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Timothy J Foster - One of the best experts on this subject based on the ideXlab platform.

  • Lessons from the CrystAl Structure of the S. Aureus SurfAce Protein Clumping FActor A in Complex With TefibAzumAb, An Inhibiting MonoclonAl Antibody.
    EBioMedicine, 2016
    Co-Authors: Vannakambadi K Ganesh, Xiaowen Liang, Timothy J Foster, Joan A Geoghegan, Ana Luisa V. Cohen, Nagarajan Venugopalan, Magnus Hook
    Abstract:

    AbstrAct The StAphylococcus Aureus fibrinogen binding MSCRAMM (MicrobiAl SurfAce Components Recognizing Adhesive MAtrix Molecules), ClfA (Clumping FActor A) is An importAnt virulence FActor in stAphylococcAl infections And A component of severAl vAccines currently under clinicAl evAluAtion. The mouse monoclonAl Antibody Aurexis (Also cAlled 12-9), And the humAnized version tefibAzumAb Are therApeutic monoclonAl Antibodies tArgeting ClfA thAt in combinAtion with conventionAl Antibiotics were effective in AnimAl models but showed less impressive efficAcy in A limited PhAse II clinicAl triAl. We here report the crystAl structure And A biochemicAl chArActerizAtion of the ClfA/tefibAzumAb (FAb) complex. The epitope for tefibAzumAb is locAted to the "top" of the N3 subdomAin of ClfA And pArtiAlly overlAps with A previously unidentified second binding site for fibrinogen. A high-Affinity binding of ClfA to fibrinogen involves both An interAction At the N3 site And the previously identified docking of the C-terminAl segment of the fibrinogen γ-chAin in the N2N3 trench. Although tefibAzumAb binds ClfA with high Affinity we observe A modest IC 50 vAlue for the inhibition of fibrinogen binding to the MSCRAMM. This observAtion, pAired with A common nAturAl occurring vAriAnt of ClfA thAt is not effectively recognized by the mAb, mAy pArtly explAin the modest effect tefibAzumAb showed in the initiAl clinic trAil. This informAtion will provide guidAnce for the design of the next generAtion of therApeutic Anti-stAphylococcAl mAbs tArgeting ClfA.

  • CApsulAr PolysAcchAride MAsks Clumping FActor A–MediAted Adherence of StAphylococcus Aureus to Fibrinogen And PlAtelets
    2016
    Co-Authors: Allison L. Risley, Anthony Loughman, Timothy J Foster, Colette Cywes-bentley, Jean C. Lee
    Abstract:

    BAckground. Clumping FActor A (ClfA) is A StAphylococcus Aureus cell wAll–AssociAted Adhesin thAt mediAtes stAphylococcAl binding to fibrinogen And plAtelets. Our goAls were to determine whether expression of cApsulAr polysAcchAride (CP) Affected ClfA-mediAted Adherence of S. Aureus And to Assess whether the length of the ClfA repeAt region influenced this interAction. Methods. ClfA constructs with repeAt regions of different lengths were introduced into isogenic S. Aureus strAins thAt expressed CP5, CP8, or no CP. S. Aureus binding to fibrinogen wAs Assessed in rAbbit plAsmA And on fibrinogen-coAted microtiter plAtes. Adherence of S. Aureus strAins to plAtelets wAs evAluAted by flow cytometry And confocAl microscopy. Results. As the length of the ClfA repeAt region increAsed, binding of AcApsulAr S. Aureus to fibrinogen-coAted microtiter plAtes wAs enhAnced. By contrAst, encApsulAted S. Aureus expressing the full-length ClfA were poorly Adherent. The AcApsulAr S. Aureus mutAnt strAin showed A 2-fold increAse in plAtelet binding, compAred with the isogenic encApsulAted strAins. By contrAst, plAtelet AggregAtion wAs unAffected by CP production. Conclusion. CP expression inhibits S. Aureus ClfA-mediAted binding to fibrinogen And plAtelets, And A full-length repeAt region cAnnot overcome this inhibition. These findings hAve importAnt implicAtions for vAccine development, given thAt CP mAy mAsk surfAce Adhesins

  • A short sequence within subdomAin n1 of region A of the stAphylococcus Aureus mscrAmm Clumping FActor A is required for export And surfAce displAy
    Microbiology, 2014
    Co-Authors: Niamh Mccormack, Timothy J Foster, Joan A Geoghegan
    Abstract:

    Clumping FActor A (ClfA) is the ArchetypAl fibrinogen-binding surfAce protein of StAphylococcus Aureus And A member of the microbiAl surfAce component recognizing Adhesive mAtrix molecules (MSCRAMM) fAmily. An N-terminAl signAl sequence directs export of the MSCRAMM by the Sec pAthwAy And the C-terminAl cell wAll-Anchoring domAin Allows covAlent AttAchment of ClfA to peptidoglycAn by sortAse. Region A of ClfA comprises three independently folded subdomAins N1, N2 And N3. SubdomAins N2N3 comprise IgG-like folds And promote fibrinogen binding. Nothing is known About the structure or function of subdomAin N1. Here we demonstrAte An unexpected role for N1 in the export And surfAce locAlizAtion of ClfA. Attempted expression of A ClfA vAriAnt lAcking subdomAin N1 resulted in impAired growth of S. Aureus And AccumulAtion of ClfA protein in the cytoplAsm And cytoplAsmic membrAne. The presence of residues 211–228 of N1 wAs required to Allow displAy of ClfA on the bActeriAl surfAce. The importAnce of this region wAs confirmed when A ClfA vAriAnt lAcking residues 211–220 wAs Also mislocAlized to the cytoplAsm And cytoplAsmic membrAne. However, these residues were not required for export of ClfA lAcking the Ser-Asp repeAts thAt link region A to the wAll-Anchoring domAin. SimilArly, subdomAin N1 of A relAted MSCRAMM fibronectin-binding protein B wAs required for export And surfAce displAy of the full-length protein, but not A derivAtive lAcking fibronectin-binding repeAts. In summAry, we demonstrAte thAt residues in the N1 subdomAin Are required for export And cell wAll locAlizAtion of S. Aureus MSCRAMM proteins.

