Esta investigación fue financiada por una beca de Wellcome Trust Superior otorgó a Ian Goodfellow, y una beca Marie Curie Intra Europea (7PM Consejo Europeo de Investigación) otorgado a Armando Arias. Nos gustaría dar las gracias a Io Hong Cheong, la Dra. Rebecca Robey y el Dr. Mike Skinner por darnos permiso para usar su Bioanalyser Agilent y ayudar con el funcionamiento de las muestras de ARN.

<ol>
	<li>. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Outbreaks+of+gastroenteritis+associated+with+noroviruses+on+cruise+ships--United+States.">Outbreaks of gastroenteritis associated with noroviruses on cruise ships--United States.</a> MMWR Morb. Mortal. Wkly. Rep. 51, 1112-1115 (2002).</li><li>Lopman, B. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Epidemiology+and+cost+of+nosocomial+gastroenteritis,+Avon,+England,+2002-2003.">Epidemiology and cost of nosocomial gastroenteritis, Avon, England, 2002-2003.</a> Emerg. Infect. Dis. 10, 2002-2003 (2004).</li><li>Duizer, E. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Laboratory+efforts+to+cultivate+noroviruses.">Laboratory efforts to cultivate noroviruses.</a> J. Gen. Virol. 85, 79-87 (2004).</li><li>Karst, S. M., Wobus, C. E., Lay, M., Davidson, J., Virgin, H. W. T. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=STAT1-dependent+innate+immunity+to+a+Norwalk-like+virus.">STAT1-dependent innate immunity to a Norwalk-like virus.</a> Science. 299, 1575-1575 (2003).</li><li>Wobus, C. E. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Replication+of+Norovirus+in+cell+culture+reveals+a+tropism+for+dendritic+cells+and+macrophages.">Replication of Norovirus in cell culture reveals a tropism for dendritic cells and macrophages.</a> PLoS Biol. 2, e432 (2004).</li><li>Bok, K. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Inhibition+of+norovirus+replication+by+morpholino+oligomers+targeting+the+5'-end+of+the+genome.">Inhibition of norovirus replication by morpholino oligomers targeting the 5'-end of the genome.</a> Virology. 380, 328-337 (2008).</li><li>Kim, Y., Thapa, M., Hua, D. H., Chang, K. O. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Biodegradable+nanogels+for+oral+delivery+of+interferon+for+norovirus+infection.">Biodegradable nanogels for oral delivery of interferon for norovirus infection.</a> Antiviral Res. 89, 165-173 (2011).</li><li>McFadden, N. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Norovirus+Regulation+of+the+Innate+Immune+Response+and+Apoptosis+Occurs+via+the+Product+of+the+Alternative+Open+Reading+Frame+4.">Norovirus Regulation of the Innate Immune Response and Apoptosis Occurs via the Product of the Alternative Open Reading Frame 4.</a> PLoS Pathog. 7, e1002413 (2011).</li><li>Kormelink, R., van Poelwijk, F., Peters, D., Goldbach, R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Non-viral+heterogeneous+sequences+at+the+5'+ends+of+tomato+spotted+wilt+virus+mRNAs.">Non-viral heterogeneous sequences at the 5' ends of tomato spotted wilt virus mRNAs.</a> J. Gen. Virol. 73, 2125-2128 (1992).</li><li>Shuman, S., Hurwitz, J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Mechanism+of+mRNA+capping+by+vaccinia+virus+guanylyltransferase:+characterization+of+an+enzyme--guanylate+intermediate.">Mechanism of mRNA capping by vaccinia virus guanylyltransferase: characterization of an enzyme--guanylate intermediate.</a> Proc. Natl. Acad. Sci. U.S.A. 78, 187-191 (1981).</li><li>Jang, S. K., Pestova, T. V., Hellen, C. U., Witherell, G. W., Wimmer, E. