O apoio financeiro para este trabalho foi fornecido pela Comunidade Europeia (ERC-STG INTRACELLTB Grant n° 260901, MM4TB Grant n° 260872), pela Agence Nationale de Recherche, pela Feder (12001407 (D-AL) Equipex Imaginex BioMed) e pela Região Nord Pas de Calais. Agradecemos a assistência técnica de Gaspard Deloison, Elizabeth Werkmeister, Antonino Bongiovanni e Frank Lafont da plataforma BICeL.

1. Triagem de siRNA de genoma de alto rendimento
Triagem realizada em uma linha celular tipo-II humana modelo A549 após infecção com Mtb H37Rv expressando proteína fluorescente verde (GFP). Este procedimento está descrito na Figura 1A.
<ol><li>Resuspend a biblioteca de siRNA seca que é armazenada em placas maternas (placas de 96 poços) com 1x tampão siRNA para atingir uma concentração de 4 μM, em seguida, transferir 10 μl da mistura para uma placa filha de 384 poços (placa filha 1).</li>
	<li>Adicione 10 μl de tampão de siRNA de 1x na placa da filha 1 para diluir o siRNA em 2 vezes. Após a ressuspensão do siRNA, as placas são seladas com vedação de alumínio descascado e podem ser armazenadas a -20 °C pelo menos 6 meses e até 2-3 anos, mas o tempo de armazenamento pode variar dependendo das recomendações do fabricante da biblioteca siRNA.</li>
	<li>Diluir siRNAs na placa da filha 1 no prato da filha 2 para atingir uma concentração de 500 nM. Após a ressuspensão do siRNA, as placas são seladas com vedação de alumínio descascado e podem ser armazenadas a -20 °C pelo menos 6 meses e até 2-3 anos, mas o tempo de armazenamento pode variar dependendo das recomendações do fabricante da biblioteca siRNA.</li>
	<li>Antes de usar, descongele o prato da filha 2 em temperatura ambiente.</li>
	<li>Pegue 2,5 μl de siRNA da placa da filha 2 e coloque em uma placa de ensaio de 384 poços.</li>
	<li>Na mesma placa de ensaio de 384 poços na etapa 1.5, adicione 2,5 μl de controle negativo e positivo siRNA aos seus respectivos poços.</li>
	<li>Diluir o reagente de transfecção em 1x D-PBS para produzir solução suficiente para fornecer reagente de transfecção de 0,1 μl em cada poço e preinubar a solução de transfecção diluída à temperatura ambiente por 5 minutos.</li>
	<li>Adicione 7,5 μl da mistura de solução de reagente/PBS de transfecção a cada poço na placa de ensaio e incubar por 30 minutos à temperatura ambiente.</li>
	<li>Adicione 40 μl de células A549 (1.500 células/poço) suspensas em RPMI 1640 médio suplementado com 10% de soro bovino fetal (FBS). Manter as células por um período de incubação de 3 dias a 37 °C em uma atmosfera contendo 5% de CO2. Essas células se dividem a cada 24 horas, portanto cerca de 12.000 células estão nos poços três dias após a transfecção.</li>
	<li>Lave uma cultura MTB H37Rv de duas semanas de idade expressando com D-PBS (livre de MgCl2 e CaCl2) por centrifugação a 4.000 x g por 5 min e descarte as lavagens. Repita esta etapa 3x. (Para condições de culturaGFP-Mtb H37Rv ver Protocolo 3).</li>
	<li>Suspenda a pelota bacteriana em 10 ml de RPMI 1640 médio suplementado com 10% de FBS e decante por 1 hora à temperatura ambiente para permitir agregados bacterianos aos sedimentos.</li>
	<li>Recolher o supernascer bacteriano e medir OD600 (OD600 deve estar entre 0,6-0,8) e GFP-fluorescência (valor RFU) usando um leitor de microplaca para determinar a concentração bacteriana. Calcule o título da suspensão utilizando uma linha de regressão de referência exibindo valor RFU = f (valor da UFC) que havia sido gerado antes do experimento em outra cultura que havia sido preparada nas mesmas condições. Prepare a suspensão bacteriana contendo 2,4 x 106 bactérias/ml, o que corresponde a uma multiplicidade de infecção (MOI) de 5.</li>
	<li>Retire o meio na placa de ensaio de 384 poços e adicione 25 μl de suspensão bacteriana recém-preparada.</li>
	<li>Incubar a placa de ensaio de 384 poços a 37 °C por 5 horas em uma atmosfera contendo 5% de CO2.</li>
	<li>Remova o meio e lave suavemente as células com meio RPMI suplementado com 10% de FBS 3x.</li>
	<li>Para matar as bactérias extracelulares restantes, trate as células com 50 μl de meio RPMI-FBS fresco contendo 50 μg/ml de amikacina a 37 °C por 1 hora em uma atmosfera contendo 5% de CO2.</li>
	<li>Remova a amikacina de média contenção e adicione 50 μl de meio RPMI fresco complementado com 10% de FBS. Incubar a placa de ensaio de 384 poços a 37 °C durante 5 dias em uma atmosfera contendo 5% de CO2.</li>
	<li>Antes da aquisição de imagem, adicione 10 μl de 30 μg/ml recém-preparados de DAPI em PBS (concentração final 5 μg/ml) e incubar por 10 min a 37 °C.</li>
	<li>Carregue a placa em microscópio confocal automatizado. <img fo:content-width="5in" fo:src="/files/ftp_upload/51114/screenshot_1highres.jpg" src="/files/ftp_upload/51114/screenshot_1.jpg"> <a href="https://www.jove.com/files/ftp_upload/51114/screenshot_1highres.jpg" target="_blank">Clique aqui para ver imagem maior.</a></li>
	<li>Defina os parâmetros de exposição. Fluorescência de REGISTRO DAPI usando laser de excitação 405 nm com filtro de emissão 450 nm e fluorescência GFP usando laser de excitação 488 nm com filtro de emissão 520 nm. <img fo:content-width="5in" fo:src="/files/ftp_upload/51114/screenshot_2-1highres.jpg" src="/files/ftp_upload/51114/screenshot_2-1.jpg"> <a href="https://www.jove.com/files/ftp_upload/51114/screenshot_2-1highres.jpg" target="_blank">Clique aqui para ver imagem maior.</a> <img fo:content-width="5in" fo:src="/files/ftp_upload/51114/screenshot_2-2highres.jpg" src="/files/ftp_upload/51114/screenshot_2-2.jpg"> <a href="https://www.jove.com/files/ftp_upload/51114/screenshot_2-2highres.jpg" target="_blank">Clique aqui para ver imagem maior.</a></li>
	<li>Selecione os poços e os campos em cada poço a ser adquirido, que é então chamado de layout e parâmetros de subcamada. <img fo:content-width="5in" fo:src="/files/ftp_upload/51114/screenshot_3-1highres.jpg" src="/files/ftp_upload/51114/screenshot_3-1.jpg"> <a href="https://www.jove.com/files/ftp_upload/51114/screenshot_3-1highres.jpg" target="_blank">Clique aqui para ver imagem maior.</a> <img fo:content-width="5in" fo:src="/files/ftp_upload/51114/screenshot_3-2highres.jpg" src="/files/ftp_upload/51114/screenshot_3-2.jpg"> <a href="https://www.jove.com/files/ftp_upload/51114/screenshot_3-2highres.jpg" target="_blank">Clique aqui para ver imagem maior.</a></li>
	<li>Gere o arquivo de experimento usando os parâmetros das etapas 1.20 e 1.21, e execute a aquisição automática. <img fo:content-width="5in" fo:src="/files/ftp_upload/51114/screenshot_4-1highres.jpg" src="/files/ftp_upload/51114/screenshot_4-1.jpg"> <a href="https://www.jove.com/files/ftp_upload/51114/screenshot_4-1highres.jpg" target="_blank">Clique aqui para ver imagem maior.</a> <img fo:content-width="5in" fo:src="/files/ftp_upload/51114/screenshot_4-2highres.jpg" src="/files/ftp_upload/51114/screenshot_4-2.jpg"> <a href="https://www.jove.com/files/ftp_upload/51114/screenshot_4-2highres.jpg" target="_blank">Clique aqui para ver imagem maior.</a></li>
	<li>Transfira imagens para o servidor remoto. <img fo:content-width="5in" fo:src="/files/ftp_upload/51114/screenshot_5highres.jpg" src="/files/ftp_upload/51114/screenshot_5.jpg"> <a href="https://www.jove.com/files/ftp_upload/51114/screenshot_5highres.jpg" target="_blank">Clique aqui para ver imagem maior.</a></li>
	<li>Avalie imagens usando software de análise de imagens. Detecte núcleos celulares do canal DAPI usando algoritmo de detecção de núcleos e a área bacteriana do canal GFP usando o algoritmo de propriedades de intensidade de pixel(Figura 4A).</li>
</ol>Nota: Este protocolo é otimizado para estudar o efeito do silenciamento genético no crescimento de Mtb intracelular. Mtb é uma bactéria de crescimento lento que divide a cada 20 horas em condições ideais. Após 5 dias após a infecção, a quantidade de Mtb extracelular ainda é baixa na ausência de lise celular e não afetou a qualidade da análise. Este protocolo deve ser otimizado em termos de tempo de tratamento com antibióticos e tempo de incubação para ser adaptado para telas de siRNA usando bactérias de crescimento rápido como Mycobacteria smegmatis e Escherichia coli que são amplamente liberadas e podem infectar novas células.
2. Triagem composta de alto rendimento
Triagem realizada em células hospedeiras infectadas por Mtb H37Rv. Este procedimento está descrito na Figura 1B.
<ol><li>Descongele as placas-mãe de 384 poços contendo a biblioteca composta solubilizada em DMSO 100%. Transfira 0,5 μl dos compostos em placas filhas de 384 poços contendo 10 μl de RPMI 1640 médio suplementado com 10% de FBS.</li>