  • the sbi protein is A multifunctionAl immune evAsion FActor of stAphylococcus Aureus
    Infection and Immunity, 2011
    Co-Authors: Emma J Smith, Pietro Speziale, Livia Visai, Steven W Kerrigan, Timothy J Foster
    Abstract:

    ABSTRACT The second immunoglobulin-binding protein (Sbi) of StAphylococcus Aureus hAs two N-terminAl domAins thAt bind the Fc region of IgG in A fAshion similAr to thAt of protein A And two domAins thAt cAn bind to the complement protein C3 And promote its futile consumption in the fluid phAse. It hAs been proposed thAt Sbi helps bActeriA to Avoid innAte immune defenses. By compAring A mutAnt defective in Sbi with mutAnts defective in protein A, Clumping FActor A, iron-regulAted surfAce determinAnt H, And cApsulAr polysAcchAride, it wAs shown thAt Sbi is indeed An immune evAsion FActor thAt promotes bActeriAl survivAl in whole humAn blood And the AvoidAnce of neutrophil-mediAted opsonophAgocytosis. Sbi is present in the culture supernAtAnt And is Also AssociAted with the cell envelope. S. Aureus strAins thAt expressed truncAtes of Sbi lAcking N-terminAl domAins D1 And D2 (D1D2) or D3 And D4 (D3D4) or A C-terminAl truncAte thAt wAs no longer retAined in the cell envelope were AnAlyzed. Both the secreted And envelope-AssociAted forms of Sbi contributed to immune evAsion. The IgG-binding domAins contributed only when Sbi wAs AttAched to the cell, while only the secreted C3-binding domAins were biologicAlly Active.

  • the A domAin of fibronectin binding protein b of stAphylococcus Aureus contAins A novel fibronectin binding site
    FEBS Journal, 2011
    Co-Authors: Fiona M Burke, Pietro Speziale, Antonella Di Poto, Timothy J Foster
    Abstract:

    The fibronectin-binding proteins FnBPA And FnBPB Are multifunctionAl Adhesins thAn cAn Also bind to fibrinogen And elAstin. In this study, the N2N3 subdomAins of region A of FnBPB were shown to bind fibrinogen with A similAr Affinity to those of FnBPA (2 μm). The binding site for FnBPB in fibrinogen wAs locAlized to the C-terminus of the γ-chAin. Like Clumping FActor A, region A of FnBPB bound to the γ-chAin of fibrinogen in A CA2+-inhibitAble mAnner. The deletion of 17 residues from the C-terminus of domAin N3 And the substitution of two residues in equivAlent positions for cruciAl residues for fibrinogen binding in Clumping FActor A And FnBPA eliminAted fibrinogen binding by FnBPB. This indicAtes thAt FnBPB binds fibrinogen by the dock–lock–lAtch mechAnism. In contrAst, the A domAin of FnBPB bound fibronectin with KD = 2.5 μm despite lAcking Any of the known fibronectin-binding tAndem repeAts. A truncAte lAcking the C-terminAl 17 residues (lAtching peptide) bound fibronectin with the sAme Affinity, suggesting thAt the FnBPB A domAin binds fibronectin by A novel mechAnism. The substitution of the two residues required for fibrinogen binding Also resulted in A loss of fibronectin binding. This, combined with the observAtion thAt purified subdomAin N3 bound fibronectin with A meAsurAble, but reduced, KD of 20 μm, indicAtes thAt the type I modules of fibronectin bind to both the N2 And N3 subdomAins. The fibronectin-binding Ability of the FnBPB A domAin wAs Also functionAl when the protein wAs expressed on And Anchored to the surfAce of stAphylococcAl cells, showing thAt it is not An ArtifAct of recombinAnt protein expression. Structured digitAl AbstrAct •  Fibronectin binds to fnbB by filter binding (View interAction) •  Fibronectin binds to fnbB by surfAce plAsmon resonAnce (View InterAction 1, 2)

Kenji M Cunnion - One of the best experts on this subject based on the ideXlab platform.

  • new potentiAl role of serum Apolipoprotein e mediAted by its binding to Clumping FActor A during stAphylococcus Aureus invAsive infections to humAns
    Journal of Medical Microbiology, 2015
    Co-Authors: Walid F Elkhatib, Pamela S Hair, Julius O Nyalwidhe, Kenji M Cunnion
    Abstract:

    StAphylococcus Aureus is A cruciAl humAn pAthogen expressing vArious immune-evAsion proteins thAt interAct with the host-cell molecules. Clumping FActor A (ClfA) is A microbiAl surfAce protein thAt promotes S. Aureus binding to fibrinogen, And is AssociAted with septic Arthritis And infective endocArditis. In order to identify the mAjor humAn serum proteins thAt bind the ClfA, we utilized recombinAnt ClfA region A in A plAte-bAsed AssAy. SDS-PAGE AnAlysis of the bound proteins yielded five prominent bAnds, which were AnAlysed by MS yielding Apolipoprotein E (ApoE) As the predominAnt protein. ClfA-sufficient S. Aureus bound purified ApoE by more thAn one log greAter thAn An isogenic ClfA-deficient mutAnt. An immunodot-blot AssAy yielded A lineArity model for ClfA binding to humAn ApoE with A stoichiometric-binding rAtio of 1.702 At mAximAl PeArson's correlAtion coefficient (0.927). These dAtA suggest thAt ApoE could be A mAjor And novel binding tArget for the S. Aureus virulence FActor ClfA. Thus, ClfA recruitment of serum ApoE to the S. Aureus surfAce mAy sequester ApoE And blunt its host defence function AgAinst S. Aureus-invAsive infections to humAns. In this context, compounds thAt cAn block or suppress ClfA binding to ApoE might be utilized As prophylActic or therApeutic Agents.

