Nous remercions le personnel de l’installation de cytométrie de débit, de l’installation ABSL2 et de l’installation animale SPF de l’Institut Pasteur de Shanghai pour leur aide technique et leurs conseils. Ces travaux ont été soutenus par les subventions suivantes : Programme de recherche stratégique prioritaire de l’Académie chinoise des sciences (XDB29030103), Programme national de R-D de la Chine (2016YFA0502202), Fondation nationale des sciences naturelles de Chine (31570886).

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I., 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=Bcl6+mediates+the+development+of+T+follicular+helper+cells.">Bcl6 mediates the development of T follicular helper cells.</a> Science. 325 (5943), 1001-1005 (2009).</li><li>Yu, D., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+transcriptional+repressor+Bcl-6+directs+T+follicular+helper+cell+lineage+commitment.">The transcriptional repressor Bcl-6 directs T follicular helper cell lineage commitment.</a> Immunity. 31 (3), 457-468 (2009).</li><li>Pedros, C., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+TRAF-like+motif+of+the+inducible+costimulator+ICOS+controls+development+of+germinal+center+TFH+cells+via+the+kinase+TBK1.">A TRAF-like motif of the inducible costimulator ICOS controls development of germinal center TFH cells via the kinase TBK1.</a> Nature Immunology. 17 (7), 825-833 (2016).</li><li>Xu, H., 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=Follicular+T-helper+cell+recruitment+governed+by+bystander+B+cells+and+ICOS-driven+motility.">Follicular T-helper cell recruitment governed by bystander B cells and ICOS-driven motility.</a> Nature. 496 (7446), 523-527 (2013).</li><li>Lee, S. K., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=B+cell+priming+for+extrafollicular+antibody+responses+requires+Bcl-6+expression+by+T+cells.">B cell priming for extrafollicular antibody responses requires Bcl-6 expression by T cells.</a> The Journal of Experimental Medicine. 208 (7), 1377-1388 (2011).</li><li>Zotos, D., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=IL-21+regulates+germinal+center+B+cell+differentiation+and+proliferation+through+a+B+cell-intrinsic+mechanism.">IL-21 regulates germinal center B cell differentiation and proliferation through a B cell-intrinsic mechanism.</a> The Journal of Experimental Medicine. 207 (2), 365-378 (2010).</li><li>Vogelzang, 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=A+fundamental+role+for+interleukin-21+in+the+generation+of+T+follicular+helper+cells.">A fundamental role for interleukin-21 in the generation of T follicular helper cells.</a> Immunity. 29 (1), 127-137 (2008).</li><li>Ansel, K. M., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+chemokine-driven+positive+feedback+loop+organizes+lymphoid+follicles.">A chemokine-driven positive feedback loop organizes lymphoid follicles.</a> Nature. 406 (6793), 309-314 (2000).</li><li>Shi, J., 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=PD-1+Controls+Follicular+T+Helper+Cell+Positioning+and+Function.">PD-1 Controls Follicular T Helper Cell Positioning and Function.</a> Immunity. 49 (2), 264-274 (2018).</li><li>Methot, S. P., Di Noia, J. 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En raison de rôles spécialisés dans la fourniture d’aide à la cellule B pour la génération d’anticorps à haute affinité, les cellules tfh ont fait l’objet d’études approfondies dans les mécanismes de différenciation et de manipulation afin de fournir de nouvelles stratégies pour la conception du vaccin. L’infection par le virus grippal induit des réponses vigoureuses des cellules Tfh et GC B, ce qui est un modèle approprié pour ce domaine de recherche. Dans cet article, nous avons décrit des pro...