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Cap-independent+translation+of+picornavirus+RNAs:+structure+and+function+of+the+internal+ribosomal+entry+site.">Cap-independent translation of picornavirus RNAs: structure and function of the internal ribosomal entry site.</a> Enzyme. 44, 292-309 (1990).</li><li>Chaudhry, Y. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Caliciviruses+differ+in+their+functional+requirements+for+eIF4F+components.">Caliciviruses differ in their functional requirements for eIF4F components.</a> J. Biol. Chem. 281, 25315-25325 (2006).</li><li>Goodfellow, I. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Calicivirus+translation+initiation+requires+an+interaction+between+VPg+and+eIF+4.">Calicivirus translation initiation requires an interaction between VPg and eIF 4.</a> E. EMBO Rep. 6, 968-972 (2005).</li><li>Herbert, T. P., Brierley, I., Brown, T. D. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Identification+of+a+protein+linked+to+the+genomic+and+subgenomic+mRNAs+of+feline+calicivirus+and+its+role+in+translation.">Identification of a protein linked to the genomic and subgenomic mRNAs of feline calicivirus and its role in translation.</a> J. Gen. Virol. 78 ( Pt5 ), 1033-1040 (1997).</li><li>Chaudhry, Y., Skinner, M. A., Goodfellow, I. G. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Recovery+of+genetically+defined+murine+norovirus+in+tissue+culture+by+using+a+fowlpox+virus+expressing+T7+RNA+polymerase.">Recovery of genetically defined murine norovirus in tissue culture by using a fowlpox virus expressing T7 RNA polymerase.</a> J. Gen. Virol. 88, 2091-20100 (2007).</li><li>Ward, V. K. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Recovery+of+infectious+murine+norovirus+using+pol+II-driven+expression+of+full-length+cDNA.">Recovery of infectious murine norovirus using pol II-driven expression of full-length cDNA.</a> Proc. Natl. Acad. Sci. U.S.A. 104, 11050-11055 (2007).</li><li>Yunus, M. A., Chung, L. M., Chaudhry, Y., Bailey, D., Goodfellow, I. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Development+of+an+optimized+RNA-based+murine+norovirus+reverse+genetics+system.">Development of an optimized RNA-based murine norovirus reverse genetics system.</a> J. Virol. Methods. 169, 112-118 (2010).</li><li>Arias, A., Perales, C., Escarmis, C., Domingo, E. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Deletion+mutants+of+VPg+reveal+new+cytopathology+determinants+in+a+picornavirus.">Deletion mutants of VPg reveal new cytopathology determinants in a picornavirus.</a> PLoS One. 5, e10735 (2010).</li><li>Werf, S. v. a. n. d. e. r., Bradley, J., Wimmer, E., Studier, F. W., Dunn, J. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Synthesis+of+infectious+poliovirus+RNA+by+purified+T7+RNA+polymerase.">Synthesis of infectious poliovirus RNA by purified T7 RNA polymerase.</a> Proc. Natl. Acad. Sci. U.S.A. 83, 2330-2334 (1986).</li><li>Bailey, D., Thackray, L. B., Goodfellow, I. G. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+single+amino+acid+substitution+in+the+murine+norovirus+capsid+protein+is+sufficient+for+attenuation+in+vivo.">A single amino acid substitution in the murine norovirus capsid protein is sufficient for attenuation in vivo.</a> J. Virol. 82, 7725-7728 (2008).</li><li>Bailey, D. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Functional+analysis+of+RNA+structures+present+at+the+3'+extremity+of+the+murine+norovirus+genome:+the+variable+polypyrimidine+tract+plays+a+role+in+viral+virulence.">Functional analysis of RNA structures present at the 3' extremity of the murine norovirus genome: the variable polypyrimidine tract plays a role in viral virulence.</a> J. Virol. 84, 2859-2870 (2010).</li></ol>

