La ricerca in laboratorio P. Cossart è supportata dall&#39;Istituto Pasteur, l&#39;Institut National de la Santé et de la Recherche Médicale, l&#39;Institut National de la Recherche Agronomique, ERC Advanced Grant (233.348), l&#39;Agence Nationale de la Recherche (Grant MIE- SignRupVac), la Fondazione Louis-Jeantet e la Fondation Le Roch Les Mousquetaires. AK è un destinatario di una borsa di studio dal Pasteur-Parigi Università internazionali Dottorato / Institut Carnot Maladies infectieuses. Ringraziamo Jason Mercer per ottimizzare il protocollo di trasfezione cellulare.

1. Preparazione di cellulare e batteriche culture, Strumenti di trasfezione e primari Anticorpi <ol><li> Preparare un piatto fresco agar per isolare singoli L. monocytogenes le colonie da uno stock di glicerolo batterica (50% glycerol/50% satura di cultura durante la notte liquida batterica) conservato a -80 ° C. <ol><li> Utilizzando un rack in alluminio (conservato a -80 ° C) per il trasporto di un congelati glicerolo batteriche archivi, batteri striscia su un Brain Heart Infusion (BHI) piastra di agar. </li><li> Incubare la piastra a 37 ° C durante 48 ore (o fino singole colonie batteriche possono essere isolati). </li><li> Tenere questo piano di lavoro in seguito a 4 ° C per un tempo massimo di 1 mese (sarà usato per seminare colture liquide). </li><li> Nel nostro protocollo, usiamo la L. monocytogenes sierotipo 1/2a EGDe.PrfA * ceppo, ma come illustrato in Figura 1, il L. monocytogenes sierotipo 4b P14.PrfA * ceppo dà risultati simili. </li></ol></li><li> LuiCellule CCL2 La ATCC sono coltivate in Dulbecco Modified Eagle Medium (DMEM) supplementato con 10% siero bovino fetale (FBS) in assenza di antibiotici. </li><li> Piscine indipendenti strapazzate (controllo) e anti-Met siRNA sono caricati in 384 pozzetti piastre di coltura di cellule al microscopio nero. <ol><li> Diluire 160 pmol di siRNA in 500 ml di acqua RNase-free e aggiungere 5 ml di questa soluzione per pozzetto (concentrazione finale: 1,6 pmol). </li><li> Mantenere questo piatto a -20 ° C per un periodo massimo di 1 anno. </li></ol></li><li> Anticorpi policlonali di coniglio contro la proteina batterica InlC ottenuto mediante immunizzazione utilizzando una proteina ricombinante GST-InlC come descritto in precedenza 25. </li></ol> 2. Reverse siRNA Transfection cellulare <ol><li> 72 ore prima dell&#39;infezione portare a temperatura ambiente a 384 pozzetti piastra di coltura di cellule al microscopio nero contenente 1,6 pmol siRNA in 5 ml di acqua RNase-free in ogni pozzetto. </li><li> Centrifugare la piastra per 3 min a 300RCF a temperatura ambiente per abbattere siRNA che avrebbero potuto essere depositato nelle pareti dei pozzetti. </li><li> Preparare temperatura ambiente DMEM supplementato con 0,4% Lipofectamine RNAiMAX. </li><li> Aggiungere 25 ml di medium trasfezione DMEM / RNAiMAX a ciascun pozzetto (non incubare il mezzo trasfezione più di 20 minuti prima di aggiungere il siRNA). </li><li> Spostare la piastra avanti e indietro per mescolare il siRNA con la soluzione di trasfezione, quindi tenere la piastra per 1 ora a temperatura ambiente per consentire complessi siRNA-Lipofectamine per formare. </li><li> Lavare le cellule HeLa da un pallone-confluenti o coltura cellulare sub-confluenti una volta con 10 ml 37 ° C preriscaldata PBS. </li><li> Staccare cellule HeLa aggiungendo 1 ml 37 ° C preriscaldata tripsina al pallone di coltura cellulare e incubare per 3 a 5 min a 37 ° C. </li><li> Risospendere le cellule in 10 ml 37 ° C preriscaldata DMEM supplementato con 16% FBS. </li><li> Contare le celle e preparare una sospensione cellulare di 12.000 cellule per ml in DMEM supplementato con16% FBS. </li><li> Aggiungere 50 ml di sospensione cellulare in ciascun pozzetto nella piastra a 384 pozzetti. </li><li> Spostare la piastra rapidamente avanti e indietro per distribuire le cellule e lasciare che le cellule stabilirsi per 10 minuti a temperatura ambiente. </li><li> Sigillare la piastra con Parafilm e tenerlo per 72 ore in un umidificata al 5% CO 2 contenente l&#39;atmosfera a 37 ° C. </li></ol> 3. Infezione cellulare e colorazione <ol><li> Il giorno prima infezione, prendere una singola colonia di L. monocytogenes dalla piastra BHI agar e risospendere in 5 ml di terreno BHI liquido in provette di polistirene 15 ml. </li><li> Incubare per una notte a 37 ° C in un dispositivo Shacking per consentire la crescita batterica. </li><li> Il giorno di infezione, lavare 1 ml della notte L. monocytogenes cultura mediante centrifugazione 2 min a 10,600 rcf in una centrifuga da tavolo. </li><li> Scartare il surnatante (che contiene il secreto citotossina listeriolysin O) e risospendere il pellet in 1 ml di PBS (ripett la fase di lavaggio altre 3 volte). </li><li> Leggere la densità ottica a 600 nm batterica e stimare il numero di batteri (OD = 1 corrisponde a 1E9 batteri / ml). </li><li> Preparare l&#39;adeguato L. monocytogenes diluizione in DMEM supplementato con 1% FBS: utilizzando ceppi altamente invasive come EGDe.PrfA *, si consiglia l&#39;uso di batteri 5E4 in 30 ml di mezzo per pozzetto (la molteplicità di infezione è stimato al 25 per 2.000 celle). </li><li> Rimuovere il terreno di coltura cellulare in ciascun pozzetto (80 microlitri) e sostituirlo con l&#39;aggiunta di 30 ml di L. monocytogenes contenenti medie. </li><li> Centrifugare la piastra a 200 rcf per 5 min a temperatura ambiente per sincronizzare il processo di infezione. </li><li> Incubare la piastra per 1 ora in un umidificata al 5% CO 2 contenente atmosfera a 37 ° C su un blocco di alluminio preriscaldata. </li><li> Rimuovere la L. monocytogenes contenente medio di ogni bene e aggiungere 30 ml di DMEM preriscaldata supplementato con 10% FBS e40 mg / ml di gentamicina per uccidere extracellulare L. monocytogenes. </li><li> Incubare per 4 ore in un CO 2-atmosfera contenente 5% a 37 ° C su un blocco di metallo preriscaldato. </li><li> Preparare una soluzione di PBS supplementato con 8% di formaldeide (questa soluzione deve essere preparato fresco in modo che i monomeri formaldeide, piuttosto che i polimeri paraformaldeide, vengono utilizzati). </li><li> Senza scartare il mezzo di coltura cellulare, aggiungere 30 ml di PBS addizionato con 8% di formaldeide (concentrazione finale: 4%) e incubare per 15 min a temperatura ambiente. </li><li> Rimuovere il fissativo e lavare le cellule tre volte con 80 ml di PBS per pozzetto (mantenere le cellule in un volume finale di 80 ml di PBS per pozzetto). </li><li> Preparare una diluizione 1:250 del coniglio anti-InlC siero in PBS completato con 0,2% di saponina. </li><li> Aggiungere 10 ml di soluzione di anticorpo primario a ciascun pozzetto dopo aver rimosso il PBS e incubare per 30 min a temperatura ambiente. </li><li> Scartare il primariosoluzione di anticorpi e lavare quattro volte con 40 ml di PBS per pozzetto. </li><li> Diluire il Alexa Fluor 546-coupled anticorpo secondario anti-coniglio (1:250), la soluzione DAPI (1:1,500), e falloidina-Dy647 (1:150) in PBS integrato con 0,2% saponina. </li><li> Aggiungere 10 ml di questa soluzione colorante secondario in ciascun pozzetto ed incubare per 30 minuti a temperatura ambiente. </li><li> Eliminare la soluzione colorante secondario e lavare quattro volte con 40 ml di PBS per pozzetto (lasciare un volume finale di 40 microlitri in ciascun pozzetto e sigillare la piastra). </li><li> La piastra può essere ripreso immediatamente o può essere conservato a 4 ° C al riparo dalla luce (coprire con un foglio di alluminio) per successive analisi. </li></ol> 4. Image Acquisition and Analysis <ol><li> Acquisire immagini in tre diversi canali (350 nm, 546 nm e 647 nm) con un obiettivo 10X montato su un microscopio automatizzato (acquisire preferenzialmente 9 immagini per bene). </li><li> Il segnale InlC può essere misurata con immaginesoftware di analisi come CellProfiler che consente la segmentazione automatica di nuclei e corpi cellulari che utilizzano il DAPI e la colorazione falloidina, rispettivamente. </li></ol>

