Os autores gostariam de agradecer Cui Chao, Andar de Kort, Stoop Esther e Ralph Carvalho de imagens na Figura 4, Nehrdich Ulrike e de Davy Witt para cuidado dos peixes, e os membros do laboratório para outras discussões úteis. Este trabalho é apoiado pelo Programa Mix inteligente do Ministério neerlandês dos Assuntos Económicos e do Ministério da Educação, Cultura e Ciência, a Comissão Europeia sétimo projeto quadro ZF-SAÚDE (SAÚDE-F4-2010-242048), o Europeu Marie-Curie Formação inicial Rede FishForPharma (PITN-GA-2011-289209), e pelo NHMRC australiano (637.394). O australiano Medicina Regenerativa Institute é suportado por concessões do Governo do Estado de Victoria e do governo australiano.

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Os métodos de infecção descritas neste artigo são frequentemente usados ​​para estudar a função dos genes hospedeiros inatas imunidade ou genes de virulência bacterianos 1. Os micro-injecção intravenosa métodos (protocolos 5 e 6.1) são usados ​​com mais freqüência para tais estudos. A veia caudal no ilha de sangue posterior é o local mais conveniente para injecção intravenosa de um dia de idade embriões. Como a veia caudal torna-se mais difícil de penetrar em fases posteriores, preferimos o ducto de Cuvier como local da injeção intravenosa de embriões em 2-3 dpf. Em todos os casos é fundamental para injetar os embriões com números consistentes de bactérias, que devem ser verificados por inóculos injeção de revestimento para a contagem de ufc. Os seguintes aspectos devem ser considerados para alcançar injeções reprodutíveis. Em primeiro lugar, é essencial ter vidro de alta qualidade agulhas de injecção microcapilar. Se a ponta da agulha é muito grande, a injecção irá criar um orifício de punção grande o suficiente para que ocorra o sangramento eas bactérias injectadas fluirá para fora da circulação sanguínea. Em segundo lugar, as bactérias devem ser injectado directamente para a circulação sanguínea. Se a ponta da agulha não está dentro da veia ou se espalha injecção de fluido para a extensão saco vitelino, o embrião deve ser descartada a partir da experiência. Em terceiro lugar, usando PVP40 como um portador para injectar M. marinum irá ajudar a prevenir as bactérias de afundar-se na agulha de vidro. PVP40 melhora a homogeneidade da suspensão, resultando em inóculos mais reprodutível durante toda a duração de injecções. PVP40 pode também ser utilizado para S. injecções typhimurium, mas aqui, é menos importante, porque o tamanho maior e fluorescência brilhante das bactérias permite um controlo visual sobre o inoculo de injecção durante as experiências. Para praticar as injecções recomenda-se a utilização de fenol corante vermelho (1% v / v) ou 1 mícron esferas fluorescentes disponíveis em cores diferentes (Invitrogen). Uma vez que a técnica é dominada, leva cerca de 30 minutes para injectar 50-100 embriões, incluindo o tempo necessário para alinhar os embriões em placas de agarose e ajustando o volume de injecção bacteriana. Enquanto injeções intravenosas para a ilha de sangue (protocolo 5) ou no ducto de Cuvier (protocolo 6.1) são os mais usados, as vias alternativas de infecção descritos neste artigo de vídeo têm se mostrado úteis para estudar a quimiotaxia de macrófagos e neutrófilos (protocolos 6.2, 6.3 , e 6,4), para estudar o crescimento de estirpes bacterianas atenuadas (protocolo 6,5), e para adaptar o modelo de infecção do peixe-zebra para aplicações de alto rendimento (protocolo 6,6) 4-8. As micro-injecção descritos métodos também podem ser aplicados para injecções de vírus 18, 19, esporos de fungos 