	<li>Lave uma cultura MTB H37Rv de duas semanas de idade expressando com D-PBS (livre de MgCl2 e CaCl2) por centrifugação a 4.000 x g por 5 min e descarte as lavagens. Repita esta etapa 3x (Para condições de culturaGFP-Mtb H37Rv ver Protocolo 3).</li>
	<li>Suspenda a pelota bacteriana em 10 ml de RPMI 1640 médio suplementado com 10% de FBS e decante por 1 hora à temperatura ambiente para permitir agregados bacterianos aos sedimentos.</li>
	<li>Recolher o supernascer bacteriano e medir OD600 (OD600 deve estar entre 0,6-0,8) e GFP-fluorescência (valor RFU) usando um leitor de microplaca. Calcule o título da suspensão usando uma linha de regressão de referência exibindo valor RFU = f (valor da UFC) que havia sido gerado antes do experimento. A concentração típica é de 1 x 108 bactérias/ml.</li>
	<li>Colher macrófagos humanos primários de 6 dias de idade a 4 x 105 células/ml em RPMI 1640 médio suplementado com 10% de soro bovino fetal (FBS) e 50 ng/ml recombinando humano M-CSF (Para purificação de células de monócito de sangue periférico humano e diferenciação de macrófagos ver Protocolo 4).</li>
	<li>Incubar as células primárias diluídas com bacilos em diferentes MOI, variando de 1 a 5, em suspensão com leve agitação a 90 rpm por 2 horas a 37 °C.</li>
	<li>Lave as células infectadas por centrifugação a 350 x g para remover as bactérias extracelulares. Após cada etapa de centrifugação, resuspense a pelota em RPMI 1640 médio suplementado com 10% de FBS. Repita esta etapa 2x.</li>
	<li>Suspenda as células infectadas em RPMI 1640 médio suplementado com 10% de FBS e amikacina a 50 μg/ml e incubar a suspensão com leve agitação por 1 hora a 37 °C.</li>
	<li>Remova o meio de cultura celular contendo amikacina por centrifugação a 350 x g e lave as células infectadas com meio RPMI completo 1640 suplementado com 10% de FBS e 50 ng/ml humano recombinante M-CSF. Repita uma vez.</li>
	<li>Adicione 40 μl da suspensão dos macrófagos infectados na mesma placa de ensaio na etapa 2.1, que já contém 10 μl das diluições compostas. A concentração final de DMSO em cada poço chegou agora a 1%.</li>
	<li>Incubar as placas de ensaio por 5 dias a 37 °C em uma atmosfera contendo 5% de CO2.</li>
	<li>Manche as células vivas com corante fluorescente vermelho-permeante de células.</li>
	<li>Carregue a placa em microscópio confocal automatizado. <img fo:content-width="5in" fo:src="/files/ftp_upload/51114/screenshot_1highres.jpg" src="/files/ftp_upload/51114/screenshot_1.jpg"> <a href="https://www.jove.com/files/ftp_upload/51114/screenshot_1highres.jpg" target="_blank">Clique aqui para ver imagem maior.</a></li>
	<li>Defina os parâmetros de exposição. Registre fluorescência distante-vermelha usando laser de excitação de 640 nm com filtro de emissão 690 nm e fluorescência GFP usando laser de excitação 488 nm com filtro de emissão de 520 nm. <img fo:content-width="5in" fo:src="/files/ftp_upload/51114/screenshot_2-1highres.jpg" src="/files/ftp_upload/51114/screenshot_2-1.jpg"> <a href="https://www.jove.com/files/ftp_upload/51114/screenshot_2-1highres.jpg" target="_blank">Clique aqui para ver imagem maior.</a> <img fo:content-width="5in" fo:src="/files/ftp_upload/51114/screenshot_2-2highres.jpg" src="/files/ftp_upload/51114/screenshot_2-2.jpg"> <a href="https://www.jove.com/files/ftp_upload/51114/screenshot_2-2highres.jpg" target="_blank">Clique aqui para ver imagem maior.</a></li>
	<li>Selecione os poços e os campos em cada poço a ser adquirido, que é então chamado de layout e parâmetros de subcamada. <img fo:content-width="5in" fo:src="/files/ftp_upload/51114/screenshot_3-1highres.jpg" src="/files/ftp_upload/51114/screenshot_3-1.jpg"> <a href="https://www.jove.com/files/ftp_upload/51114/screenshot_3-1highres.jpg" target="_blank">Clique aqui para ver imagem maior.</a> <img fo:content-width="5in" fo:src="/files/ftp_upload/51114/screenshot_3-2highres.jpg" src="/files/ftp_upload/51114/screenshot_3-2.jpg"> <a href="https://www.jove.com/files/ftp_upload/51114/screenshot_3-2highres.jpg" target="_blank">Clique aqui para ver imagem maior.</a></li>
	<li>Gere o arquivo de experimento usando os parâmetros das etapas 2.14 e 2.15 e execute a aquisição automática. <img fo:content-width="5in" fo:src="/files/ftp_upload/51114/screenshot_4-1highres.jpg" src="/files/ftp_upload/51114/screenshot_4-1.jpg"> <a href="https://www.jove.com/files/ftp_upload/51114/screenshot_4-1highres.jpg" target="_blank">Clique aqui para ver imagem maior.</a> <img fo:content-width="5in" fo:src="/files/ftp_upload/51114/screenshot_4-2highres.jpg" src="/files/ftp_upload/51114/screenshot_4-2.jpg"> <a href="https://www.jove.com/files/ftp_upload/51114/screenshot_4-2highres.jpg" target="_blank">Clique aqui para ver imagem maior.</a></li>
	<li>Transfira imagens para o servidor remoto. <img fo:content-width="5in" fo:src="/files/ftp_upload/51114/screenshot_5highres.jpg" src="/files/ftp_upload/51114/screenshot_5.jpg"> <a href="https://www.jove.com/files/ftp_upload/51114/screenshot_5highres.jpg" target="_blank">Clique aqui para ver imagem maior.</a></li>
	<li>Avalie imagens usando software de análise de imagens. Detecte a área celular do canal vermelho usando o algoritmo de propriedades de intensidade de pixel e área bacteriana do canal GFP usando o algoritmo de propriedades de intensidade de pixel(Figura 4B).</li>
</ol>Nota: Este protocolo pode ser adaptado para a triagem da biblioteca mutante Mtb substituindo compostos por mutantes que expressam uma proteína fluorescente (Um mutante bem/Um) (Figura 1C, veja também Brodin et al. 4). Mutantes fluorescentes são primeiro semeados em poços (20 μl de suspensão bacteriana por poço). As bactérias são então recuperadas por 30 μl de suspensão celular. Após centrifugação a 350 x g por 1 min, a placa é incubada a 37 °C em uma atmosfera contendo 5% de CO2. O tempo de incubação e o MOI dependem do ensaio. Como exemplo, para visualização de eventos celulares precoces, como acidificação de fagosome, as células podem ser infectadas por 2 horas com MOI variando de 1 a 20. Os lysosomos são manchados usando corante lysotracker a 2 μM por 1,5 h a 37 °C em uma atmosfera contendo 5% de CO 2 edepois fixado com 10% de formalina ou 4% de paraformaldeído (PFA). As imagens confocal são adquiridas e finalmente analisadas usando scripts de análise de imagem com algoritmos apropriados para detecção de lysososomes e localização subcelular4.
3. Proteína Fluorescente Verde Expressando Mycobacterium tuberculosis H37Rv (GFP-H37Rv) Condições de Cultura
Para armazenamento a longo prazo, o GFP-H37Rv foi congelado em D-PBS (cerca de 1 x 108 micobactérias por frasco).
<ol><li>Resuspend um frasco de caldo congelado de GFP-H37Rv em um frasco Erlenmeyer contendo 50 ml de caldo 7H9 médio suplementado com enriquecimento Middlebrook OADC 10%, Glicerol 0,5%, Tween-80 0,05% e Hygromycin B (50 μg/ml).</li>
	<li>Incubar 8 dias a 37 °C.</li>
	<li>Medir OD600 da cultura GFP-H37Rv.</li>
	<li>Diluir a cultura GFP-H37Rv para obter OD600 = 0,1 em caldo fresco 7H9 complementado com enriquecimento Middlebrook OADC 10%, Glicerol 0,5%, Tween-80 0,05% e Hygromycin B (50 μg/ml).</li>
	<li>Incubar o GFP-H37Rv a 37 °C por mais 8 dias antes de usar para o ensaio.</li>
</ol>4. Purificação de células de monócitos de sangue periférico humano a partir de preparação de sangue inteiro ou casaco de buffy
<ol><li>Diluir a bolsa de sangue 2x em 1x D-PBS (livre de MgCl2 e CaCl2) contendo 1% de FBS.</li>
	<li>Isole os monócitos por Centrifugação gradiente de densidade ficoll a 400 x g por 20 min.</li>
	<li>Recolher os monócitos isolados.</li>
	<li>Lave os monócitos 3x com 1x D-PBS (livre de MgCl2 e CaCl2) contendo 1% de FBS por centrifugação a 400 x g por 10 minutos à temperatura ambiente.</li>
	<li>Concentre as células até 1 x 107 células/ml.</li>
	<li>Purificar monócitos usando contas magnéticas CD14 de acordo com o protocolo do fabricante (ver Materiais).</li>
	<li>Após a purificação de cd14-monócitos, semeou as células em 1,5 x 106 células/ml em RPMI 1640 complementada com 10% FBS e 40 ng/ml de Fator Estimulante da Colônia de Macrófagos Humanos (hM-CSF) e incubada por 4 dias a 37 °C em uma atmosfera contendo 5% CO2.</li>
	<li>Após 4 dias substitua o meio por RPMI fresco 1640 complementado com 10% de FBS e 40 ng/ml de hM-CSF e incubado por 2 dias a 37 °C em uma atmosfera contendo 5% de CO2.</li>
	<li>Após 6 dias, as células podem ser usadas para o ensaio.</li>
</ol>