Au cours de la dernière décennie, de nombreuses études ont été axées sur le sous-ensemble de cellules CD4+ T nouvellement identifié, sous-ensemble de cellules Tfh, pour ses rôles essentiels dans le développement du centre germinal (GC) B. Le lymphome à cellules B 6 (Bcl6), qui est principalement considéré comme un répresseur génétique, est le facteur déterminant de la lignée des cellules tfh pour la preuve que l’expression ectopique de Bcl6 est suffisante pour conduire la différenciation de Tfh tandis que l’insuffisance de Bcl6 entraîne la disparition de la différenciation tfh1,2,3. Contrairement à d’autres sous-ensembles CD4+ T helper effectuant leur fonction effectrice par migration vers les sites de l’inflammation, les cellules Tfh fournissent l’aide de la cellule B principalement dans la zone folliculaire de la cellule B de la rate et du ganglion lymphatique. Les molécules co-stimulantes ICOS et CD40L jouent un rôle important dans l’interaction entre les cellules Tfh et GC B. Au cours de la différenciation tfh, l’ICOS transmet les signaux nécessaires des cellules B cognées et agit également comme un récepteur recevant des signaux de migration des cellules B du spectateur pour la localisation de la zone cellulaire B4,5. CD40L est un médiateur des signaux des cellules tfh pour la prolifération des cellules B et la survie6. Un autre facteur jouant le même rôle que CD40L est la cytokine IL21, qui est principalement sécrété par les cellules tfh. IL21 régule directement le développement et la production d’anticorps à haute affinité par les cellules GC B, mais son rôle dans la différenciation de Tfhest encore controversé 7,8. Pd-1 et CXCR5, qui sont maintenant les plus fréquemment utilisés dans l’identification des cellules tfh dans l’analyse de cytométrie de flux, jouent également un rôle important dans la différenciation et la fonction de ce sous-ensemble. CXCR5 est le récepteur de la chimiokine folliculaire à cellules B et médie la localisation des cellules tfh dans les follicules cellulaires B9. PD-1 est maintenant identifié non seulement pour avoir la fonction de guidage folliculaire, mais aussi transmettre des signaux critiques dans le processus de maturation d’affinité des cellules GC B10. Sur la base de ces résultats, l’évaluation de l’expression de ces molécules pourrait essentiellement refléter la maturation et la fonction des cellules tfh.
Gc est une structure microanatomique transitoire induite dans les organes lymphoïdes secondaires et fortement dépendante des cellules de Tfh, étant ainsi une lecture parfaite pour évaluer la réponse de Tfh. Dans GC, après réception des signaux 2010 par des cytokines et des molécules co-stimulantes, les cellules B sont soumises à la commutation de classe et à l’hypermutation somatique pour générer des anticorps à haute affinité11. La commutation différentielle de classe d’anticorps se produit dans le créneau différentiel de cytokine, dans lequel IL4 et IL21 induisent le commutation de classe IgG1 tandis que IFNγ induit le commutation de classe IgG212. Les cellules plasmatiques sont les producteurs d’anticorps sécrétés et sont des cellules différenciées en phase terminale. Comme les cellules Tfh, le développement de cellules B dans GC est associé à l’expression dynamique de nombreuses molécules significatives. Selon l’étude actuelle, les cellules GC B peuvent être identifiées comme B220+PNA+Fas+ ou B220+GL7 + Fas+celluleset cellules plasmatiques, par rapport à leurs précurseurs, l’expression downregulate de B220 et upregulate CD138 expression13. Qui plus est, ces deux caractéristiques peuvent être détectées dans l’analyse de cytométrie de flux et d’immunofluorescence, étant ainsi l’évaluation appropriée de la réponse de GC.
Des réponses cellulaires et humoristiques robustes sont induites dans l’infection par le virus de la grippe, les cellules Tfh et Th1 dominant la réponse des cellules CD4+ T14,ce qui en fait un modèle parfait pour l’étude de différenciation des cellules Tfh. La grippe A/Porto Rico/8/34 H1N1(PR8), qui est une souche couramment utilisée adaptée à la souris, est fréquemment utilisée dans cetteétude 14,15,16. Ici, nous décrivons quelques protocoles de base de l’essai tfh étude pertinente dans l’infection par le virus de la grippe: 1) l’inoculation intranasale du virus PR8; 2) cellules tfh spécifiques aux antigènes, cellules GC B et plasma et détection IL21 avec cytométrie d’écoulement; 3) visualisation histologique de GC ; 4) détection du titer d’anticorps antigène-spécifique dans le sérum avec ELISA. Ces protocoles fournissent les techniques nécessaires aux nouveaux chercheurs dans l’étude associée à Tfh.

