O projeto descrito foi apoiado por fundos da Universidade de Ciências da saúde serviços fardado a JJM. As opiniões ou declarações contidas neste documento são os privados dos autores e não são ser interpretado como oficiais ou refletindo as opiniões do departamento de defesa, a Universidade de serviços fardado de Ciências da saúde ou qualquer outra agência dos Estados Unidos Governo.
WGV executadas todas as experiências e analisa os dados; JJM projetou e supervisionou o estudo; WGW e JJM escreveram o jornal.

As amostras de soro usadas para demonstrar o protocolo descrito aqui foram obtidas de macacos rhesus que estavam alojadas e cuidadas de acordo com o local, estado e federais condições em uma associação para avaliação e acreditação do cuidado de Animal de laboratório Internacional (AAALAC)-credenciado com facilidade. Todos os experimentos com animais foram revistos e aprovados pela Comissão de uso e cuidado institucional do Animal e as amostras foram adquiridas através de um protocolo de compartilhamento de tecido.
1. dia-1
Nota: Execute todos os passos descritos abaixo em uma fluxo de laminar estéril biossegurança armário usada para cultura de tecidos em um laboratório BSL-2.
<ol><li>Descongelar as amostras de soro à temperatura ambiente e transferir 100 µ l de cada amostra de soro a um tubo estéril. Calor inativar por 30 min a 56° C em banho-maria ou um thermomixer temperatura ajustável. Fazer 10 vezes seriais diluições da amostra soro variando de 1:1 a 1:1,000 usando frio RPMI-10 (RPMI com 10% de soro fetal bovino).</li>
	<li>Transferência de 10 µ l de amostra de soro diluído em série a cada poço um estéril 96 poços V-da placa de base. Incluem dois conjuntos de controle poços, RPMI-10 com RVPs só e sem amostra de soro e RPMI-10 só que sem RVPs e sem amostra de soro. Configure cada amostra de soro e RPMI-10 controles em triplica.</li>
	<li>Retire a Dengue-1, 2, 3 e 4 RVPs do congelador-80 ° C e descongele-os em banho maria a 37 ° C. Transferi os RVPs descongelados imediatamente em gelo. Obter RVPs aproximadamente 170 µ l de cada amostra de soro (10 µ l de poços RVPs x 3 para cada diluição (1:1, 01:10, 1: 100, 1:1, 000) e 10 µ l de poços RVPs x 3 para cada um dos 10-RPMI com RVP só controlam poços).</li>
	<li>Pipete 10 µ l de RVPs em cada bem a 96 poços V-da placa de base que contém a amostra de soro e o RPMI-10 com poços de controle RVPs (sem soro). Não adicione RVPs ao RPMI-10 só (nenhuma amostra de soro e sem RVP) poços. Misturar cuidadosamente pipetando para cima e para baixo 5-10 vezes. Adicionar 10 µ l frio RPMI-10 em vez de RVPs cada frio RPMI-10 somente (nenhuma amostra de soro e sem RVP) de controle de poços.</li>
	<li>Transferir a placa de V-fundo de 96 poços para uma incubadora e incubar a placa por 1 hora a 37 ° C, na presença de 5% de CO2. Enquanto a placa de 96 poços de V-fundo está incubando, limpe a superfície do armário com etanol a 70% da biossegurança e executar o UV luz por 15 min.</li>
	<li>Remover um balão T75 totalmente confluente de células K562 da incubadora, misturar as células bem usando uma pipeta estéril 5 mL e transferir 5ml de células para um tubo cônico estéril 15 mL. Nota: As células K562 são mantidas em RPMI-10 e repicagem em 1 x 106/mL.</li>
	<li>Contar o número de células por remover 10 µ l células do tubo cônico estéril 15 mL e misturar com o azul de tryphan 10 µ l. Conte as células usando um hemocytometer para determinar o número total de células no tubo cônico de 15 mL.</li>
	<li>Centrifugue a 15ml cónico com células a ~ 1.200 x g durante 10 minutos, decante o sobrenadante e ressuspender as células em RPMI quente-10 em uma concentração de 80.000 µ l de células/30 de mídia (2.66 x 106 células /mL).</li>