No tenemos nada que revelar.

Aquí se han puesto de manifiesto dos diferentes enfoques de genética inversa que permiten la recuperación de MNV infecciosa en cultivo celular. Ambos se aproxima efectivamente omitir el requisito absoluto para el ligamiento covalente de VPg al extremo 5 &#39;del genoma viral ARN a través de la generación de cubiertas de transcripciones MNV que luego son reconocidos por los ribosomas celulares. En la transcripción in vitro seguido por enzimáticamente nivelación es más eficiente en la recuperación de MNV infeccioso que la transcripción de los plásmidos infecciosos en las células que expresan la RNA polimerasa T7, en el que las transcripciones puede estar cubierto por las enzimas FPV de tapado. Los títulos de virus recuperados con estos sistemas de ida genética son similares a los obtenidos por transfección de virales VPg ligados ARN purificados a partir de cultivos de células infectadas 17 (Figura 5). La transfección de ARN tope MNV en células permisivas RAW264.7 hace sólo un título vírico 1-registro más bajo que los experimentos que implican la transfection de RNA total de células infectadas contienen viral VPg ligado ARN (Figura 5). Este hecho alienta investigaciones adicionales para determinar si la adición de una molécula VPg al extremo 5 &#39;de los transcritos generados por estos sistemas podrían resultar en rendimientos de virus de aumento, que pueden revelar aspectos funcionales subyacentes infectividad MNV en células asociadas a VPg. Sin embargo, consideramos que este sistema de genética inversa como una alta eficiencia comparable a la de otros virus de ARN de revertir los sistemas de la genética en la actualidad en el cual el ARN transcrito in vitro permite la recuperación de los títulos de sólo 10-100 más bajos que en las infecciones reales con viriones 19, 20. En general, las metodologías actuales constituyen un importante paso adelante en el campo de la biología molecular de los norovirus y nos proporcionan las herramientas para investigar el papel funcional de las proteínas y los motivos conservados en los genomas de ARN de norovirus. Estos enfoques han sido combinadas con cmodelo de ratón urrent disponibles y han demostrado que el MNV se recuperó de cDNA infeccioso es capaz de causar una infección letal de&gt; 80% STAT1-/ - ratones en menos de 10 días 4, 21. Haciendo uso de este sistema hemos recuperado mutantes viables norovirus murino de la proteína de la cápside y de una zona polypyrimidine implicado en la unión de los diferentes factores del huésped (PTB y PCBP) que muestran un fenotipo atenuado in vivo 21, 22. Además, recientemente se ha demostrado que los virus que carecen de la capacidad de expresar la proteína VF1 de ORF4 eficientemente replicar en cultivo celular, pero de nuevo han reducido la virulencia en ratones con respecto a WT MNV 8. Estos estudios nos animan a diseñar versiones atenuadas de los norovirus humanos basados ​​en estudios de MNV que podrían ser investigados como candidatos potenciales para la vacuna.

<table border="1"><tbody><tr><td> Nombre del reactivo </td><td> Empresa </td><td> Número de catálogo </td></tr><tr><td> Cloruro de litio precipitación solución </td><td> Ambion </td><td> AM9480 </td></tr><tr><td> ARN solución de almacenamiento </td><td> Ambion </td><td> AM7000 </td></tr><tr><td> Megascript T7 secuencia de comandos </td><td> Ambion </td><td> AM1333 </td></tr><tr><td> ScriptCap m7G Sistema de nivelación </td><td> Epicentro Biotecnologías </td><td> SCCE0610 </td></tr><tr><td> Sistema de transfección de neón </td><td> Invitrogen </td><td> MPK5000 </td></tr><tr><td> Transfección de neón kit de sistema de </td><td> Invitrogen </td><td> MPK1025 </td></tr><tr><td> Opti-MEM I </td><td> Invitrogen </td><td> 31985070 </td></tr><tr><td> Lipofectamine 2000 transfección reactivo </td><td> Invitrogen </td><td> 11668-027 </td></tr><tr><td> Agilent ARN 600 kit de Nano </td><td> Agilent </td><td> 5067-1511 </td></tr><tr><td> Agilent 2100 bioanalyzer </td><td> Agilent </td><td> G2939AA </td></tr><tr><td> Illustra GFX PCR DNA y Gel Band Purification Kit </td><td> GE Healthcare </td><td> 28-9034-70 </td></tr><tr><td> RiboMAX a gran escala de ARN Sistema de Producción-T7 </td><td> Promega </td><td> P1300 </td></tr></tbody></table>

