LLC, 1400 McKean Road, Spring House, PA 19477, USA
| | - A Simon Lynch
- Janssen Research & Development LLC, 1400 McKean Road, Spring House, PA 19477, USA.
| | - Victor J Torres
- Department of Microbiology, New York University School of Medicine, New York, NY 10016, USA.
| |
Collapse
|
43
|
Flannagan RS, Heit B, Heinrichs DE. Antimicrobial Mechanisms of Macrophages and the Immune Evasion Strategies of Staphylococcus aureus. Pathogens 2015; 4:826-68. [PMID: 26633519 PMCID: PMC4693167 DOI: 10.3390/pathogens4040826] [Citation(s) in RCA: 128] [Impact Index Per Article: 14.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2015] [Revised: 11/17/2015] [Accepted: 11/24/2015] [Indexed: 12/21/2022] Open
Abstract
Habitually professional phagocytes, including macrophages, eradicate microbial invaders from the human body without overt signs of infection. Despite this, there exist select bacteria that are professional pathogens, causing significant morbidity and mortality across the globe and Staphylococcus aureus is no exception. S. aureus is a highly successful pathogen that can infect virtually every tissue that comprises the human body causing a broad spectrum of diseases. The profound pathogenic capacity of S. aureus can be attributed, in part, to its ability to elaborate a profusion of bacterial effectors that circumvent host immunity. Macrophages are important professional phagocytes that contribute to both the innate and adaptive immune response, however from in vitro and in vivo studies, it is evident that they fail to eradicate S. aureus. This review provides an overview of the antimicrobial mechanisms employed by macrophages to combat bacteria and describes the immune evasion strategies and some representative effectors that enable S. aureus to evade macrophage-mediated killing.
Collapse
Affiliation(s)
- Ronald S Flannagan
- Department of Microbiology and Immunology, the University of Western Ontario, London, ON N6A 5C1, Canada.
| | - Bryan Heit
- Department of Microbiology and Immunology, the University of Western Ontario, London, ON N6A 5C1, Canada.
- Centre for Human Immunology, the University of Western Ontario, London, ON N6A 5C1, Canada.
| | - David E Heinrichs
- Department of Microbiology and Immunology, the University of Western Ontario, London, ON N6A 5C1, Canada.
- Centre for Human Immunology, the University of Western Ontario, London, ON N6A 5C1, Canada.
| |
Collapse
|
44
|
Adhikari RP, Kort T, Shulenin S, Kanipakala T, Ganjbaksh N, Roghmann MC, Holtsberg FW, Aman MJ. Antibodies to S. aureus LukS-PV Attenuated Subunit Vaccine Neutralize a Broad Spectrum of Canonical and Non-Canonical Bicomponent Leukotoxin Pairs. PLoS One 2015; 10:e0137874. [PMID: 26367030 PMCID: PMC4569305 DOI: 10.1371/journal.pone.0137874] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2015] [Accepted: 08/22/2015] [Indexed: 11/18/2022] Open
Abstract
S. aureus vaccine development has proven particularly difficult. The conventional approach to achieve sterile immunity through opsonophagocytic killing has been largely unsuccessful. S. aureus is highly toxigenic and a great body of evidence suggests that a successful future vaccine for this organism should target extracellular toxins which are responsible for host tissue destruction and immunosuppression. Major staphylococcal toxins are alpha toxin (a single subunit hemolysin) along with a group of bicomponent pore-forming toxins (BCPFT), namely Panton-Valentine leukocidin (PVL), gamma hemolysins (HlgCB and AB), LukAB and LukED. In our previous report, an attenuated mutant of LukS-PV (PVL- S subunit) named as “LukS-mut9” elicited high immunogenic response as well as provided a significant protection in a mouse sepsis model. Recent discovery of PVL receptors shows that mice lack receptors for this toxin, thus the reported protection of mice with the PVL vaccine may relate to cross protective responses against other homologous toxins. This manuscript addresses this issue by demonstrating that polyclonal antibody generated by LukS-mut9 can neutralize other canonical and non-canonical leukotoxin pairs. In this report, we also demonstrated that several potent toxins can be created by non-canonical pairing of subunits. Out of 5 pairs of canonical and 8 pairs of non-canonical toxins tested, anti-LukS-mut9 polyclonal antibodies neutralized all except for LukAB. We also studied the potential hemolytic activities of canonical and noncanonical pairs among biocomponent toxins and discovered that a novel non-canonical pair consisting of HlgA and LukD is a highly toxic combination. This pair can lyse RBC from different species including human blood far better than alpha hemolysin. Moreover, to follow-up our last report, we explored the correlation between the levels of pre-existing antibodies to new sets of leukotoxins subunits and clinical outcomes in adult patients with S. aureus bacteremia. We found that there is an inversed correlation between the antibody titer to sepsis for leukotoxins LukS-mut9, LukF-PV, HlgC, LukE and LukAB, suggesting the risk of sepsis was significantly lower in the patients with higher antibody titer against those toxins.