  • Clumping FActor A interAction with complement FActor I increAses C3b cleAvAge on the bActeriAl surfAce of StAphylococcus Aureus, And decreAses complement-mediAted phAgocytosis
    Infection and immunity, 2010
    Co-Authors: Pamela S Hair, Timothy J Foster, Charlene G. Echague, Amber M. Sholl, Justin A. Watkins, Kenji M Cunnion
    Abstract:

    The humAn complement system is importAnt in the immunologicAl control of StAphylococcus Aureus infection. We showed previously thAt S. Aureus surfAce protein Clumping FActor A (ClfA), when expressed in recombinAnt form, bound complement control protein FActor I And increAsed FActor I cleAvAge of C3b to iC3b. In the present study, we show thAt, compAred to the results for the wild type, when isogenic ClfA-deficient S. Aureus mutAnts were incubAted in serum, they bound less FActor I, generAted less iC3b on the bActeriAl surfAce, And bound fewer C3 frAgments. It hAs been shown previously thAt two Amino Acids in ClfA (P336 And Y338) Are essentiAl for fibrinogen binding. However, S. Aureus expressing ClfA(P336A Y338S) wAs less virulent thAn ClfA-deficient strAins in AnimAl models. This suggested thAt ClfA contributed to S. Aureus virulence by A mechAnism different thAn fibrinogen binding. In the present study, we showed thAt S. Aureus expressing ClfA(P336A Y338S) wAs more susceptible to complement-mediAted phAgocytosis thAn A ClfA-null mutAnt or the wild type. Unlike ClfA, ClfA(P336A Y338S) did not enhAnce FActor I cleAvAge of C3b to iC3b And inhibited the coFActor function of FActor H. Fibrinogen enhAnced FActor I binding to ClfA And the S. Aureus surfAce. Twenty clinicAl S. Aureus strAins All expressed ClfA And bound FActor I. High levels of FActor I binding by clinicAl strAins correlAted with poor phAgocytosis. In summAry, our results suggest thAt the interAction of ClfA with FActor I contributes to S. Aureus virulence by A complement-mediAted mechAnism.

  • stAphylococcus Aureus Clumping FActor A binds to complement regulAtor FActor i And increAses FActor i cleAvAge of c3b
    The Journal of Infectious Diseases, 2008
    Co-Authors: Pamela S Hair, Timothy J Foster, Michael D Ward, John O Semmes, Kenji M Cunnion
    Abstract:

    The humAn complement system plAys An importAnt role in the control of StAphylococcus Aureus infection. For instAnce, we previously demonstrAted thAt the centrAl complement component deposited on the orgAnism’s surfAce, C3b, cAn be cleAved by the host complement control protein, FActor I, resulting in diminished phAgocytosis of S. Aureus. In the present study, we hAve identified Clumping FActor A (ClfA) from cell wAll proteins of S. Aureus As A specific protein bound by FActor I. RecombinAnt ClfA (rClfA) contAining the full-length A region (peptides 40 –559) Also bound FActor I. We identified An 50-kDA frAgment of ClfA thAt is shed by S. Aureus into growth medium. The shed ClfA frAgment wAs derived from the A region of ClfA And bound FActor I. rClfA And the shed ClfA frAgment increAsed FActor I cleAvAge of C3b into inActive C3b. Our findings describe A new S. Aureus mechAnism for modificAtion of host complement Activities. StAphylococcus Aureus is A highly successful pAthogen, A common cAuse of community-AssociAted infection, And the most common cAuse of severe nosocomiAl infection [1–3]. S. Aureus infections cAuse consider

  • stAphylococcus Aureus Clumping FActor A binds to complement regulAtor FActor i And increAses FActor i cleAvAge of c3b
    The Journal of Infectious Diseases, 2008
    Co-Authors: Pamela S Hair, Timothy J Foster, Michael D Ward, John O Semmes, Kenji M Cunnion
    Abstract:

    The humAn complement system plAys An importAnt role in the control of StAphylococcus Aureus infection. For instAnce, we previously demonstrAted thAt the centrAl complement component deposited on the orgAnism's surfAce, C3b, cAn be cleAved by the host complement control protein, FActor I, resulting in diminished phAgocytosis of S. Aureus. In the present study, we hAve identified Clumping FActor A (ClfA) from cell wAll proteins of S. Aureus As A specific protein bound by FActor I. RecombinAnt ClfA (rClfA) contAining the full-length A region (peptides 40-559) Also bound FActor I. We identified An 50-kDA frAgment of ClfA thAt is shed by S. Aureus into growth medium. The shed ClfA frAgment wAs derived from the A region of ClfA And bound FActor I. rClfA And the shed ClfA frAgment increAsed FActor I cleAvAge of C3b into inActive C3b. Our findings describe A new S. Aureus mechAnism for modificAtion of host complement Activities.

José M. Entenza - One of the best experts on this subject based on the ideXlab platform.

  • Assessment of the DuAl Role of Clumping FActor A in S. Aureus Adhesion to Endothelium in Absence And Presence of PlAsmA.
    Thrombosis and haemostasis, 2018
    Co-Authors: Jorien Claes, Philippe Moreillon, José M. Entenza, Laurens Liesenborghs, Tiago Rafael Veloso, Marc Hoylaerts, Bartosz Ditkowski, Thomas Vanassche, Peter Verhamme, Ruth Heying
    Abstract:

    Adhesion of StAphylococcus Aureus to endotheliAl cells (ECs) is pArAmount in infective endocArditis. BActeriAl proteins such As Clumping FActor A (ClfA) And fibronectin binding protein A (FnbpA) mediAte Adhesion to EC surfAce molecules And (sub)endotheliAl mAtrix proteins including fibrinogen (Fg), fibrin, fibronectin (Fn) And von WillebrAnd FActor (vWF). We studied the influence of sheAr flow And plAsmA on the binding of ClfA And FnbpA (including its sub-domAins A, A16+, ABC, CD) to coverslip-coAted vWF, Fg/fibrin, Fn or confluent ECs, mAking use of LActococcus lActis, expressing these Adhesins heterologously. GlobAl Adherence profiles were similAr in stAtic And flow conditions. In the Absence of plAsmA, L. lActis-clfA binding to Fg increAsed with sheAr forces, whereAs binding to fibrin did not. The degree of Adhesion of L. lActis-fnbpA to EC-bound Fn And of L. lActis-clfA to EC-bound Fg, furthermore, wAs similAr to thAt of L. lActis-clfA to coAted vWF domAin A1, in the presence of vWF-binding protein (vWbp). Yet, in plAsmA, L. lActis-clfA Adherence to ActivAted EC-vWF/vWbp dropped over 10 minutes by 80% due to vWF-hydrolysis by A disintegrin And metAlloproteinAse with thrombospondin type 1 motif, member 13 And thAt of L. lActis-fnbpA likewise by > 70% compAred to the Adhesion in Absence of plAsmA. In contrAst, plAsmA Fg supported high L. lActis-clfA binding to resting And ActivAted ECs. Or, in plAsmA S. Aureus Adhesion to Active endothelium occurs mAinly viA two complementAry pAthwAys: A rApid but short-lived vWF/vWbp pAthwAy And A stAble integrin-coupled Fg-pAthwAy. Hence, the phArmAcologicAl inhibition of ClfA-Fg interActions mAy constitute A vAluAble Additive treAtment in infective endocArditis.

  • Clumping FActor A, von WillebrAnd FActor-binding protein And von WillebrAnd FActor Anchor StAphylococcus Aureus to the vessel wAll.
    Journal of thrombosis and haemostasis : JTH, 2017
    Co-Authors: Jorien Claes, Dominique Missiakas, Olaf Schneewind, José M. Entenza, Laurens Liesenborghs, Marijke Peetermans, Tiago Rafael Veloso, Stefano Mancini, Marc Hoylaerts, Ruth Heying
    Abstract:

    EssentiAls StAphylococcus Aureus (S. Aureus) binds to endothelium viA von WillebrAnd FActor (VWF). Secreted VWF-binding protein (vWbp) mediAtes S. Aureus Adhesion to VWF under sheAr stress. vWbp interActs with VWF And the SortAse A-dependent surfAce protein Clumping FActor A (ClfA). VWF-vWbp-ClfA Anchor S. Aureus to vAsculAr endothelium under sheAr stress. SUMMARY Objective When estAblishing endovAsculAr infections, StAphylococcus Aureus (S. Aureus) overcomes sheAr forces of flowing blood by binding to von WillebrAnd FActor (VWF). StAphylococcAl VWF-binding protein (vWbp) interActs with VWF, but it is unknown how this secreted protein binds to the bActeriAl cell wAll. We hypothesized thAt vWbp interActs with A stAphylococcAl surfAce protein, mediAting the Adhesion of S. Aureus to VWF And vAsculAr endothelium under sheAr stress. Methods We studied the binding of S. Aureus to vWbp, VWF And endotheliAl cells in A micro-pArAllel flow chAmber using vArious mutAnts deficient in SortAse A (SrtA) And SrtA-dependent surfAce proteins, And LActococcus lActis expressing single stAphylococcAl surfAce proteins. In vivo Adhesion of bActeriA wAs evAluAted in the murine mesenteric circulAtion using reAl-time intrAvitAl vAsculAr microscopy. Results vWbp bridges the bActeriAl cell wAll And VWF, Allowing sheAr-resistAnt binding of S. Aureus to inflAmed or dAmAged endothelium. Absence of SrtA And Clumping FActor A (ClfA) reduced Adhesion of S. Aureus to vWbp, VWF And ActivAted endotheliAl cells. ADAMTS-13 And An Anti-VWF A1 domAin Antibody, when combined, reduced S. Aureus Adhesion to ActivAted endotheliAl cells by 90%. Selective overexpression of ClfA in the membrAne of LActococcus lActis enAbled these bActeriA to bind to VWF And ActivAted endotheliAl cells but only in the presence of vWbp. Absence of ClfA Abolished bActeriAl Adhesion to the ActivAted murine vessel wAll. Conclusions vWbp interActs with VWF And with the SrtA-dependent stAphylococcAl surfAce protein ClfA. The complex formed by VWF, secreted vWbp And bActeriAl ClfA Anchors S. Aureus to vAsculAr endothelium under sheAr stress.

  • vAccinAtion AgAinst stAphylococcus Aureus experimentAl endocArditis using recombinAnt lActococcus lActis expressing clfA or fnbpA
    Vaccine, 2015
    Co-Authors: Tiago Rafael Veloso, Philippe Moreillon, Stefano Mancini, Yok-ai Que, Marlyse Giddey, Jacques Vouillamoz, José M. Entenza
    Abstract:

    AbstrAct StAphylococcus Aureus is A mAjor cAuse of serious infections in humAns And AnimAls And A vAccine is becoming A necessity. LActococcus lActis is A non-pAthogenic bActerium thAt cAn be used As A vector for the delivery of Antigens. We investigAted the Ability of non-living L. lActis heterologously expressing S. Aureus Clumping FActor A (ClfA) And fibronectin-binding protein A (FnbpA), Alone or together, to elicit An immune response in rAts And protect them from S. Aureus experimentAl infective endocArditis (IE). L. lActis ClfA wAs used for immunizAtion AgAinst S. Aureus NewmAn (expressing ClfA but not FnbpA), while L. lActis ClfA, L. lActis FnbpA, As well As L. lActis ClfA/FnbpA, were used AgAinst S. Aureus P8 (expressing ClfA And FnbpA). VAccinAtion of rAts with L. lActis ClfA elicited Antibodies thAt inhibited binding of S. Aureus NewmAn to fibrinogen, triggered the production of IL-17A And conferred protection to 13/19 (68%) of the AnimAls from IE (P  These results indicAte thAt L. lActis is A vAluAble Antigen delivery system Able to elicit efficient humorAl And cellulAr responses. However, the most AppropriAte Antigens Affording protection AgAinst S. Aureus IE Are yet to be elucidAted.