<ol>
	<li>Gandhi, N. R., 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=Multidrug-resistant+and+extensively+drug-resistant+tuberculosis:+a+threat+to+global+control+of+tuberculosis.">Multidrug-resistant and extensively drug-resistant tuberculosis: a threat to global control of tuberculosis.</a> Lancet. 375, 1830-1843 (2010).</li><li>Barry, C. 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+spectrum+of+latent+tuberculosis:+rethinking+the+biology+and+intervention+strategies.">The spectrum of latent tuberculosis: rethinking the biology and intervention strategies.</a> Nat. Rev. Microbiol. 7, 845-855 (2009).</li><li>Christophe, T., Ewann, F., Jeon, H. K., Cechetto, J., Brodin, P. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=High-content+imaging+of+Mycobacterium+tuberculosis-infected+macrophages:+an+in+vitro+model+for+tuberculosis+drug+discovery.">High-content imaging of Mycobacterium tuberculosis-infected macrophages: an in vitro model for tuberculosis drug discovery.</a> Future Med. Chem. 2, 1283-1293 (2010).</li><li>Brodin, 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=High+content+phenotypic+cell-based+visual+screen+identifies+Mycobacterium+tuberculosis+acyltrehalose-containing+glycolipids+involved+in+phagosome+remodeling.">High content phenotypic cell-based visual screen identifies Mycobacterium tuberculosis acyltrehalose-containing glycolipids involved in phagosome remodeling.</a> PLoS Pathog. 6, (2010).</li><li>Bermudez, L. E., Goodman, J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Mycobacterium+tuberculosis+invades+and+replicates+within+type+II+alveolar+cells.">Mycobacterium tuberculosis invades and replicates within type II alveolar cells.</a> Infect. Immun. 64, 1400-1406 (1996).</li><li>Dobos, K. M., Spotts, E. A., Quinn, F. D., King, C. H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Necrosis+of+lung+epithelial+cells+during+infection+with+Mycobacterium+tuberculosis+is+preceded+by+cell+permeation.">Necrosis of lung epithelial cells during infection with Mycobacterium tuberculosis is preceded by cell permeation.</a> Infect. Immun. 68, 6300-6310 (2000).</li><li>McDonough, K. A., Kress, Y. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Cytotoxicity+for+lung+epithelial+cells+is+a+virulence-associated+phenotype+of+Mycobacterium+tuberculosis.">Cytotoxicity for lung epithelial cells is a virulence-associated phenotype of Mycobacterium tuberculosis.</a> Infect. Immun. 63, 4802-4811 (1995).</li><li>Lee, H. M., Yuk, J. M., Shin, D. M., Jo, E. K. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Dectin-1+is+inducible+and+plays+an+essential+role+for+mycobacteria-induced+innate+immune+responses+in+airway+epithelial+cells.">Dectin-1 is inducible and plays an essential role for mycobacteria-induced innate immune responses in airway epithelial cells.</a> J. Clin. Immunol. 29, 795-805 (2009).</li><li>Zhang, J. H., Chung, T. D., Oldenburg, K. R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+Simple+Statistical+Parameter+for+Use+in+Evaluation+and+Validation+of+High+Throughput+Screening+Assays.">A Simple Statistical Parameter for Use in Evaluation and Validation of High Throughput Screening Assays.</a> J. Biomol. Screen. 4, 67-73 (1999).</li><li>Birmingham, 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=Statistical+methods+for+analysis+of+high-throughput+RNA+interference+screens.">Statistical methods for analysis of high-throughput RNA interference screens.</a> Nat. Methods. 6, 569-575 (2009).</li><li>Carralot, J. 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=Automated+high-throughput+siRNA+transfection+in+raw+264.7+macrophages:+a+case+study+for+optimization+procedure.">Automated high-throughput siRNA transfection in raw 264.7 macrophages: a case study for optimization procedure.</a> J. Biomol. Screen. 14, 151-160 (2009).</li><li>Zhang, X. D. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Illustration+of+SSMD,+z+score,+SSMD*,+z*+score,+and+t+statistic+for+hit+selection+in+RNAi+high-throughput+screens.">Illustration of SSMD, z score, SSMD*, z* score, and t statistic for hit selection in RNAi high-throughput screens.</a> J. Biomol. Screen. 16, 775-785 (2011).</li><li>Song, O. R., 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=Confocal-based+method+for+quantification+of+diffusion+kinetics+in+microwell+plates+and+its+application+for+identifying+a+rapid+mixing+method+for+high-content/throughput+screening.">Confocal-based method for quantification of diffusion kinetics in microwell plates and its application for identifying a rapid mixing method for high-content/throughput screening.</a> J. Biomol. Screen. 15, 138-147 (2010).</li></ol>