Collapse
Affiliation(s)
- Rajan P. Adhikari
- Integrated Biotherapeutics Inc., Gaithersburg, Maryland, United States of America
- * E-mail:
| | - Thomas Kort
- Integrated Biotherapeutics Inc., Gaithersburg, Maryland, United States of America
| | - Sergey Shulenin
- Integrated Biotherapeutics Inc., Gaithersburg, Maryland, United States of America
| | | | - Nader Ganjbaksh
- Integrated Biotherapeutics Inc., Gaithersburg, Maryland, United States of America
| | - Mary-Claire Roghmann
- Department of Epidemiology and Public Health, University of Maryland School of Medicine, Baltimore, Maryland, United States of America
- VA Maryland Health Care System, Baltimore, Maryland, United States of America
| | | | - M. Javad Aman
- Integrated Biotherapeutics Inc., Gaithersburg, Maryland, United States of America
| |
Collapse
|
45
|
Yoong P, Torres VJ. Counter inhibition between leukotoxins attenuates Staphylococcus aureus virulence. Nat Commun 2015; 6:8125. [PMID: 26330208 PMCID: PMC4562310 DOI: 10.1038/ncomms9125] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2014] [Accepted: 07/21/2015] [Indexed: 02/07/2023] Open
Abstract
Staphylococcus aureus subverts host defences by producing a collection of virulence factors including bi-component pore-forming leukotoxins. Despite extensive sequence conservation, each leukotoxin has unique properties, including disparate cellular receptors and species specificities. How these toxins collectively influence S. aureus pathogenesis is unknown. Here we demonstrate that the leukotoxins LukSF-PV and LukED antagonize each other's cytolytic activities on leukocytes and erythrocytes by forming inactive hybrid complexes. Remarkably, LukSF-PV inhibition of LukED haemolytic activity on both human and murine erythrocytes prevents the release of nutrients required for in vitro bacterial growth. Using in vivo murine models of infection, we show that LukSF-PV negatively influences S. aureus virulence and colonization by inhibiting LukED. Thus, while S. aureus leukotoxins can certainly injure immune cells, the discovery of leukotoxin antagonism suggests that they may also play a role in reducing S. aureus virulence and maintaining infection without killing the host. Staphylococcus aureus strains produce a family of highly related toxins that puncture the cytoplasmic membrane of susceptible cells. Here, Yoong and Torres show that the toxins can counteract each other in a cell type-dependent manner by forming inactive hybrid complexes, thus modulating S. aureus virulence.
