La investigación en el laboratorio de P. Cossart es apoyado por el Instituto Pasteur, el Institut National de la Santé et de la Recherche Medicale, el Instituto Nacional de Investigación Agronómica, ERC Advanced Grant (233.348), la Agence Nationale de la Recherche (Grant MIE- SignRupVac), la Fundación Louis-Jeantet y la Fondation Le Roch Les Mousquetaires. AK es un beneficiario de una beca de la Universidad de París-Pasteur Internacional de Doctorado del programa / Institut Carnot Maladies infectieuses. Damos las gracias a Jason Mercer para la optimización del protocolo de transfección celular.

1. Preparación de Celular y bacterianas Culturas, Herramientas de transfección y Anticuerpos primarios <ol><li> Preparar una placa de agar fresco para aislar individuo L. monocytogenes colonias a partir de un stock de glicerol bacteriana (50% glycerol/50% saturada cultivo de una noche de líquido bacteriano) mantuvo a -80 ° C. <ol><li> El uso de un bastidor de aluminio (se mantiene a -80 ° C) para el transporte de un Congelados glicerol bacteriana de valores, las bacterias del rayado en una infusión de corazón cerebro (BHI) placa de agar. </li><li> Incubar la placa a 37 ° C durante 48 h (o hasta que las colonias bacterianas individuales se pueden aislar). </li><li> Mantenga esta placa de trabajo después a 4 º C durante un tiempo máximo de 1 mes (que será utilizado para sembrar cultivos líquidos). </li><li> En el protocolo, se utiliza el L. monocytogenes serotipo 1/2a EGDe.PrfA * cepa, pero como se ilustra en la Figura 1, la L. serotipo monocytogenes 4b P14.PrfA * Cepa da resultados similares. </li></ol></li><li> ÉlLa ATCC CCL2 células se cultivan en medio de Eagle modificado por Dulbecco (DMEM) suplementado con suero bovino fetal al 10% (FBS) en ausencia de antibióticos. </li><li> Piscinas independientes de revuelto (control) y los anti-Met siRNAs se cargan en 384-y placas de cultivo celular de microscopía negros. <ol><li> Diluir 160 pmoles de siRNA en 500 l de RNasa libre de agua y añadir 5 l de esta solución por pocillo (concentración final: 1,6 pmol). </li><li> Mantenga esta placa a -20 ° C durante un período máximo de 1 año. </li></ol></li><li> Anticuerpos de conejo policlonales contra la proteína bacteriana InlC se han obtenido mediante inmunización usando una proteína recombinante GST-InlC como se ha descrito previamente 25. </li></ol> 2. Invierta siRNA transfección celular <ol><li> 72 horas antes de la infección llevar a temperatura ambiente un 384-así placa de cultivo celular microscopia negro que contiene 1,6 pmol siRNA en 5 l de RNasa libre de agua en cada pozo. </li><li> Se centrifuga la placa durante 3 minutos a 300fcr a temperatura ambiente para reducir siRNA que podrían haber sido depositados en las paredes de los pozos. </li><li> Preparar habitación DMEM suplementado con temperatura 0,4% Lipofectamine RNAiMAX. </li><li> Añadir 25 l de medio de transfección DMEM / RNAiMAX a cada pocillo (no incubar el medio de transfección más de 20 min antes de añadir a la ARNsi). </li><li> Mueva la placa de un lado a otro para mezclar el siRNA con la solución de transfección, a continuación, mantener la placa durante 1 hora a temperatura ambiente para permitir complejos de siRNA Lipofectamine a la forma. </li><li> Lavar las células HeLa de un frasco confluente o cultivo celular sub-confluente una vez con 10 ml 37 ° C PBS precalentado. </li><li> Separar las células HeLa mediante la adición de 1 ml de 37 ° C precalentado tripsina al matraz de cultivo celular y se incuba durante 3 a 5 min a 37 ° C. </li><li> Vuelva a suspender las células en 10 ml 37 ° C precalentado DMEM suplementado con 16% de SFB. </li><li> Contar las células y preparar una suspensión de células de 12.000 células por ml en DMEM suplementado con16% de FBS. </li><li> Añadir 50 l de la suspensión celular a cada pocillo en la placa de 384 pocillos. </li><li> Mueva la placa rápidamente hacia adelante y hacia atrás para distribuir las células y dejar que se calmen las células durante 10 minutos a temperatura