<table border="1" fo:keep-together.within-page="1" fo:keep-with-next.within-page="always">
	<tbody>
		<tr>
			<td>Immunostaining of Tfh cells, NP-specific Tfh cells and Bcl-6</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>37% formaldehyde</td>
			<td>Sigma</td>
			<td>F1635</td>
			<td></td>
		</tr>
		<tr>
			<td>Anti-CD16/32 mouse</td>
			<td>Thermo Fisher Scientific</td>
			<td>14-0161-86</td>
			<td></td>
		</tr>
		<tr>
			<td>APC-conjugated-IAbNP311-325 MHC class II tetramer</td>
			<td>NIH</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Bcl-6 PE</td>
			<td>Biolegend</td>
			<td>358504</td>
			<td>clone:7D1</td>
		</tr>
		<tr>
			<td>Biotin-CXCR5</td>
			<td>Thermo Fisher Scientific</td>
			<td>13-7185-82</td>
			<td>clone: SPRCL5</td>
		</tr>
		<tr>
			<td>CD4 Percp-eFluor 710</td>
			<td>Thermo Fisher Scientific</td>
			<td>46-0041-82</td>
			<td>clone:GK1.5</td>
		</tr>
		<tr>
			<td>CD44 eVolve 605</td>
			<td>Thermo Fisher Scientifi</td>
			<td>83-0441-42</td>
			<td>clone:IM7</td>
		</tr>
		<tr>
			<td>CD44 FITC</td>
			<td>Thermo Fisher Scientifi</td>
			<td>11-0441-82</td>
			<td>clone:IM7</td>
		</tr>
		<tr>
			<td>CD62L FITC</td>
			<td>BD Pharmingen</td>
			<td>553150</td>
			<td>clone:MEL-14</td>
		</tr>
		<tr>
			<td>ICOS BV421</td>
			<td>Biolegend</td>
			<td>564070</td>
			<td>clone:7E.17G9</td>
		</tr>
		<tr>
			<td>PD1 PE/Cy7</td>
			<td>Biolegend</td>
			<td>135216</td>
			<td>clone:29F.1A12</td>
		</tr>
		<tr>
			<td>Streptavidin BV421</td>
			<td>BD Pharmingen</td>
			<td>563259</td>
			<td></td>
		</tr>
		<tr>
			<td>Streptavidin PE</td>
			<td>BD Pharmingen</td>
			<td>554081</td>
			<td></td>
		</tr>
		<tr>
			<td>Intracelluar staining of IL21</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>37% formaldehyde</td>
			<td>Sigma</td>
			<td>F1635</td>
			<td></td>
		</tr>
		<tr>
			<td>anti-human IgG</td>
			<td>Jackson ImmunoResearch Laboratories</td>
			<td>109-605-098</td>
			<td></td>
		</tr>
		<tr>
			<td>Brefeldin A</td>
			<td>Sigma</td>
			<td>B6542</td>
			<td></td>
		</tr>
		<tr>
			<td>human FCc IL-21 receptor</td>
			<td>R&#38;D System</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>ionomycin</td>
			<td>Sigma</td>
			<td>I0634</td>
			<td></td>
		</tr>
		<tr>
			<td>Live/Dead Fixable Aqua Dead Cell staining kit</td>
			<td>Thermo Fisher Scientific</td>
			<td>L34966</td>
			<td></td>
		</tr>
		<tr>
			<td>PMA</td>
			<td>Sigma</td>
			<td>P1585</td>
			<td></td>
		</tr>
		<tr>
			<td>Saponin</td>
			<td>MP</td>
			<td>102855</td>
			<td></td>
		</tr>
		<tr>
			<td>GC B and plasma cells staining</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>B220 APC</td>
			<td>Thermo Fisher Scientific</td>
			<td>17-0452-81</td>
			<td>clone:RA3-6B2</td>
		</tr>
		<tr>
			<td>CD138 PE</td>
			<td>BD Pharmingen</td>
			<td>561070</td>
			<td>clone:281-2</td>
		</tr>
		<tr>
			<td>CD95 (FAS) PE/Cy7</td>
			<td>BD Pharmingen</td>
			<td>557653</td>
			<td>clone:Jo2</td>
		</tr>
		<tr>
			<td>IgD eFluor 450</td>
			<td>Thermo Fisher Scientific</td>
			<td>48-5993-82</td>
			<td>clone:11-26c</td>
		</tr>
		<tr>
			<td>PNA FITC</td>
			<td>Sigma</td>
			<td>L7381</td>
			<td></td>
		</tr>
		<tr>
			<td>Assay of HA-specific antibody titer with ELISA</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>PR8-HA</td>
			<td>Sino Biological</td>
			<td>11684-V08H</td>
			<td></td>
		</tr>
		<tr>
			<td>BSA</td>
			<td>SSBC</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Goat anti mouse Ig (SBA Clonotyping System-HRP)</td>
			<td>SouthernBiotech</td>
			<td>5300-05</td>
			<td></td>
		</tr>
		<tr>
			<td>Goat anti mouse IgM (SBA Clonotyping System-HRP)</td>
			<td>SouthernBiotech</td>
			<td>5300-05</td>
			<td></td>
		</tr>
		<tr>
			<td>Goat anti mouse IgG1 (SBA Clonotyping System-HRP)</td>
			<td>SouthernBiotech</td>
			<td>5300-05</td>
			<td></td>
		</tr>
		<tr>
			<td>Goat anti mouse IgG2b (SBA Clonotyping System-HRP)</td>
			<td>SouthernBiotech</td>
			<td>5300-05</td>
			<td></td>
		</tr>
		<tr>
			<td>Goat anti mouse IgG2c (SBA Clonotyping System-HRP)</td>
			<td>SouthernBiotech</td>
			<td>5300-05</td>
			<td></td>
		</tr>
		<tr>
			<td>TMB Substrate Reagent Set</td>
			<td>BD Pharmingen</td>
			<td>555214</td>
			<td></td>
		</tr>
		<tr>
			<td>Histology</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Alexa Fluor 555-Goat-anti rat IgG</td>
			<td>Life Technology</td>
			<td>A21434</td>
			<td></td>
		</tr>
		<tr>
			<td>anti-mouse IgD</td>
			<td>Biolegend</td>
			<td>405702</td>
			<td></td>
		</tr>
		<tr>
			<td>biotinylated PNA</td>
			<td>Vector laboratories</td>
			<td>B-1075</td>
			<td></td>
		</tr>
		<tr>
			<td>dilute Alexa Fluor 488-streptavidin</td>
			<td>Life Technology</td>
			<td>S11223</td>
			<td></td>
		</tr>
		<tr>
			<td>normal goat serum</td>
			<td>SouthernBiotech</td>
			<td>0060-01</td>
			<td></td>
		</tr>
		<tr>
			<td>Pro-long gold antifade reagent</td>
			<td>Thermo Fisher Scientific</td>
			<td>P3630</td>
			<td></td>
		</tr>
		<tr>
			<td>STREPTAVIDIN/BIOTIN blocking kit</td>
			<td>Vector laboratories</td>
			<td>SP-2002</td>
			<td></td>
		</tr>
	</tbody>
</table>

