Name: a simple flow cytometry based assay to determine in vitro antibody dependent enhancement of dengue virus using zika virus convalescent serum
Uploaded: 2018-04-10T14:00:00.000+00:00
Duration: 7 min 6 s
Description: Watch this Scientific Journal Video about A Simple Flow Cytometry Based Assay to Determine In Vitro Antibody Dependent Enhancement of Dengue Virus Using Zika Virus Convalescent Serum at JoVE.com

Il progetto descritto è stato sostenuto dalla Uniformed Services University Health Sciences a JJM. Le opinioni o le affermazioni contenute nel presente documento sono quelle private degli autori e non sono per essere interpretato come ufficiale o riflettenti le viste del dipartimento della difesa, la Uniformed Services University Health Sciences o qualsiasi altra agenzia degli Stati Uniti Governo.
WGV eseguito tutti gli esperimenti e analizzato i dati; JJM progettato e supervisionato lo studio; WGW e JJM ha scritto il libro.

I campioni di siero utilizzati per illustrare il protocollo descritto qui sono stati ottenuti da macaques del reso che erano alloggiate e curate secondo locale, statale e federale politiche in un'associazione per la valutazione e l'accreditamento di laboratorio Animal Care Internazionale (AAALAC)-accreditato facility. Tutti gli esperimenti sugli animali sono stati esaminati e approvati dal comitato di uso e cura degli animali istituzionali e i campioni sono stati acquisiti attraverso un protocollo di condivisione di tessuto.
1. giorno 1
Nota: Eseguire tutti i passaggi descritti di seguito in una flusso laminare sterile biosicurezza usata per coltura tissutale in un laboratorio BSL-2.
<ol><li>Scongelare i campioni di siero a temperatura ambiente e trasferire 100 µ l di ciascun campione di siero in una provetta sterile. Inattivare con il calore a 56° C in un bagno d'acqua o un thermomixer regolabile in temperatura per 30 minuti. Effettuare diluizioni seriali 10 volte campione di siero che vanno da 1:1 a 1:1,000 utilizzando freddo RPMI-10 (RPMI con 10% siero bovino fetale).</li>
	<li>Trasferire 10 µ l di campione di siero diluito serialmente in ciascun pozzetto di una piastra di fondo V 96 pozzetti sterile. Sono due serie di pozzetti di controllo, RPMI-10 con RVP solo e senza campione di siero e RPMI-10 solo senza RVP e senza campione di siero. Impostare ogni campione di siero e RPMI-10 controlli in triplici copie.</li>
	<li>Rimuovere il Dengue-1, 2, 3 e 4 RVP da-80 ° C e scongelare loro in bagnomaria a 37 ° C. Trasferire il RVP scongelati immediatamente in ghiaccio. Ottenere RVP circa 170 µ l per ogni campione di siero (10 µ l di RVP x 3 pozzi per ogni diluizione del siero (1:1, 01:10, 1: 100, 1:1, 000) e 10 µ l di RVP x 3 pozzi per ognuna delle RPMI-10 con RVP solo controllo pozzi).</li>
	<li>Pipettare 10 µ l di RVP in ciascun bene la piastra di fondo V 96 pozzetti contenenti il campione di siero e RPMI-10 con pozzetti di controllo RVP (nessun siero). Non aggiungere RVP RPMI-10 solo (nessun campione di siero e nessun RVP) pozzi. Mix accuratamente pipettando su e giù 5 – 10 volte. Aggiungere 10 µ l freddo RPMI-10 al posto di RVP per ogni freddo RPMI-10 soltanto pozzetti di controllo (nessun campione di siero e nessun RVP).</li>
	<li>Trasferire la piastra di fondo V 96 pozzetti per un'incubatrice e incubare la piastra per 1 ora a 37 ° C in presenza di 5% CO2. Mentre la piastra a 96 pozzetti fondo V è in incubazione, pulire la superficie della cappa di biosicurezza con etanolo al 70% ed eseguire la luce UV per 15 min.</li>
	<li>Rimuovere un pallone T75 completamente confluente di cellule K562 dall'incubatrice, mescolare le celle anche utilizzando una pipetta sterile 5 mL e trasferire 5 mL di cellule in una provetta conica sterile 15 mL. Nota: Le cellule K562 sono mantenute in RPMI-10 e una subcoltura a 1 x 106/ml.</li>
	<li>Contare il numero di cellule rimuovendo 10 celle µ l dalla provetta conica sterile 15 mL e mescolare con il blu di tryphan 10 µ l. Contare le celle utilizzando un emocitometro per determinare il numero totale di cellule nella provetta conica da 15 mL.</li>
	<li>Centrifugare il 15 mL conica con cellule a ~ 1.200 x g per 10 minuti, decantare il supernatante e risospendere le cellule in caldo RPMI-10 ad una concentrazione di 80.000 cellule/30 µ l di media (2,66 x 106 cellule/ml).</li>