Collapse
Affiliation(s)
- Pauline Yoong
- Department of Microbiology, New York University School of Medicine, New York, New York 10016, USA
| | - Victor J Torres
- Department of Microbiology, New York University School of Medicine, New York, New York 10016, USA
| |
Collapse
|
46
|
Staphylococcus aureus Biofilms Induce Macrophage Dysfunction Through Leukocidin AB and Alpha-Toxin. mBio 2015; 6:mBio.01021-15. [PMID: 26307164 PMCID: PMC4550693 DOI: 10.1128/mbio.01021-15] [Citation(s) in RCA: 119] [Impact Index Per Article: 13.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023] Open
Abstract
The macrophage response to planktonic Staphylococcus aureus involves the induction of proinflammatory microbicidal activity. However, S. aureus biofilms can interfere with these responses in part by polarizing macrophages toward an anti-inflammatory profibrotic phenotype. Here we demonstrate that conditioned medium from mature S. aureus biofilms inhibited macrophage phagocytosis and induced cytotoxicity, suggesting the involvement of a secreted factor(s). Iterative testing found the active factor(s) to be proteinaceous and partially agr-dependent. Quantitative mass spectrometry identified alpha-toxin (Hla) and leukocidin AB (LukAB) as critical molecules secreted by S. aureus biofilms that inhibit murine macrophage phagocytosis and promote cytotoxicity. A role for Hla and LukAB was confirmed by using hla and lukAB mutants, and synergy between the two toxins was demonstrated with a lukAB hla double mutant and verified by complementation. Independent confirmation of the effects of Hla and LukAB on macrophage dysfunction was demonstrated by using an isogenic strain in which Hla was constitutively expressed, an Hla antibody to block toxin activity, and purified LukAB peptide. The importance of Hla and LukAB during S. aureus biofilm formation in vivo was assessed by using a murine orthopedic implant biofilm infection model in which the lukAB hla double mutant displayed significantly lower bacterial burdens and more macrophage infiltrates than each single mutant. Collectively, these findings reveal a critical synergistic role for Hla and LukAB in promoting macrophage dysfunction and facilitating S. aureus biofilm development in vivo. Staphylococcus aureus has a propensity to form multicellular communities known as biofilms. While growing in a biofilm, S. aureus displays increased tolerance to nutrient deprivation, antibiotic insult, and even host immune challenge. Previous studies have shown that S. aureus biofilms thwart host immunity in part by preventing macrophage phagocytosis. It remained unclear whether this was influenced solely by the considerable size of biofilms or whether molecules were also actively secreted to circumvent macrophage-mediated phagocytosis. This is the first report to demonstrate that S. aureus biofilms inhibit macrophage phagocytosis and induce macrophage death through the combined action of leukocidin AB and alpha-toxin. Loss of leukocidin AB and alpha-toxin expression resulted in enhanced S. aureus biofilm clearance in a mouse model of orthopedic implant infection, suggesting that these toxins could be targeted therapeutically to facilitate biofilm clearance in humans.
Collapse
|
47
|
Melehani JH, James DBA, DuMont AL, Torres VJ, Duncan JA. Staphylococcus aureus Leukocidin A/B (LukAB) Kills Human Monocytes via Host NLRP3 and ASC when Extracellular, but Not Intracellular. PLoS Pathog 2015; 11:e1004970. [PMID: 26069969 PMCID: PMC4466499 DOI: 10.1371/journal.ppat.1004970] [Citation(s) in RCA: 98] [Impact Index Per Article: 10.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2014] [Accepted: 05/22/2015] [Indexed: 12/27/2022] Open
Abstract
Staphylococcus aureus infections are a growing health burden worldwide, and paramount to this bacterium’s pathogenesis is the production of virulence factors, including pore-forming leukotoxins. Leukocidin A/B (LukAB) is a recently discovered toxin that kills primary human phagocytes, though the underlying mechanism of cell death is not understood. We demonstrate here that LukAB is a major contributor to the death of human monocytes. Using a variety of in vitro and ex vivo intoxication and infection models, we found that LukAB activates Caspase 1, promotes IL-1β secretion and induces necrosis in human monocytes. Using THP1 cells as a model for human monocytes, we found that the inflammasome components NLRP3 and ASC are required for LukAB-mediated IL-1β secretion and necrotic cell death. S. aureus was shown to kill human monocytes in a LukAB dependent manner under both extracellular and intracellular ex vivo infection models. Although LukAB-mediated killing of THP1 monocytes from extracellular S. aureus requires ASC, NLRP3 and the LukAB-receptor CD11b, LukAB-mediated killing from phagocytosed S. aureus is independent of ASC or NLRP3, but dependent on CD11b. Altogether, this study provides insight into the nature of LukAB-mediated killing of human monocytes. The discovery that S. aureus LukAB provokes differential host responses in a manner dependent on the cellular contact site is critical for the development of anti-infective/anti-inflammatory therapies that target the NLRP3 inflammasome. Staphylococcus aureus infections are becoming increasingly common, aggressive, and difficult to manage clinically. S. aureus produces a number of pore-forming toxins that target and kill immune cells. In this study, we demonstrate that LukAB is primarily responsible for S. aureus-mediated targeting and killing of human monocytes. We show that the NLRP3-ASC inflammasome, a sensor of cell membrane damage and trigger of inflammation, is critical for this response. S. aureus uses LukAB to kill immune cells both through external interactions (LukAB on the cell surface) and through internal interactions (LukAB secretion after S. aureus is engulfed by the immune cell). Interestingly, we show that the mechanism by which LukAB kills immune cells in these two settings differs. This is the first report of a S. aureus toxin manipulating unique immune signaling pathways depending on the cellular site of contact. Understanding the multitude of ways by which S. aureus evades the immune response is critical for our ability to treat infections with this pathogen.