evaluation of t follicular helper cells and germinal center response during influenza a virus infection in mice

Les cellules T Follicular Helper (Tfh) sont un sous-ensemble indépendant de cellules CD4+ T spécialisé dans le développement du centre germinal (GC) et la génération d’anticorps à haute affinité. Dans l’infection par le virus de la grippe, des réponses robustes des cellules Tfh et GC B sont induites pour faciliter l’éradication efficace du virus, ce qui confère un modèle de souris qualifié pour l’étude associée à Tfh. Dans cet article, nous avons décrit des protocoles dans la détection de la réponse immunitaire tfh-associée de base pendant l’infection de virus de grippe chez les souris. Ces protocoles comprennent : l’inoculation intranasale du virus grippal; coloration et analyse de cytométrie d’écoulement des cellules polyclonales et antigène-spécifiques de Tfh, des cellules de GC B et des cellules de plasma ; détection de l’immunofluorescence des PG; test immunosorbent lié aux enzymes (ELISA) de l’anticorps spécifique au virus de la grippe dans le sérum. Ces analyses quantifient essentiellement la différenciation et la fonction des cellules tfh dans l’infection par le virus de la grippe, fournissant ainsi une aide pour des études dans l’élucidation du mécanisme de différenciation et de la stratégie de manipulation.

Caractérisation de la morbidité des souris dans l’infection par le virus de la grippe Après l’infection par le virus de la grippe, les souris sont moins actives et anorexiques en raison d’une maladie, qui se reflète par une perte de poids grave, un symptôme couramment utilisé pour surveiller la morbidité dela souris 19. Comme le montre la figure 1a, les souris infectées par le virus PR8 ont commencé à perdre du poi...

Watch this Scientific Journal Video about Evaluation of T Follicular Helper Cells and Germinal Center Response During Influenza A Virus Infection in Mice at JoVE.com

Evaluation of T Follicular Helper Cells and Germinal Center Response During Influenza A Virus Infection in Mice

Cet article décrit les protocoles d’évaluation de la réponse de Tfh et de GC B dans le modèle murin de l’infection par le virus de la grippe.

Évaluation des cellules d’aide folliculaire t et de la réponse du Centre germinal pendant l’infection virale de la grippe A chez la souris

T Follicular Helper (Tfh) cells are an independent CD4+&#160;T cell subset specialized in providing help for germinal center (GC) development and ...

evaluation-t-follicular-helper-cells-germinal-center-response-during

Research

JoVE Journal

Immunology and Infection

5.1K vues.  University of Chinese Academy of Sciences. Cet article décrit les protocoles d’évaluation de la réponse de Tfh et de GC B dans le modèle murin de l’infection par le virus de la grippe.