14, 20 ou parasitas protozoários (Maria Forlenza, comunicação pessoal). Uma adição útil para os procedimentos de injecção descritos neste artigo de vídeo é um procedimento recentemente descrito para a injecção subcutânea de bactérias em zebrembriões afish 21. Este procedimento foi aplicado para estudar a fagocitose de bactérias por neutrófilos, que foram encontrados para as bactérias de forma eficiente engolfam em superfícies de tecido, mas, em contraste com os macrófagos, eram virtualmente incapaz de fagocitam bactérias mediante injecção no sangue ou em cavidades cheias de fluido do corpo. Para embriões injecções subcutâneas são posicionados semelhante como para as injecções de cauda musculares descritos neste artigo de vídeo, mas a agulha é inserida debaixo da pele para injectar as bactérias durante um somito. É importante considerar que a micro-injecção é essencialmente uma rota artificial de infecção. No entanto, os embriões precoces são altamente resistentes à exposição externa para agentes patogénicos bacterianos. De facto, os ensaios de imersão, em que os embriões são banhadas numa suspensão bacteriana, não são reprodutíveis nas nossas mãos 22. Enquanto alguns embriões podem ser infectados após imersão, temos observado uma grande variação nas taxas de mortalidade e na expressaião de genes marcadores inflamatórios entre os embriões individuais em tais ensaios. Os métodos de micro-injecção descritos neste artigo atingir infecções reprodutíveis e são particularmente úteis para estudar as interacções bacterianas com hospedeiras inatos células imunes. Uma abordagem eficiente para quantificar a infecção bacteriana em embriões individuais é analisar as imagens fluorescentes de embriões infectados com custom-made software de quantificação, dedicado pixels 17, 23. Esta abordagem tem sido demonstrado que se correlacionam bem com os resultados das contagens de UFC após o plaqueamento de embriões infectados. Da mesma forma, mudanças relativas no número de leucócitos por embrião foram quantificados pela análise de imagem digital em transgênicos leucócitos linhas repórter fluoróforo; esta abordagem seria aplicável para quantificar a resposta do hospedeiro à infecção leukopoietic 24. A função do hospedeiro inatos genes imunes podem ser investigadas eficientemente in vivo através da combinação dos modelos de infecção descritascom knockdown morfolino. Morpholinos são oligonucleótidos anti-sentido sintéticos que têm como alvo RNAs específicos e reduzir a expressão dos produtos dos genes quando injectado 1 de células de embriões peixe-zebra fase, como mostrado na outros artigos de vídeo nesta revista 10, 25. Em estudos knockdown morfolino, é de grande importância que todos os grupos de embriões a serem comparadas são testados correctamente antes de injecções bacterianas. Isto é especialmente importante porque os embriões têm um desenvolvimento do sistema imunitário que se torna cada vez mais competente ao longo do tempo. Existem várias linhas transgénicas repórter actualmente disponíveis para distinguir os principais inatos subconjuntos imunes, macrófagos e neutrófilos, em embriões de peixe-zebra. A MPX e promotores LYZ têm sido usados ​​para gerar as linhas de repórter de neutrófilos 16, 26, 27, eo csf1r (SFM) e MPEG1 promotores foram usados ​​para produzir repórteres de macrófagos 14, 28. Enquanto csf1r (FMS) é adicionalmente expressa em xanthophores, mpeg1 expressão é exclusivamente nos macrófagos. Como mostrado neste artigo de vídeo, os recentemente desenvolvidos mpeg1 linhas repórter são altamente úteis para a fagocitose de imagem bacteriana por macrófagos.