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M., Cossart, P. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=E-cadherin+is+the+receptor+for+internalin,+a+surface+protein+required+for+entry+of+L.+monocytogenes+into+epithelial+cells.">E-cadherin is the receptor for internalin, a surface protein required for entry of L. monocytogenes into epithelial cells.</a> Cell. 84, 923-932 (1996).</li><li>Shen, Y., Naujokas, M., Park, M., Ireton, K. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=InIB-dependent+internalization+of+Listeria+is+mediated+by+the+Met+receptor+tyrosine+kinase.">InIB-dependent internalization of Listeria is mediated by the Met receptor tyrosine kinase.</a> Cell. 103, 501-510 (2000).</li><li>Lecuit, M., Hurme, R., Pizarro-Cerda, J., Ohayon, H., Geiger, B., Cossart, P. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+role+for+alpha-and+beta-catenins+in+bacterial+uptake.">A role for alpha-and beta-catenins in bacterial uptake.</a> Proceedings of the National Academy of Sciences USA. 97, 10008-10013 (2000).</li><li>Ireton, K., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+role+for+phosphoinositide+3-kinase+in+bacterial+invasion.">A role for phosphoinositide 3-kinase in bacterial invasion.</a> Science. 274, 780-782 (1996).</li><li>Ireton, K., Payrastre, B., Cossart, P. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+Listeria+monocytogenes+protein+InlB+is+an+agonist+of+mammalian+phosphoinositide+3-kinase.">The Listeria monocytogenes protein InlB is an agonist of mammalian phosphoinositide 3-kinase.</a> Journal of Biological Chemistry. 274, 17025-17032 (1999).</li><li>Pizarro-Cerd&#225;, J., Jonqui&#232;res, R., Gouin, E., Vandekerckhove, J., Garin, J., Cossart, P. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Distinct+protein+patterns+associated+with+Listeria+monocytogenes+InlA-+or+InlB+phagosomes.">Distinct protein patterns associated with Listeria monocytogenes InlA- or InlB phagosomes.</a> Cellular Microbiology. 4, 101-115 (2002).</li><li>Pizarro-Cerd&#225;, J., Payrastre, B., Wang, Y. -. 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Non abbiamo nulla da rivelare.

Diversi parametri sono fondamentali per il successo del nostro protocollo InlC rilevamento, compreso l&#39;uso di linee di cellule sane visualizzazione sufficientemente grande citoplasma per consentire una rilevazione univoca del segnale InlC. Nel saggio che presentiamo in questo articolo vi proponiamo l&#39;uso di cellule HeLa CCL2, che sono particolarmente adatti per la nostra analisi a causa della estensione del loro spazio citosolico; altri cloni HeLa come le cellule HeLa Kyoto mostrano un citoplasma più piccolo, m...