Collapse
Affiliation(s)
- Jason H. Melehani
- Department of Pharmacology, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, United States of America
| | - David B. A. James
- Department of Microbiology, New York University School of Medicine, New York, New York, United States of America
| | - Ashley L. DuMont
- Department of Microbiology, New York University School of Medicine, New York, New York, United States of America
| | - Victor J. Torres
- Department of Microbiology, New York University School of Medicine, New York, New York, United States of America
- * E-mail: (VJT); (JAD)
| | - Joseph A. Duncan
- Department of Pharmacology, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, United States of America
- Department of Medicine, Division of Infectious Diseases, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, United States of America
- Lineberger Comprehensive Cancer Center, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, United States of America
- * E-mail: (VJT); (JAD)
| |
Collapse
|
48
|
Affiliation(s)
- Jan T Poolman
- Crucell Hollland B. V. one of the Janssen Pharmaceutical Companies of Johnson & Johnson - Bacterial Vaccines Research and Development Archimedesweg 4-6, Zernikedreef 9, Leiden 2333 CK, The Netherlands
| |
Collapse
|
49
|
The bicomponent pore-forming leucocidins of Staphylococcus aureus. Microbiol Mol Biol Rev 2015; 78:199-230. [PMID: 24847020 DOI: 10.1128/mmbr.00055-13] [Citation(s) in RCA: 192] [Impact Index Per Article: 21.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
The ability to produce water-soluble proteins with the capacity to oligomerize and form pores within cellular lipid bilayers is a trait conserved among nearly all forms of life, including humans, single-celled eukaryotes, and numerous bacterial species. In bacteria, some of the most notable pore-forming molecules are protein toxins that interact with mammalian cell membranes to promote lysis, deliver effectors, and modulate cellular homeostasis. Of the bacterial species capable of producing pore-forming toxic molecules, the Gram-positive pathogen Staphylococcus aureus is one of the most notorious. S. aureus can produce seven different pore-forming protein toxins, all of which are believed to play a unique role in promoting the ability of the organism to cause disease in humans and other mammals. The most diverse of these pore-forming toxins, in terms of both functional activity and global representation within S. aureus clinical isolates, are the bicomponent leucocidins. From the first description of their activity on host immune cells over 100 years ago to the detailed investigations of their biochemical function today, the leucocidins remain at the forefront of S. aureus pathogenesis research initiatives. Study of their mode of action is of immediate interest in the realm of therapeutic agent design as well as for studies of bacterial pathogenesis. This review provides an updated perspective on our understanding of the S. aureus leucocidins and their function, specificity, and potential as therapeutic targets.