Nenhum conflito de interesses declarado.

Descrevemos aqui os métodos necessários para um ensaio fenotípico usando uma cepa Mtb H37Rv expressante gfp para infectar células host fluorescentes rotuladas, o que o torna apropriado para telas de alto conteúdo/alto rendimento. Este protocolo poderia ser aplicado a uma ampla gama de compostos, sondas fluorescentes e mutantes Mtb. Para cada protocolo descrito acima, as etapas de fixação e imunolabelamento poderiam ser realizadas antes da aquisição da imagem. Usamos um microscópio confocal flu...

Entre os patógenos infecciosos emergentes e ressurgindo relatados nos últimos anos, o Mycobacterium tuberculosis (Mtb)ocupa um lugar de destaque sendo responsável por 1,4 milhão de mortes e 8,7 milhões de novas infecções em 2011 (Relatório Global de Tuberculose 2012, www.who.int/topics/tuberculosis/en/). Apesar da disponibilidade de terapias multidroga, o número de pessoas infectadas ainda está em ascensão e a resistência multidroga (MDR), bem como mtb extensivamente resistente a medicamentos (XDR) estão se espalhando rapidamente por todo o mundo1. Além disso, ao levar em consideração a presença de antígenos de Mtb, é evidente que um terço da população global é considerada latentemente infectada pelo Mtb. Estatisticamente, em um caso em cada dez, há evolução para a forma ativa da doença com sintomas clínicos subsequentes2. Portanto, novos meios para combater o Mtb são urgentemente necessários. Nesse contexto, desenvolvemos um ensaio fenotípico visual in vitro que conta com o monitoramento da invasão e multiplicação de Mtb em células hospedeiras por microscopia automatizada de fluorescência confocal3. A adaptação do ensaio em placas de microtização de 384 poços em combinação com aquisição e análise automatizada de imagens permitiu a triagem de alto conteúdo/high-throughput (HC/HTS) de bibliotecas de média escala de compostos, siRNAs e mutantes bacterianos. A triagem de uma biblioteca RNAi de genoma em larga neste ensaio fenotípico permitiu assim a identificação dos principais fatores hospedeiros envolvidos no tráfico de Mtb e na replicação intracelular, mas também a elucidação de vias hospedeiras exploradas pelo bacilo tubérculo. Outra adaptação deste ensaio fenotípico em particular foi para a identificação de fatores bacterianos essenciais à persistência intra-fagossômica de Mtb. Por exemplo, a prisão do amadurecimento fágora é considerada como um dos principais mecanismos que facilita a sobrevivência e a replicação do Mtb no macrófago. O monitoramento da localização subcelular de mutantes eliminados de Mtb em compartimentos fluorescentes rotulados-ácidos permitiu a identificação de genes bacterianos envolvidos no processo de sobrevivência4. Finalmente, a imagem de alto teor de Mtb também oferece um excelente método para quantificar a eficiência das drogas para inibir vários fenômenos como o crescimento bacteriano intracelular3. Ao todo, esse tipo de ensaio fenotípico de alto rendimento permite acelerar a descoberta de drogas contra a TB e os dados coletados por essas diferentes abordagens contribuem para uma melhor compreensão da manipulação do hospedeiro exercida pelo Mtb.