A correction was made to <a href="http://www.jove.com/video/51043">Imaging InlC Secretion to Investigate Cellular Infection by the Bacterial Pathogen Listeria monocytogenes</a>. Three authors were omitted from the article at the time of publication. The acknowledgments section was also updated. The author list has been updated from:
Andreas K&#252;hbacher1,2,3, Edith Gouin1,2,3, Pascale Cossart1,2,3, Javier Pizarro-Cerd&#225;1,2,3 
1Unit&#233; des Interactions Bact&#233;ries Cellules, Pasteur Institute, 2INSERM U604, 3Institut National de la Recherche Agronomique (INRA), USC2020
to
Andreas K&#252;hbacher1,2,3, Edith Gouin1,2,3, Jason Mercer4, Mario Emmenlauer5, Christoph Dehio5, Pascale Cossart1,2,3, Javier Pizarro-Cerd&#225;1,2,3 
1Unit&#233; des Interactions Bact&#233;ries Cellules, Pasteur Institute,2INSERM U604, 3Institut National de la Recherche Agronomique (INRA), USC2020, 4Institute of Biochemistry, ETH Z&#252;rich 5Focal Area Infection Biology, Biozentrum, University of Basel
The acknowledgments where update from:
Research in P. Cossart laboratory is supported by the Pasteur Institute, the Institut National de la Sant&eacute; et de la Recherche M&eacute;dicale, the Institut National de la Recherche Agronomique, ERC Advanced Grant (233348), the Agence Nationale de la Recherche (Grant MIE-SignRupVac), the Louis-Jeantet Foundation and the Fondation Le Roch Les Mousquetaires. A.K. is a recipient of a scholarship from the Pasteur-Paris University International Doctoral Program/Institut Carnot Maladies Infectieuses. We thank Jason Mercer for optimizing the cellular transfection protocol.
to
Research in P. Cossart laboratory is supported by the Pasteur Institute, the Institut National de la Sant&eacute; et de la Recherche M&eacute;dicale, the Institut National de la Recherche Agronomique, ERC Advanced Grant (233348), the Agence Nationale de la Recherche (Grant MIE-SignRupVac), the Louis-Jeantet Foundation and the Fondation Le Roch Les Mousquetaires. A.K. is a recipient of a scholarship from the Pasteur-Paris University International Doctoral Program/Institut Carnot Maladies Infectieuses. We acknowledge support by grant 51RT 0_126008 for the Research and Technology Development (RTD) project InfectX in the frame of SystemsX.ch, the Swiss Initiative for Systems Biology (to C.D.).

A correction to author list has been made for the article Imaging InlC Secretion to Investigate Cellular Infection by the Bacterial Pathogen Listeria monocytogenes. Three authors were omitted from the article at the time of publication.

Erratum: Imaging InlC Secretion to Investigate Cellular Infection by the Bacterial Pathogen Listeria monocytogenes

Il batterio Gram positivi Listeria monocytogenes è un patogeno di origine alimentare che invade cellule ospiti, interrompe la sua vacuolo interiorizzazione e replica nel citoplasma delle cellule ospiti 1. L. monocytogenes facilità di manipolazione nel contesto laboratorio (rapida crescita, bassa tossicità per gli individui sani) associato con la persistenza di tratti di virulenza batterica osservati nei modelli cellulari e animali (attività emolitica, leucocitosi) ha permesso l&#39;uso iniziale nel 1960 come un modello importante per lo studio del parassitismo intracellulare e per l&#39;istituzione dei fondamenti teorici della immunità cellulare contro l&#39;infezione 2. Alla fine del 1980 e all&#39;inizio del 1990, la dissezione del ciclo intracellulare batterica 3, nonché la caratterizzazione molecolare dei più importanti fattori di virulenza batterica 4-7 favorito l&#39;uso di L. monocytogenes come strumento molecolare fondamentale per la manipolazione e studY di funzioni della cellula ospite. La presenza di virulenti (L. innocua) e virulenti (L. monocytogenes) specie del genere Listeria aperto la strada a studi di genomica comparativa 8 che, assieme alla recente istituzione del completo L. monocytogenes trascrittoma 9, hanno aumentato la nostra comprensione dell&#39;evoluzione del L. monocytogenes come agente patogeno umano e come sistema modello per l&#39;infezione Studi 10. L. monocytogenes induce la sua internalizzazione nelle cellule ospiti su interazione delle proteine ​​di superficie batterica dell&#39;INLA e InlB con i loro recettori della cellula ospite E-caderina e Met, rispettivamente, 11-12. Studi basati candidati-iniziali hanno portato all&#39;identificazione del collegamento catenine-actina α / β come componente significativa del percorso inlA-invasione 13 e del phosphoinositide 3-chinasi (PI 3-K) come effettore critica del InlB- dipendente invasione Cascade 14-15. Analisi proteomica e basati funzionale successivamente consentito l&#39;identificazione degli elementi del citoscheletro nuovi 16 e secondi messaggeri lipidici 17 necessari per l&#39;invasione della cellula ospite. Studi trascrizionali 18 e di massa a base di spettrometria di proteomica quantitativa 19 hanno recentemente gettato nuova luce concernente l&#39;attivazione di accoglienza cascate di segnalazione e la repressione delle risposte immunitarie durante L. monocytogenes infezione. La biologia dei sistemi si avvicina basato sulla inattivazione di grandi insiemi di geni (kinomes, genomi completi) da piccoli RNA interferenti (siRNA) silenziamento hanno recentemente aperto nuove strade per l&#39;analisi di accoglienza globale cascate di segnalazione nel contesto di specifiche funzioni cellulari, tra cui la fagocitosi e patogeno interiorizzazione 20. Schermi siRNA genome-wide sono stati precedentemente eseguiti per studiare cascate cellulari necessarie per l&#39;infezione di L. monocytogenes in phagocytic Drosophila </em&gt; cellule S2 21-22, ma questo tipo di analisi non è stata eseguita in cellule non fagocitarie, che rappresentano bersagli critici per l&#39;infezione in vivo. Abbiamo ottimizzato un protocollo per la rilevazione microscopica delle ultime fasi di infezione da L. monocytogenes che è adatto per gli studi high-throughput siRNA di entrata batterica all&#39;interno delle cellule epiteliali. La nostra analisi si avvale di una L. altamente invasiva monocytogenes che presenta una mutazione puntiforme nel PrfA, il regolatore trascrizionale maggiore di L. monocytogenes fattori di virulenza 6: questa mutazione (denominata PrfA *) rende PrfA costitutivamente attivo 23 e porta ad un aumento dell&#39;espressione delle proteine ​​invasione dell&#39;INLA e InlB, quindi favorendo l&#39;ingresso di batteri in cellule non fagocitarie altrimenti poco infetti. La nostra lettura di infezione si basa sulla rilevazione dell&#39;accumulo citosolica della proteina secreta batterica InlC: questa molecola èun effettore pleiotropici che si esprime preferenzialmente da intra-citoplasmatica L. monocytogenes 9 e che partecipa non solo nella cella cellula-batterica distribuite 24, ma che modula anche la risposta immunitaria 25. La marcatura fluorescente di InlC secrezione da batteri intracellulari permette non solo di distinguere chiaramente infetto da cellule non infette, ma rappresenta anche una lettura end-point che può essere utilizzato per analizzare successivamente infezione nelle sue diverse fasi: entrata, fuga vacuolare, citosolica batterica proliferazione e diffusione cellula-cellula. Questo protocollo basato microscopia può essere accoppiato a schermi siRNA quindi studiare vie cellulari coinvolti nella infezione di cellule ospiti di L. monocytogenes.