ambiente. </li><li> Sellar la placa con Parafilm y mantenerlo durante 72 horas en un 5% de CO 2 que contienen atmósfera húmeda a 37 ° C. </li></ol> 3. La infección celular y tinción <ol><li> El día antes de la infección, tome una sola colonia de L. monocytogenes de la placa de agar BHI y resuspender en 5 ml de medio BHI líquido en un tubo de poliestireno de 15 ml. </li><li> Incubar durante la noche a 37 ° C en un dispositivo de shacking para permitir el crecimiento bacteriano. </li><li> El día de la infección, lave 1 ml de la noche a la mañana L. monocytogenes cultura centrifugando 2 min a 10.600 FCR en una centrífuga de mesa. </li><li> Descartar el sobrenadante (que contiene el secretado listeriolisina citotoxina O) y resuspender el precipitado en 1 ml de PBS (REPEAt la etapa de lavado 3 veces más). </li><li> Leer la densidad óptica a 600 nm bacteriana y estimar el número de bacterias (OD = 1 es equivalente a 1E9 bacterias / ml). </li><li> Prepare la adecuada L. monocytogenes dilución en DMEM suplementado con 1% de SFB: el uso de cepas altamente invasivos como EGDe.PrfA *, se sugiere el uso de bacterias 5E4 en 30 l de medio por pocillo (la multiplicidad de la infección se estima en 25 por 2.000 células). </li><li> Retire el medio de cultivo celular en cada pocillo (80 l) y sustituirla por la adición de 30 l de la L. monocytogenes que contienen medio. </li><li> Centrifugar la placa a 200 rcf durante 5 min a temperatura ambiente para sincronizar el proceso de infección. </li><li> Incubar la placa durante 1 hora en un 5% de CO 2 que contienen atmósfera húmeda a 37 ° C en un bloque de aluminio precalentado. </li><li> Retire la L. monocytogenes que contienen medio de cada pocillo y añadir 30 l de DMEM precalentado suplementado con 10% de FBS y40 mg / ml de gentamicina para matar extracelular L. monocytogenes. </li><li> Se incuba durante 4 horas en un CO 2-atmósfera que contiene 5% a 37 ° C en un bloque metálico precalentado. </li><li> Preparar una solución de PBS suplementado con 8% de formaldehído (esta solución debe prepararse fresca de modo que los monómeros de formaldehído, en lugar de los polímeros de paraformaldehído, se utilizan). </li><li> Sin desechar el medio de cultivo de células, añadir 30 l de PBS suplementado con 8% de formaldehído (concentración final: 4%) y se incuba durante 15 min a temperatura ambiente. </li><li> Quite el fijador y lavar las células tres veces con 80 l de PBS por pocillo (mantener las células en un volumen final de 80 l de PBS por pocillo). </li><li> Preparar una dilución 1:250 del anticuerpo de conejo anti-InlC suero en PBS suplementado con 0,2% de saponina. </li><li> Añadir 10 l de la solución de anticuerpo primario a cada pocillo después de retirar el PBS y se incuba durante 30 min a temperatura ambiente. </li><li> Deseche la primariasolución de anticuerpo y lavar cuatro veces con 40 l de PBS por pocillo. </li><li> Diluir el anticuerpo secundario Alexa Fluor 546 acoplado-anti-conejo (1:250), la solución de DAPI (1:1.500) y faloidina-Dy647 (1:150) en PBS suplementado con 0,2% de saponina. </li><li> Añadir 10 l de esta solución de tinción secundaria a cada pocillo e incubar durante 30 min a temperatura ambiente. </li><li> Deseche la solución de tinción secundaria y lavar cuatro veces con 40 l de PBS por pocillo (dejar un volumen final de 40 l en cada pocillo y sellar la placa). </li><li> La placa se pueden visualizar inmediatamente o se puede almacenar a 4 ° C protegido de la luz (cubrir con papel de aluminio) para su posterior análisis. </li></ol> 4. Adquisición de imágenes y análisis <ol><li> Adquirir imágenes en tres canales diferentes (350 nm, 546 nm y 647 nm) utilizando un objetivo de 10X montada en un microscopio automatizado (adquirir con preferencia 9 imágenes por pocillo). </li><li> La señal de InlC se puede medir usando la imagensoftware de análisis como CellProfiler que permite la segmentación automatizada de núcleos y cuerpos celulares utilizando el DAPI y la tinción phalloidin, respectivamente. </li></ol>