<table border="1"><tbody><tr><td> Reagente </td><td> Fornecedor </td><td> Número de catálogo </td></tr><tr><td> Vermelho de Fenol </td><td> Sigma </td><td> P0290 </td></tr><tr><td> Glicerina </td><td> Sigma-Aldrich </td><td> 228210 </td></tr><tr><td> Difco ágar Middlebrook 7H10 </td><td> Becton, Dickinson and Company </td><td> 262710 </td></tr><tr><td> BBL Middlebrook Enrichment OADC </td><td> Becton, Dickinson and Company </td><td> 211886 </td></tr><tr><td> Middlebrook 7H9 Broth Difco </td><td> Becton, Dickinson and Company </td><td> 271310 </td></tr><tr><td> BBL Middlebrook Enrichment ADC </td><td> Becton, Dickinson and Company </td><td> 211887 </td></tr><tr><td> Tween 80 </td><td> Sigma-Aldrich </td><td> P1754 </td></tr><tr><td> Polivinilpirrolidona (PVP40) </td><td> Calbiochem, Merck KGaA </td><td> 529504 </td></tr><tr><td> N &lt;/ Em&gt;-Phenylthiourea (PTU) </td><td> Sigma-Aldrich </td><td> P7629 </td></tr><tr><td> 3-aminobenzoato de etilo sal metanossulfonato (tricaina) </td><td> Sigma-Aldrich </td><td> A5040 </td></tr><tr><td> Metil celulose </td><td> Sigma-Aldrich </td><td> M0387 </td></tr><tr><td> SeaPlaque Agarose (baixo ponto de fusão de agarose) </td><td> Lonza Inc. </td><td> 50100 </td></tr><tr><td> FluoSpheres (1,0 uM, vermelho fluorescente (580/605)) </td><td> Invitrogen </td><td> F8821 </td></tr><tr><td> FluoSpheres (1,0 mM, amarelo-verde fluorescente (505/515)) </td><td> Invitrogen </td><td> F8823 </td></tr></tbody></table>

infection of zebrafish embryos with intracellular bacterial pathogens

Peixe-zebra (Danio rerio) embriões são cada vez mais utilizado como um modelo para estudar a função do sistema inato vertebrado imune no hospedeiro de organismos patogénicos interacções 1. Os principais tipos de células do sistema imune inato, macrófagos e neutrófilos, desenvolver-se durante os primeiros dias de embriogénese antes da maturação dos linfócitos que são necessários para as respostas imunitária adaptativa. A facilidade de obtenção de um grande número de embriões, a sua acessibilidade devido ao desenvolvimento externo, a transparência óptica de estágios embrionários e larval, uma ampla gama de ferramentas genéticas, extensos recursos mutantes e coleções de linhas repórter transgênicos, tudo isto contribui para a versatilidade do peixe-zebra modelo. Salmonella enterica serovar Typhimurium (S. typhimurium) e Mycobacterium marinum pode residir intracelularmente em macrófagos e são frequentemente usados ​​para estudar interações patógeno-hospedeiro em embriões de peixe zebra. Os processos a infecção destas duaspatógenos bacterianos são interessantes para comparar porque S. infecção typhimurium é aguda e letal dentro de um dia, enquanto M. marinum infecção é crônica e pode ser trabalhada até o estágio larval 2, 3. O local de micro-injecção de bactérias no embrião (Figura 1) determina se a infecção se tornar-se rapidamente sistémica ou será inicialmente permanecer localizada. Uma infecção sistémica rápida pode ser estabelecida por micro-injecção de bactérias directamente para a circulação do sangue através da veia caudal no ilha de sangue posterior ou através do duto de Cuvier, um canal de circulação de largura no saco vitelino de ligar o coração para a vasculatura do tronco. Em 1 dpf, quando embriões nesta fase têm macrófagos phagocytically ativos, mas neutrófilos ainda não amadureceram, injetando na ilha de sangue é o preferido. Para injeções em 2-3 dpf, quando os embriões também desenvolveram funcionais (mieloperoxidase produtora) neutrófilos, o ducto de Cuvier é preferido como tele no local da injecção. Para estudar a migração dirigida de células mielóides no sentido infecções locais, as bactérias podem ser injectado no músculo da cauda, ​​vesícula ótica, ou ventrículo rombencéfalo 4-6. Além disso, o notocórdio, uma estrutura que parece ser normalmente inacessíveis às células mielóides, é altamente susceptíveis à infecção local 7. Uma alternativa útil para aplicações de alto rendimento é a injeção de bactérias na gema de embriões nas primeiras horas após a fertilização 8. Combinando as bactérias fluorescentes e linhas de zebrafish transgênicos fluorescentes com macrófagos ou neutrófilos cria condições ideais para multi-cor de imagem de sistema patógeno-hospedeiro interações. Este artigo irá descrever vídeo protocolos detalhados para a infecção por via intravenosa e local de embriões de zebrafish com S. typhimurium ou M. bactérias marinum e para imagens de fluorescência posterior da interação com células do sistema imune inato.