	<li>Rimuovere la piastra a 96 pozzetti fondo V dall'incubatrice (passo 1.6), trasferire 30 µ l di cellule K562 in ciascun pozzetto della piastra 96 pozzetti fondo V e mescolare accuratamente pipettando su e giù 5 – 10 volte. Trasferire la piastra di fondo V 96 pozzetti per un'incubatrice e incubare la piastra per 1 ora a 37 ° C in presenza di 5% CO2.</li>
	<li>Dopo incubazione per 1 h, è necessario rimuovere la piastra a 96 pozzetti fondo V dall'incubatore e centrifugare a ~ 1.200 x g per 5 minuti. Dopo la centrifugazione, decantare i media dai pozzetti ruotando la piastra capovolta in un contenitore contenente candeggina al 10%.</li>
	<li>Lavare le cellule in ogni pozzetto da loro risospendere in 125 µ l di RPMI-10 caldo, mescolare accuratamente con una pipetta e centrifugare la piastra a ~ 1.200 x g per 5 min, decantare i media girando la piastra capovolta in un contenitore contenente candeggina al 10%. Ripetere questo passaggio di lavaggio due volte.</li>
	<li>Dopo il lavaggio, aggiungere 100 µ l di caldo RPMI-10 a ciascuno mescolare bene, su e giù con la pipetta e incubare la piastra per 48 h a 37 ° C in presenza di 5% CO2.</li>
</ol>2. giorno 3
<ol><li>Rimuovere la piastra di fondo V 96 pozzetti contenenti 100 µ l di cellule e media/pozzetto dall'incubatrice e spostarlo in una cappa di biosicurezza. Usando una pipetta multicanale, miscela il contenuto di ogni bene e trasferire le cellule e media per un fondo U ben 96 piastra o per pre-etichettata provette in polipropilene da 5 mL.</li>
	<li>Sciacquare ciascun pozzetto della piastra di fondo V 96 pozzetti con 100 µ l di 1% paraformaldeide (PFA) 1 x Phosphate Buffered Saline (PBS) e trasferimento ai rispettivi pozzetti in 96 ben U-fondo piatto o tubi in polipropilene da 5 mL con etichetta dal passaggio 2.1 per produrre una finale concentrazione dello 0,5% PFA/pozzetto o tubo. Mescolare accuratamente usando una pipetta multicanale, coprire la piastra con un foglio di alluminio e lasciarlo riposare nell'incubatrice per 30 minuti per fissare le cellule.</li>
	<li>Preparare il citometro a flusso (Vedi ad esempio la Tabella materiali ) eseguendo le cellule K562 non macchiate per calibrare il lato e forward scatter insieme alle impostazioni di fluorescenza. Il canale di fluorescenza solo richiesto è FL1, come GFP è l'unica fluorescenza emessa dalle cellule. Acquisire ~ 30, 000 – 50.000 cellule da ciascun campione. Nota: Qualsiasi cytometer di flusso in grado di leggere una singola fluorescenza può essere utilizzato per l'acquisizione dei dati, come le cellule infettate con RVP solo emette fluorescenza verde per la presenza di GFP, e nessun altro canale di fluorescenza sono necessari.</li>
</ol>3. analisi dei dati
<ol><li>
Analizzare i dati acquisiti sul citofluorimetro utilizzando qualsiasi software di analisi di citometria a flusso (Vedi tabella materiali).
	<ol>
<li>Insieme al primo cancello basato su FSC-A (forward scatter – zona) vs FSC-H (forward scatter – altezza) per includere singole cellule ed escludere auto-fluorescente doppietti da analisi12. Quindi, cancello singoletto-gated celle basate su SSC-A (dispersione laterale – zona) vs FSC-A per escludere eventuali detriti autofluorescenti.</li>
		<li>Analizzare vs SSC-A cellule gated FSC-A per l'espressione della GFP basato su vs SSC-A GFP-A. Determinare la percentuale di cellule GFP + per ogni diluizione dei campioni del siero e controllo impostando un cancello intorno cellule GFP +.</li>
	</ol>
</li>
	<li>Determinare la percentuale media di cellule GFP + per ogni diluizione del campione di siero e pozzetti di controllo dividendo la percentuale totale di cellule GFP + nei pozzetti triplicate per 3.</li>
	<li>Piega-potenziamento dell'infezione viene calcolato dividendo la percentuale media di cellule GFP + nei campioni del siero per ogni diluizione diviso per la percentuale media di cellule GFP + in RPMI-10 con pozzetti di controllo RVP (nessun campione di siero).</li>
	<li>Piega-valorizzazione (asse y) del grafico contro diluizione (asse x) ed effettuare analisi statistiche, facendo uso di ANOVA seguito dal test post-hoc di Tukey per i confronti multipli.</li>
</ol>