reverse genetics mediated recovery of infectious murine norovirus

Norovirus humanos son responsables de la mayoría de los casos de gastroenteritis humana (GE) en todo el mundo y son un problema recurrente en los entornos en los que cerca de persona a persona de contacto no pueden ser evitados 1, 2. Durante los últimos años un aumento en la incidencia de los brotes en hospitales se ha informado, causando trastornos significativos en su capacidad operativa, así como grandes pérdidas económicas. La identificación de nuevos enfoques antivirales se ha limitado debido a la incapacidad de los norovirus humanos para completar una infección productiva en cultivo celular 3. El aislamiento reciente de un norovirus murino (MNV), estrechamente relacionado con el norovirus humanos 4, pero que se puede propagar en las células 5 ha abierto nuevas vías para la investigación de estos patógenos 6, 7. MNV resultados de replicación en la síntesis de nuevo genómico sentido positivo y moléculas de ARN subgenómico, el último de los cuales corresponde a la última thiRD del genoma viral (Figura 1). MNV contiene cuatro diferentes marcos de lectura abierta (ORF), de los cuales ORF1 ocupa la mayor parte del genoma y codifica siete proteínas no estructurales (NS1-7) liberados de un precursor de poliproteína. ORF2 y ORF3 están contenidas dentro de la región subgenómico ARN y codificar las proteínas de la cápside (VP1 y VP2, respectivamente) (Figura 1). Recientemente, hemos identificado que ORF4 adicional superposición ORF2, pero en un marco de lectura diferente es funcional y codifica para un factor de virulencia mitocondrial localizada (VF1) 8. La replicación de los virus de ARN de sentido positivo, incluyendo los norovirus, tiene lugar en el citoplasma que resulta en la síntesis de nuevos niveladas genomas de ARN. Para promover la traducción viral, los virus explotan diferentes estrategias dirigidas a la contratación de la maquinaria de síntesis proteica celular 11.9. Curiosamente, la traducción norovirus es impulsado por el multifuncional proteína viral-cebador VPgcovalentemente al extremo 5 &#39;final de ambos RNAs genómicos y subgenómico 12-14. Este mecanismo sofisticado de la traducción es probable que sea un factor importante en la eficiencia limitada de recuperación viral mediante enfoques convencionales inversa genética. Aquí mostramos dos estrategias diferentes en función de la generación de norovirus murino-1 (conocida como la presente MNV) transcripciones de un límite máximo en el extremo 5 &#39;. Uno de los métodos implica tanto en la síntesis in vitro y la nivelación de ARN viral, mientras que el segundo enfoque implica la transcripción de MNV ADNc en células que expresan la RNA polimerasa T7. La disponibilidad de estos sistemas de genética inversa para el estudio de MNV y un modelo de animal pequeño ha proporcionado una capacidad sin precedentes para diseccionar el papel de las secuencias virales en la replicación y la patogénesis de 15-17.

Watch this Scientific Journal Video about Reverse Genetics Mediated Recovery of Infectious Murine Norovirus at JoVE.com

Reverse Genetics Mediated Recovery of Infectious Murine Norovirus

Los norovirus son la causa principal de gastroenteritis sin embargo, las técnicas moleculares para su caracterización son todavía relativamente nuevos. Aquí mostramos dos diferentes enfoques genética inversa para la recuperación eficiente de los norovirus murino (MNV), el único miembro de este género, que puede ser propagado en cultivos celulares.

Recuperación Genética inversa mediada por norovirus murino Infecciosas

Human noroviruses are responsible for most cases of human gastroenteritis (GE) worldwide and are recurrent problem in environments where close ...

reverse-genetics-mediated-recovery-of-infectious-murine-norovirus

Research

JoVE Journal

Immunology and Infection

16.5K vistas.  Imperial College London. Los norovirus son la causa principal de gastroenteritis sin embargo, las técnicas moleculares para su caracterización son todavía relativamente nuevos. Aquí mostramos dos diferentes enfoques genética inversa para la recuperación eficiente de los norovirus murino (MNV), el único miembro de este género, que puede ser propagado en cultivos celulares.

Video: Reverse Genetics Mediated Recovery of Infectious Murine Norovirus

Using Reverse Genetics to Manipulate the NSs Gene of the Rift Valley Fever Virus MP-12 Strain to Improve Vaccine Safety and Efficacy