Watch this Scientific Journal Video about Infection of Zebrafish Embryos with Intracellular Bacterial Pathogens at JoVE.com

Infection of Zebrafish Embryos with Intracellular Bacterial Pathogens

Embriões do zebrafish transparente provaram anfitriões modelo útil para visualizar e interações de estudo funcional entre as células imunes inatas e patógenos bacterianos intracelulares, tais como<em&gt; Salmonella typhimurium</em&gt; E<em&gt; Mycobacterium marinum</em&gt;. A micro-injecção de bactérias e de multi-cor de imagem de fluorescência são técnicas essenciais envolvidos na aplicação de modelos de infecção peixe-zebra de embriões.

A infecção de embriões de zebrafish com patógenos bacterianos intracelulares

Zebrafish (Danio rerio) embryos are increasingly used as a model for studying the function of the vertebrate innate immune system in host-pathogen ...

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JoVE Journal

Immunology and Infection

43.5K visualizações.  Leiden University. Embriões do zebrafish transparente provaram anfitriões modelo útil para visualizar e interações de estudo funcional entre as células imunes inatas e patógenos bacterianos intracelulares, tais como Salmonella typhimurium E Mycobacterium marinum. A micro-injecção de bactérias e de multi-cor de imagem de fluorescência são técnicas essenciais envolvidos na aplicação de modelos de infecção peixe-zebra de embriões.

Vídeo: Infection of Zebrafish Embryos with Intracellular Bacterial Pathogens

'Bioluminescent' Reporter Phage for the Detection of Category A Bacterial Pathogens

Yersinia pestis and Bacillus anthracis are Category A bacterial pathogens that are the causative agents of the plague and anthrax, respectively 1. Although the natural occurrence of both diseases&#39; is now relatively rare, the possibility of terrorist groups using these pathogens as a bioweapon is real. Because of the disease&#39;s inherent communicability, rapid clinical course, and high mortality rate, it is critical that an outbreak be detected quickly. Therefore methodologies that provide rapid detection and diagnosis are essential to ensure immediate implementation of public health measures and activation of crisis management.
Recombinant reporter phage may provide a rapid and specific approach for the detection of Y. pestis and B. anthracis. The Centers for Disease Control and Prevention currently use the classical phage lysis assays for the confirmed identification of these bacterial pathogens 2-4. These assays take advantage of naturally occurring phage which are specific and lytic for their bacterial hosts. After overnight growth of the cultivated bacterium in the presence of the specific phage, the formation of plaques (bacterial lysis) provides a positive identification of the bacterial target. Although these assays are robust, they suffer from three shortcomings: 1) they are laboratory based; 2) they require bacterial isolation and cultivation from the suspected sample, and 3) they take 24-36 h to complete. To address these issues, recombinant &#34;light-tagged&#34; reporter phage were genetically engineered by integrating the Vibrio harveyi luxAB genes into the genome of Y. pestis and B. anthracis specific phage 5-8. The resulting luxAB reporter phage were able to detect their specific target by rapidly (within minutes) and sensitively conferring a bioluminescent phenotype to recipient cells. Importantly, detection was obtained either with cultivated recipient cells or with mock-infected clinical specimens 7.
For demonstration purposes, here we describe the method for the phage-mediated detection of a known Y. pestis isolate using a luxAB reporter phage constructed from the CDC plague diagnostic phage &#934;A1122 6,7 (Figure 1). A similar method, with minor modifications (e.g. change in growth temperature and media), may be used for the detection of B. anthracis isolates using the B. anthracis reporter phage W&#946;::luxAB 8. The method describes the phage-mediated transduction of a biolumescent phenotype to cultivated Y. pestis cells which are subsequently measured using a microplate luminometer. The major advantages of this method over the traditional phage lysis assays is the ease of use, the rapid results, and the ability to test multiple samples simultaneously in a 96-well microtiter plate format.
<img alt="Figure 1" src="/files/ftp_upload/2740/2740fig1.jpg" /> 
Figure 1. Detection schematic. The phage are mixed with the sample, the phage infects the cell, luxAB are expressed, and the cell bioluminesces. Sample processing is not necessary; the phage and cells are mixed and subsequently measured for light.