<ol>
	<li>George, 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=Prior+exposure+to+zika+virus+significantly+enhances+peak+dengue-2+viremia+in+rhesus+macaques.">Prior exposure to zika virus significantly enhances peak dengue-2 viremia in rhesus macaques.</a> Sci Rep. 7 (1), 10498 (2017).</li><li>Stettler, 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=Specificity,+cross-reactivity,+and+function+of+antibodies+elicited+by+Zika+virus+infection.">Specificity, cross-reactivity, and function of antibodies elicited by Zika virus infection.</a> Science. 353 (6301), 823-826 (2016).</li><li>Mattia, 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=Dengue+reporter+virus+particles+for+measuring+neutralizing+antibodies+against+each+of+the+four+dengue+serotypes.">Dengue reporter virus particles for measuring neutralizing antibodies against each of the four dengue serotypes.</a> PLoS One. 6 (11), e27252 (2011).</li><li>Chiofalo, M. S., Teti, G., Goust, J. M., Trifiletti, R., La Via, ., F, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Subclass+specificity+of+the+Fc+receptor+for+human+IgG+on+K562.">Subclass specificity of the Fc receptor for human IgG on K562.</a> Cell Immunol. 114 (2), 272-281 (1988).</li><li>Klein, E., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Properties+of+the+K562+cell+line,+derived+from+a+patient+with+chronic+myeloid+leukemia.">Properties of the K562 cell line, derived from a patient with chronic myeloid leukemia.</a> Int J Cancer. 18 (4), 421-431 (1976).</li><li>Kliks, S. C., Nisalak, A., Brandt, W. E., Wahl, L., Burke, D. S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Antibody-dependent+enhancement+of+dengue+virus+growth+in+human+monocytes+as+a+risk+factor+for+dengue+hemorrhagic+fever.">Antibody-dependent enhancement of dengue virus growth in human monocytes as a risk factor for dengue hemorrhagic fever.</a> Am J Trop Med Hyg. 40 (4), 444-451 (1989).</li><li>Littaua, R., Kurane, I., Ennis, F. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Human+IgG+Fc+receptor+II+mediates+antibody-dependent+enhancement+of+dengue+virus+infection.">Human IgG Fc receptor II mediates antibody-dependent enhancement of dengue virus infection.</a> J Immunol. 144 (8), 3183-3186 (1990).</li><li>Wang, T. T., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=IgG+antibodies+to+dengue+enhanced+for+FcgammaRIIIA+binding+determine+disease+severity.">IgG antibodies to dengue enhanced for FcgammaRIIIA binding determine disease severity.</a> Science. 355 (6323), 395-398 (2017).</li><li>Dejnirattisai, W., 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=Cross-reacting+antibodies+enhance+dengue+virus+infection+in+humans.">Cross-reacting antibodies enhance dengue virus infection in humans.</a> Science. 328 (5979), 745-748 (2010).</li><li>Kawiecki, A. B., Christofferson, R. C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Zika+virus-induced+antibody+response+enhances+dengue+virus+serotype+2+replication+in+vitro.">Zika virus-induced antibody response enhances dengue virus serotype 2 replication in vitro.</a> J Infect Dis. 214 (9), 1357-1360 (2016).</li><li>Morens, D. M., Halstead, S. B. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Measurement+of+antibody-dependent+infection+enhancement+of+four+dengue+virus+serotypes+by+monoclonal+and+polyclonal+antibodies.">Measurement of antibody-dependent infection enhancement of four dengue virus serotypes by monoclonal and polyclonal antibodies.</a> J Gen Virol. 71 (Pt 12), 2909-2914 (1990).</li><li>Perfetto, S. P., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Amine+reactive+dyes:+an+effective+tool+to+discriminate+live+and+dead+cells+in+polychromatic+flow+cytometry.">Amine reactive dyes: an effective tool to discriminate live and dead cells in polychromatic flow cytometry.</a> J Immunol Methods. 313 (1-2), 199-208 (2006).</li><li>Priyamvada, L., 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+responses+during+secondary+dengue+virus+infection+are+dominated+by+highly+cross-reactive,+memory-derived+plasmablasts.">B Cell responses during secondary dengue virus infection are dominated by highly cross-reactive, memory-derived plasmablasts.</a> J Virol. 90 (12), 5574-5585 (2016).</li><li>Priyamvada, L., 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=Human+antibody+responses+after+dengue+virus+infection+are+highly+cross-reactive+to+Zika+virus.">Human antibody responses after dengue virus infection are highly cross-reactive to Zika virus.</a> Proc Natl Acad Sci U S A. 113 (28), 7852-7857 (2016).</li></ol>

Gli autori non hanno nulla a rivelare.

Flavivirus come DENV e ZIKV condividere testimonianze significative di omologia in entrambe le loro proteine strutturali e non strutturali che generano gli anticorpi che cross-reagiscono con a vicenda13,14. Queste risposte di anticorpi cross-reattivi sono state indicate per migliorare di infezione sia in vivo che in vitro con un sierotipo eterologo o altro relativi flavivirus1,2. Il pote...