Vidéo: Evaluation of T Follicular Helper Cells and Germinal Center Response During Influenza A Virus Infection in Mice

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

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

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

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

Utiliser l&#39;imagerie Bioluminescent chargé d&#39;enquêter sur une synergie entre Streptococcus pneumoniae Et virus Influenza A de souriceaux

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

Recherche

Immunologie et infection

In Vitro Analysis of Myd88-mediated Cellular Immune Response to West Nile Virus Mutant Strain Infection

An attenuated West Nile virus (WNV), a nonstructural (NS) 4B-P38G mutant, induced higher innate cytokine and T cell responses than the wild-type WNV in mice. Recently, myeloid differentiation factor 88 (MyD88) signaling was shown to be important for initial T cell priming and memory T cell development during WNV NS4B-P38G mutant infection. In this study, two flow cytometry-based methods &#8211; an in vitro T cell priming assay and an intracellular cytokine staining (ICS) &#8211; were utilized to assess dendritic cells (DCs) and T cell functions. In the T cell priming assay, cell proliferation was analyzed by flow cytometry following co-culture of DCs from both groups of mice with carboxyfluorescein succinimidyl ester (CFSE) - labeled CD4+ T cells of OTII transgenic mice. This approach provided an accurate determination of the percentage of proliferating CD4+ T cells with significantly improved overall sensitivity than the traditional assays with radioactive reagents. A microcentrifuge tube system was used in both cell culture and cytokine staining procedures of the ICS protocol. Compared to the traditional tissue culture plate-based system, this modified procedure was easier to perform at biosafety level (BL) 3 facilities. Moreover, WNV- infected cells were treated with paraformaldehyde in both assays, which enabled further analysis outside BL3 facilities. Overall, these in vitro immunological assays can be used to efficiently assess cell-mediated immune responses during WNV infection.

In Vitro Analysis of Myd88-mediated Cellular Immune Response to West Nile Virus Mutant Strain Infection

Two flow cytometry-based methods &#8211; an in vitro T cell priming assay and intracellular cytokine staining were utilized to measure antigen presenting capacity of dendritic cells and antigen-specific T cell responses to a West Nile virus mutant infection in mice.

Analyse in vitro de la réponse immunitaire cellulaire Myd88 médiation au virus du Nil occidental souche mutante Infection

An attenuated West Nile virus (WNV), a nonstructural (NS) 4B-P38G mutant, induced higher innate cytokine and T cell responses than the wild-type WNV in ...

Influenza Virus Propagation in Embryonated Chicken Eggs

Influenza infection is associated with about 36,000 deaths and more than 200,000 hospitalizations every year in the United States. The continuous emergence of new influenza virus strains due to mutation and re-assortment complicates the control of the virus and necessitates the permanent development of novel drugs and vaccines. The laboratory-based study of influenza requires a reliable and cost-effective method for the propagation of the virus. Here, a comprehensive protocol is provided for influenza A virus propagation in fertile chicken eggs, which consistently yields high titer viral stocks. In brief, serum pathogen-free (SPF) fertilized chicken eggs are incubated at 37 &#176;C and 55-60% humidity for 10 &#8211; 11 days. Over this period, embryo development can be easily monitored using an egg candler. Virus inoculation is carried out by injection of virus stock into the allantoic cavity using a needle. After 2 days of incubation at 37 &#176;C, the eggs are chilled for at least 4 hr at 4 &#176;C. The eggshell above the air sac and the chorioallantoic membrane are then carefully opened, and the allantoic fluid containing the virus is harvested. The fluid is cleared from debris by centrifugation, aliquoted and transferred to -80 &#176;C for long-term storage. The large amount (5-10 ml of virus-containing fluid per egg) and high virus titer which is usually achieved with this protocol has made the usage of eggs for virus preparation our favorable method, in particular for in vitro studies which require large quantities of virus in which high dosages of the same virus stock are needed.

Fertile chicken eggs are widely used to produce large amounts of human influenza A virus as they provide a convenient and cost-effective system to prove high yields of virus.

Virus de la grippe Propagation dans embryonnés de poulet Oeufs

Influenza infection is associated with about 36,000 deaths and more than 200,000 hospitalizations every year in the United States. The continuous ...