&#039;Bioluminescent&#039; Reporter Phage for the Detection of Category A Bacterial Pathogens

A simple method for the identification of priority bacterial pathogens is to use genetically engineered reporter phage. These reporter phage, which are specific to their particular host species, are capable of rapidly transducing a bioluminescent signal response to host cells. Herein, we describe the use of reporter phage for the detection of Yersinia pestis.

&quot;Bioluminescent &#39;Phage Reporter para a detecção de patógenos bacterianos Categoria A

Yersinia pestis and Bacillus anthracis are Category A bacterial pathogens that are the causative agents of the plague and anthrax, respectively 1. ...

Imunologia e Infecção

Single Cell Measurements of Vacuolar Rupture Caused by Intracellular Pathogens

Shigella flexneri are pathogenic bacteria that invade host cells entering into an endocytic vacuole. Subsequently, the rupture of this membrane-enclosed compartment allows bacteria to move within the cytosol, proliferate and further invade neighboring cells. Mycobacterium tuberculosis is phagocytosed by immune cells, and has recently been shown to rupture phagosomal membrane in macrophages. We developed a robust assay for tracking phagosomal membrane disruption after host cell entry of Shigella flexneri or Mycobacterium tuberculosis. The approach makes use of CCF4, a FRET reporter sensitive to &beta;-lactamase that equilibrates in the cytosol of host cells. Upon invasion of host cells by bacterial pathogens, the probe remains intact as long as the bacteria reside in membrane-enclosed compartments. After disruption of the vacuole, &beta;-lactamase activity on the surface of the intracellular pathogen cleaves CCF4 instantly leading to a loss of FRET signal and switching its emission spectrum. This robust ratiometric assay yields accurate information about the timing of vacuolar rupture induced by the invading bacteria, and it can be coupled to automated microscopy and image processing by specialized algorithms for the detection of the emission signals of the FRET donor and acceptor. Further, it allows investigating the dynamics of vacuolar disruption elicited by intracellular bacteria in real time in single cells. Finally, it is perfectly suited for high-throughput analysis with a spatio-temporal resolution exceeding previous methods. Here, we provide the experimental details of exemplary protocols for the CCF4 vacuolar rupture assay on HeLa cells and THP-1 macrophages for time-lapse experiments or end points experiments using Shigella flexneri as well as multiple mycobacterial strains such as Mycobacterium marinum, Mycobacterium bovis, and Mycobacterium tuberculosis.

We describe a method for tracking the endomembrane rupture elicited by the intracellular bacteria Shigella flexneri and Mycobacterium tuberculosis upon host cell invasion. Our assay makes use of CCF4, a host cytoplasmic FRET probe in live or fixed cells. This reporter is degraded by an enzyme activity present on the bacterial surface.

Medidas de ruptura vacuolar única célula causadas por patógenos intracelulares

Shigella flexneri are pathogenic bacteria that invade host cells entering into an endocytic vacuole. Subsequently, the rupture of this membrane-enclosed ...