Anticorpo dipendente miglioramento (ADE) dell'infezione è un processo per cui le risposte parzialmente traversa-reattivo anticorpo indotte da un sierotipo del virus migliora l'assorbimento di un altro sierotipo del virus, che conduce la viremia e replicazione virale aumentata. ADE è stato ampiamente documentato nelle infezioni di Dengue virus (DENV) dove quattro principali sierotipi sono prevalenti. In un sottogruppo di pazienti, ADE è associata con febbre emorragica Dengue (DHF). Abbiamo recentemente dimostrato che l'infezione del virus (ZIKV) di Zika indotto significativamente elevati livelli di risposte di anticorpi cross-reattivi DENV causato ADE di DENV in vitro , che probabilmente ha contribuito alla valorizzazione di DENV viremia in vivo1 , 2. analisi dell'anticorpo dipendente di potenziamento sono uno strumento prezioso per valutare la capacità degli anticorpi per migliorare secondario infezione con virus collegati e offrire preziose comprensioni nella patogenesi delle infezioni da flavivirus e informare il sviluppo di vaccini.
Il test descritto qui usa DENV RVP insieme con le cellule K562 che sono normalmente inammissibile all'infezione. RVP sono strutturalmente intatto replica incompetente DENV particelle virali che codificano un replicone sub-genomica della proteina fluorescente verde (GFP) che è espresso dopo un singolo ciclo di replica3. Come tale, le cellule che infettano con RVP reagiscono in verde e possono essere facilmente individuate mediante citometria a flusso o microscopia. La RVP usato per questo test sono stati ottenuti da fonti commerciali. Tuttavia, possono essere generati contro altri virus e usato per il test descritto in questo manoscritto. Nel frattempo, le cellule K562 sono un'espressione FcγIII-linea cellulare di leucemia che si legano alla regione Fc degli anticorpi e infettarsi in presenza di Sub-neutralizzare le concentrazioni di anticorpi4,5.
Saggi di ADE sono stati ampiamente utilizzati negli studi che studiano i fattori di rischio per grave dengue e di delineare i meccanismi di in vitro ADE6,7,8. Il dosaggio di ADE descritto qui può essere rapidamente e facilmente utilizzato per determinare la capacità del siero per migliorare l'infezione in vitro utilizzando RVP e flusso cytometry, rispetto ad altri dosaggi utilizzati attualmente, che richiedono sia la determinazione della placca formando unità (pfu) in cellule Vero o macchiatura dell'anticorpo di infetti cellule6,7,8,9,10,11, entrambi i quali sono in termini di tempo e manodopera intensivo.

<table><tbody><tr><td>DENV 1-4 RVP</td><td>Integral Molecular</td><td>RVP-501</td><td></td></tr><tr><td>K562 cells</td><td>ATCC</td><td>CCL-243</td><td></td></tr><tr><td>RPMI</td><td>Corning</td><td>10-040-CV</td><td></td></tr><tr><td>FBS</td><td>GE lifesceinces</td><td>SH 30910.03</td><td>10% FBS in RPMI-10</td></tr><tr><td>Penicillin-Streptomycin</td><td>MP biomedicals</td><td>1670049</td><td>100 IU Pen/mL, 100 ug Strep/mL in RPMI-10</td></tr><tr><td>HEPES</td><td>Cellegro</td><td>25-060-Cl</td><td>0.025M in RPMI-10</td></tr><tr><td>MEM Non-essential Amino Acid Solution (100&amp;times;)</td><td>Sigma</td><td>M7145</td><td>1x in RPMI-10</td></tr><tr><td>Sodium Pyruvate</td><td>Cellegro</td><td>25-000-Cl</td><td>1mM in RPMI-10</td></tr><tr><td>L-glutamine</td><td>Fisher Scientific</td><td>MT25005CI&amp;nbsp;</td><td></td></tr><tr><td>Sterile V-bottom plates</td><td>Thomas Scientific</td><td>333-8001-01V</td><td></td></tr><tr><td>BD Falcon Polypropylene 5 ml FACS tubes</td><td>VWR</td><td>60819-728</td><td></td></tr><tr><td>Non-sterile U-bottom plates</td><td>Falcon</td><td>Ref 353910</td><td>A high throughput alternative to FACS tubes</td></tr><tr><td>5mL, sterile, serological pipette</td><td>Denville</td><td>P7127</td><td></td></tr><tr><td>200uL sterile pipette tips</td><td>Denville</td><td>P3020 CPS</td><td></td></tr><tr><td>20uL sterile pipette tips</td><td>Denville</td><td>P1121</td><td></td></tr><tr><td>50-200uL multichannel pipette</td><td>Denville</td><td>P3975-8-B</td><td></td></tr><tr><td>5-50uL multichannel pipette</td><td>Denville</td><td>P3975-9-B</td><td></td></tr><tr><td>20% formadehyde</td><td>Tousimis</td><td>&amp;nbsp;#1008B</td><td></td></tr><tr><td>Water Bath</td><td>ThermoFisher</td><td>TSCOL35</td><td></td></tr><tr><td>thermomixer</td><td>Eppendorf</td><td>2231000387</td><td>An alternative to a waterbath for heat inactivation</td></tr><tr><td>CO2 Incubator</td><td>ThermoFisher</td><td>13-998-213</td><td></td></tr><tr><td>Ethanol</td><td>Sigma Aldrich</td><td>E7023</td><td></td></tr><tr><td>Liquid Bleach</td><td>Fisher Scientific</td><td>NC9724348</td><td></td></tr><tr><td>Flowjo 9.8</td><td>TreeStar, Inc.</td><td></td><td>Flow cytometry analysis software</td></tr><tr><td>BD FACSDiva 6.1.2</td><td>Becton Dikinson</td><td></td><td></td></tr><tr><td>BD LSR II flow cytometer</td><td>Becton Dikinson</td><td></td><td></td></tr><tr><td>Liquid Bleach</td><td>Fisher Scientific</td><td>NC9724348</td><td></td></tr></tbody></table>