	<li>Remova a placa de 96 poços de V-fundo da incubadora (passo 1.6), transferir 30 µ l de células K562 a cada poço da placa de 96 poços V-fundo e homogeneiza pipetando para cima e para baixo 5-10 vezes. Transferir a placa de V-fundo de 96 poços para uma incubadora e incubar a placa por 1 hora a 37 ° C, na presença de 5% de CO2.</li>
	<li>Após incubação por 1h, remova a placa de 96 poços de V-fundo da incubadora e centrifugar ~ 1.200 x g por 5 minutos. Após a centrifugação, decante a mídia dos poços, girando o prato de cabeça para baixo em um recipiente contendo água sanitária 10%.</li>
	<li>Lavar as células em cada poço por resuspending-los em 125 µ l de RPMI-10 quente, misture bem com uma pipeta e centrifugar a placa a ~ 1.200 x g durante 5 min. decantar a mídia girando o prato de cabeça para baixo em um recipiente contendo água sanitária 10%. Repita este passo de lavar duas vezes.</li>
	<li>Após a lavagem, adicionar 100 µ l de morno RPMI-10 a cada misture bem, subindo e descendo com a pipeta e incubar a placa por 48 h a 37 ° C, na presença de 5% de CO2.</li>
</ol>2. dia 3
<ol><li>Remover a placa de V-fundo de 96 poços contendo 100 µ l de células e de mídia/poço da incubadora e movê-lo para uma armário de biossegurança. Usando uma pipeta multicanal, misturar o conteúdo de cada bem e transferir as células e mídia para um fundo bem U 96 placa ou para pre-rotulado tubos polipropileno de 5 mL.</li>
	<li>Enxágue a cada poço em placa de 96 poços V-fundo com 100 µ l de 1% paraformaldeído (PFA) em 1 x fosfato tamponado salino (PBS) e transferência aos respectivos poços no 96 bem U-parte inferior da placa ou polipropileno tubos etiquetados 5ml da etapa 2.1 para produzir uma final concentração de 0,5% PFA/poço ou tubo. Misturar cuidadosamente com uma pipeta multicanal, cubra o prato com papel alumínio e deixe descansar na incubadora durante 30 minutos para consertar as células.</li>
	<li>Preparar o citômetro de fluxo (ver Tabela de materiais , por exemplo) executando imaculadas células K562 para calibrar o lado e espalhe para a frente, juntamente com as configurações de fluorescência. O canal de fluorescência apenas exigido é FL1, como GFP é a única fluorescência emitida a partir das células. Adquirir ~ 30, 000 – 50.000 células de cada amostra. Nota: Qualquer citômetro de fluxo capaz de ler uma única fluorescência pode ser usado para a aquisição de dados, como as células infectadas com RVPs só emitirão fluorescência verde devido à presença de GFP, e nenhum outro canal de fluorescência são necessários.</li>
</ol>3. análise de dados
<ol><li>
Analisar dados adquiridos sobre o citômetro de fluxo usando qualquer software de análise de citometria de fluxo (ver tabela de materiais).
	<ol>
<li>Conjunto o primeiro Portal baseado no FSC-A (dispersão frente – área) vs FSC-H (frente dispersão – altura) para incluir células únicas e excluir autofluorescente parelhas de análise12. Então, portão células dependentes de singlete baseadas no SSC-A (dispersão lateral – área) vs FSC-A para excluir todos os restos de autofluorescent.</li>
		<li>Analisar o SSC-A vs células gated FSC-A para a expressão de GFP baseado no SSC-A vs GFP-A. Determine a porcentagem de células GFP + para cada diluição das amostras de soro e controle definindo um portão ao redor de células GFP +.</li>
	</ol>
</li>
	<li>Determine a percentagem média de células GFP + para cada diluição da amostra de soro e controle de poços, dividindo a percentagem de células GFP + em poços de três vias por 3.</li>
	<li>Calcule dobra-realce de infecção dividindo a percentagem média de células GFP + nas amostras de soro para cada diluição dividido pela percentagem média de células GFP + na RPMI-10 com poços de controle RVPs (nenhuma amostra de soro).</li>
	<li>Gráfico dobra-realce (eixo y) contra diluição (eixo x) e realizar análise estatística utilizando ANOVA seguida pelo teste post-hoc de Tukey para comparações múltiplas.</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>

Os autores não têm nada para divulgar.