<ol>
	<li>Pizarro-Cerd&#225;, J., K&#252;hbacher, A., 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=Entry+of+Listeria+monocytogenes+in+mammalian+epithelial+cells:+an+updated+view.">Entry of Listeria monocytogenes in mammalian epithelial cells: an updated view.</a> Cold Spring Harbor Perspectives in Medicine. 2, 1-17 (2012).</li><li>Mackaness, G. B. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Cellular+resistance+to+infection.">Cellular resistance to infection.</a> Journal of Experimental Medicine. 116, 381-406 (1962).</li><li>Tilney, L. G., Portnoy, D. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Actin+filaments+and+the+growth,+movement,+and+spread+of+the+intracellular+bacterial+parasite,+Listeria+monocytogenes.">Actin filaments and the growth, movement, and spread of the intracellular bacterial parasite, Listeria monocytogenes.</a> Journal of Cell Biology. 109, 1597-1608 (1989).</li><li>Mengaud, J., Chenevert, J., Geoffroy, C., Gaillard, J. L., 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=Identification+of+the+structural+gene+encoding+the+SH-activated+hemolysin+of+Listeria+monocytogenes:+listeriolysin+O+is+homologous+to+streptolysin+O+and+pneumolysin.">Identification of the structural gene encoding the SH-activated hemolysin of Listeria monocytogenes: listeriolysin O is homologous to streptolysin O and pneumolysin.</a> Infection and Immunity. 55, 3225-3227 (1987).</li><li>Gaillard, J. L., Berche, P., Frehel, C., Gouin, E., 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=Entry+of+L.+monocytogenes+into+cells+is+mediated+by+internalin,+a+repeat+protein+reminiscent+of+surface+antigens+from+gram-positive+cocci.">Entry of L. monocytogenes into cells is mediated by internalin, a repeat protein reminiscent of surface antigens from gram-positive cocci.</a> Cell. 65, 1127-1141 (1991).</li><li>Mengaud, J., Dramsi, S., Gouin, E., Vazquez-Boland, J. A., Milon, G., 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=Pleiotropic+control+of+Listeria+monocytogenes+virulence+factors+by+a+gene+that+is+autoregulated.">Pleiotropic control of Listeria monocytogenes virulence factors by a gene that is autoregulated.</a> Molecular Microbiology. 5, 2273-2283 (1991).</li><li>Kocks, C., Gouin, E., Tabouret, M., Berche, P., Ohayon, H., 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=L.+monocytogenes-induced+actin+assembly+requires+the+actA+gene+product,+a+surface+protein.">L. monocytogenes-induced actin assembly requires the actA gene product, a surface protein.</a> Cell. 68, 521-52 (1992).</li><li>Glaser, P., 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=Comparative+genomics+of+Listeria+species.">Comparative genomics of Listeria species.</a> Science. 294, 849-852 (2001).</li><li>Toledo-Arana, A., 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=The+Listeria+transcriptional+landscape:+from+saprophytism+to+virulence.">The Listeria transcriptional landscape: from saprophytism to virulence.</a> Nature. 459, 950-956 (2009).</li><li>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=Illuminating+the+landscape+of+host-pathogen+interactions+with+the+bacterium+Listeria+monocytogenes.">Illuminating the landscape of host-pathogen interactions with the bacterium Listeria monocytogenes.</a> Proceedings of the National Academy of Sciences USA. 108, 19484-19491 (1073).</li><li>Mengaud, J., Ohayon, H., Gounon, P., Mege, R. -. 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. -. J., Veiga, E., Yin, H. L., 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=Type+II+phosphatidylinositol+4-kinases+promote+Listeria+monocytogenes+entry+into+target+cells.">Type II phosphatidylinositol 4-kinases promote Listeria monocytogenes entry into target cells.</a> Cellular Microbiology. 9, 2381-2390 (2007).