a simple flow cytometry based assay to determine in vitro antibody dependent enhancement of dengue virus using zika virus convalescent serum

Il potenziamento dipendente dell'anticorpo dell'infezione ha dimostrato di giocare un ruolo importante nella patogenesi virale Dengue. Tradizionale analisi che misurano la capacità di anticorpi o siero per migliorare infezione nelle linee cellulari impermissible hanno fatto affidamento sull'utilizzo uscita virale nei media seguiti da saggi di placca per quantificare l'infezione. Più recentemente, queste analisi hanno esaminato l'infezione di febbre rompiossa virus (DENV) nelle linee cellulari usando gli anticorpi fluorescente contrassegnati. Entrambi questi approcci presentano limitazioni che limitano l'uso molto diffuso di queste tecniche. Qui, descriviamo un'analisi semplice in vitro usando Dengue virus reporter particelle virali (RVP) che esprimono la proteina fluorescente verde e le cellule K562 per esaminare potenziamento dipendente dell'anticorpo (ADE) dell'infezione di DENV usando il siero che è stato ottenuto da rhesus macachi 16 settimane dopo l'infezione con il virus di Zika (ZIKV). Questa tecnica è affidabile, comporta la minima manipolazione delle cellule, non implicano l'uso di virus competente replica dal vivo e può essere eseguita in un formato di throughput elevato per ottenere una lettura quantitativa mediante citometria a flusso. Inoltre, questo test può essere facilmente adattato per esaminare aumento dipendente dell'anticorpo (ADE) di altre infezioni da flavivirus come il virus della febbre gialla (YFV), virus dell'encefalite equina giapponese (JEEV), virus del Nilo occidentale (WNV) ecc dove RVP sono disponibili. La facilità di configurazione di test, analisi dei dati e interpretazione dei risultati rende altamente favorevole alla maggior parte delle impostazioni di laboratorio.

I sieri da 4 rhesus macaques erano raccolti a 16 settimane dopo l'infezione con ZIKV e testato per il loro potenziale migliorare DENV-1, 2, 3 e 4 infezione in cellule K562. Gli animali hanno avuti viremia di picco di ~ 1 x 105 copie di ZIKV RNA/mL di plasma dal giorno 3 dopo infezione che è sceso a livelli che erano sotto il limite di rilevazione di 7 giorni dopo l'infezione. No la viremia è stata rilevata nel plasma post-all'infezione 16 settimane. L'analisi RVP è stata ese...

Watch this Scientific Journal Video about A Simple Flow Cytometry Based Assay to Determine In Vitro Antibody Dependent Enhancement of Dengue Virus Using Zika Virus Convalescent Serum at JoVE.com

A Simple Flow Cytometry Based Assay to Determine In Vitro Antibody Dependent Enhancement of Dengue Virus Using Zika Virus Convalescent Serum

Descriviamo un protocollo semplice e facile per misurare il miglioramento dipendente dell'anticorpo dell'infezione di siero convalescente di Zika virus utilizzando le particelle virali di Reporter di virus della Dengue.

Base di un semplice flusso Cytometry Assay per determinare In Vitro dell'anticorpo dipendente valorizzazione del Virus di febbre rompiossa utilizzando siero convalescente Zika Virus

Antibody dependent enhancement of infection has been shown to play a major role in Dengue viral pathogenesis. Traditional assays that measure the capacity ...

a-simple-flow-cytometry-based-assay-to-determine-vitro-antibody

Universidad de Cartagena UDEC

Research

JoVE Journal

Immunology and Infection

A Simple Flow Cytometry Based Assay to Determine In Vitro Antibody Dependent Enhancement of Dengue Virus Using Zika Virus Convalescent Serum

8.7K Views.  Uniformed Services University. Descriviamo un protocollo semplice e facile per misurare il miglioramento dipendente dell'anticorpo dell'infezione di siero convalescente di Zika virus utilizzando le particelle virali di Reporter di virus della Dengue.