<table border="1">
		<tbody>
		 <tr>
			<td>Name of Material/ Equipment</td>
			<td>Company</td>
			<td>Catalog Number</td>
			<td>Comments/Description</td>
		 </tr>
		 <tr>
			<td>Bacto Brain Heart Infusion</td>
			<td>BD</td>
			<td>237500</td>
			<td>For liquid BHI preparation</td>
		 </tr>
		 <tr>
			<td>Bacto Agar</td>
			<td>BD</td>
			<td>214010</td>
			<td>Supplement to liquid BHI for BHI agar plates </td>
		 </tr>
		 <tr>
			<td>Heat-Inactivated Fetal Bovine Serum</td>
			<td>Biowest</td>
			<td>51830-500</td>
			<td></td>
		 </tr>
		 <tr>
			<td>DMEM</td>
			<td>Invitrogen</td>
			<td>61965-026</td>
			<td></td>
		 </tr>
		 <tr>
			<td>Lipofectamine RNAiMax</td>
			<td>Invitrogen</td>
			<td>13778-100</td>
			<td></td>
		 </tr>
		 <tr>
			<td>Gentamicin</td>
			<td>Sigma </td>
			<td>G1397-10ML</td>
			<td></td>
		 </tr>
		 <tr>
			<td>Formaldehyde (16%)</td>
			<td>EMS</td>
			<td>15710</td>
			<td>Prepare fresh before each experiment</td>
		 </tr>
		 <tr>
			<td>Anti-Rabbit Alexa Fluor 546</td>
			<td>Invitrogen</td>
			<td>A-11035</td>
			<td></td>
		 </tr>
		 <tr>
			<td>DAPI</td>
			<td>Invitrogen</td>
			<td>D-1306</td>
			<td></td>
		 </tr>
		 <tr>
			<td>Phalloidin Dy647</td>
			<td>Dyomics</td>
			<td>647-33</td>
			<td></td>
		 </tr>
		 <tr>
			<td>siRNA Scramble</td>
			<td>Dharmacon</td>
			<td>D-001810-10</td>
			<td></td>
		 </tr>
		 <tr>
			<td>siRNA Met</td>
			<td>Dharmacon</td>
			<td>L-003156-00-0005</td>
			<td></td>
		 </tr>
		 <tr>
			<td>Black 384-well microscopy cell culture plate</td>
			<td>Corning</td>
			<td>3985</td>
			<td></td>
		 </tr>
		 <tr>
			<td>AxioObserver Z1 microscope</td>
			<td>Zeiss</td>
			<td>431007 9901</td>
			<td></td>
		 </tr>
		 <tr>
			<td>sCMOS camera</td>
			<td>Andor</td>
			<td>Neo</td>
			<td></td>
		 </tr>
		 <tr>
			<td>Metamorph analysis software</td>
			<td>Molecular Devices</td>
			<td>4000</td>
			<td></td>
		 </tr>
		 <tr>
			<td>CellProfiler analysis software</td>
			<td>Broad Institute</td>
			<td>Public software available at <a href="http://www.cellprofiler.org/" target="_blank">http://www.cellprofiler.org/</a></td>
			<td></td>
		 </tr>
		</tbody>
 </table>

imaging inlc secretion to investigate cellular infection by the bacterial pathogen listeria monocytogenes

Patogeni intracellulari batteriche possono essere concepite come strumenti molecolari per sezionare cascate di segnalazione cellulare a causa della loro capacità di manipolare squisitamente e sovvertire le funzioni cellulari che sono necessarie per l&#39;infezione dei tessuti bersaglio ospitanti. Tra questi batteri patogeni, Listeria monocytogenes è un microrganismo Gram positivo che è stato usato come paradigma per parassitismo intracellulare nella caratterizzazione delle risposte immunitarie cellulari, e che ha avuto un ruolo strumentale nella scoperta di percorsi molecolari che controllano citoscheletro e membrana dinamiche di traffico. In questo articolo descriviamo un saggio microscopica robusto per l&#39;individuazione di fasi tardive infezione cellulare di L. monocytogenes basano sulla marcatura fluorescente di InlC, una proteina batterica secreto che si accumula nel citoplasma delle cellule infette; questo dosaggio può essere accoppiato ad alto throughput schermi piccoli RNA interferenti automatizzati per charziazioni che caratterizzano vie di segnalazione cellulari coinvolti nella up o down-regulation di infezione.