Rift Valley fever virus (RVFV), which causes hemorrhagic fever, neurological disorders or blindness in humans, and a high rate abortion and fetal malformation in ruminants1, has been classified as a HHS/USDA overlap select agent and a risk group 3 pathogen. It belongs to the genus Phlebovirus in the family Bunyaviridae and is one of the most virulent members of this family. Several reverse genetics systems for the RVFV MP-12 vaccine strain2,3 as well as wild-type RVFV strains 4-6, including ZH548 and ZH501, have been developed since 2006. The MP-12 strain (which is a risk group 2 pathogen and a non-select agent) is highly attenuated by several mutations in its M- and L-segments, but still carries virulent S-segment RNA3, which encodes a functional virulence factor, NSs. The rMP12-C13type (C13type) carrying 69% in-frame deletion of NSs ORF lacks all the known NSs functions, while it replicates as efficient as does MP-12 in VeroE6 cells lacking type-I IFN. NSs induces a shut-off of host transcription including interferon (IFN)-beta mRNA7,8 and promotes degradation of double-stranded RNA-dependent protein kinase (PKR) at the post-translational level.9,10 IFN-beta is transcriptionally upregulated by interferon regulatory factor 3 (IRF-3), NF-kB and activator protein-1 (AP-1), and the binding of IFN-beta to IFN-alpha/beta receptor (IFNAR) stimulates the transcription of IFN-alpha genes or other interferon stimulated genes (ISGs)11, which induces host antiviral activities, whereas host transcription suppression including IFN-beta gene by NSs prevents the gene upregulations of those ISGs in response to viral replication although IRF-3, NF-kB and activator protein-1 (AP-1) can be activated by RVFV7. . Thus, NSs is an excellent target to further attenuate MP-12, and to enhance host innate immune responses by abolishing the IFN-beta suppression function. Here, we describe a protocol for generating a recombinant MP-12 encoding mutated NSs, and provide an example of a screening method to identify NSs mutants lacking the function to suppress IFN-beta mRNA synthesis. In addition to its essential role in innate immunity, type-I IFN is important for the maturation of dendritic cells and the induction of an adaptive immune response12-14. Thus, NSs mutants inducing type-I IFN are further attenuated, but at the same time are more efficient at stimulating host immune responses than wild-type MP-12, which makes them ideal candidates for vaccination approaches.

The reverse genetics system for the Rift Valley fever virus MP-12 vaccine strain is a useful tool for creating additional MP-12 mutants with increased attenuation and immunogenicity. We describe the protocol to generate and characterize NSs mutant strains.

Mediante genética inversa para manipular el gen de Sociedades Nacionales del virus de la fiebre de Rift Valley MP-12 Cepa para mejorar la seguridad de la vacuna y la eficacia

Rift Valley fever virus (RVFV), which causes hemorrhagic fever, neurological disorders or blindness in humans, and a high rate abortion and fetal ...

Investigación

Inmunología e Infección

Plaque Assay for Murine Norovirus

Murine norovirus (MNV) is the only member of the Norovirus genus that efficiently grows in tissue culture 1, 2. Cell lysis and cytopathic effect (CPE) are observed during MNV-1 infection of murine dendritic cells or macrophages 1. This property of MNV-1 can be used to quantify the number of infectious particles in a given sample by performing a plaque assay 1. The plaque assay relies on the ability of MNV-1 to lyse cells and to form holes in a confluent cell monolayer, which are called plaques 3.
Multiple techniques can be used to detect viral infections in tissue culture, harvested tissue, clinical, and environmental samples, but not all measure the number of infectious particles (e.g. qRT-PCR). One way to quantify infectious viral particles is to perform a plaque assay 3, which will be described in detail below. A variation on the MNV plaque assay is the fluorescent focus assay, where MNV antigen is immunostained in cell monolayers 4. This assay can be faster, since viral antigen expression precedes plaque formation. It is also useful for titrating viruses unable to form plaques. However, the fluorescent focus assay requires additional resources beyond those of the plaque assay, such as antibodies and a microscope to count focus-forming units. Infectious MNV can also be quantified by determining the 50% Tissue Culture Infective Dose (TCID50) 3. This assay measures the amount of virus required to produce CPE in 50% of inoculated tissue culture cells by endpoint titration 5. However, its limit of detection is higher compared to a plaque assay 4.
In this article, we describe a plaque assay protocol that can be used to effectively determine the number of infectious MNV particles present in biological or environmental samples 1, 4, 6. This method is based on the preparation of 10-fold serial dilutions of MNV-containing samples, which are used to inoculate a monolayer of permissive cells (RAW 264.7 murine macrophage cells). Virus is allowed to attach to the cell monolayer for a given period of time and then aspirated before covering cells with a mixture of agarose and cell culture media. The agar enables the spread of viral progeny to neighboring cells while limiting spread to distantly located cells. Consequently, infected cells are lysed and form holes in the monolayer known as plaques. Upon sufficient spread of virus, plaques become visible following staining of cells with dyes, like neutral red, methylene blue, or crystal violet. At low dilutions, each plaque originates from one infectious viral particle and its progeny, which spread to neighboring cells. Thus, counting the number of plaques allows one to calculate plaque-forming units (PFU) present in the undiluted sample 3.

Here we describe a method to quantify infectious particles of murine norovirus (MNV), which is the only norovirus that efficiently replicates in cell culture. The plaque assay takes advantage of MNV&#x2019;s tropism for murine macrophages and can be adapted for use with biological or environmental samples containing MNV.