<table border="0" cellpadding="0" cellspacing="0" width="1010">
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	<tbody>
		<tr height="21">
			<td height="21" style="height:21px;width:287px;">&#181;clear-plate black, 384 well</td>
			<td style="width:160px;">Greiner bio-one</td>
			<td style="width:175px;">781091</td>
			<td style="width:388px;">127.8/86/15 MM with Lid, TC treated</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:287px;">CellCarrier 384 well plate</td>
			<td style="width:160px;">PerkinElmer</td>
			<td style="width:175px;">6007550</td>
			<td>Black, Clear Bottom, with Lid, TC treated</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:287px;">V-bottom white , 384 well-plate</td>
			<td style="width:160px;">Greiner bio-one</td>
			<td style="width:175px;">781280</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:287px;">sealing tape, breathable, sterile</td>
			<td style="width:160px;">Corning</td>
			<td style="width:175px;">3345</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:287px;">Lipofectamine RNAiMax</td>
			<td style="width:160px;">Life Technologies</td>
			<td style="width:175px;">13778150</td>
			<td>Transfection reagent</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:287px;">Dimethyl sulfoxide</td>
			<td style="width:160px;">Sigma-Aldrich</td>
			<td style="width:175px;">34943</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:287px;">RPMI 1640 + GlutaMAX-I</td>
			<td style="width:160px;">Life Technologies</td>
			<td style="width:175px;">61870-010</td>
			<td>Cell culture medium</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:287px;">D-PBS 1X [-]MgCl2/[-]CaCl2</td>
			<td style="width:160px;">Life Technologies</td>
			<td style="width:175px;">14190-094</td>
			<td>Dulbecco&#39;s Phosphate Salin Buffer</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:287px;">D-PBS 1X [+]MgCl2/[+]CaCl2</td>
			<td style="width:160px;">Life Technologies</td>
			<td style="width:175px;">14190-091</td>
			<td>Dulbecco&#39;s Phosphate Salin Buffer</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:287px;">Fetal bovine serum</td>
			<td style="width:160px;">Life Technologies</td>
			<td style="width:175px;">2610040-79</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:287px;">FICOLL PAQUE PLUS</td>
			<td style="width:160px;">DUTSCHER</td>
			<td style="width:175px;">17-1440-03</td>
			<td>Ficoll for Peripherical Blood Monocyte Cells purification</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:287px;">CD14 MicroBeads, human</td>
			<td style="width:160px;">Miltenyi</td>
			<td style="width:175px;">130-050-201</td>
			<td>Purification of CD14+ Monocytes</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:287px;">Human M-CSF, premium gr. (1000 &#956;g)</td>
			<td style="width:160px;">Miltenyi</td>
			<td style="width:175px;">130-096-493</td>
			<td>Macrophage Colony Stimulating Factor</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:287px;">LS Columns</td>
			<td style="width:160px;">Miltenyi</td>
			<td style="width:175px;">130-042-401</td>
			<td>Columns for CD14+ Monocytes isolation</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:287px;">Tween 80</td>
			<td style="width:160px;">Euromedex</td>
			<td style="width:175px;">2002-A</td>
			<td>Mycobacteria culture</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:287px;">Glycerol high purity </td>
			<td style="width:160px;">Euromedex</td>
			<td style="width:175px;">50405-EX</td>
			<td>Mycobacteria culture</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:287px;"> Middlebrook OADC enrichment</td>
			<td style="width:160px;">Becton-Dickinson</td>
			<td style="width:175px;">211886</td>
			<td>Mycobacteria culture</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:287px;">7H9</td>
			<td style="width:160px;">Becton-Dickinson</td>
			<td style="width:175px;">W1701P</td>
			<td>Mycobacteria culture</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:287px;">Versene 1X</td>
			<td style="width:160px;">Life Technologies</td>
			<td style="width:175px;">15040033</td>
			<td>Non enzymatic cell dissociation solution</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:287px;">DAPI</td>
			<td style="width:160px;">Life Technologies</td>
			<td style="width:175px;">D1306</td>
			<td>Nuclei dye</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:287px;">Hoechst 33342</td>
			<td style="width:160px;">Life Technologies</td>
			<td style="width:175px;">H3570</td>
			<td>Nuclei dye</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:287px;">Syto60</td>
			<td style="width:160px;">Life Technologies</td>
			<td style="width:175px;">S11342</td>
			<td>Nuclei/cytoplasm dye</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:287px;">Formalin</td>
			<td style="width:160px;">Sigma-Aldrich</td>
			<td style="width:175px;">HT5014</td>
			<td>Cell fixation solution</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:287px;">siRNA targeting Dectin-1</td>
			<td style="width:160px;">Santa-Cruz</td>
			<td style="width:175px;">sc-63276</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:287px;">*siGenome* Non targeted siRNA pool </td>
			<td style="width:160px;">Dharmacon</td>
			<td style="width:175px;">D-001206-14</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:287px;">Rifampicin</td>
			<td style="width:160px;">Sigma-Aldrich</td>
			<td style="width:175px;">R3501</td>
			<td>antibiotic</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:287px;">Isoniazid (INH)</td>
			<td style="width:160px;">Sigma-Aldrich</td>
			<td style="width:175px;">I3377-50G</td>
			<td>antibiotic</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:287px;">Hygromycin B</td>
			<td style="width:160px;">Life Technologies</td>
			<td style="width:175px;">10687-010</td>
			<td>antibiotic</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:287px;">Amikacin</td>
			<td style="width:160px;">Sigma-Aldrich</td>
			<td style="width:175px;">A1774</td>
			<td>antibiotic</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:287px;">Automated Confocal Microscope OPERA</td>
			<td style="width:160px;">PerkinElmer</td>
			<td style="width:175px;"> </td>
			<td>Image acquisition</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:287px;">Columbus 2.3.1 Server Database</td>
			<td style="width:160px;">PerkinElmer</td>
			<td style="width:175px;"> </td>
			<td>Data transfert, storage and analysis</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:287px;">Acapella 2.6 software</td>
			<td style="width:160px;">PerkinElmer</td>
			<td style="width:175px;"> </td>
			<td>Image-based analysis</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:287px;">GraphPad Prism5 software</td>
			<td style="width:160px;">GraphPad </td>
			<td style="width:175px;"> </td>
			<td>Statistical analysis</td>
		</tr>
		<tr height="22">
			<td height="22" style="height:22px;width:287px;">Excel 2010</td>
			<td style="width:160px;">Microsoft</td>
			<td style="width:175px;"> </td>
			<td>Statistical analysis</td>
		</tr>
	</tbody>
</table>

a microscopic phenotypic assay for the quantification of intracellular mycobacteria adapted for high-throughput/high-content screening

Apesar da disponibilidade de terapia e vacina, a tuberculose (TB) continua sendo uma das infecções bacterianas mais letais e generalizadas do mundo. Desde várias décadas, a súbita explosão de cepas multi e extensivamente resistentes a medicamentos é uma séria ameaça para o controle da tuberculose. Por isso, é essencial identificar novos alvos e caminhos críticos para o agente causador da tuberculose, Mycobacterium tuberculosis (Mtb)e buscar novos produtos químicos que possam se tornar medicamentos para TB. Uma abordagem é criar métodos adequados para as telas genéticas e químicas de bibliotecas de grande escala que permitem a busca de uma agulha em um palheiro. Para isso, desenvolvemos um ensaio fenotípico que conta com a detecção de Mtb rotulado fluorescentemente dentro de células host fluorescentes rotuladas usando microscopia confocal automatizada. Este ensaio in vitro permite uma quantificação baseada em imagem do processo de colonização de Mtb para o hospedeiro e foi otimizado para o formato de microplacão de 384 poços, que é adequado para telas de siRNA-, composto químico ou bibliotecas mutantes Mtb. As imagens são então processadas para análise multiparamétrica, que fornece leitura sobre a patogênese de Mtb dentro das células hospedeiras.

Triagem de siRNA de genoma de alto rendimento
Mtb é capaz de colonizar células imunes in vitro, bem como várias outras células epiteliais pulmonares. Por exemplo, o Mtbé capaz de infectar e danificar células epiteliais A549 que são comumente usadas como modelo para pneumócitos tipo II humano5-7. O Dectin-1 foi relatado como um receptor de células hospedeiras envolvido na absorção de Mtb, resposta proinflamatória e efeito antibacteriano no...

Watch this Scientific Journal Video about A Microscopic Phenotypic Assay for the Quantification of Intracellular Mycobacteria Adapted for High-throughput/High-content Screening at JoVE.com

A Microscopic Phenotypic Assay for the Quantification of Intracellular Mycobacteria Adapted for High-throughput/High-content Screening

Aqui, descrevemos um ensaio fenotípico aplicável às telas de alto rendimento/alto conteúdo de pequenas interfissões de RNA sintético (siRNA), composto químico e bibliotecas mutantes mycobacterium tuberculosis. Este método baseia-se na detecção de Mycobacterium tuberculosis rotulado fluorescentemente dentro de célula hospedeira fluorescente rotulada usando microscopia confocal automatizada.

Um ensaio fenotípico microscópico para quantificação de micobactérias intracelulares adaptadas para triagem de alto rendimento/alto conteúdo

Despite the availability of therapy and vaccine, tuberculosis (TB) remains one of the most deadly and widespread bacterial infections in the world. Since ...

a-microscopic-phenotypic-assay-for-quantification-intracellular

Research

JoVE Journal

Immunology and Infection

7.6K visualizações.  Université de Lille. Aqui, descrevemos um ensaio fenotípico aplicável às telas de alto rendimento/alto conteúdo de pequenas interfissões de RNA sintético (siRNA), composto químico e bibliotecas mutantes mycobacterium tuberculosis. Este método baseia-se na detecção de Mycobacterium tuberculosis rotulado fluorescentemente dentro de célula hospedeira fluorescente rotulada usando microscopia confocal automatizada.