Marcatura fluorescente di citoplasmatica InlC fornisce una lettura affidabile per l&#39;infezione delle cellule di L. monocytogenes, come illustrato in Figura 1: la cella centrale nella micrografia è altamente infettati dal ceppo P14.PrfA * 23 come si può osservare l&#39;immagine a contrasto di fase (frecce, figura 1A) e viene confermata dal segnale DAPI dove i singoli batteri possono essere chiaramente distinti (Figura 1B). La colorazione InlC (so...

Watch this Scientific Journal Video about Imaging InlC Secretion to Investigate Cellular Infection by the Bacterial Pathogen Listeria monocytogenes at JoVE.com

Imaging InlC Secretion to Investigate Cellular Infection by the Bacterial Pathogen Listeria monocytogenes

Listeria monocytogenes è un batterio patogeno Gram positivi frequentemente usato come modello importante per lo studio di parassitismo intracellulare. Imaging tardi L. monocytogenes fasi di infezione nel contesto di schermi piccole interferenti RNA permette per lo studio globale di vie cellulari necessarie per infezione batterica delle cellule ospiti bersaglio.

Imaging InlC secrezione per Indagare infezione Cellular dalla batterica patogeni<em&gt; Listeria monocytogenes</em

Bacterial intracellular  pathogens can be conceived as molecular tools to dissect cellular signaling  cascades due to their capacity to exquisitely ...

imaging-inlc-secretion-to-investigate-cellular-infection-bacterial

Research

JoVE Journal

Immunology and Infection

Imaging InlC Secretion to Investigate Cellular Infection by the Bacterial Pathogen Listeria monocytogenes

9.8K Views.  Pasteur Institute.  Listeria monocytogenes è un batterio patogeno Gram positivi frequentemente usato come modello importante per lo studio di parassitismo intracellulare. Imaging tardi L. monocytogenes fasi di infezione nel contesto di schermi piccole interferenti RNA permette per lo studio globale di vie cellulari necessarie per infezione batterica delle cellule ospiti bersaglio. 

Video: Imaging InlC Secretion to Investigate Cellular Infection by the Bacterial Pathogen Listeria monocytogenes

Using Bioluminescent Imaging to Investigate Synergism Between Streptococcus pneumoniae and Influenza A Virus in Infant Mice

During the 1918 influenza virus pandemic, which killed approximately 50 million people worldwide, the majority of fatalities were not the result of infection with influenza virus alone. Instead, most individuals are thought to have succumbed to a secondary bacterial infection, predominately caused by the bacterium Streptococcus pneumoniae (the pneumococcus). The synergistic relationship between infections caused by influenza virus and the pneumococcus has subsequently been observed during the 1957 Asian influenza virus pandemic, as well as during seasonal outbreaks of the virus (reviewed in 1, 2). Here, we describe a protocol used to investigate the mechanism(s) that may be involved in increased morbidity as a result of concurrent influenza A virus and S. pneumoniae infection. We have developed an infant murine model to reliably and reproducibly demonstrate the effects of influenza virus infection of mice colonised with S. pneumoniae. Using this protocol, we have provided the first insight into the kinetics of pneumococcal transmission between co-housed, neonatal mice using in vivo imaging 3.

Using Bioluminescent Imaging to Investigate Synergism Between Streptococcus pneumoniae and Influenza A Virus in Infant Mice

A concurrent infection with influenza A virus is one of the factors implicated in the induction of invasive pneumococcal disease during asymptomatic Streptococcus pneumoniae carriage. Here we describe a mixed infection method using infant mice to investigate the synergism between these two respiratory pathogens.

Utilizzando Imaging Bioluminescent per Indagare il sinergismo tra Streptococcus pneumoniae E Influenza A virus in topi neonati

During the 1918 influenza virus pandemic, which killed approximately 50 million people worldwide, the majority of fatalities were not the result of ...

Ricerca

Immunologia e infezioni

Invasion of Human Cells by a Bacterial Pathogen

Here we will describe how we study the invasion of human endothelial cells by bacterial pathogen Staphylococcus aureus . The general protocol can be applied to the study of cell invasion by virtually any culturable bacterium. The stages at which specific aspects of invasion can be studied, such as the role of actin rearrangement or caveolae, will be highlighted. Host cells are grown in flasks and when ready for use are seeded into 24-well plates containing Thermanox coverslips. Using coverslips allows subsequent removal of the cells from the wells to reduce interference from serum proteins deposited onto the sides of the wells (to which S. aureus would attach). Bacteria are grown to the required density and washed to remove any secreted proteins (e.g. toxins). Coverslips with confluent layers of endothelial cells are transferred to new 24-well plates containing fresh culture medium before the addition of bacteria. Bacteria and cells are then incubated together for the required amount of time in 5% CO2 at 37&deg;C. For S. aureus this is typically between 15-90 minutes. Thermanox coverslips are removed from each well and dip-washed in PBS to remove unattached bacteria. If total associated bacteria (adherent and internalised) are to be quantified, coverslips are then placed in a fresh well containing 0.5% Triton X-100 in PBS. Gentle pipetting leads to complete cell lysis and bacteria are enumerated by serial dilution and plating onto agar. If the number of bacteria that have invaded the cells is needed, coverslips are added to wells containing 500 &mu;l tissue culture medium supplemented with gentamicin and incubation continued for 1 h, which will kill all external bacteria. Coverslips can then be washed, cells lysed and bacteria enumerated by plating onto agar as described above. If the experiment requires direct visualisation, coverslips can be fixed and stained for light, fluorescence or confocal microscopy or prepared for electron microscopy.