Placa de Ensayo para Norovirus murino

Murine norovirus (MNV) is the only member of the Norovirus genus that efficiently grows in tissue culture 1, 2. Cell lysis and cytopathic effect (CPE) are ...

Isolating And Immunostaining Lymphocytes and Dendritic Cells from Murine Peyer's Patches

Peyer's patches (PPs) are integral components of the gut-associated lymphoid tissues (GALT) and play a central role in intestinal immunosurveillance and homeostasis. Particulate antigens and microbes in the intestinal lumen are continuously sampled by PP M cells in the follicle-associated epithelium (FAE) and transported to an underlying network of dendritic cells (DCs), macrophages, and lymphocytes. In this article, we describe protocols in which murine PPs are (i) dissociated into single cell suspensions and subjected to flow cytometry and (ii) prepared for cryosectioning and immunostaining. For flow cytometry, PPs are mechanically dissociated and then filtered through 70 &mu;m membranes to generate single cell suspensions free of epithelial cells and large debris. Starting with 20-25 PPs (from four mice), this quick and reproducible method yields a population of &gt;2.5 x 106 cells with &gt;90% cell viability. For cryosectioning, freshly isolated PPs are immersed in Optimal Cutting Temperature (OCT) medium, snap-frozen in liquid nitrogen, and then sectioned using a cryomicrotome. Tissue sections (5-12 &mu;m) are air-dried, fixed with acetone or methanol, and then subjected to immunolabeling.

Isolating And Immunostaining Lymphocytes and Dendritic Cells from Murine Peyer&#039;s Patches

There is an increasing interest in understanding the immunological functions of specific subpopulations of cells in Peyer's patches (PPs), the primary inductive sites of gut-associated lymphoid tissues. Here we outline parallel protocols for preparing PP single cell preparations for flow cytometric analysis and PP cryosections for immunostaining.

Aislar y inmunoticción Los linfocitos y las células dendríticas de las placas de Peyer murinas de

Peyer's  patches (PPs) are integral components of the gut-associated lymphoid tissues  (GALT) and play a central role in intestinal immunosurveillance and ...

VIGS-Mediated Forward Genetics Screening for Identification of Genes Involved in Nonhost Resistance

Nonhost disease resistance of plants against bacterial pathogens is controlled by complex defense pathways. Understanding this mechanism is important for developing durable disease-resistant plants against wide range of pathogens. Virus-induced gene silencing (VIGS)-based forward genetics screening is a useful approach for identification of plant defense genes imparting nonhost resistance. Tobacco rattle virus (TRV)-based VIGS vector is the most efficient VIGS vector to date and has been efficiently used to silence endogenous target genes in Nicotiana benthamiana.

	In this manuscript, we demonstrate a forward genetics screening approach for silencing of individual clones from a cDNA library in N. benthamiana and assessing the response of gene silenced plants for compromised nonhost resistance against nonhost pathogens, Pseudomonas syringae pv. tomato T1, P. syringae pv. glycinea, and X. campestris pv. vesicatoria. These bacterial pathogens are engineered to express GFPuv protein and their green fluorescing colonies can be seen by naked eye under UV light in the nonhost pathogen inoculated plants if the silenced target gene is involved in imparting nonhost resistance. This facilitates reliable and faster identification of gene silenced plants susceptible to nonhost pathogens. Further, promising candidate gene information can be known by sequencing the plant gene insert in TRV vector. Here we demonstrate the high throughput capability of VIGS-mediated forward genetics to identify genes involved in nonhost resistance. Approximately, 100 cDNAs can be individually silenced in about two to three weeks and their relevance in nonhost resistance against several nonhost bacterial pathogens can be studied in a week thereafter. In this manuscript, we enumerate the detailed steps involved in this screening. VIGS-mediated forward genetics screening approach can be extended not only to identifying genes involved in nonhost resistance but also to studying genes imparting several biotic and abiotic stress tolerances in various plant species.

Virus-induced gene silencing is an useful tool for identifying genes involved in nonhost resistance of plants. We demonstrate the use of bacterial pathogens expressing GFPuv in identifying gene silenced plants susceptible to nonhost pathogens. This approach is easy, fast and facilitates large scale screening and similar protocol can be applied to studying various other plant-microbe interactions.