Flavivírus como DENV e ZIKV compartilham significativa evidência de homologia em ambas as suas proteínas estruturais e não estruturais que geram anticorpos que reagem de forma cruzada com os outros13,14. Estas respostas de anticorpos cross-reactive têm sido mostradas para melhorar da infecção in vivo e em vitro com um sorotipo heterólogo ou outros relacionados flavivírus1,2. O p...

Reforço de dependente de anticorpos (ADE) da infecção é um processo pelo qual respostas parcialmente cross-reactive anticorpos induzidas por um sorotipo de vírus aumenta a absorção de outro sorotipo do vírus, levando a virémia e aumento de replicação viral. ADE tem sido extensivamente documentada em infecções por vírus (DENV) Dengue onde quatro sorotipos principais são predominantes. Em um subconjunto de pacientes, ADE está associada com febre hemorrágica da Dengue (FHD). Recentemente mostramos que infecção por vírus (ZIKV) Zika induzido níveis significativamente elevados de respostas de anticorpos cross-reactive DENV que causou ADE de DENV em vitro e provavelmente contribuíram para o reforço da virémia no vivoDENV1 , 2. ensaios de realce dependente de anticorpo são uma ferramenta valiosa para avaliar a capacidade dos anticorpos para melhorar a infecção secundária com vírus relacionados e fornecer insights valiosos sobre a patogênese das infecções flavivirus e informar o desenvolvimento de vacinas.
O ensaio descrito aqui usa DENV RVPs juntamente com células K562 que são normalmente inadmissíveis à infecção. RVPs são estruturalmente intacta replicação incompetente DENV partículas virais que codificar um Replicão subgenômica de proteína verde fluorescente (GFP) que manifesta-se após uma única rodada de replicação3. Como tal, as células que são infectadas com RVPs fluorescem verde e podem ser facilmente detectadas usando citometria de fluxo ou microscopia. Os RVPs usadas neste ensaio foram obtidas de fontes comerciais. Eles podem, no entanto, ser gerado contra outros vírus e utilizada no ensaio descrito neste manuscrito. Enquanto isso, as células K562 são uma linhagem de células de leucemia FcγIII-receptor-expressando que se ligam à região Fc dos anticorpos e tornar-se infectado na presença de sub, neutralizando as concentrações de anticorpos4,5.
ADE ensaios têm sido amplamente utilizados em estudos investigando os fatores de risco para dengue grave e para delinear os mecanismos em vitro ADE6,7,8. O ensaio de ADE descrito aqui pode ser rapidamente e facilmente usado para determinar a capacidade do soro para aumentar a infecção em vitro usando RVPs e fluxo cytometry, em comparação com outros ensaios utilizados atualmente, que também exigem a determinação da formação de placa bacteriana unidades (pfu) em células Vero ou mancha do anticorpo de infectados células6,7,8,9,10,11, ambos os quais são demorados e trabalhistas intensiva.