A general protocol for the study of invasion of host cells by a bacterial pathogen, focusing on Staphylococcus aureus and human endothelial cells.

Invasione di cellule umane da un agente patogeno batterico

Here we will describe how we study the invasion of human endothelial cells by bacterial pathogen Staphylococcus aureus . The general protocol can be ...

Measuring Bacterial Load and Immune Responses in Mice Infected with Listeria monocytogenes

Listeria monocytogenes (Listeria) is a Gram-positive facultative intracellular pathogen1. Mouse studies typically employ intravenous injection of Listeria, which results in systemic infection2. After injection, Listeria quickly disseminates to the spleen and liver due to uptake by CD8&alpha;+ dendritic cells and Kupffer cells3,4. Once phagocytosed, various bacterial proteins enable Listeria to escape the phagosome, survive within the cytosol, and infect neighboring cells5. During the first three days of infection, different innate immune cells (e.g. monocytes, neutrophils, NK cells, dendritic cells) mediate bactericidal mechanisms that minimize Listeria proliferation. CD8+ T cells are subsequently recruited and responsible for the eventual clearance of Listeria from the host, typically within 10 days of infection6.
Successful clearance of Listeria from infected mice depends on the appropriate onset of host immune responses6	. There is a broad range of sensitivities amongst inbred mouse strains7,8. Generally, mice with increased susceptibility to Listeria infection are less able to control bacterial proliferation, demonstrating increased bacterial load and/or delayed clearance compared to resistant mice. Genetic studies, including linkage analyses and knockout mouse strains, have identified various genes for which sequence variation affects host responses to Listeria infection6,8-14. Determination and comparison of infection kinetics between different mouse strains is therefore an important method for identifying host genetic factors that contribute to immune responses against Listeria. Comparison of host responses to different Listeria strains is also an effective way to identify bacterial virulence factors that may serve as potential targets for antibiotic therapy or vaccine design.
We describe here a straightforward method for measuring bacterial load (colony forming units [CFU] per tissue) and preparing single-cell suspensions of the liver and spleen for FACS analysis of immune responses in Listeria-infected mice. This method is particularly useful for initial characterization of Listeria infection in novel mouse strains, as well as comparison of immune responses between different mouse strains infected with Listeria. We use the Listeria monocytogenes EGD strain15 that, when cultured on blood agar, exhibits a characteristic halo zone around each colony due to &beta;-hemolysis1 (Figure 1). Bacterial load and immune responses can be determined at any time-point after infection by culturing tissue homogenate on blood agar plates and preparing tissue cell suspensions for FACS analysis using the protocols described below. We would note that individuals who are immunocompromised or pregnant should not handle Listeria, and the relevant institutional biosafety committee and animal facility management should be consulted before work commences.

Measuring Bacterial Load and Immune Responses in Mice Infected with Listeria monocytogenes

Listeria monocytogenes is a model organism for studying immune responses and genetic susceptibility to intracellular bacteria in mice. This method enables one to measure bacterial load and generate single-cell suspensions of the liver and spleen from mice for FACS analysis to determine changes in immune cells due to Listeria infection.

Misurazione della carica batterica e Risposte immunitarie in topi infettati con Listeria monocytogenes</em

Listeria monocytogenes (Listeria) is a Gram-positive facultative intracellular pathogen1. Mouse studies typically employ intravenous injection of ...

The Insect Galleria mellonella as a Powerful Infection Model to Investigate Bacterial Pathogenesis

The study of bacterial virulence often requires a suitable animal model. Mammalian models of infection are costly and may raise ethical issues. The use of insects as infection models provides a valuable alternative. Compared to other non-vertebrate model hosts such as nematodes, insects have a relatively advanced system of antimicrobial defenses and are thus more likely to produce information relevant to the mammalian infection process. Like mammals, insects possess a complex innate immune system1. Cells in the hemolymph are capable of phagocytosing or encapsulating microbial invaders, and humoral responses include the inducible production of lysozyme and small antibacterial peptides2,3. In addition, analogies are found between the epithelial cells of insect larval midguts and intestinal cells of mammalian digestive systems. Finally, several basic components essential for the bacterial infection process such as cell adhesion, resistance to antimicrobial peptides, tissue degradation and adaptation to oxidative stress are likely to be important in both insects and mammals1. Thus, insects are polyvalent tools for the identification and characterization of microbial virulence factors involved in mammalian infections.
Larvae of the greater wax moth Galleria mellonella have been shown to provide a useful insight into the pathogenesis of a wide range of microbial infections including mammalian fungal (Fusarium oxysporum, Aspergillus fumigatus, Candida albicans) and bacterial pathogens, such as Staphylococcus aureus, Proteus vulgaris, Serratia marcescens Pseudomonas aeruginosa, Listeria monocytogenes or Enterococcus faecalis4-7. Regardless of the bacterial species, results obtained with Galleria larvae infected by direct injection through the cuticle consistently correlate with those of similar mammalian studies: bacterial strains that are attenuated in mammalian models demonstrate lower virulence in Galleria, and strains causing severe human infections are also highly virulent in the Galleria model8-11. Oral infection of Galleria is much less used and additional compounds, like specific toxins, are needed to reach mortality.
G. mellonella larvae present several technical advantages: they are relatively large (last instar larvae before pupation are about 2 cm long and weight 250 mg), thus enabling the injection of defined doses of bacteria; they can be reared at various temperatures (20 &deg;C to 30 &deg;C) and infection studies can be conducted between 15 &deg;C to above 37 &deg;C12,13, allowing experiments that mimic a mammalian environment. In addition, insect rearing is easy and relatively cheap. Infection of the larvae allows monitoring bacterial virulence by several means, including calculation of LD5014, measurement of bacterial survival15,16 and examination of the infection process17. Here, we describe the rearing of the insects, covering all life stages of G. mellonella. We provide a detailed protocol of infection by two routes of inoculation: oral and intra haemocoelic. The bacterial model used in this protocol is Bacillus cereus, a Gram positive pathogen implicated in gastrointestinal as well as in other severe local or systemic opportunistic infections18,19.