Collapse
|
50
|
Badarau A, Rouha H, Malafa S, Logan DT, Håkansson M, Stulik L, Dolezilkova I, Teubenbacher A, Gross K, Maierhofer B, Weber S, Jägerhofer M, Hoffman D, Nagy E. Structure-function analysis of heterodimer formation, oligomerization, and receptor binding of the Staphylococcus aureus bi-component toxin LukGH. J Biol Chem 2014; 290:142-56. [PMID: 25371205 DOI: 10.1074/jbc.m114.598110] [Citation(s) in RCA: 47] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023] Open
Abstract
The bi-component leukocidins of Staphylococcus aureus are important virulence factors that lyse human phagocytic cells and contribute to immune evasion. The γ-hemolysins (HlgAB and HlgCB) and Panton-Valentine leukocidin (PVL or LukSF) were shown to assemble from soluble subunits into membrane-bound oligomers on the surface of target cells, creating barrel-like pore structures that lead to cell lysis. LukGH is the most distantly related member of this toxin family, sharing only 30-40% amino acid sequence identity with the others. We observed that, unlike other leukocidin subunits, recombinant LukH and LukG had low solubility and were unable to bind to target cells, unless both components were present. Using biolayer interferometry and intrinsic tryptophan fluorescence we detected binding of LukH to LukG in solution with an affinity in the low nanomolar range and dynamic light scattering measurements confirmed formation of a heterodimer. We elucidated the structure of LukGH by x-ray crystallography at 2.8-Å resolution. This revealed an octameric structure that strongly resembles that reported for HlgAB, but with important structural differences. Structure guided mutagenesis studies demonstrated that three salt bridges, not found in other bi-component leukocidins, are essential for dimer formation in solution and receptor binding. We detected weak binding of LukH, but not LukG, to the cellular receptor CD11b by biolayer interferometry, suggesting that in common with other members of this toxin family, the S-component has the primary contact role with the receptor. These new insights provide the basis for novel strategies to counteract this powerful toxin and Staphylococcus aureus pathogenesis.
Collapse
Affiliation(s)
- Adriana Badarau
- From Arsanis Biosciences, Vienna Biocenter Campus, Helmut-Qualtinger-Gasse 2, 1030 Vienna, Austria and
| | - Harald Rouha
- From Arsanis Biosciences, Vienna Biocenter Campus, Helmut-Qualtinger-Gasse 2, 1030 Vienna, Austria and
| | - Stefan Malafa
- From Arsanis Biosciences, Vienna Biocenter Campus, Helmut-Qualtinger-Gasse 2, 1030 Vienna, Austria and
| | - Derek T Logan
- SARomics Biostructures AB, Medicon Village, S-223 81 Lund, Sweden
| | - Maria Håkansson
- SARomics Biostructures AB, Medicon Village, S-223 81 Lund, Sweden
| | - Lukas Stulik
- From Arsanis Biosciences, Vienna Biocenter Campus, Helmut-Qualtinger-Gasse 2, 1030 Vienna, Austria and
| | - Ivana Dolezilkova
- From Arsanis Biosciences, Vienna Biocenter Campus, Helmut-Qualtinger-Gasse 2, 1030 Vienna, Austria and
| | - Astrid Teubenbacher
- From Arsanis Biosciences, Vienna Biocenter Campus, Helmut-Qualtinger-Gasse 2, 1030 Vienna, Austria and
| | - Karin Gross
- From Arsanis Biosciences, Vienna Biocenter Campus, Helmut-Qualtinger-Gasse 2, 1030 Vienna, Austria and
| | - Barbara Maierhofer
- From Arsanis Biosciences, Vienna Biocenter Campus, Helmut-Qualtinger-Gasse 2, 1030 Vienna, Austria and
| | - Susanne Weber
- From Arsanis Biosciences, Vienna Biocenter Campus, Helmut-Qualtinger-Gasse 2, 1030 Vienna, Austria and
| | - Michaela Jägerhofer
- From Arsanis Biosciences, Vienna Biocenter Campus, Helmut-Qualtinger-Gasse 2, 1030 Vienna, Austria and
| | - David Hoffman
- From Arsanis Biosciences, Vienna Biocenter Campus, Helmut-Qualtinger-Gasse 2, 1030 Vienna, Austria and
| | - Eszter Nagy
- From Arsanis Biosciences, Vienna Biocenter Campus, Helmut-Qualtinger-Gasse 2, 1030 Vienna, Austria and
| |
Collapse
|