  • fibrinogen And fibronectin binding cooperAte for vAlve infection And invAsion in stAphylococcus Aureus experimentAl endocArditis
    Journal of Experimental Medicine, 2005
    Co-Authors: Yok-ai Que, Eleonora Widmer, Jacques-antoine Haefliger, Lionel Piroth, Patrice Francois, José M. Entenza, Bhanu Sinha, Mathias Herrmann, Patrick Francioli
    Abstract:

    The expression of StAphylococcus Aureus Adhesins in LActococcus lActis identified Clumping FActor A (ClfA) And fibronectin-binding protein A (FnBPA) As criticAl for vAlve colonizAtion in rAts with experimentAl endocArditis. This study further AnAlyzed their role in diseAse evolution. Infected AnimAls were followed for 3 d. ClfA-positive lActococci successfully colonized dAmAged vAlves, but were spontAneously erAdicAted over 48 h. In contrAst, FnBPA-positive lActococci progressively increAsed bActeriAl titers in vegetAtions And spleens. At imAging, ClfA-positive lActococci were restricted to the vegetAtions, whereAs FnBPA-positive lActococci Also invAded the AdjAcent endothelium. This reflected the cApAcity of FnBPA to trigger cell internAlizAtion in vitro. BecAuse FnBPA cArries both fibrinogen- And fibronectin-binding domAins, we tested the role of these functionAlities by deleting the fibrinogen-binding domAin of FnBPA And supplementing it with the fibrinogen-binding domAin of ClfA in cis or in trAns. Deletion of the fibrinogen-binding domAin of FnBPA did not Alter fibronectin binding And cell internAlizAtion in vitro. However, it totAlly AbrogAted vAlve infectivity in vivo. This Ability wAs restored in cis by inserting the fibrinogen-binding domAin of ClfA into truncAted FnBPA, And in trAns by coexpressing full-length ClfA And truncAted FnBPA on two sepArAte plAsmids. Thus, fibrinogen And fibronectin binding could cooperAte for S. Aureus vAlve colonizAtion And endotheliAl invAsion in vivo.

  • role of σb in the expression of stAphylococcus Aureus cell wAll Adhesins clfA And fnbA And contribution to infectivity in A rAt model of experimentAl endocArditis
    Infection and Immunity, 2005
    Co-Authors: Philippe Moreillon, José M. Entenza, Maria M Senn, Jan Kormanec, Paul M Dunman, Brigitte Bergerbachi, Steven J Projan, Markus Bischoff
    Abstract:

    Isogenic StAphylococcus Aureus strAins with different cApAcities to produce sigmA(B) Activity were AnAlyzed for their Ability to AttAch to fibrinogen- or fibronectin-coAted surfAces or plAtelet-fibrin clots And to cAuse endocArditis in rAts. In compArison to the sigmA(B)-deficient strAin, BB255, which hArbors An rsbU mutAtion, both rsbU-complemented And sigmA(B)-overproducing derivAtives exhibited At leAst five times greAter AttAchment to fibrinogen- And fibronectin-coAted surfAces And showed increAsed Adherence to plAtelet-fibrin clots. No differences in Adherence were seen between BB255 And A DeltArsbUVWsigB isogen. Northern blotting AnAlyses reveAled thAt trAnscription of clfA, encoding fibrinogen-binding protein Clumping FActor A, And fnbA, encoding fibronectin-binding protein A, were positively influenced by sigmA(B). SigmA(B) overproduction resulted in A stAtisticAlly significAnt increAse in positive spleen cultures And enhAnced bActeriAl densities in both the Aortic vegetAtions And spleens At 16 h postinoculAtion. In contrAst, At 72 h postinoculAtion, tissues infected with the sigmA(B) overproducer hAd lower bActeriAl densities thAn did those infected with BB255. These results suggest thAt Although sigmA(B) AppeArs to increAse the Adhesion of S. Aureus to vArious host cell-mAtrix proteins in vitro, it hAs limited effect on pAthogenesis in the rAt endocArditis model. SigmA(B) AppeArs to hAve A trAnsient enhAncing effect on bActeriAl density in the eArly stAges of infection thAt is lost during progression.

Philippe Moreillon - One of the best experts on this subject based on the ideXlab platform.

  • Assessment of the DuAl Role of Clumping FActor A in S. Aureus Adhesion to Endothelium in Absence And Presence of PlAsmA.
    Thrombosis and haemostasis, 2018
    Co-Authors: Jorien Claes, Philippe Moreillon, José M. Entenza, Laurens Liesenborghs, Tiago Rafael Veloso, Marc Hoylaerts, Bartosz Ditkowski, Thomas Vanassche, Peter Verhamme, Ruth Heying
    Abstract:

    Adhesion of StAphylococcus Aureus to endotheliAl cells (ECs) is pArAmount in infective endocArditis. BActeriAl proteins such As Clumping FActor A (ClfA) And fibronectin binding protein A (FnbpA) mediAte Adhesion to EC surfAce molecules And (sub)endotheliAl mAtrix proteins including fibrinogen (Fg), fibrin, fibronectin (Fn) And von WillebrAnd FActor (vWF). We studied the influence of sheAr flow And plAsmA on the binding of ClfA And FnbpA (including its sub-domAins A, A16+, ABC, CD) to coverslip-coAted vWF, Fg/fibrin, Fn or confluent ECs, mAking use of LActococcus lActis, expressing these Adhesins heterologously. GlobAl Adherence profiles were similAr in stAtic And flow conditions. In the Absence of plAsmA, L. lActis-clfA binding to Fg increAsed with sheAr forces, whereAs binding to fibrin did not. The degree of Adhesion of L. lActis-fnbpA to EC-bound Fn And of L. lActis-clfA to EC-bound Fg, furthermore, wAs similAr to thAt of L. lActis-clfA to coAted vWF domAin A1, in the presence of vWF-binding protein (vWbp). Yet, in plAsmA, L. lActis-clfA Adherence to ActivAted EC-vWF/vWbp dropped over 10 minutes by 80% due to vWF-hydrolysis by A disintegrin And metAlloproteinAse with thrombospondin type 1 motif, member 13 And thAt of L. lActis-fnbpA likewise by > 70% compAred to the Adhesion in Absence of plAsmA. In contrAst, plAsmA Fg supported high L. lActis-clfA binding to resting And ActivAted ECs. Or, in plAsmA S. Aureus Adhesion to Active endothelium occurs mAinly viA two complementAry pAthwAys: A rApid but short-lived vWF/vWbp pAthwAy And A stAble integrin-coupled Fg-pAthwAy. Hence, the phArmAcologicAl inhibition of ClfA-Fg interActions mAy constitute A vAluAble Additive treAtment in infective endocArditis.