<table border="0" cellpadding="0" cellspacing="0" width="794">
	<tbody>
		<tr height="21">
			<td height="21" style="height:21px;width:215px;">DENV 1-4 RVP</td>
			<td style="width:139px;">Integral Molecular</td>
			<td style="width:119px;">RVP-501</td>
			<td style="width:323px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:215px;">K562 cells</td>
			<td style="width:139px;">ATCC</td>
			<td style="width:119px;">CCL-243</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:215px;">RPMI</td>
			<td style="width:139px;">Corning</td>
			<td style="width:119px;">10-040-CV</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:215px;">FBS</td>
			<td style="width:139px;">GE lifesceinces</td>
			<td style="width:119px;">SH 30910.03</td>
			<td>10% FBS in RPMI-10</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:215px;">Penicillin-Streptomycin</td>
			<td style="width:139px;">MP biomedicals</td>
			<td style="width:119px;">1670049</td>
			<td>100 IU Pen/mL, 100 ug Strep/mL in RPMI-10</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:215px;">HEPES</td>
			<td style="width:139px;">Cellegro</td>
			<td style="width:119px;">25-060-Cl</td>
			<td>0.025M in RPMI-10</td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:215px;">MEM Non-essential Amino Acid Solution (100&#215;)</td>
			<td style="width:139px;">Sigma</td>
			<td style="width:119px;">M7145</td>
			<td>1x in RPMI-10</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:215px;">Sodium Pyruvate</td>
			<td style="width:139px;">Cellegro</td>
			<td style="width:119px;">25-000-Cl</td>
			<td>1mM in RPMI-10</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:215px;">L-glutamine</td>
			<td style="width:139px;">Fisher Scientific</td>
			<td style="width:119px;">MT25005CI&#160;</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:215px;">Sterile V-bottom plates</td>
			<td style="width:139px;">Thomas Scientific</td>
			<td style="width:119px;">333-8001-01V</td>
			<td></td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:215px;">BD Falcon Polypropylene 5 ml FACS tubes</td>
			<td style="width:139px;">VWR</td>
			<td style="width:119px;">60819-728</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:215px;">Non-sterile U-bottom plates</td>
			<td style="width:139px;">Falcon</td>
			<td style="width:119px;">Ref 353910</td>
			<td>A high throughput alternative to FACS tubes</td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:215px;">5mL, sterile, serological pipette</td>
			<td style="width:139px;">Denville</td>
			<td style="width:119px;">P7127</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:215px;">200uL sterile pipette tips</td>
			<td style="width:139px;">Denville</td>
			<td style="width:119px;">P3020 CPS</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:215px;">20uL sterile pipette tips</td>
			<td style="width:139px;">Denville</td>
			<td style="width:119px;">P1121</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:215px;">50-200uL multichannel pipette</td>
			<td style="width:139px;">Denville</td>
			<td style="width:119px;">P3975-8-B</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:215px;">5-50uL multichannel pipette</td>
			<td style="width:139px;">Denville</td>
			<td style="width:119px;">P3975-9-B</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:215px;">20% formadehyde</td>
			<td style="width:139px;">Tousimis</td>
			<td style="width:119px;">&#160;#1008B</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:215px;">Water Bath</td>
			<td style="width:139px;">ThermoFisher</td>
			<td style="width:119px;">TSCOL35</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:215px;">thermomixer</td>
			<td style="width:139px;">Eppendorf</td>
			<td style="width:119px;">2231000387</td>
			<td>An alternative to a waterbath for heat inactivation</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:215px;">CO2 Incubator</td>
			<td style="width:139px;">ThermoFisher</td>
			<td style="width:119px;">13-998-213</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:215px;">Ethanol</td>
			<td style="width:139px;">Sigma Aldrich</td>
			<td style="width:119px;">E7023</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:215px;">Liquid Bleach</td>
			<td style="width:139px;">Fisher Scientific</td>
			<td style="width:119px;">NC9724348</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:215px;">Flowjo 9.8</td>
			<td style="width:139px;">TreeStar, Inc.</td>
			<td style="width:119px;"></td>
			<td>Flow cytometry analysis software</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">BD FACSDiva 6.1.2</td>
			<td style="width:139px;">Becton Dikinson</td>
			<td style="width:119px;"></td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:215px;">BD LSR II flow cytometer</td>
			<td style="width:139px;">Becton Dikinson</td>
			<td style="width:119px;"></td>
			<td></td>
		</tr>
		<tr height="22">
			<td height="22" style="height:22px;width:215px;">Liquid Bleach</td>
			<td style="width:139px;">Fisher Scientific</td>
			<td style="width:119px;">NC9724348</td>
			<td></td>
		</tr>
	</tbody>
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a simple flow cytometry based assay to determine in vitro antibody dependent enhancement of dengue virus using zika virus convalescent serum

Realce dependente de anticorpo da infecção foi mostrado para jogar um papel importante na patogênese viral de Dengue. Os ensaios tradicionais que medem a capacidade dos anticorpos ou soro para aumentar a infecção em linhas celulares impermissible têm invocado usando saída viral na mídia seguida de ensaios de placa para quantificar a infecção. Mais recentemente, estes ensaios examinaram a infecção por vírus (DENV) Dengue em linhas celulares usando anticorpos fluorescente etiquetados. Ambas as abordagens têm limitações que restringem o uso generalizado destas técnicas. Aqui, descrevemos um ensaio simples em vitro usando Dengue vírus repórter partículas virais (RVPs) que expressam a proteína verde fluorescente e células K562 para examinar o anticorpo dependente do realce (ADE) de infecção DENV usando soro que foi obtido a partir do rhesus macacos de 16 semanas após a infecção com vírus Zika (ZIKV). Esta técnica é confiável, envolve manipulação mínima das células, não envolve a utilização de vírus competente de replicação ao vivo e pode ser executada em um formato de alta taxa de transferência para obter uma leitura quantitativa usando citometria de fluxo. Além disso, este ensaio pode ser facilmente adaptado para examinar o anticorpo dependente do realce (ADE) de outros flavivirus infecções tais como o vírus da febre amarela (YFV), vírus da encefalite equina japonesa (LILICA), vírus do Nilo Ocidental (WNV) etc onde RVPs estão disponíveis. A facilidade de criação de ensaio, analisando os dados e interpretação de resultados tornam altamente receptivos a maioria das configurações de laboratório.