Measuring Attachment and Internalization of Influenza A Virus in A549 Cells by Flow Cytometry

Attachment to target cells followed by internalization are the very first steps of the life cycle of influenza A virus (IAV). We provide here a detailed protocol for measuring relative changes in the amount of viral particles that attach to A549 cells, a human lung epithelial cell line, as well as in the amount of particles that are internalized into the cell. We use biotinylated virus which can be easily detected following staining with Cy3-labeled streptavidin (STV-Cy3). We describe the growth, purification and biotinylation of A/WSN/33, a widely used IAV laboratory strain. Cold-bound biotinylated IAV particles on A549 cells are stained with STV-Cy3 and measured using flow cytometry. To investigate uptake of viral particles, cold-bound virus is allowed to internalize at 37 &#176;C. In order to differentiate between external and internalized viral particles, a blocking step is applied: Free binding spots on the biotin of attached virus on the cell surface are bound by unlabeled streptavidin (STV). Subsequent cell permeabilization and staining with STV-Cy3 then enables detection of internalized viral particles. We present a calculation to determine the relative amount of internalized virus. This assay is suitable to measure effects of drug-treatments or other manipulations on attachment or internalization of IAV.

We present a protocol describing a semi-quantitative method for measuring both, the attachment of influenza A virus to A549 cells, as well as the internalization of virus particles into the target cells by flow cytometry.

Mesurer l&#39;attachement et l&#39;internalisation du virus grippal A dans les cellules A549 par cytométrie en flux

Attachment to target cells followed by internalization are the very first steps of the life cycle of influenza A virus (IAV). We provide here a detailed ...

Neutrophil Isolation and Analysis to Determine their Role in Lymphoma Cell Sensitivity to Therapeutic Agents

Neutrophils are the most abundant (40% to 75%) type of white blood cells and among the first inflammatory cells to migrate towards the site of inflammation. They are key players in the innate immune system and play major roles in cancer biology. Neutrophils have been proposed as key mediators of malignant transformation, tumor progression, angiogenesis and in the modulation of the antitumor immunity; through their release of soluble factors or their interaction with tumor cells. To characterize the specific functions of neutrophils, a fast and reliable method is coveted for in vitro isolation of neutrophils from human blood. Here, a density gradient separation method is demonstrated to isolate neutrophils as well as mononuclear cells from the blood. The procedure consists of layering the density gradient solution such as Ficoll carefully above the diluted blood obtained from patients diagnosed with chronic lymphocytic leukemia (CLL), followed by centrifugation, isolation of mononuclear layer, separation of neutrophils from RBCsby dextran then lysis of residual erythrocytes. This method has been shown to isolate neutrophils &#8805; 90 % pure. To mimic the tumor microenvironment, 3-dimensional (3D) experiments were performed using basement membrane matrix such as Matrigel. Given the short half-life of neutrophils in vitro, 3D experiments with fresh human neutrophils cannot be performed. For this reason promyelocytic HL60 cells are differentiated along the granulocytic pathway using the differentiation inducers dimethyl sulfoxide (DMSO) and retinoic acid (RA). The aim of our experiments is to study the role of neutrophils on the sensitivity of lymphoma cells to anti-lymphoma agents. However these methods can be generalized to study the interactions of neutrophils or neutrophil-like cells with a large range of cell types in different situations.

Neutrophils are the most abundant type of white blood cells. The isolation of neutrophils from human blood by density gradient separation method and the differentiation of human promyelocytic (HL60) cells along the granulocytic pathway are described here; to test their role on sensitivity of lymphoma cells to anti-lymphoma agents.

Neutrophiles Isolement et analyse pour déterminer leur rôle dans le lymphome cellulaire Sensibilité aux agents thérapeutiques

Neutrophils are the most abundant (40% to 75%) type of white blood cells and among the first inflammatory cells to migrate towards the site of ...

In Vitro Disassembly of Influenza A Virus Capsids by Gradient Centrifugation

Acid-triggered molecular processes closely control cell entry of many viruses that enter through the endocytic system. In the case of influenza A virus (IAV), virus fusion with the endosomal membrane as well as the subsequent disassembly of the viral capsid, called uncoating, is governed by the ionic conditions inside endocytic vesicles. The early steps in the virus life cycle are hard to study because endosomes cannot be directly accessed experimentally, creating the need for an in vitro approach. Here, we describe a method based on velocity gradient centrifugation of purified virions through a two-layer glycerol gradient, which enables analysis of the IAV core and its stability. The gradient contains a non-ionic detergent (NP-40) in its lower layer to remove the viral membrane by solubilization as the virus sediments toward the bottom. At neutral pH, viral cores are pelleted as stable structures. The major core components, matrix protein (M1) and the viral ribonucleoproteins (vRNPs), can be clearly identified in the pellet fraction by SDS-PAGE. Decreasing the pH to 6.0 or lower in the bottom layer selectively removes M1 from the pellet followed by release of vRNPs at more acidic conditions. Viral protein bands on Coomassie-stained gels can be subjected to densitometric quantification to monitor intermediate states of IAV disassembly. Besides pH, other factors that influence viral core stability can be assessed, such as salt concentration and putative viral uncoating factors, simply by modifying the detergent-containing glycerol layer accordingly. Taken together, the presented technique allows highly reproducible and quantitative analysis of viral uncoating in vitro. It can be applied to other enveloped viruses that undergo complex uncoating processes.