Discovery of New Intracellular Pathogens by Amoebal Coculture and Amoebal Enrichment Approaches

Intracellular pathogens such as legionella, mycobacteria and Chlamydia-like organisms are difficult to isolate because they often grow poorly or not at all on selective media that are usually used to cultivate bacteria. For this reason, many of these pathogens were discovered only recently or following important outbreaks. These pathogens are often associated with amoebae, which serve as host-cell and allow the survival and growth of the bacteria. We intend here to provide a demonstration of two techniques that allow isolation and characterization of intracellular pathogens present in clinical or environmental samples: the amoebal coculture and the amoebal enrichment. Amoebal coculture allows recovery of intracellular bacteria by inoculating the investigated sample onto an amoebal lawn that can be infected and lysed by the intracellular bacteria present in the sample. Amoebal enrichment allows recovery of amoebae present in a clinical or environmental sample. This can lead to discovery of new amoebal species but also of new intracellular bacteria growing specifically in these amoebae. Together, these two techniques help to discover new intracellular bacteria able to grow in amoebae. Because of their ability to infect amoebae and resist phagocytosis, these intracellular bacteria might also escape phagocytosis by macrophages and thus, be pathogenic for higher eukaryotes.

Amoebal coculture is a cell culture system using adherent amoebae to selectively grow intracellular pathogens able to resist phagocytic cells such as amoebae and macrophages. It thus represents a key tool to discover new infectious agents. Amoebal enrichment allows discovery of new amoebal species and of their specific intracellular bacteria.

Descoberta de Novos intracelulares Patógenos por amebas Coculture e Abordagens de amebas de enriquecimento

Intracellular pathogens such as legionella, mycobacteria and Chlamydia-like organisms are difficult to isolate because they often grow poorly or not at ...

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 ...

Applying an Inducible Expression System to Study Interference of Bacterial Virulence Factors with Intracellular Signaling

The technique presented here allows one to analyze at which step a target protein, or alternatively a small molecule, interacts with the components of a signaling pathway. The method is based, on the one hand, on the inducible expression of a specific protein to initiate a signaling event at a defined and predetermined step in the selected signaling cascade. Concomitant expression, on the other hand, of the gene of interest then allows the investigator to evaluate if the activity of the expressed target protein is located upstream or downstream of the initiated signaling event, depending on the readout of the signaling pathway that is obtained. Here, the apoptotic cascade was selected as a defined signaling pathway to demonstrate protocol functionality. Pathogenic bacteria, such as Coxiella burnetii, translocate effector proteins that interfere with host cell death induction in the host cell to ensure bacterial survival in the cell and to promote their dissemination in the organism. The C. burnetii effector protein CaeB effectively inhibits host cell death after induction of apoptosis with UV-light or with staurosporine. To narrow down at which step CaeB interferes with the propagation of the apoptotic signal, selected proteins with well-characterized pro-apoptotic activity were expressed transiently in a doxycycline-inducible manner. If CaeB acts upstream of these proteins, apoptosis will proceed unhindered. If CaeB acts downstream, cell death will be inhibited. The test proteins selected were Bax, which acts at the level of the mitochondria, and caspase 3, which is the major executioner protease. CaeB interferes with cell death induced by Bax expression, but not by caspase 3 expression. CaeB, thus, interacts with the apoptotic cascade between these two proteins.

The method described here is used to induce the apoptotic signaling cascade at defined steps in order to dissect the activity of an anti-apoptotic bacterial effector protein. This method can also be used for inducible expression of pro-apoptotic or toxic proteins, or for dissecting interference with other signaling pathways.

Aplicando um sistema de expressão induzível para estudar interferência de fatores de virulência bacteriana com Sinalização Intracelular

The technique presented here allows one to analyze at which step a target protein, or alternatively a small molecule, interacts with the components of a ...

Identification of Rare Bacterial Pathogens by 16S rRNA Gene Sequencing and MALDI-TOF MS

There are a number of rare and, therefore, insufficiently described bacterial pathogens which are reported to cause severe infections especially in immunocompromised patients. In most cases only few data, mostly published as case reports, are available which investigate the role of such pathogens as an infectious agent. Therefore, in order to clarify the pathogenic character of such microorganisms, it is necessary to conduct epidemiologic studies which include large numbers of these bacteria. The methods used in such a surveillance study have to meet the following criteria: the identification of the strains has to be accurate according to the valid nomenclature, they should be easy to handle (robustness), economical in routine diagnostics and they have to generate comparable results among different laboratories. Generally, there are three strategies for identifying bacterial strains in a routine setting: 1) phenotypic identification characterizing the biochemical and metabolic properties of the bacteria, 2) molecular techniques such as 16S rRNA gene sequencing and 3) mass spectrometry as a novel proteome based approach. Since mass spectrometry and molecular approaches are the most promising tools for identifying a large variety of bacterial species, these two methods are described. Advances, limitations and potential problems when using these techniques are discussed.