Vídeo: A Microscopic Phenotypic Assay for the Quantification of Intracellular Mycobacteria Adapted for High-throughput/High-content Screening

A Functional Whole Blood Assay to Measure Viability of Mycobacteria, using Reporter-Gene Tagged BCG or M.Tb (BCG lux/M.Tb lux)

Functional assays have long played a key role in measuring of immunogenicity of a given vaccine. This is conventionally expressed as serum bactericidal titers. Studies of serum bactericidal titers in response to childhood vaccines have enabled us to develop and validate cut-off levels for protective immune responses and such cut-offs are in routine use. No such assays have been taken forward into the routine assessment of vaccines that induce primarily cell-mediated immunity in the form of effector T cell responses, such as TB vaccines. In the animal model, the performance of a given vaccine candidate is routinely evaluated in standardized bactericidal assays, and all current novel TB-vaccine candidates have been subjected to this step in their evaluation prior to phase 1 human trials. The assessment of immunogenicity and therefore likelihood of protective efficacy of novel anti-TB vaccines should ideally undergo a similar step-wise evaluation in the human models now, including measurements in bactericidal assays.
Bactericidal assays in the context of tuberculosis vaccine research are already well established in the animal models, where they are applied to screen potentially promising vaccine candidates. Reduction of bacterial load in various organs functions as the main read-out of immunogenicity. However, no such assays have been incorporated into clinical trials for novel anti-TB vaccines to date.
Although there is still uncertainty about the exact mechanisms that lead to killing of mycobacteria inside human macrophages, the interaction of macrophages and T cells with mycobacteria is clearly required. The assay described in this paper represents a novel generation of bactericidal assays that enables studies of such key cellular components with all other cellular and humoral factors present in whole blood without making assumptions about their relative individual contribution. The assay described by our group uses small volumes of whole blood and has already been employed in studies of adults and children in TB-endemic settings. We have shown immunogenicity of the BCG vaccine, increased growth of mycobacteria in HIV-positive patients, as well as the effect of anti-retroviral therapy and Vitamin D on mycobacterial survival in vitro. Here we summarise the methodology, and present our reproducibility data using this relatively simple, low-cost and field-friendly model.
Note: Definitions/Abbreviations
BCG lux = M. bovis BCG, Montreal strain, transformed with shuttle plasmid pSMT1 carrying the luxAB genes from Vibrio harveyi, under the control of the mycobacterial GroEL (hsp60) promoter. 
CFU = Colony Forming Unit (a measure of mycobacterial viability).

A Functional Whole Blood Assay to Measure Viability of Mycobacteria, using Reporter-Gene Tagged BCG or M.Tb BCG lux/M.Tb lux

We describe an alternative approach to the enumeration of mycobacteria in vitro, which uses reporter-gene tagged mycobacteria instead of colony-forming units (CFU). &#x201C;Survival&#x201D; of organisms as well as host response-markers are measured simultaneously, providing a low-cost, versatile and functional system for studies of host/pathogen interactions in the context of tuberculosis.

Um Ensaio de sangue Funcional inteiro para medir a viabilidade de micobactérias, utilizando-Reporter Gene Tagged BCG ou M. Tb (BCG Lux / M. Tb Lux)

Functional assays have long played a key role in measuring of immunogenicity of a given vaccine. This is conventionally expressed as serum bactericidal ...

Imunologia e Infecção

A Parasite Rescue and Transformation Assay for Antileishmanial Screening Against Intracellular Leishmania donovani Amastigotes in THP1 Human Acute Monocytic Leukemia Cell Line

Leishmaniasis is one of the world's most neglected diseases, largely affecting the poorest of the poor, mainly in developing countries. Over 350 million people are considered at risk of contracting leishmaniasis, and approximately 2 million new cases occur yearly1. Leishmania donovani is the causative agent for visceral leishmaniasis (VL), the most fatal form of the disease. The choice of drugs available to treat leishmaniasis is limited 2;current treatments provide limited efficacy and many are toxic at therapeutic doses. In addition, most of the first line treatment drugs have already lost their utility due to increasing multiple drug resistance 3. The current pipeline of anti-leishmanial drugs is also severely depleted. Sustained efforts are needed to enrich a new anti-leishmanial drug discovery pipeline, and this endeavor relies on the availability of suitable in vitro screening models.
In vitro promastigotes 4 and axenic amastigotes assays5 are primarily used for anti-leishmanial drug screening however, may not be appropriate due to significant cellular, physiological, biochemical and molecular differences in comparison to intracellular amastigotes. Assays with macrophage-amastigotes models are considered closest to the pathophysiological conditions of leishmaniasis, and are therefore the most appropriate for in vitro screening. Differentiated, non-dividing human acute monocytic leukemia cells (THP1) (make an attractive) alternative to isolated primary macrophages and can be used for assaying anti-leishmanial activity of different compounds against intracellular amastigotes.
Here, we present a parasite-rescue and transformation assay with differentiated THP1 cells infected in vitro with Leishmania donovani for screening pure compounds and natural products extracts and determining the efficacy against the intracellular Leishmania amastigotes. The assay involves the following steps: (1) differentiation of THP1 cells to non-dividing macrophages, (2) infection of macrophages with L. donovani metacyclic promastigotes, (3) treatment of infected cells with test drugs, (4) controlled lysis of infected macrophages, (5) release/rescue of amastigotes and (6) transformation of live amastigotes to promastigotes. The assay was optimized using detergent treatment for controlled lysis of Leishmania-infected THP1 cells to achieve almost complete rescue of viable intracellular amastigotes with minimal effect on their ability to transform to promastigotes. Different macrophage:promastigotes ratios were tested to achieve maximum infection. Quantification of the infection was performed through transformation of live, rescued Leishmania amastigotes to promastigotes and evaluation of their growth by an alamarBlue fluorometric assay in 96-well microplates. This assay is comparable to the currently-used microscopic, transgenic reporter gene and digital-image analysis assays. This assay is robust and measures only the live intracellular amastigotes compared to reporter gene and image analysis assays, which may not differentiate between live and dead amastigotes. Also, the assay has been validated with a current panel of anti-leishmanial drugs and has been successfully applied to large-scale screening of pure compounds and a library of natural products fractions (Tekwani et al. unpublished).

A Parasite Rescue and Transformation Assay for Antileishmanial Screening Against Intracellular Leishmania donovani Amastigotes in THP1 Human Acute Monocytic Leukemia Cell Line

A parasite-rescue and transformation assay with THP1 cells infected in vitro with Leishmania donovani has been optimized for anti-leishmanial drug screening. The assay involves differentiation of THP1 cells, infection with promastigotes, treatment with test drugs, controlled lysis of the infected macrophages, rescue of amastigotes, transformation to promastigotes and monitoring promastigote growth and proliferation with a fluorometric assay.

Um parasita Ensaio de Resgate e Transformação de Triagem leishmanicida contra intracelular<em&gt; Leishmania donovani</em&gt; Amastigotas em THP1 linha celular humana aguda Monocytic Leucemia

Leishmaniasis is  one of the world's most neglected diseases, largely affecting the  poorest of the poor, mainly in developing countries. Over 350 million ...