Video: A Simple Flow Cytometry Based Assay to Determine In Vitro Antibody Dependent Enhancement of Dengue Virus Using Zika Virus Convalescent Serum

Multiplexed Isothermal Amplification Based Diagnostic Platform to Detect Zika, Chikungunya, and Dengue 1

Zika, dengue, and chikungunya viruses are transmitted by mosquitoes, causing diseases with similar patient symptoms. However, they have different downstream patient-to-patient transmission potentials, and require very different patient treatments. Thus, recent Zika outbreaks make it urgent to develop tools that rapidly discriminate these viruses in patients and trapped mosquitoes, to select the correct patient treatment, and to understand and manage their epidemiology in real time.
Unfortunately, current diagnostic tests, including those receiving 2016 emergency use authorizations and fast-track status, detect viral RNA by reverse transcription polymerase chain reaction (RT-PCR), which requires instrumentation, trained users, and considerable sample preparation. Thus, they must be sent to &#34;approved&#34; reference laboratories, requiring time. Indeed, in August 2016, the Center for Disease Control (CDC) was asking pregnant women who had been bitten by a mosquito and developed a Zika-indicating rash to wait an unacceptable 2 to 4 weeks before learning whether they were infected. We very much need tests that can be done on site, with few resources, and by trained but not necessarily licensed personnel.
This video demonstrates an assay that meets these specifications, working with urine or serum (for patients) or crushed mosquito carcasses (for environmental surveillance), all without much sample preparation. Mosquito carcasses are captured on paper carrying quaternary ammonium groups (Q-paper) followed by ammonia treatment to manage biohazards. These are then directly, without RNA isolation, put into assay tubes containing freeze-dried reagents that need no chain of refrigeration. A modified form of reverse transcription loop-mediated isothermal amplification with target-specific fluorescently tagged displaceable probes produces readout, in 30 min, as a three-color fluorescence signal. This is visualized with a handheld, battery-powered device with an orange filter. Forward contamination is prevented with sealed tubes, and the use of thermolabile uracil DNA glycosylase (UDG) in the presence of dUTP in the amplification mixture.

Current multiplexed diagnostics to detect Zika, chikungunya, and dengue viruses require complex sample preparation and expensive instrumentation, and are difficult to use in low resource environments. We show a diagnostic that uses isothermal amplification with target-specific strand displaceable probes to detect and differentiate these viruses with high sensitivity and specificity.

Amplificazione isotermica multiplex basato su piattaforma diagnostica per rilevare Zika, Chikungunya e Dengue 1

Zika, dengue, and chikungunya viruses are transmitted by mosquitoes, causing diseases with similar patient symptoms. However, they have different ...

Ricerca

Biochimica

Zika Virus Infectious Cell Culture System and the In Vitro Prophylactic Effect of Interferons

Zika Virus (ZIKV) is an emerging pathogen that is linked to fetal developmental abnormalities such as microcephaly, eye defects, and impaired growth. ZIKV is an RNA virus of the Flaviviridae family. ZIKV is mainly transmitted by mosquitoes, but can also be spread by maternal to fetal vertical transmission as well as sexual contact. To date, there are no reliable treatment or vaccine options available to protect those infected by the virus. The development of a reproducible, effective Zika virus infectious cell culture system is critical for studying the molecular mechanisms of ZIKV replication as well as drug and vaccine development. In this regard, a protocol describing a mammalian cell-based in vitro Zika virus culture system for viral production and growth analysis is reported here. Details on the formation of plaques by Zika virus on a cell monolayer and plaque assay for measuring viral titer are presented. Viral genome replication kinetics and double-stranded RNA genome replicatory intermediates are determined. This culture platform was utilized to screen against a library of a small set of cytokines resulting in the identification of interferon-&#945; (IFN-&#945;), IFN-&#946; and IFN-&#947; as potent inhibitors of Zika viral growth. In summary, an in vitro infectious Zika viral culture system and various virological assays are demonstrated in this study, which has the potential to greatly benefit the research community in elucidating further the mechanisms of viral pathogenesis and the evolution of viral virulence. Antiviral IFN-alpha can further be evaluated as a prophylactic, post-exposure prophylactic, and treatment option for Zika virus infections in high-risk populations, including infected pregnant women.

Zika Virus Infectious Cell Culture System and the In Vitro Prophylactic Effect of Interferons

Zika Virus (ZIKV), an emerging pathogen, is linked to fetal developmental abnormalities and microcephaly. The establishment of an effective infectious cell culture system is crucial for studies of ZIKV replication as well as vaccine and drug development. In this study, various virological assays pertaining to ZIKV are illustrated and discussed.