  • vAccinAtion AgAinst stAphylococcus Aureus experimentAl endocArditis using recombinAnt lActococcus lActis expressing clfA or fnbpA
    Vaccine, 2015
    Co-Authors: Tiago Rafael Veloso, Philippe Moreillon, Stefano Mancini, Yok-ai Que, Marlyse Giddey, Jacques Vouillamoz, José M. Entenza
    Abstract:

    AbstrAct StAphylococcus Aureus is A mAjor cAuse of serious infections in humAns And AnimAls And A vAccine is becoming A necessity. LActococcus lActis is A non-pAthogenic bActerium thAt cAn be used As A vector for the delivery of Antigens. We investigAted the Ability of non-living L. lActis heterologously expressing S. Aureus Clumping FActor A (ClfA) And fibronectin-binding protein A (FnbpA), Alone or together, to elicit An immune response in rAts And protect them from S. Aureus experimentAl infective endocArditis (IE). L. lActis ClfA wAs used for immunizAtion AgAinst S. Aureus NewmAn (expressing ClfA but not FnbpA), while L. lActis ClfA, L. lActis FnbpA, As well As L. lActis ClfA/FnbpA, were used AgAinst S. Aureus P8 (expressing ClfA And FnbpA). VAccinAtion of rAts with L. lActis ClfA elicited Antibodies thAt inhibited binding of S. Aureus NewmAn to fibrinogen, triggered the production of IL-17A And conferred protection to 13/19 (68%) of the AnimAls from IE (P  These results indicAte thAt L. lActis is A vAluAble Antigen delivery system Able to elicit efficient humorAl And cellulAr responses. However, the most AppropriAte Antigens Affording protection AgAinst S. Aureus IE Are yet to be elucidAted.

  • Fibronectin-binding proteins And Clumping FActor A in StAphylococcus Aureus experimentAl endocArditis: FnBPA is sufficient to ActivAte humAn endotheliAl cells
    Thrombosis and haemostasis, 2007
    Co-Authors: Ruth Heying, Philippe Moreillon, Yok-ai Que, Joke S. Van De Gevel, H. Beekhuizen
    Abstract:

    SurfAce molecules of StAphylococcus Aureus Are involved in the colonizAtion of vAsculAr endothelium which is A cruciAl primAry event in the pAthogenesis of infective endocArditis (IE).The Ability of these molecules to Also lAunch endotheliAl procoAgulAnt And proinflAmmAtory responses, which chArActerize IE, is not known.In the present study we investigAted the individuAl cApAcities of three prominent S. Aureus surfAce molecules; fibronectinbinding protein A (FnBPA) And B (FnBPB) And Clumping FActor A (ClfA), to promote bActeriAl Adherence to cultured humAn endotheliAl cells (ECs) And to ActivAte phenotypic And functionAl chAnges in these ECs. Non-invAsive surrogAte bActerium LActococcus lActis, which, by gene trAnsfer, expressed stAphylococcAl FnBPA, FnBPB or ClfA molecules were used. Infection of ECs increAsed 50- to 100-fold with FnBPA- or FnBPB-positive recombinAnt lActococci. This coincided with EC ActivAtion, interleukin- 8 secretion And surfAce expression of ICAM-1 AndVCAM-1 And concomitAnt monocyte Adhesion. Infection with ClfA-positive lActococci did not ActivAte EC. FnBPA-positive L. lActis Also induced A prominent tissue FActor-dependent endotheliAl coAgulAtion response thAt wAs intensified by cell-bound monocytes. Thus S. Aureus FnBPs, but not ClfA, confer invAsiveness And pAthogenicity to non-pAthogenic L. lActis orgAnisms indicAting thAt bActerium-EC interActions mediAted by these Adhesins Are sufficient to evoke inflAmmAtion As well As procoAgulAnt Activity At infected endovAsculAr sites

  • role of σb in the expression of stAphylococcus Aureus cell wAll Adhesins clfA And fnbA And contribution to infectivity in A rAt model of experimentAl endocArditis
    Infection and Immunity, 2005
    Co-Authors: Philippe Moreillon, José M. Entenza, Maria M Senn, Jan Kormanec, Paul M Dunman, Brigitte Bergerbachi, Steven J Projan, Markus Bischoff
    Abstract:

    Isogenic StAphylococcus Aureus strAins with different cApAcities to produce sigmA(B) Activity were AnAlyzed for their Ability to AttAch to fibrinogen- or fibronectin-coAted surfAces or plAtelet-fibrin clots And to cAuse endocArditis in rAts. In compArison to the sigmA(B)-deficient strAin, BB255, which hArbors An rsbU mutAtion, both rsbU-complemented And sigmA(B)-overproducing derivAtives exhibited At leAst five times greAter AttAchment to fibrinogen- And fibronectin-coAted surfAces And showed increAsed Adherence to plAtelet-fibrin clots. No differences in Adherence were seen between BB255 And A DeltArsbUVWsigB isogen. Northern blotting AnAlyses reveAled thAt trAnscription of clfA, encoding fibrinogen-binding protein Clumping FActor A, And fnbA, encoding fibronectin-binding protein A, were positively influenced by sigmA(B). SigmA(B) overproduction resulted in A stAtisticAlly significAnt increAse in positive spleen cultures And enhAnced bActeriAl densities in both the Aortic vegetAtions And spleens At 16 h postinoculAtion. In contrAst, At 72 h postinoculAtion, tissues infected with the sigmA(B) overproducer hAd lower bActeriAl densities thAn did those infected with BB255. These results suggest thAt Although sigmA(B) AppeArs to increAse the Adhesion of S. Aureus to vArious host cell-mAtrix proteins in vitro, it hAs limited effect on pAthogenesis in the rAt endocArditis model. SigmA(B) AppeArs to hAve A trAnsient enhAncing effect on bActeriAl density in the eArly stAges of infection thAt is lost during progression.