A New Screening Method for the Directed Evolution of Thermostable Bacteriolytic Enzymes

Directed evolution is defined as a method to harness natural selection in order to engineer proteins to acquire particular properties that are not associated with the protein in nature. Literature has provided numerous examples regarding the implementation of directed evolution to successfully alter molecular specificity and catalysis1. The primary advantage of utilizing directed evolution instead of more rational-based approaches for molecular engineering relates to the volume and diversity of variants that can be screened2. One possible application of directed evolution involves improving structural stability of bacteriolytic enzymes, such as endolysins. Bacteriophage encode and express endolysins to hydrolyze a critical covalent bond in the peptidoglycan (i.e. cell wall) of bacteria, resulting in host cell lysis and liberation of progeny virions. Notably, these enzymes possess the ability to extrinsically induce lysis to susceptible bacteria in the absence of phage and furthermore have been validated both in vitro and in vivo for their therapeutic potential3-5. The subject of our directed evolution study involves the PlyC endolysin, which is composed of PlyCA and PlyCB subunits6. When purified and added extrinsically, the PlyC holoenzyme lyses group A streptococci (GAS) as well as other streptococcal groups in a matter of seconds and furthermore has been validated in vivo against GAS7. Significantly, monitoring residual enzyme kinetics after elevated temperature incubation provides distinct evidence that PlyC loses lytic activity abruptly at 45 &deg;C, suggesting a short therapeutic shelf life, which may limit additional development of this enzyme. Further studies reveal the lack of thermal stability is only observed for the PlyCA subunit, whereas the PlyCB subunit is stable up to ~90 &deg;C (unpublished observation). In addition to PlyC, there are several examples in literature that describe the thermolabile nature of endolysins. For example, the Staphylococcus aureus endolysin LysK and Streptococcus pneumoniae endolysins Cpl-1 and Pal lose activity spontaneously at 42 &deg;C, 43.5 &deg;C and 50.2 &deg;C, respectively8-10. According to the Arrhenius equation, which relates the rate of a chemical reaction to the temperature present in the particular system, an increase in thermostability will correlate with an increase in shelf life expectancy11. Toward this end, directed evolution has been shown to be a useful tool for altering the thermal activity of various molecules in nature, but never has this particular technology been exploited successfully for the study of bacteriolytic enzymes. Likewise, successful accounts of progressing the structural stability of this particular class of antimicrobials altogether are nonexistent. In this video, we employ a novel methodology that uses an error-prone DNA polymerase followed by an optimized screening process using a 96 well microtiter plate format to identify mutations to the PlyCA subunit of the PlyC streptococcal endolysin that correlate to an increase in enzyme kinetic stability (Figure 1). Results after just one round of random mutagenesis suggest the methodology is generating PlyC variants that retain more than twice the residual activity when compared to wild-type (WT) PlyC after elevated temperature treatment.

A novel directed evolution method specific to the field of thermostability engineering was developed and consequently validated for bacteriolytic enzymes. After only one round of random mutagenesis, an evolved bacteriolytic enzyme, PlyC 29C3, displayed greater than twice the residual activity when compared to the wild-type protein after elevated temperature incubation.

Novo método de triagem para a evolução dirigida de enzimas termoestáveis ​​Bacteriolytic

Directed evolution is defined as a method to harness natural selection in order to engineer proteins to acquire particular properties that are not ...

Generation and Multi-phenotypic High-content Screening of Coxiella burnetii Transposon Mutants

Invasion and colonization of host cells by bacterial pathogens depend on the activity of a large number of prokaryotic proteins, defined as virulence factors, which can subvert and manipulate key host functions. The study of host/pathogen interactions is therefore extremely important to understand bacterial infections and develop alternative strategies to counter infectious diseases. This approach however, requires the development of new high-throughput assays for the unbiased, automated identification and characterization of bacterial virulence determinants. Here, we describe a method for the generation of a GFP-tagged mutant library by transposon mutagenesis and the development of high-content screening approaches for the simultaneous identification of multiple transposon-associated phenotypes. Our working model is the intracellular bacterial pathogen Coxiellaburnetii, the etiological agent of the zoonosis Q fever, which is associated with severe outbreaks with a consequent health and economic burden. The obligate intracellular nature of this pathogen has, until recently, severely hampered the identification of bacterial factors involved in host pathogen interactions, making of Coxiella the ideal model for the implementation of high-throughput/high-content approaches.

Generation and Multi-phenotypic High-content Screening of Coxiella burnetii Transposon Mutants

Coxiella burnetii is an obligate intracellular Gram-negative bacterium responsible for the zoonotic disease Q fever. Here we describe methods for the generation of Coxiella fluorescent transposon mutants as well as the automated identification and analysis of the resulting internalization, replication and cytotoxic phenotypes.

Geração e Multi-fenotípica rastreio de alto teor de<em&gt; Coxiella burnetii</em&gt; mutantes por transposões

Invasion and colonization of host cells by bacterial pathogens depend on the activity of a large number of prokaryotic proteins, defined as virulence ...

Visualization of the Charcoal Agar Resazurin Assay for Semi-quantitative, Medium-throughput Enumeration of Mycobacteria

There is an urgent need to discover and progress anti-infectives that shorten the duration of tuberculosis (TB) treatment. Mycobacterium tuberculosis, the etiological agent of TB, is refractory to rapid and lasting chemotherapy due to the presence of bacilli exhibiting phenotypic drug resistance. The charcoal agar resazurin assay (CARA) was developed as a tool to characterize active molecules discovered by high-throughput screening campaigns against replicating and non-replicating M. tuberculosis. Inclusion of activated charcoal in bacteriologic agar medium helps mitigate the impact of compound carry-over, and eliminates the requirement to pre-dilute cells prior to spotting on CARA microplates. After a 7-10 day incubation period at 37 &#176;C, the reduction of resazurin by mycobacterial microcolonies growing on the surface of CARA microplate wells permits semi-quantitative assessment of bacterial numbers via fluorometry. The CARA detects approximately a 2-3 log10 difference in bacterial numbers and predicts a minimal bactericidal concentration leading to &#8805;99% bacterial kill (MBC&#8805;99). The CARA helps determine whether a molecule is active on bacilli that are replicating, non-replicating, or both. Pilot experiments using the CARA facilitate the identification of which concentration of test agent and time of compound exposure require further evaluation by colony forming unit (CFU) assays. In addition, the CARA can predict if replicating actives are bactericidal or bacteriostatic.

The charcoal agar resazurin assay (CARA) is a semi-quantitative, medium-throughput method to assess activity of test agents against mycobacteria that are replicating, non-replicating, or both. The CARA permits rapid evaluation of time- and concentration-dependent activity and identifies parameters to pursue by colony forming unit (CFU) assays.

Visualização do carvão Agar resazurina Ensaio para a semi-quantitativa, médio rendimento enumeração de micobactérias

There is an urgent need to discover and progress anti-infectives that shorten the duration of tuberculosis (TB) treatment. Mycobacterium tuberculosis, the ...

A Simple Fluorescence Assay for Quantification of Canine Neutrophil Extracellular Trap Release

Neutrophil extracellular traps are networks of DNA, histones and neutrophil proteins released in response to infectious and inflammatory stimuli. Although a component of the innate immune response, NETs are implicated in a range of disease processes including autoimmunity and thrombosis. This protocol describes a simple method for canine neutrophil isolation and quantification of NETs using a microplate fluorescence assay. Blood is collected using conventional venipuncture techniques. Neutrophils are isolated using dextran sedimentation and a density gradient using conditions optimized for dog blood. After allowing time for attachment to the wells of a 96 well plate, neutrophils are treated with NET-inducing agonists such as phorbol-12-myristate-13-acetate or platelet activating factor. DNA release is measured by the fluorescence of a cell-impermeable nucleic acid dye. This assay is a simple, inexpensive method for quantifying NET release, but NET formation rather than other causes of cell death must be confirmed with alternative methods.

Neutrophil extracellular traps (NETs) are networks of DNA, histones and neutrophil proteins. Although a component of the innate immune response, NETs are implicated in autoimmunity and thrombosis. This protocol describes a simple method for canine neutrophil isolation and quantification of NETs using a microplate fluorescence assay.

A fluorescência ensaio simples para a quantificação de Canine neutrófilos Extracelular Armadilha lançamento

Neutrophil extracellular traps are networks of DNA, histones and neutrophil proteins released in response to infectious and inflammatory stimuli. Although ...