VIGS mediada por delante de detección genética para la identificación de genes implicados en la resistencia no huésped


	Nonhost disease resistance of plants against bacterial pathogens is controlled by complex defense pathways. Understanding this mechanism is important ...

Organoids as Model for Infectious Diseases: Culture of Human and Murine Stomach Organoids and Microinjection of Helicobacter Pylori

Recently infection biologists have employed stem cell derived cultures to answer the need for new and better models to study host-pathogen interactions. Three cellular sources have been used: Embryonic stem cells (ESC), induced pluripotent stem cells (iPSC) or adult stem cells. Here, culture of mouse and human gastric organoids derived from adult stem cells is described and used for infection with the gastric pathogen Helicobacter pylori. Human gastric glands are isolated from resection material, seeded in a basement matrix and embedded in medium containing growth factors epidermal growth factor (EGF), R-spondin, Noggin, Wnt, fibroblast growth factor (FGF) 10, gastrin and transforming growth factor (TGF) beta inhibitor. In these conditions, gastric glands grow into 3-dimensional organoids containing 4 lineages of the stomach. The organoids expand indefinitely and can be frozen and thawed similarly as cell lines. For infection studies, bacteria are microinjected into the lumen of the organoids. Infected organoids are processed for imaging. The described methods can be adapted to other organoids and infections with other bacteria, viruses or parasites. This allows the study of infection-induced changes in primary cells.

Stem cell derived cultures harbor tremendous potential to model infectious diseases. Here, the culture of mouse and human gastric organoids derived from adult stem cells is described. The organoids are microinjected with the gastric pathogen Helicobacter pylori.

Organoides como Modelo para Enfermedades Infecciosas: Cultura de Derechos Humanos y organoides estomacales murinos y microinyección de Helicobacter Pylori

Recently infection biologists have employed stem cell derived cultures to answer the need for new and better models to study host-pathogen interactions. ...

Isolation and Flow Cytometric Characterization of Murine Small Intestinal Lymphocytes

The intestines &#8212; which contain the largest number of immune cells of any organ in the body &#8212; are constantly exposed to foreign antigens, both microbial and dietary. Given an increasing understanding that these luminal antigens help shape the immune response and that education of immune cells within the intestine is critical for a number of systemic diseases, there has been increased interest in characterizing the intestinal immune system. However, many published protocols are arduous and time-consuming. We present here a simplified protocol for the isolation of lymphocytes from the small-intestinal lamina propria, intraepithelial layer, and Peyer&#39;s patches that is rapid, reproducible, and does not require laborious Percoll gradients. Although the protocol focuses on the small intestine, it is also suitable for analysis of the colon. Moreover, we highlight some aspects that may need additional optimization depending on the specific scientific question. This approach results in the isolation of large numbers of viable lymphocytes that can subsequently be used for flow cytometric analysis or alternate means of characterization.

There is growing interest in the quantitative characterization of intestinal lymphocytes owing to increasing recognition that these cells play a critical role in a variety of intestinal and systemic diseases. In this protocol, we describe how to isolate single cell populations from different small-intestinal compartments for subsequent flow cytometric characterization.

El aislamiento y la citometría de flujo Caracterización de murino Small intestinal linfocitos

The intestines &#8212; which contain the largest number of immune cells of any organ in the body &#8212; are constantly exposed to foreign antigens, both ...

Swab Sampling Method for the Detection of Human Norovirus on Surfaces

Human noroviruses are a leading cause of epidemic and sporadic gastroenteritis worldwide. Because most infections are either spread directly via the person-to-person route or indirectly through environmental surfaces or food, contaminated fomites and inanimate surfaces are important vehicles for the spread of the virus during norovirus outbreaks.
We developed and evaluated a protocol using macrofoam swabs for the detection and typing of human noroviruses from hard surfaces. Compared with fiber-tipped swabs or antistatic wipes, macrofoam swabs allow virus recovery (range 1.2-33.6%) from toilet seat surfaces of up to 700 cm2. The protocol includes steps for the extraction of the virus from the swabs and further concentration of the viral RNA using spin columns. In total, 127 (58.5%) of 217 swab samples that had been collected from surfaces in cruise ships and long-term care facilities where norovirus gastroenteritis had been reported tested positive for GII norovirus by RT-qPCR. Of these 29 (22.8%) could be successfully genotyped. In conclusion, detection of norovirus on environmental surfaces using the protocol we developed may assist in determining the level of environmental contamination during outbreaks as well as detection of virus when clinical samples are not available; it may also facilitate monitoring of effectiveness of remediation strategies.