Matrix-assisted laser desorption/ionization time of flight mass spectrometry (MALDI-TOF MS) and molecular techniques (16S rRNA gene sequencing) permit the identification of rare bacterial pathogens in routine diagnostics. The goal of this protocol lies in the combination of both techniques which leads to more accurate and reliable data.

Identificação de patógenos bacterianos raras, seqüência do gene 16rRNA e MALDI-TOF MS

There are a number of rare and, therefore, insufficiently described bacterial pathogens which are reported to cause severe infections especially in ...

Isolation of Single Intracellular Bacterial Communities Generated from a Murine Model of Urinary Tract Infection for Downstream Single-cell Analysis

In this article, we outline a procedure used to isolate individual intracellular bacterial communities from a mouse that has been experimentally infected in the urinary tract. The protocol can be broadly divided into three sections: the infection, bladder epithelial cell harvesting, and mouth micropipetting to isolate individual infected epithelial cells. The isolated epithelial cell contains viable bacterial cells and is nearly free of contaminating extracellular bacteria, making it ideal for downstream single-cell analysis. The time taken from the start of infection to obtaining a single intracellular bacterial community is about 8 h. This protocol is inexpensive to deploy and uses widely available materials, and we anticipate that it can also be utilized in other infection models to isolate single infected cells from cell mixtures even if those infected cells are rare. However, due to a potential risk in mouth micropipetting, this procedure is not recommended for highly infectious agents.

This protocol describes a simple method of isolating single, infected-bladder epithelial cells from a murine model of urinary tract infection.

Isolamento de comunidades de bacterianas intracelulares único gerado a partir de um modelo murino de infecção do trato urinário para análise de célula única a jusante

In this article, we outline a procedure used to isolate individual intracellular bacterial communities from a mouse that has been experimentally infected ...

Opsonophagocytic Killing Assay to Assess Immunological Responses Against Bacterial Pathogens

A key aspect of the immune response to bacterial colonization of the host is phagocytosis. An opsonophagocytic killing assay (OPKA) is an experimental procedure in which phagocytic cells are co-cultured with bacterial units. The immune cells will phagocytose and kill the bacterial cultures in a complement-dependent manner. The efficiency of the immune-mediated cell killing is dependent on a number of factors and can be used to determine how different bacterial cultures compare with regard to resistance to cell death. In this way, the efficacy of potential immune-based therapeutics can be assessed against specific bacterial strains and/or serotypes. In this protocol, we describe a simplified OPKA that utilizes basic culture conditions and cell counting to determine bacterial cell viability after co-culture with treatment conditions and HL-60 immune cells. This method has been successfully utilized with a number of different pneumococcal serotypes, capsular and acapsular strains, and other bacterial species. The advantages of this OPKA protocol are its simplicity, versatility (as this assay is not limited to antibody treatments as opsonins), and minimization of time and reagents to assess basic experimental groups.

This opsonophagocytic killing assay is used to compare the ability of phagocytic immune cells to respond to and kill bacteria based on different treatments and/or conditions. Classically, this assay serves as the gold&#160;standard for assessing effector functions of antibodies raised against a bacterium as opsonin.

Ensaio de matar Opsonophagocytic para avaliar as respostas imunológicas contra patógenos bacterianos

A key aspect of the immune response to bacterial colonization of the host is phagocytosis. An opsonophagocytic killing assay (OPKA) is an experimental ...