</li><li>Hamon, M. A., 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=Histone+modifications+induced+by+a+family+of+bacterial+toxins.">Histone modifications induced by a family of bacterial toxins.</a> Proceedings of the National Academy of Sciences USA. 104, 17555-17559 (2007).</li><li>Ribet, D., 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=Listeria+monocytogenes+impairs+SUMOylation+for+efficient+infection.">Listeria monocytogenes impairs SUMOylation for efficient infection.</a> Nature. 464, 1192-1195 (2010).</li><li>R&#228;met, M., Manfruelli, P., Pearson, A., Mathey-Prevot, B., Ezekowitz, R. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Functional+genomic+analysis+of+phagocytosis+and+identification+of+a+Drosophila+receptor+for+E.+coli.">Functional genomic analysis of phagocytosis and identification of a Drosophila receptor for E. coli.</a> Nature. 416, 644-648 (2002).</li><li>Agaisse, H., Burrack, L. S., Philips, J. A., Rubin, E. J., Perrimon, N., Higgins, D. E. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Genome-wide+RNAi+screen+for+host+factors+required+for+intracellular+bacterial+infection.">Genome-wide RNAi screen for host factors required for intracellular bacterial infection.</a> Science. 309, 1248-1251 (2005).</li><li>Cheng, L. W., Viala, J. P., Stuurman, N., Wiedemann, U., Vale, R. D., Portnoy, D. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Use+of+RNA+interference+in+Drosophila+S2+cells+to+identify+host+pathways+controlling+compartmentalization+of+an+intracellular+pathogen.">Use of RNA interference in Drosophila S2 cells to identify host pathways controlling compartmentalization of an intracellular pathogen.</a> Proceedings of the National Academy of Sciences USA. 102, 13646-13651 (2005).</li><li>Ripio, M. T., Dom&#237;nguez-Bernal, G., Lara, M., Su&#225;rez, M., Vazquez-Boland, J. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+Gly145Ser+substitution+in+the+transcriptional+activator+PrfA+causes+constitutive+overexpression+of+virulence+factors+in+Listeria+monocytogenes.">A Gly145Ser substitution in the transcriptional activator PrfA causes constitutive overexpression of virulence factors in Listeria monocytogenes.</a> Journal of Bacteriology. 179, 1533-1540 (1997).</li><li>Rajabian, T., 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=The+bacterial+virulence+factor+InlC+perturbs+apical+cell+junctions+and+promotes+cell-to-cell+spread+of+Listeria.">The bacterial virulence factor InlC perturbs apical cell junctions and promotes cell-to-cell spread of Listeria.</a> Nature Cell Biology. 11, 1212-1218 (2009).</li><li>Gouin, E., 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=The+Listeria+monocytogenes+InlC+protein+interferes+with+innate+immune+responses+by+targeting+the+I&#954;B+kinase+subinit+IKK&#945;.">The Listeria monocytogenes InlC protein interferes with innate immune responses by targeting the I&#954;B kinase subinit IKK&#945;.</a> Proceedings of the National Academy of Sciences USA. 107, 17333-17338 (2010).</li><li>Pizarro-Cerd&#225;, J., Lecuit, 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=Measuring+and+analysing+invasion+of+mammalian+cells+by+bacterial+pathogens:+the+Listeria+monocytogenes+system.">Measuring and analysing invasion of mammalian cells by bacterial pathogens: the Listeria monocytogenes system.</a> Methods in Molecular Microbiology. 31, 161-177 (2002).</li><li>Snijder, B., Sacher, R., R&#228;m&#246;, P., Damm, E. M., Liberali, P., Pelkmans, L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Population+context+determines+cell-to-cell+variability+in+endocytosis+and+virus+infection.">Population context determines cell-to-cell variability in endocytosis and virus infection.</a> Nature. 461, 520-523 (2009).</li></ol>