A macrofoam based sampling methodology was developed and evaluated for the detection and quantification of norovirus on environmental hard surfaces.

Método de muestreo hisopo para la Detección de norovirus humano en superficies

Human noroviruses are a leading cause of epidemic and sporadic gastroenteritis worldwide. Because most infections are either spread directly via the ...

A Method to Assess Fc-mediated Effector Functions Induced by Influenza Hemagglutinin Specific Antibodies

Antibodies play a crucial role in coupling the innate and adaptive immune responses against viral pathogens through their antigen binding domains and Fc-regions. Here, we describe how to measure the activation of Fc effector functions by monoclonal antibodies targeting the influenza virus hemagglutinin with the use of a genetically engineered Jurkat cell line expressing an activating type 1 Fc-Fc&#947;R. Using this method, the contribution of specific Fc-Fc&#947;R interactions conferred by immunoglobulins can be determined using an in vitro assay.

We describe a method to measure the activation of Fc-mediated effector functions by antibodies that target the influenza virus hemagglutinin. This assay can also be adapted to assess the ability of monoclonal antibodies or polyclonal sera targeting other viral surface glycoproteins to induce Fc-mediated immunity.

Un método para evaluar las funciones efectoras mediadas por Fc inducidas por los anticuerpos específicos de la hemaglutinina de la gripe

Antibodies play a crucial role in coupling the innate and adaptive immune responses against viral pathogens through their antigen binding domains and ...

Isolating Lymphocytes from the Mouse Small Intestinal Immune System

The intestinal immune system plays an essential role in maintaining the barrier function of the gastrointestinal tract by generating tolerant responses to dietary antigens and commensal bacteria while mounting effective immune responses to enteropathogenic microbes. In addition, it has become clear that local intestinal immunity has a profound impact on distant and systemic immunity. Therefore, it is important to study how an intestinal immune response is induced and what the immunologic outcome of the response is. Here, a detailed protocol is described for the isolation of lymphocytes from small intestine inductive sites like the gut-associated lymphoid tissue Peyer&#39;s patches and the draining mesenteric lymph nodes and effector sites like the lamina propria and the intestinal epithelium. This technique ensures isolation of a large numbers of lymphocytes from small intestinal tissues with optimal purity and viability and minimal cross compartmental contamination within acceptable time constraints. The technical capability to isolate lymphocytes and other immune cells from intestinal tissues enables the understanding of immune responses to gastrointestinal infections, cancers, and inflammatory diseases.

Here we describe a detailed protocol for the isolation of lymphocytes from the inductive sites including the gut-associated lymphoid tissue Peyer&#39;s patches and the draining mesenteric lymph nodes, and the effector sites including the lamina propria and the intestinal epithelium of the small intestinal immune system.

Aislar los linfocitos desde el sistema de inmune Intestinal pequeño ratón

The intestinal immune system plays an essential role in maintaining the barrier function of the gastrointestinal tract by generating tolerant responses to ...

Preparation of Murine Submandibular Salivary Gland for Upright Intravital Microscopy

The submandibular salivary gland (SMG) is one of the three major salivary glands, and is of interest for many different fields of biological research, including cell biology, oncology, dentistry, and immunology. The SMG is an exocrine gland comprised of secretory epithelial cells, myofibroblasts, endothelial cells, nerves, and extracellular matrix. Dynamic cellular processes in the rat and mouse SMG have previously been imaged, mostly using inverted multi-photon microscope systems. Here, we describe a straightforward protocol for the surgical preparation and stabilization of the murine SMG in anesthetized mice for in vivo imaging with upright multi-photon microscope systems. We present representative intravital image sets of endogenous and adoptively transferred fluorescent cells, including the labeling of blood vessels or salivary ducts and second harmonic generation to visualize fibrillar collagen. In sum, our protocol allows for surgical preparation of mouse salivary glands in upright microscopy systems, which are commonly used for intravital imaging in the field of immunology.

We describe a protocol to surgically expose and stabilize the murine submandibular salivary gland for intravital imaging using upright intravital microscopy. This protocol is easily adaptable to other exocrine glands of the head and neck region of mice and other small rodents.

Preparación de glándula salival submaxilar murino para la microscopia Intravital vertical

The submandibular salivary gland (SMG) is one of the three major salivary glands, and is of interest for many different fields of biological research, ...