In Vitro Disassembly of Influenza A Virus Capsids by Gradient Centrifugation

Disassembly of influenza A virus cores during virus entry into host cells is a multistep process. We describe an in vitro method to analyze the early stages of viral uncoating. In this approach, velocity gradient centrifugation is used to biochemically dissect the steps that initiate uncoating under defined conditions.

In Vitro désassemblage du virus grippal A capsides par Centrifugation Gradient

Acid-triggered molecular processes closely control cell entry of many viruses that enter through the endocytic system. In the case of influenza A virus ...

Influenza A Virus Studies in a Mouse Model of Infection

Influenza viruses cause over 500,000 deaths worldwide1 and are associated with an annual cost of 12 - 14 billion USD in the United States alone considering direct medical and hospitalization expenses and work absenteeism2. Animal models are crucial in Influenza A virus (IAV) studies to evaluate viral pathogenesis, host-pathogen interactions, immune responses, and the efficacy of current and/or novel vaccine approaches as well as antivirals. Mice are an advantageous small animal model because their immune system is evolutionarily similar to that found in humans, they are available from commercial vendors as genetically identical subjects, there are multiple strains that can be exploited to evaluate the genetic basis of infections, and they are relatively inexpensive and easy to manipulate. To recapitulate IAV infection in humans via the airways, mice are first anesthetized prior to intranasal inoculation with infectious IAVs under proper biosafety containment. After infection, the pathogenesis of IAVs is determined by monitoring daily the morbidity (body weight loss) and mortality (survival) rate. In addition, viral pathogenesis can also be evaluated by assessing virus replication in the upper (nasal mucosa) or lower (lungs) respiratory tract of infected mice. Humoral responses upon IAV infection can be rapidly evaluated by non-invasive bleeding and secondary antibody detection assays aimed at detecting the presence of total or neutralizing antibodies. Here, we describe the common methods used to infect mice intranasally (i.n) with IAV and evaluate pathogenesis, humoral immune responses and protection efficacy.

Influenza A viruses (IAVs) are important human respiratory pathogens. To understand the pathogenicity of IAVs and to perform preclinical testing of novel vaccine approaches, animal models mimicking human physiology are required. Here, we describe techniques to evaluate IAV pathogenesis, humoral responses and vaccine efficacy using a mouse model of infection.

Études de Virus influenza de type A dans un modèle murin d’Infection

Influenza viruses cause over 500,000 deaths worldwide1 and are associated with an annual cost of 12 - 14 billion USD in the United States alone ...

Evaluation of Zika Virus-specific T-cell Responses in Immunoprivileged Organs of Infected Ifnar1-/- Mice

The Zika virus (ZIKV) can induce inflammation in immunoprivileged organs (e.g., the brain and testis), leading to the Guillain-Barr&#233; syndrome and damaging the testes. During an infection with the ZIKV, immune cells have been shown to infiltrate into the tissues. However, the cellular mechanisms that define the protection and/or immunopathogenesis of these immune cells during a ZIKV infection are still largely unknown. Herein, we describe methods to evaluate the virus-specific T-cell functionality in these immunoprivileged organs of ZIKV-infected mice. These methods include a) a ZIKV infection and vaccine inoculation in Ifnar1-/- mice; b) histopathology, immunofluorescence, and immunohistochemistry assays to detect the virus infection and inflammation in the brain, testes, and spleen; c) the preparation of a tetramer of ZIKV-derived T-cell epitopes; d) the detection of ZIKV-specific T cells in the monocytes isolated from the brain, testes, and spleen. Using these approaches, it is possible to detect the antigen-specific T cells that have infiltrated into the immunoprivileged organs and to evaluate the functions of these T cells during the infection: potential immune protection via virus clearance and/or immunopathogenesis to exacerbate the inflammation. These findings may also help to clarify the contribution of T cells induced by the immunization against ZIKV.