Zika Virus System infettiva coltura cellulare e la<em&gt; In Vitro</em&gt; Effetto profilattico di interferoni

Zika Virus (ZIKV) is an emerging pathogen that is linked to fetal developmental abnormalities such as microcephaly, eye defects, and impaired growth. ZIKV ...

Immunologia e infezioni

Zika Virus Specific Diagnostic Epitope Discovery

High-density peptide microarrays allow screening of more than six thousand peptides on a single standard microscopy slide. This method can be applied for drug discovery, therapeutic target identification, and developing of diagnostics. Here, we present a protocol to discover specific Zika virus (ZIKV) diagnostic peptides using a high-density peptide microarray. A human serum sample validated for ZIKV infection was incubated with a high-density peptide microarray containing the entire ZIKV protein translated into 3,423 unique 15 linear amino acid (aa) residues with a 14-aa residue overlap printed in duplicate. Staining with different secondary antibodies within the same array, we detected peptides that bind to Immunoglobulin M (IgM) and Immunoglobulin G (IgG) antibodies present in serum. These peptides were selected for further validation experiments. In this protocol, we describe the strategy followed to design, process, and analyze a high-density peptide microarray.

In this protocol, we describe a technique to discover Zika virus specific diagnostic peptides using a high-density peptide microarray. This protocol can readly be adapted for other emerging infectious diseases.

Virus di Zika specifico diagnostico dell'epitopo Discovery

High-density peptide microarrays allow screening of more than six thousand peptides on a single standard microscopy slide. This method can be applied for ...

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.

Valutazione delle risposte a cellula T Zika Virus-specifici in organi di nuova di Ifnar1 infetti- / - 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 ...

Quantification of Antibody-dependent Enhancement of the Zika Virus in Primary Human Cells

The recent emergence of the flavivirus Zika and neurological complications, such as Guillain-Barr&#233; syndrome and microcephaly in infants, has brought serious public safety concerns. Among the risk factors, antibody-dependent enhancement (ADE) poses the most significant threat, as the recent re-emergence of the Zika virus (ZIKV) is primarily in areas where the population has been exposed and is in a state of pre-immunity to other closely related flaviviruses, especially dengue virus (DENV). Here, we describe a protocol for quantifying the effect of human serum antibodies against DENV on ZIKV infection in primary human cells or cell lines.

We describe a method to evaluate the effect of pre-existing immunity against dengue virus on the Zika virus infection by using human serum, primary human cells, and infection quantification by quantitative real-time polymerase chain reaction.

Quantificazione di esaltazione anticorpo-dipendente del Virus in cellule umane primarie Zika

The recent emergence of the flavivirus Zika and neurological complications, such as Guillain-Barr&#233; syndrome and microcephaly in infants, has brought ...

Isolation and Quantification of Zika Virus from Multiple Organs in a Mouse

The methods being presented demonstrate laboratory procedures for the isolation of organs from Zika virus infected animals and the quantification of viral load. The purpose of the procedure is to quantify viral titers in peripheral and CNS areas of the mouse at different time points post infection or under different experimental conditions to identify virologic and immunological factors that regulate Zika virus infection. The organ isolation procedures demonstrated allow for both focus forming assay quantification and quantitative PCR assessment of viral titers. The rapid organ isolation techniques are designed for the preservation of virus titer. Viral titer quantification by focus forming assay allows for the rapid throughput assessment of Zika virus. The benefit of the focus forming assay is the assessment of infectious virus, the limitation of this assay is the potential for organ toxicity reducing the limit of detection. Viral titer assessment is combined with quantitative PCR, and using a recombinant RNA copy control viral genome copy number within the organ is assessed with low limit of detection. Overall these techniques provide an accurate rapid high throughput method for the analysis of Zika viral titers in the periphery and CNS of Zika virus infected animals and can be applied to the assessment of viral titers in the organs of animals infected with most pathogens, including Dengue virus.

The goal of the protocol is to demonstrate the techniques used to investigate viral disease by isolating and quantifying Zika virus, from multiple organs in a mouse following infection.

Isolamento e quantificazione del virus zika da più organi in un mouse

The methods being presented demonstrate laboratory procedures for the isolation of organs from Zika virus infected animals and the quantification of viral ...

Vector Competence Analyses on Aedes aegypti Mosquitoes using Zika Virus

The procedures presented describe a generalized methodology to infect Aedes aegypti mosquitoes with Zika virus under laboratory conditions to determine the rate of infection, disseminated infection, and potential transmission of the virus in the mosquito population in question. These procedures are widely utilized with various modifications in vector competence evaluations globally. They are important in determining the potential role that a given mosquito (i.e., species, population, individual) may play in the transmission of a given agent.

Vector Competence Analyses on Aedes aegypti Mosquitoes using Zika Virus

The presented protocol can determine the vector competence of Aedes aegypti mosquito populations for a given virus, such as Zika, in a containment setting.