No tenemos nada que revelar.

Varios parámetros son críticos para el éxito de nuestro protocolo InlC-detección, incluyendo el uso de líneas de células sanas que muestran un citoplasma suficientemente grande para permitir una detección inequívoca de la señal de InlC. En el ensayo se presentan en este artículo se propone el uso de células HeLa CCL2, que son particularmente muy adecuado para nuestro ensayo debido a la extensión de su espacio citosólico; otros clones de HeLa tales como células HeLa Kioto muestran un citoplasma más pequeñ...

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

La bacteria Gram positiva Listeria monocytogenes es un patógeno transmitido por los alimentos que invade las células huésped, interrumpe su vacuola internalización y se replica en el citoplasma de las células huésped 1. L. monocytogenes facilidad de manipulación en el contexto de laboratorio (rápido crecimiento, baja toxicidad para los individuos sanos) asociado con la persistencia de rasgos de virulencia bacterianas observadas en modelos celulares y animales (actividad hemolítica, leucocitosis) permite su uso inicial en la década de 1960 como un modelo importante para el estudio de parasitismo intracelular y para el establecimiento de los fundamentos teóricos de la inmunidad celular contra la infección 2. A finales de 1980 y principios de 1990, la disección del ciclo intracelular bacteriano 3, así como la caracterización molecular de la virulencia bacteriana más importante factores de 4-7 favoreció el uso de L. monocytogenes como una herramienta clave molecular para la manipulación y el pernoy de las funciones de la célula huésped. La presencia de no virulenta (L. innocua) y (Listeria monocytogenes) especies virulentas en el género Listeria allanaron el camino para estudios genómicos comparativos 8 que, junto con la reciente creación de la completa L. monocytogenes transcriptoma 9, han aumentado nuestra comprensión de la evolución de la L. monocytogenes como un patógeno humano y como un sistema modelo para estudios de infección 10. L. monocytogenes induce su internalización en las células huésped en la interacción de las proteínas de la superficie bacteriana INLA y InlB con sus receptores de células huésped E-cadherina y Met, respectivamente 11-12. Estudios basados ​​en la candidata inicial condujeron a la identificación del enlace cateninas-actina α / β como un componente importante de la vía InlA-13 y la invasión de la fosfoinosítido 3-quinasa (PI 3-K) como un efector crítico de la InlB- casca invasión dependientede 14-15. Ensayos proteómicos y basados ​​funcional posteriormente permitieron la identificación de nuevos elementos del citoesqueleto y 16 segundos mensajeros lipídicos 17 requeridos para la invasión de la célula huésped. Estudios transcripcionales 18 y proteómica cuantitativa basada en la espectrometría de masas 19 se han esclarecido algunos puntos en relación con la activación de cascadas de señalización de acogida y la represión de la respuesta inmune durante la L. monocytogenes infección. La biología de sistemas se acerca basado en la inactivación de los grandes conjuntos de genes (kinomes, genomas completos) por pequeños ARN de interferencia (siRNA) silenciamiento se han abierto recientemente nuevas vías para el análisis de la serie mundial de las cascadas de señalización en el contexto de las funciones celulares específicas, incluyendo la fagocitosis y internalización patógeno 20. Pantallas siRNA del genoma completo han realizado anteriormente para investigar cascadas celulares requeridos para la infección de L. monocytogenes en fagocítica Drosophila </eM&gt; células S2 21-22, pero este tipo de análisis no ha sido realizado en las células no fagocíticas, que representan objetivos críticos para la infección in vivo. Hemos optimizado un protocolo para la detección microscópica de las etapas tardías de la infección por L. monocytogenes que es adecuado para siRNA estudios de alto rendimiento de la entrada de bacterias dentro de las células epiteliales. Nuestro ensayo se aprovecha de una L. altamente invasiva monocytogenes cepa que presenta una mutación puntual en PrfA, el principal regulador de la transcripción de L. monocytogenes factores de virulencia 6: esta mutación (llamado PrfA *) hace que PrfA constitutivamente activa 23 y conduce a un aumento de la expresión de las proteínas de invasión inlA y InlB, por lo tanto, favorecer la entrada de bacterias en células no fagocíticas de lo contrario pobremente infectados. Nuestra lectura para la infección se basa en la detección de la acumulación citosólica de la secretada InlC proteína bacteriana: esta molécula esun efector pleiotrópica que se expresa preferentemente por intra-citoplasmática L. monocytogenes 9 y que participa no sólo en la célula de células-a-bacteriana propagan 24 pero que también modula las respuestas inmunes del huésped 25. El marcaje fluorescente de la secreción de InlC por bacterias intracelulares no sólo permite distinguir claramente infectado a partir de células no infectadas, sino que también representa una lectura de punto final que se puede utilizar para diseccionar posteriormente infección en sus diferentes pasos: entrada, de escape vacuolar, citosólica bacteriana la proliferación y propagación de célula a célula. Este protocolo basado en microscopía-puede estar acoplado a las pantallas de siRNA por lo tanto, para estudiar las vías celulares implicadas en la infección de células huésped por 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