Evaluation of Zika Virus-specific T-cell Responses in Immunoprivileged Organs of Infected Ifnar1-/- Mice

A protocol to evaluate antigen-specific T-cell responses in the immunoprivileged organs of the Ifnar1-/- murine model for the Zika virus (ZIKV) infection is described. This method is pivotal for investigating the cellular mechanisms of the protection and immunopathogenesis of ZIKV vaccines and is also valuable for their efficacy evaluation.

Évaluation des réponses de cellules T spécifiques du Virus Zika dans les organes Immunoprivileged des Ifnar1 infecté les souris- / -

The Zika virus (ZIKV) can induce inflammation in immunoprivileged organs (e.g., the brain and testis), leading to the Guillain-Barr&#233; syndrome and ...

Imaging Cell Interaction in Tracheal Mucosa During Influenza Virus Infection Using Two-photon Intravital Microscopy

The analysis of cell-cell or cell-pathogen interaction in vivo is an important tool to understand the dynamics of the immune response to infection. Two-photon intravital microscopy (2P-IVM) allows the observation of cell interactions in deep tissue in living animals, while minimizing the photobleaching generated during image acquisition. To date, different models for 2P-IVM of lymphoid and non-lymphoid organs have been described. However, imaging of respiratory organs remains a challenge due to the movement associated with the breathing cycle of the animal.
Here, we describe a protocol to visualize in vivo immune cell interactions in the trachea of mice infected with influenza virus using 2P-IVM. To this purpose, we developed a custom imaging platform, which included the surgical exposure and intubation of the trachea, followed by the acquisition of dynamic images of neutrophils and dendritic cells (DC) in the mucosal epithelium. Additionally, we detailed the steps needed to perform influenza intranasal infection and flow cytometric analysis of immune cells in the trachea. Finally, we analyzed neutrophil and DC motility as well as their interactions during the course of a movie. This protocol allows for the generation of stable and bright 4D images necessary for the assessment of cell-cell interactions in the trachea.

In this study, we present a protocol to perform two-photon intravital imaging and cell interaction analysis in the murine tracheal mucosa after infection with influenza virus. This protocol will be relevant for researchers studying immune cell dynamics during respiratory infections.

Imagerie cellulaire Interaction dans la muqueuse trachéale au cours de l’infection par le Virus grippal à l’aide de la microscopie intravitale biphotonique

The analysis of cell-cell or cell-pathogen interaction in vivo is an important tool to understand the dynamics of the immune response to infection. ...

A Luciferase-fluorescent Reporter Influenza Virus for Live Imaging and Quantification of Viral Infection

Influenza A viruses (IAVs) cause human respiratory disease that is associated with significant health and economic consequences. As with other viruses, studying IAV requires the use of laborious secondary approaches to detect the presence of the virus in infected cells and/or in animal models of infection. This limitation has been recently circumvented with the generation of recombinant IAVs expressing easily traceable fluorescent or bioluminescent (luciferase) reporter proteins. However, researchers have been forced to select fluorescent or luciferase reporter genes due to the restricted capacity of the IAV genome for including foreign sequences. To overcome this limitation, we have generated a recombinant replication-competent bi-reporter IAV (BIRFLU) stably expressing both a fluorescent and a luciferase reporter gene to easily track IAV infections in vitro and in vivo. To this end, the viral non-structural (NS) and hemagglutinin (HA) viral segments of influenza A/Puerto Rico/8/34 H1N1 (PR8) were modified to encode the fluorescent Venus and the bioluminescent Nanoluc luciferase proteins, respectively. Here, we describe the use of BIRFLU in a mouse model of IAV infection and the detection of both reporter genes using an in vivo imaging system. Notably, we have observed a good correlation between the expressions of both reporters and viral replication. The combination of cutting-edge techniques in molecular biology, animal research and imaging technologies, provides researchers the unique opportunity to use this tool for influenza research, including the study of virus-host interactions and dynamics of viral infections. Importantly, the feasibility to genetically alter the viral genome to express two foreign genes from different viral segments opens up opportunities to use this approach for: (i) the development of novel IAV vaccines, (ii) the generation of recombinant IAVs that can be used as vaccine vectors for the treatment of other human pathogen infections.

Influenza A viruses (IAVs) are contagious respiratory pathogens that cause annual epidemics and occasional pandemics. Here, we describe a protocol to track viral infections in vivo using a novel recombinant luciferase and fluorescence-expressing bi-reporter IAV (BIRFLU). This approach provides researchers with an excellent tool to study IAV in vivo.

Un virus de la grippe Luciferase-fluorescent Reporter pour l'imagerie en direct et la quantification de l'infection virale

Influenza A viruses (IAVs) cause human respiratory disease that is associated with significant health and economic consequences. As with other viruses, ...