Analisi di competenza vettoriale sulle zanzare Aedes aegypti utilizzando il virus Zika

The procedures presented describe a generalized methodology to infect Aedes aegypti mosquitoes with Zika virus under laboratory conditions to determine ...

Virus Propagation and Cell-Based Colorimetric Quantification

Zika virus (ZIKV) is a mosquito-borne virus belonging to the genus Flavivirus. ZIKV infection has been associated with congenital brain abnormalities and potentially Guillain-Barr&#233; syndrome in adults. Research on ZIKV to understand the disease mechanisms is important to facilitate vaccine and treatment development. The method of quantifying viruses is crucial and fundamental in the field of virology. The focus forming assay (FFA) is a virus quantification assay that detects the viral antigen with antibodies and identifies the infection foci of cells using the peroxidase immunostaining technique. The current study describes the virus propagation and quantification protocol using both 24-well and 96-well (high throughput) formats. Compared with other similar studies, this protocol has further described foci size optimization, which can serve as a guide to expand the use of this assay for other viruses. Firstly, ZIKV propagation is performed in Vero cells for 3 days. The culture supernatant containing ZIKV is harvested and quantitated using the FFA. Briefly, the virus culture is inoculated onto Vero cells and incubated for 2-3 days. Foci formation is then determined after optimized staining processes, including cell fixation, permeabilization, blocking, antibody binding, and incubation with peroxidase substrate. The stained virus foci are visualized using a stereo microscope (manual counting in 24-well format) or software analyzer (automated counting in 96-well format). The FFA provides reproducible, relatively fast results (3-4 days) and is suitable to be used for different viruses, including non-plaque-forming viruses. Subsequently, this protocol is useful for the study of ZIKV infection and could be used to detect other clinically important viruses.

The present protocol describes the propagation of Zika virus (ZIKV) in Vero African green monkey kidney cells and the quantification of ZIKV using cell-based colorimetric immunodetection methods in 24-well and 96-well (high throughput) formats.

Propagazione del virus e quantificazione colorimetrica cellulare

Zika virus (ZIKV) is a mosquito-borne virus belonging to the genus Flavivirus. ZIKV infection has been associated with congenital brain abnormalities and ...

Cell-Based Electrical Impedance Platform to Evaluate Zika Virus Inhibitors in Real Time

Cell-based electrical impedance (CEI)&#160;technology measures changes in impedance caused by a growing or manipulated adherent cell monolayer on culture plate wells embedded with electrodes. The technology can be used to monitor the consequences of Zika virus (ZIKV) infection and adherent cell replication in real time, as this virus is highly cytopathogenic. It is a straightforward assay that does not require the use of labels or invasive methods and has the benefit of providing real-time data. The kinetics of ZIKV infection are highly dependent on the employed cell line, virus strain, and multiplicity of infection (MOI), which cannot be easily studied with conventional endpoint assays. Furthermore, the CEI assay can also be used for the evaluation and characterization of antiviral compounds, which can also have dynamic inhibitory properties over the course of infection. This methods article gives a detailed explanation of the practical execution of the CEI assay and its potential applications in ZIKV research and antiviral research in general.

Here, we demonstrate the use of cell-based electrical impedance (CEI) as a very easy and straightforward method to study Zika virus infection and replication in human cells in real time. Furthermore, the CEI assay is useful for the evaluation of antiviral compounds.

Piattaforma di impedenza elettrica basata su cellule per valutare gli inibitori del virus Zika in tempo reale

Cell-based electrical impedance (CEI)&#160;technology measures changes in impedance caused by a growing or manipulated adherent cell monolayer on culture ...

An In Vitro Assay for Screening Interferons as Potent Inhibitors of Zika Virus Growth

Source: Contreras, D. et al., <a href="https://appjove.unicartagenaproxy.elogim.com/v/54767">Zika Virus Infectious Cell Culture System and the In Vitro Prophylactic Effect of Interferons.</a> J. Vis. Exp. (2016)
The video demonstrates an in vitro assay for screening interferons with antiviral activity against the Zika virus, a human pathogen. Within the host cell, the Zika virus undergoes multiplication upon internalization, infecting neighboring cells and creating distinct zones or viral plaques. Type I interferon, acting as an antiviral agent, hinders virus multiplication, thereby preventing the formation of viral plaques in the host cell monolayer.

Un test in vitro per lo screening degli interferoni come potenti inibitori della crescita del virus Zika

1. Screening Cytokine Library against Zika Virus Infection

	Seed naive Vero cells at 1 x 105 cells per well using a 12-well plate. Once the cells are ...

Base di un semplice flusso Cytometry Assay per determinare In Vitro dell'anticorpo dipendente valorizzazione del Virus di febbre rompiossa utilizzando siero convalescente Zika Virus

Riepilogo

Esplora Altri Video

Capitoli in questo video