Patógenos bacterianos intracelulares pueden ser concebidos como herramientas moleculares para disecar cascadas de señalización celular debido a su capacidad para manipular exquisitamente y subvertir las funciones celulares que se requieren para la infección de tejidos diana del huésped. Entre estos agentes patógenos bacterianos, Listeria monocytogenes es un microorganismo Gram positiva que se ha utilizado como un paradigma para el parasitismo intracelular en la caracterización de la respuesta inmune celular, y que ha desempeñado un papel decisivo en el descubrimiento de las vías moleculares que controlan la dinámica del citoesqueleto y de la membrana de la trata. En este artículo se describe un ensayo microscópico robusta para la detección de las etapas de la infección celular tardías de L. monocytogenes basan en el etiquetado fluorescente de InlC, una proteína secretada bacteriana que se acumula en el citoplasma de las células infectadas; este ensayo se puede acoplar a las pequeñas pantallas de ARN de alto rendimiento de interferencia automatizados con el fin de carbonizarterizar vías de señalización celular implicadas en la altura o hacia abajo-regulación de la infección.

Etiquetado fluorescente de citoplasmática InlC proporciona una lectura robusta para la infección de células por L. monocytogenes, como se ilustra en la Figura 1: la célula central en la micrografía es altamente infectadas por la cepa P14.PrfA * 23 como se puede observar en la imagen de contraste de fase (puntas de flecha, Figura 1A) y se confirma por la señal DAPI donde bacterias individuales se pueden distinguir con claridad (fig. 1B). La tinc...

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 es un patógeno bacteriano Gram positiva utilizado frecuentemente como un modelo importante para el estudio de parasitismo intracelular. Imágenes tardías L. monocytogenes etapas de infección en el contexto de los pequeños ARN de interferencia pantallas permite el estudio global de las vías celulares requeridos para la infección bacteriana de las células huésped diana.

Imaging InlC secreción de investigar la infección celular por el patógeno bacteriano<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 vistas.  Pasteur Institute.  Listeria monocytogenes es un patógeno bacteriano Gram positiva utilizado frecuentemente como un modelo importante para el estudio de parasitismo intracelular. Imágenes tardías L. monocytogenes etapas de infección en el contexto de los pequeños ARN de interferencia pantallas permite el estudio global de las vías celulares requeridos para la infección bacteriana de las células huésped diana. 

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.

Utilizando imágenes bioluminiscentes encargado de investigar la sinergia entre Streptococcus pneumoniae Y el Virus de la Influenza en ratones lactantes

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

Investigación

Inmunología e Infección

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.

La invasión de las células humanas por un patógeno bacteriano

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.

La medición de la carga bacteriana y la respuesta inmune en ratones infectados 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.

El insecto<em&gt; Galleria mellonella</em&gt; Como un modelo de infección poderosa para investigar la patogénesis bacteriana

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.

La transmisión oral de<em&gt; Listeria monocytogenes</em&gt; En ratones a través de la ingestión de alimentos contaminados

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.

La separación automatizada de<em&gt; C. elegans</em&gt; Variablemente colonizada por un patógeno bacteriano

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.

Evaluación De La Invasión Bacteriana De Las Células Cardíacas En Cultivo Y Colonización Del Corazón En Ratones Infectados Usando 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.

La purificación del ARN intracelularmente Grown<em&gt; Listeria monocytogenes</em&gt; En los macrófagos

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.

La infección experimental con<em&gt; Listeria monocytogenes</em&gt; Como un modelo para el estudio de host Respuestas interferón gamma

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.