Visualization of Macrophage Lytic Cell Death During Mycobacterial Infection in Zebrafish Embryos via Intravital Microscopy

Zebrafish is an excellent model organism for studying innate immune cell behavior due to its transparent nature and reliance solely on its innate immune system during early development. The Zebrafish Mycobacterium marinum (M. marinum) infection model has been well-established in studying host immune response against mycobacterial infection. It has been suggested that different macrophage cell death types will lead to the diverse outcomes of mycobacterial infection. Here we describe a protocol using intravital microscopy to observe macrophage cell death in zebrafish embryos following M. marinum infection. Zebrafish transgenic lines that specifically label macrophages and neutrophils are infected via intramuscular microinjection of fluorescently labeled M. marinum in either the midbrain or the trunk. Infected zebrafish embryos are subsequently mounted on low melting agarose and observed by confocal microscopy in X-Y-Z-T dimensions. Because long-term live imaging requires using low laser power to avoid photobleaching and phototoxicity, a strongly expressing transgenic is highly recommended. This protocol facilitates the visualization of the dynamic processes in vivo, including immune cell migration, host pathogen interaction, and cell death.

This protocol describes a technique for visualizing macrophage behavior and death in embryonic zebrafish during Mycobacterium marinum infection. Steps for the preparation of bacteria, infection of the embryos, and intravital microscopy are included. This technique may be applied to the observation of cellular behavior and death in similar scenarios involving infection or sterile inflammation.

Visualização da morte de células ticas de macrófago durante infecção micobacteriana em embriões de zebrafish via microscopia intravital

Zebrafish is an excellent model organism for studying innate immune cell behavior due to its transparent nature and reliance solely on its innate immune ...

Determination of Chemical Inhibitor Efficiency against Intracellular Toxoplasma Gondii Growth Using a Luciferase-Based Growth Assay

Toxoplasma gondii is a protozoan pathogen that widely affects the human population. The current antibiotics used for treating clinical toxoplasmosis are limited. In addition, they exhibit adverse side effects in certain groups of people. Therefore, discovery of novel therapeutics for clinical toxoplasmosis is imperative. The first step of novel antibiotic development is to identify chemical compounds showing high efficacy in inhibition of parasite growth using a high throughput screening strategy. As an obligate intracellular pathogen, Toxoplasma can only replicate within host cells, which prohibits the use of optical absorbance measurements as a quick indicator of growth. Presented here is a detailed protocol for a luciferase-based growth assay. As an example, this method is used to calculate the doubling time of wild-type Toxoplasma parasites and measure the efficacy of morpholinurea-leucyl-homophenyl-vinyl sulfone phenyl (LHVS, a cysteine protease-targeting compound) regarding inhibition of parasite intracellular growth. Also described, is a CRISPR-Cas9-based gene deletion protocol in Toxoplasma using 50 bp homologous regions for homology-dependent recombination (HDR). By quantifying the inhibition efficacies of LHVS in wild-type and TgCPL (Toxoplasma cathepsin L-like protease)-deficient parasites, it is shown that LHVS inhibits wild-type parasite growth more efficiently than &#916;cpl growth, suggesting that TgCPL is a target that LHVS binds to in Toxoplasma. The high sensitivity and easy operation of this luciferase-based growth assay make it suitable for monitoring Toxoplasma proliferation and evaluating drug efficacy in a high throughput manner.

Determination of Chemical Inhibitor Efficiency against Intracellular Toxoplasma Gondii Growth Using a Luciferase-Based Growth Assay

Presented here is a protocol to evaluate the inhibition efficacy of chemical compounds against in vitro intracellular growth of Toxoplasma gondii using a luciferase-based growth assay. The technique is used to confirm inhibition specificity by genetic deletion of the corresponding target gene. The inhibition of LHVS against TgCPL protease is evaluated as an example.

Determinação da eficiência do inibidor químico contra o crescimento intracelular toxoplasma Gondii usando um ensaio de crescimento baseado em luciferase

Toxoplasma gondii is a protozoan pathogen that widely affects the human population. The current antibiotics used for treating clinical toxoplasmosis are ...