The Insect Galleria mellonella as a Powerful Infection Model to Investigate Bacterial Pathogenesis

Oral and intra haemocolic infection of larvae of the greater wax moth Galleria mellonella is described. This insect can be used to study virulence factors of entomopathogenic as well as mammalian opportunistic bacteria. Rearing of the insects, methods of infection and examples of in vivo analysis are described.

L&#39;insetto<em&gt; Galleria mellonella</em&gt; Come un modello di infezione potente per Indagare Patogenesi batterica

The study of bacterial virulence often requires a suitable animal model. Mammalian models of infection are costly and may raise ethical issues. The use of ...

Oral Transmission of Listeria monocytogenes in Mice via Ingestion of Contaminated Food

L. monocytogenes are facultative intracellular bacterial pathogens that cause food borne infections in humans. Very little is known about the gastrointestinal phase of listeriosis due to the lack of a small animal model that closely mimics human disease. This paper describes a novel mouse model for oral transmission of L. monocytogenes. Using this model, mice fed L. monocytogenes-contaminated bread have a discrete phase of gastrointestinal infection, followed by varying degrees of systemic spread in susceptible (BALB/c/By/J) or resistant (C57BL/6) mouse strains. During the later stages of the infection, dissemination to the gall bladder and brain is observed. The food borne model of listeriosis is highly reproducible, does not require specialized skills, and can be used with a wide variety of bacterial isolates and laboratory mouse strains. As such, it is the ideal model to study both virulence strategies used by L. monocytogenes to promote intestinal colonization, as well as the host response to invasive food borne bacterial infection.

Oral Transmission of Listeria monocytogenes in Mice via Ingestion of Contaminated Food

This paper describes a novel method for oral infection of mice using Listeria monocytogenes-contaminated food. The protocol can readily be adapted for use with other food borne bacterial pathogens.

Trasmissione orale di<em&gt; Listeria monocytogenes</em&gt; Nei topi tramite ingestione di alimenti contaminati

L. monocytogenes are facultative intracellular bacterial pathogens that cause food borne infections in humans. Very little is known about the ...

Automated Separation of C. elegans Variably Colonized by a Bacterial Pathogen

The wormsorter is an instrument analogous to a FACS machine that is used in studies of Caenorhabditis elegans, typically to sort worms based on expression of a fluorescent reporter. Here, we highlight an alternative usage of this instrument, for sorting worms according to their degree of colonization by a GFP-expressing pathogen. This new usage allowed us to address the relationship between colonization of the worm intestine and induction of immune responses. While C. elegans immune responses to different pathogens have been documented, it is still unknown what initiates them. The two main possibilities (which are not mutually exclusive) are recognition of pathogen-associated molecular patterns, and detection of damage caused by infection. To differentiate between the two possibilities, exposure to the pathogen must be dissociated from the damage it causes. The wormsorter enabled separation of worms that were extensively-colonized by the Gram-negative pathogen Pseudomonas aeruginosa, with the damage likely caused by pathogen load, from worms that were similarly exposed, but not, or marginally, colonized. These distinct populations were used to assess the relationship between pathogen load and the induction of transcriptional immune responses. The results suggest that the two are dissociated, supporting the possibility of pathogen recognition.

Automated Separation of C. elegans Variably Colonized by a Bacterial Pathogen

The wormsorter facilitates genetic screens in Caenorhabditis elegans by sorting worms according to expression of fluorescent reporters. Here, we describe a new usage:&#160;sorting according to colonization by a GFP-expressing pathogen, and we employ it to examine the poorly understood role of pathogen recognition in initiating immune responses.

Separazione automatica di<em&gt; C. elegans</em&gt; Variabilmente Colonizzato da un batterio patogeno

The wormsorter is an instrument analogous to a FACS machine that is used in studies of Caenorhabditis elegans, typically to sort worms based on expression ...

Assessing Bacterial Invasion of Cardiac Cells in Culture and Heart Colonization in Infected Mice Using Listeria monocytogenes

Listeria monocytogenes is a Gram-positive facultative intracellular pathogen that is capable of causing serious invasive infections in immunocompromised patients, the elderly, and pregnant women. The most common manifestations of listeriosis in humans include meningitis, encephalitis, and fetal abortion. A significant but much less documented sequelae of invasive L. monocytogenes infection involves the heart. The death rate from cardiac illness can be up to 35% despite treatment, however very little is known regarding L. monocytogenes colonization of cardiac tissue and its resultant pathologies. In addition, it has recently become apparent that subpopulations of L. monocytogenes have an enhanced capacity to invade and grow within cardiac tissue. This protocol describes in detail in vitro and in vivo methods that can be used for assessing cardiotropism of L. monocytogenes isolates. Methods are presented for the infection of H9c2 rat cardiac myoblasts in tissue culture as well as for the determination of bacterial colonization of the hearts of infected mice. These methods are useful not only for identifying strains with the potential to colonize cardiac tissue in infected animals, but may also facilitate the identification of bacterial gene products that serve to enhance cardiac cell invasion and/or drive changes in heart pathology. These methods also provide for the direct comparison of cardiotropism between multiple L. monocytogenes strains.