  • reAssessing the role of stAphylococcus Aureus Clumping FActor And fibronectin binding protein by expression in lActococcus lActis
    Infection and Immunity, 2001
    Co-Authors: Patrice Francois, Jacques-antoine Haefliger, Pierre Vaudaux, José M. Entenza, Philippe Moreillon
    Abstract:

    Since StAphylococcus Aureus expresses multiple pAthogenic FActors, studying their individuAl roles in single-gene-knockout mutAnts is difficult. To circumvent this problem, S. Aureus Clumping FActor A (clfA) And fibronectin-binding protein A (fnbA) genes were constitutively expressed in poorly pAthogenic LActococcus lActis using the recently described pOri23 vector. The recombinAnt orgAnisms were tested in vitro for their Adherence to immobilized fibrinogen And fibronectin And in vivo for their Ability to infect rAts with cAtheter-induced Aortic vegetAtions. In vitro, both clfA And fnbA increAsed the Adherence of lActococci to their specific ligAnds to A similAr extent As the S. Aureus gene donor. In vivo, the minimum inoculum size producing endocArditis in > or =80% of the rAts (80% infective dose [ID80]) with the pArent lActococcus wAs > or =10(7) CFU. In contrAst, clfA-expressing And fnbA-expressing lActococci required only 10(5) CFU to infect the mAjority of the AnimAls (P < 0.00005). This wAs compArAble to the infectivities of clAssicAl endocArditis pAthogens such As S. Aureus And streptococci (ID80 = 10(4) to 10(5) CFU) in this model. The results confirmed the role of clfA in endovAsculAr infection, but with A much higher degree of confidence thAn with single-gene-inActivAted stAphylococci. Moreover, they identified fnbA As A criticAl virulence FActor of equivAlent importAnce. This wAs in contrAst to previous studies thAt produced controversiAl results regArding this very determinAnt. TAken together, the present observAtions suggest thAt if AntiAdhesin therApy were to be developed, At leAst both of the clfA And fnbA products should be blocked for the therApy to be effective.

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  • neutrophil killing of stAphylococcus Aureus in diAbetes obesity And metAbolic syndrome A prospective cellulAr surveillAnce study
    Diabetology & Metabolic Syndrome, 2017
    Co-Authors: Ingrid L Scully, Lisa K Mcneil, Douglas Girgenti, Sudam Pathirana, Christine Singer, Yongdong Liu, Stanley Mullen, Alejandra Gurtman, Michael W Pride, Kathrin U Jansen
    Abstract:

    Obesity, metAbolic syndrome (MetS), And diAbetes Are frequent in surgicAl populAtions And cAn enhAnce susceptibility to postoperAtive surgicAl site infections. Reduced neutrophil function hAs been linked with diAbetes And risk of StAphylococcus Aureus infection. Therefore, neutrophil function in diAbetic And obese subjects (± MetS) wAs Assessed in this prospective serologicAl And cellulAr surveillAnce study to determine whether vAccines Administered to protect AgAinst infections After surgery could be effective in these populAtions. Neutrophil function (chemotAxis, phAgocytosis, And opsonophAgocytic killing of S. Aureus) wAs Assessed in subjects clAssified According to diAbetes stAtus, body mAss index, And presence/Absence of MetS. Neutrophils were chArActerized within functionAl subsets by flow cytometry. A serologic AssAy wAs used to meAsure bAseline Antibody presence to eAch Antigen in SA4Ag: cApsulAr polysAcchAride (CP) type 5, CP8, recombinAnt mutAnt Clumping FActor A (rmClfA), And recombinAnt MAngAnese trAnsport protein C (rMntC). Neutrophil function wAs similAr for comorbid And heAlthy cohorts, with no significAnt between-group differences in cell counts, migrAtion, phAgocytosis Ability, neutrophil subset proportions, And S. Aureus killing Ability when neutrophils were isolAted 3–6 months ApArt (Visit 1 [n = 90] And Visit 2 [n = 70]) And Assessed. MediAn pre-existing Antibody titers to CP5, CP8, And rmClfA were compArAble for All cohorts (insufficient subjects with rMntC titers for determinAtion). MetS, diAbetes, And obesity do not impAct in vitro neutrophil function with regArd to S. Aureus killing, suggesting thAt if An effective S. Aureus vAccine is developed it mAy be effective in individuAls with these comorbidities.

  • sA4Ag A 4 Antigen stAphylococcus Aureus vAccine rApidly induces high levels of bActeriA killing Antibodies
    Vaccine, 2017
    Co-Authors: Kathrin U Jansen, Joseph Eiden, William C Gruber, Elizabeth Begier, David Seiden, Michael Patton, Edward T Zito, Joseph M Severs, David K C Cooper, Annaliesa S. Anderson
    Abstract:

    AbstrAct BAckground StAphylococcus Aureus is A leAding cAuse of heAlthcAre-AssociAted infections. No preventive vAccine is currently licensed. SA4Ag is An investigAtionAl 4-Antigen S. Aureus vAccine, composed of cApsulAr polysAcchAride conjugAtes of serotypes 5 And 8 (CP5 And CP8), recombinAnt surfAce protein Clumping FActor A (r m ClfA), And recombinAnt mAngAnese trAnsporter protein C (rMntC). This PhAse 1 study Aimed to confirm the sAfety And immunogenicity of SA4Ag produced by the finAl mAnufActuring process before efficAcy study initiAtion in A surgicAl populAtion. Methods HeAlthy Adults (18– S. Aureus clinicAl isolAtes. For MntC And ClfA, Antigen-specific immunogenicity wAs Assessed viA competitive Luminex® immunoAssAy (cLIA) And viA fibrinogen-binding inhibition (FBI) AssAy for ClfA only. ReActogenicity And Adverse event dAtA were collected. Results One hundred pArticipAnts were vAccinAted. SA4Ag wAs well tolerAted, with A sAtisFActory sAfety profile. On DAy 29, OPA geometric meAn titers (GMTs) were 45,738 (CP5, 95% CI: 38,078–54,940) And 42,652 (CP8, 95% CI: 32,792–55,477), consistent with 69.2- And 28.9-fold rises in bActeriA-killing Antibodies, respectively; cLIA GMTs were 2064.4 (MntC, 95% CI: 1518.2–2807.0) And 3081.4 (ClfA, 95% CI: 2422.2–3920.0), consistent with 19.6- And 12.3-fold rises, respectively. SimilAr to cLIA results, ClfA FBI titers rose 11.0-fold (GMT: 672.2, 95% CI: 499.8–904.2). The vAst mAjority of pArticipAnts Achieved the pre-defined biologicAlly relevAnt thresholds: CP5: 100%; CP8: 97.9%, ClfA: 87.8%; And MntC 96.9%. Conclusions SA4Ag wAs sAfe, well tolerAted, And rApidly induced high levels of bActeriA-killing Antibodies in heAlthy Adults. A PhAse 2B efficAcy triAl in Adults (18–85 yeArs) undergoing elective spinAl fusion is ongoing to Assess SA4Ag’s Ability to prevent postoperAtive invAsive surgicAl site And bloodstreAm infections cAused by S. Aureus . ClinicAltriAls.gov Identifier : NCT02364596 .

  • StAphylococcus Aureus Clumping FActor A RemAins A ViAble VAccine TArget for Prevention of S. Aureus Infection
    mBio, 2016
    Co-Authors: Annaliesa S. Anderson, Ingrid L Scully, Ed T. Buurman, Joseph Eiden, Kathrin U Jansen
    Abstract:

    In A recent Article, X. Li et Al. [mBio 7(1):e02232-15, 2016, http://dx.doi.org/10.1128/mBio.02232-15] investigAte the utility of A vAccine composed of the StAphylococcus Aureus protein Clumping FActor A (ClfA) in protecting mice from S. Aureus infection. ClfA, one of the first proteins to be identified As A potentiAl vAccine Antigen for S. Aureus prophylAxis, is currently A component of severAl investigAtionAl vAccines. The Authors conclude thAt ClfA mAy not be effective for S. Aureus prophylAxis. In contrAst, previously published pApers reporting positive dAtA suggested thAt ClfA wAs potentiAlly An importAnt vAccine tArget to prevent invAsive S. Aureus diseAse. This commentAry Addresses the observed differences between the findings of Li et Al. And those from other publicAtions, highlighting the importAnce for preclinicAl vAccine Antigen Assessments to reflect the biologicAl role of sAid Antigen in virulence And, consequently, the importAnce of choosing AppropriAte preclinicAl diseAse models to test such Antigens.

  • DemonstrAtion of the preclinicAl correlAte of protection for StAphylococcus Aureus Clumping FActor A in A murine model of infection
    Vaccine, 2015
    Co-Authors: Ingrid L Scully, Jasdeep Singh Nanra, Yekaterina Timofeyeva, Yury V Matsuka, Lisa K Mcneil, Elena Severina, David Keeney, Paul Liberator, Kathrin U Jansen
    Abstract:

    The StAphylococcus Aureus virulence FActor Clumping FActor A (ClfA) is A component of An investigAtionAl S. Aureus prophylActic vAccine. ClfA enAbles S. Aureus to bind to fibrinogen And plAtelets during the initiAl stAges of invAsive diseAse. Here we demonstrAte thAt ectopic expression of ClfA is sufficient to render nonpAthogenic LActococcus lActis lethAl in A murine model of systemic infection. In contrAst, L. lActis expressing ClfAY338A, which cAnnot bind fibrinogen, did not cAuse deAth in the mice. PAthogenicity wAs Also prevented by immunizAtion with ClfA. This model wAs then used to define A preclinicAl correlAte of protection by meAsuring functionAl Antibody in A S. Aureus fibrinogen binding inhibition AssAy (FBI) And correlAting thAt titer with protective outcomes. Although mAny humAns hAve pre-existing Antibodies thAt bind to ClfA, only serA with A threshold functionAl titer in the FBI were protective in this preclinicAl model. This confirms thAt fibrinogen binding is criticAl for ClfA-mediAted pAthogenesis And demonstrAtes thAt functionAl Antibodies AgAinst ClfA Are sufficient to protect AgAinst ClfA-mediAted pAthogenesis in vivo, enAbling the definition of A preclinicAl correlAte of protection for ClfA-contAining vAccines bAsed on FBI titer.

  • A recombinAnt Clumping FActor A contAining vAccine induces functionAl Antibodies to stAphylococcus Aureus thAt Are not observed After nAturAl exposure
    Clinical and Vaccine Immunology, 2012
    Co-Authors: Julio Hawkins, Yury V Matsuka, Terri Mininni, Srinivas Kodali, Lisa K Mcneil, Ingrid L Scully, John H Vernachio, Elena Severina, Douglas Girgenti, Kathrin U Jansen
    Abstract:

    StAphylococcus Aureus is A GrAm-positive pAthogen thAt cAuses devAstAting diseAse And whose pAthogenesis is dependent on interActions with host cell FActors. StAphylococcAl Clumping FActor A (ClfA) is A highly conserved fibrinogen (Fg)-binding protein And virulence FActor thAt contributes to host tissue Adhesion And initiAtion of infection. ClfA is being investigAted As A possible component of A stAphylococcAl vAccine. We report the development of An Fg-binding AssAy thAt is specific for ClfA-mediAted binding. Using the AssAy, we show thAt despite the presence of Anti-ClfA Antibodies, humAn serA from unvAccinAted subjects Are unAble to prevent the binding of S. Aureus to An Fg-coAted surfAce. In contrAst, Antibodies elicited by A recombinAnt ClfA-contAining vAccine were cApAble of blocking the ClfA-dependent binding of A diverse And clinicAlly relevAnt collection of stAphylococcAl strAins to Fg. These functionAl Antibodies were Also Able to displAce S. Aureus AlreAdy bound to Fg, suggesting thAt the ligAnd-binding Activity of ClfA cAn be effectively neutrAlized through vAccinAtion.