A Fluorescence-based Lymphocyte Assay Suitable for High-throughput Screening of Small Molecules

High-throughput screening (HTS) is currently the mainstay for the identification of chemical entities capable of modulating biochemical reactions or cellular processes. With the advancement of biotechnologies and the high translational potential of small molecules, a number of innovative approaches in drug discovery have evolved, which explains the resurgent interest in the use of HTS. The oncology field is currently the most active research area for drug screening, with no major breakthrough made for the identification of new immunomodulatory compounds targeting transplantation-related complications or autoimmune ailments. Here, we present a novel in vitro murine fluorescent-based lymphocyte assay easily adapted for the identification of new immunomodulatory compounds. This assay uses T or B cells derived from a transgenic mouse, in which the Nur77 promoter drives GFP expression upon T- or B-cell receptor stimulation. As the GFP intensity reflects the activation/transcriptional activity of the target cell, our assay defines a novel tool to study the effect of given compound(s) on cellular/biological responses. For instance, a primary screening was performed using 4,398 compounds in the absence of a &#34;target hypothesis&#34;, which led to the identification of 160 potential hits displaying immunomodulatory activities. Thus, the use of this assay is suitable for drug discovery programs exploring large chemical libraries prior to further in vitro/in vivo validation studies.

We present in the current study a novel fluorescence-based assay using lymphocytes derived from a transgenic mouse. This assay is suitable for high-throughput screening (HTS) of small molecules endowed with the capacity of either inhibiting or promoting lymphocyte activation.

A Fluorescência baseada em Linfócitos ensaio adequado para high-throughput screening de pequenas moléculas

High-throughput screening (HTS) is currently the mainstay for the identification of chemical entities capable of modulating biochemical reactions or ...

System for Efficacy and Cytotoxicity Screening of Inhibitors Targeting Intracellular Mycobacterium tuberculosis

Mycobacterium tuberculosis, the causative agent of tuberculosis (TB), is a leading cause of morbidity and mortality worldwide. With the increased spread of multi drug-resistant TB (MDR-TB), there is a real urgency to develop new therapeutic strategies against M. tuberculosis infections. Traditionally, compounds are evaluated based on their antibacterial activity under in vitro growth conditions in broth; however, results are often misleading for intracellular pathogens like M. tuberculosis since in-broth phenotypic screening conditions are significantly different from the actual disease conditions within the human body. Screening for inhibitors that work inside macrophages has been traditionally difficult due to the complexity, variability in infection, and slow replication rate of M. tuberculosis. In this study, we report a new approach to rapidly assess the effectiveness of compounds on the viability of M. tuberculosis in a macrophage infection model. Using a combination of a cytotoxicity assay and an in-broth M. tuberculosis viability assay, we were able to create a screening system that generates a comprehensive analysis of compounds of interest. This system is capable of producing quantitative data at a low cost that is within reach of most labs and yet is highly scalable to fit large industrial settings.

System for Efficacy and Cytotoxicity Screening of Inhibitors Targeting Intracellular Mycobacterium tuberculosis

We have developed a modular high-throughput screening system for discovering novel compounds against Mycobacterium tuberculosis, targeting intracellular and in-broth growing bacteria as well as cytotoxicity against the mammalian host cell.

Sistema de Eficácia e citotoxicidade Rastreio de inibidores Segmentação intracelular<em&gt; Mycobacterium tuberculosis</em

Mycobacterium tuberculosis, the causative agent of tuberculosis (TB), is a leading cause of morbidity and mortality worldwide. With the increased spread ...

Quantification of Intracellular Growth Inside Macrophages is a Fast and Reliable Method for Assessing the Virulence of Leishmania Parasites

The lifecycle of Leishmania, the causative agent of leishmaniasis, alternates between promastigote and amastigote stages inside the insect and vertebrate hosts, respectively. While pathogenic symptoms of leishmaniasis can vary widely, from benign cutaneous lesions to highly fatal visceral disease forms depending on the infective species, all Leishmania species reside inside host macrophages during the vertebrate stage of their lifecycle. Leishmania infectivity is therefore directly related to its ability to invade, survive and replicate within parasitophorous vacuoles (PVs) inside macrophages. Thus, assessing the parasite&#39;s ability to replicate intracellularly serves as a dependable method for determining virulence. Studying leishmaniasis development using animal models is time-consuming, tedious and often difficult, particularly with the pathogenically important visceral forms. We describe here a methodology to follow the intracellular development of Leishmania in bone marrow-derived macrophages (BMMs). Intracellular parasite numbers are determined at 24 h intervals for 72 - 96 h following infection. This method allows for a reliable determination of the effects of various genetic factors on Leishmania virulence. As an example, we show how a single allele deletion of the Leishmania Mitochondrial Iron Transporter gene (LMIT1) impairs the ability of the Leishmania amazonensis mutant strain LMIT1/&#916;Lmit1 to grow inside BMMs, reflecting a drastic reduction in virulence compared to wild-type. This assay also allows precise control of experimental conditions, which can be individually manipulated to analyze the influence of various factors (nutrients, reactive oxygen species, etc.) on the host-pathogen interaction. Therefore, the appropriate execution and quantification of BMM infection studies provide a non-invasive, rapid, economical, safe and reliable alternative to conventional animal model studies.

Quantification of Intracellular Growth Inside Macrophages is a Fast and Reliable Method for Assessing the Virulence of Leishmania Parasites

All pathogenic Leishmania species reside and replicate inside macrophages of their vertebrate hosts. Here, we present a protocol to infect murine bone marrow-derived macrophages in culture with Leishmania, followed by precise quantification of intracellular growth kinetics. This method is useful for studying individual factors influencing host-pathogen interaction and Leishmania virulence.

Quantificação de crescimento intracelular dentro de macrófagos é um rápido e confiável método para avaliar a virulência de Leishmania parasitas

The lifecycle of Leishmania, the causative agent of leishmaniasis, alternates between promastigote and amastigote stages inside the insect and vertebrate ...

A High-throughput, High-content, Liquid-based C. elegans Pathosystem

The number of new drugs identified by traditional, in vitro screens has waned, reducing the success of this approach in the search for new weapons to combat multiple drug resistance. This has led to the conclusion that researchers do not only need to find new drugs, but also need to develop new ways of finding them. Amongst the most promising candidate methods are whole-organism, in vivo assays that use high-throughput, phenotypic readouts and hosts that range from Caenorhabditis elegans to Danio rerio. These hosts have several powerful advantages, including dramatic reductions in false positive hits, as compounds that are toxic to the host and/or biounavailable are typically dropped in the initial screen, prior to costly follow up.
Here we show how our assay has been used to interrogate host variation in the well-documented C. elegans&#8212;Pseudomonas aeruginosa liquid killing pathosystem. We also demonstrate several extensions of this well-worked out technique. For example, we are able to carry out high-throughput genetic screens using RNAi in 24- or 96-well plate formats to query host factors in this host-pathogen interaction. Using this assay, whole genome screens can be completed in only a few months, which can dramatically simplify the task of identifying drug targets, potentially without the need for laborious biochemical purification approaches.
We also report here a variation of our method that substitutes the gram-positive bacterium Enterococcus faecalis for the gram-negative pathogen P. aeruginosa. Much as is the case for P. aeruginosa, killing by E. faecalis is time-dependent. Unlike previous C. elegans&#8212;E. faecalis assays, our assay for E. faecalis does not require preinfection, improving its safety profile and reducing the chances of contaminating liquid-handling equipment. The assay is highly robust, showing ~95% death rates 96 h post infection.

A High-throughput, High-content, Liquid-based C. elegans Pathosystem

Here we describe a protocol that is an adaptable, whole host, high-content screening tool that can be utilized to study host-pathogen interactions and be used for drug discovery.

Uma alta produtividade, alto teor, baseada em líquido c. elegans patossistema

The number of new drugs identified by traditional, in vitro screens has waned, reducing the success of this approach in the search for new weapons to ...