Assessing Bacterial Invasion of Cardiac Cells in Culture and Heart Colonization in Infected Mice Using Listeria monocytogenes

Listeria monocytogenes causes fetal infections in pregnant women and meningitis in susceptible populations. Subpopulations of bacteria can colonize cardiac tissue, causing myocarditis in patients and laboratory animals. Here we present a protocol that describes how to assess L. monocytogenes cardiac cell invasion in vitro and cardiac colonization in infected animals.

Valutazione dell'invasione batterica delle cellule cardiache in coltura e colonizzazione cardiaca nei topi infetti utilizzando listeria monocytogenes

Listeria monocytogenes is a Gram-positive facultative intracellular pathogen that is capable of causing serious invasive infections in immunocompromised ...

RNA Purification from Intracellularly Grown Listeria monocytogenes in Macrophage Cells

Analysis of the transcriptome of bacterial pathogens during mammalian infection is a valuable tool for studying genes and factors that mediate infection. However, isolating bacterial RNA from infected cells or tissues is a challenging task, since mammalian RNA mostly dominates the lysates of infected cells. Here we describe an optimized method for RNA isolation of Listeria monocytogenes bacteria growing within bone marrow derived macrophage cells. Upon infection, cells are mildly lysed and rapidly filtered to discard most of the host proteins and RNA, while retaining intact bacteria. Next, bacterial RNA is isolated using hot phenol-SDS extraction followed by DNase treatment. The extracted RNA is suitable for gene transcription analysis by multiple techniques. This method is successfully employed in our studies of Listeria monocytogenes gene regulation during infection of macrophage cells 1-4. The protocol can be easily modified to study other bacterial pathogens and cell types.

RNA Purification from Intracellularly Grown Listeria monocytogenes in Macrophage Cells

Here we describe a method for bacterial RNA isolation from Listeria monocytogenes bacteria growing inside murine macrophages. This technique can be used with other intracellular pathogens and mammalian host cells.

RNA Purificazione da nella cellula Grown<em&gt; Listeria monocytogenes</em&gt; In macrofagi

Analysis of the transcriptome of bacterial pathogens during mammalian infection is a valuable tool for studying genes and factors that mediate infection. ...

Experimental Infection with Listeria monocytogenes as a Model for Studying Host Interferon-&#947; Responses

L. monocytogenes is a gram-positive bacterium that is a cause of food borne disease in humans. Experimental infection of mice with this pathogen has been highly informative on the role of innate and adaptive immune cells and specific cytokines in host immunity against intracellular pathogens. Production of IFN-&#947; by innate cells during sublethal infection with L. monocytogenes is important for activating macrophages and early control of the pathogen1-3. In addition, IFN-&#947; production by adaptive memory lymphocytes is important for priming the activation of innate cells upon reinfection4. The L. monocytogenes infection model thus serves as a great tool for investigating whether new therapies that are designed to increase IFN-&#947; production have an impact on IFN-&#947; responses in vivo and have productive biological effects such as increasing bacterial clearance or improving mouse survival from infection. Described here is a basic protocol for how to conduct intraperitoneal infections of C57BL/6J mice with the EGD strain of L. monocytogenes and to measure IFN-&#947; production by NK cells, NKT cells, and adaptive lymphocytes by flow cytometry. In addition, procedures are described to: (1) grow and prepare the bacteria for inoculation, (2) measure bacterial load in the spleen and liver, and (3) measure animal survival to endpoints. Representative data are also provided to illustrate how this infection model can be used to test the effect of specific agents on IFN-&#947; responses to L. monocytogenes and survival of mice from this infection.

Experimental Infection with &lt;em&gt;Listeria monocytogenes&lt;/em&gt; as a Model for Studying Host Interferon-&amp;#947; Responses

This protocol describes how to inoculate C57BL/6J mice with the EGD strain of Listeria monocytogenes (L. monocytogenes) and to measure interferon-&#947; (IFN-&#947;) responses by natural killer (NK) cells, natural killer T (NKT) cells, and adaptive T lymphocytes post-infection. This protocol also describes how to conduct survival studies in mice after infection with a modified LD50 dose of the pathogen.

Infezione sperimentale con<em&gt; Listeria monocytogenes</em&gt; Come modello per lo studio Host Interferone-gamma Risposte

L. monocytogenes is a gram-positive bacterium that is a cause of food borne disease in humans. Experimental infection of mice with this pathogen has been ...

Listeria monocytogenes Infection of the Brain

Listeria monocytogenes is an intracellular bacterial pathogen that is frequently associated with food-borne infection. The ability of&#160;L. monocytogenes to cross the blood-brain barrier (BBB) is concerning as it can lead to life-threatening meningitis and encephalitis. The BBB protects the brain microenvironment from various toxic metabolites and microbial pathogens found in the blood following infection, and therefore supports brain homeostasis. The mechanisms by which L. monocytogenes present in the bloodstream cross the BBB to cause brain infections are not fully understood and there is also a lack of a robust model system to study brain infections by L. monocytogenes. Here, we present a simple mouse infection model to determine whether bacteria have crossed the BBB and to quantitate the burden of bacteria that have colonized the brain in vivo. In this method, animals were infected intravenously with L. monocytogenes and were humanely euthanized by exposure to CO2 followed by cervical dislocation. Cardiac perfusion of the animals was performed prior to harvesting infected organs. Blood was collected before perfusion and the number of bacteria per organ or mL of blood was determined by plating dilutions of the blood or organ homogenates on agar plates and counting the number of colonies formed. This method can be used to study novel receptor-ligand interactions that enhance infection of the brain by L. monocytogenes and can be easily adapted for the study of multiple bacterial pathogens.

Listeria monocytogenes Infection of the Brain

During infection, Listeria monocytogenes is capable of crossing the blood-brain barrier to colonize the brain. In this protocol, we demonstrate how to assess bacterial colonization of organs following infection of mice. A procedure to perform whole organ perfusion for specific determination of bacterial numbers in the brain parenchyma is provided.