Os soros de 4 do rhesus macaques foram coletadas 16 semanas após a infecção com ZIKV e testaram por seu potencial melhorar o DENV-1, 2, 3 e 4 infecção em células K562. Os animais tiveram virémia pico de ~ 1 x 105 cópias de RNA/mL ZIKV de plasma por dia 3 após infecção que recusou-se a níveis que estavam abaixo do limite de detecção por 7 dias após a infecção. Não virémia foi detectada no plasma a pós-infecção 16 semanas. Em seguida, realizou-se o ensaio da...

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

Descreveremos um protocolo simples e fácil para medição de reforço dependente de anticorpo da infecção por Zika vírus soro convalescente usando partículas virais da Dengue vírus repórter.

A citometria de fluxo simples com base em ensaio para determinar In Vitro anticorpo dependente do realce do vírus da Dengue, usando soro convalescente vírus Zika

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

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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 visualizações.  Uniformed Services University. Descreveremos um protocolo simples e fácil para medição de reforço dependente de anticorpo da infecção por Zika vírus soro convalescente usando partículas virais da Dengue vírus repórter.

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

Visualizing Dengue Virus through Alexa Fluor Labeling

The early events in the interaction between virus and cell can have profound influence on the outcome of infection. Determining the factors 
that influence this interaction could lead to improved understanding of disease pathogenesis and thus influence vaccine or therapeutic design. Hence, the development 
of methods to probe this interaction would be useful. Recent advancements in fluorophores development1-3 and imaging technology4 can be exploited to 
improve our current knowledge on dengue pathogenesis and thus pave the way to reduce the millions of dengue infections occurring annually.

The enveloped dengue virus has an external scaffold consisting of 90 envelope glycoprotein (E) dimers protecting the nucleocapsid shell, 
which contains a single positive strand RNA genome5. The identical protein subunits on the virus surface can thus be labeled with an amine reactive dye and visualized 
through immunofluorescent microscopy. Here, we present a simple method of labeling of dengue virus with Alexa Fluor succinimidyl ester dye dissolved directly in a sodium 
bicarbonate buffer that yielded highly viable virus after labeling. There is no standardized procedure for the labeling of live virus and existing manufacturer&#x2019;s protocol 
for protein labeling usually requires the reconstitution of dye in dimethyl sulfoxide. The presence of dimethyl sulfoxide, even in minute quantities, can block 
productive infection of virus and also induce cell cytotoxicity6. The exclusion of the use of dimethyl sulfoxide in this protocol thus reduced this possibility. 
Alexa Fluor dyes have superior photostability and are less pH-sensitive than the common dyes, such as fluorescein and rhodamine2, making them ideal for 
studies on cellular uptake and endosomal transport of the virus. The conjugation of Alexa Fluor dye did not affect the recognition of labeled dengue 
virus by virus-specific antibody and its putative receptors in host cells7. This method could have useful applications in virological studies.

Taking advantage of the advancements in fluorophore development and imaging technology, a simple method of Alexa Fluor labeling of dengue virus was devised to visualize the early interactions between virus and cell.

Visualizando Vírus da Dengue por meio Alexa Fluor Labeling

The early events in the interaction between virus and cell can have profound influence on the outcome of infection. Determining the factors 
that ...

Imunologia e Infecção

Image-based Flow Cytometry Technique to Evaluate Changes in Granulocyte Function In Vitro

Granulocytes play a key role in the body&#8217;s innate immune response to bacterial and viral infections. While methods exist to measure granulocyte function, in general these are limited in terms of the information they can provide. For example, most existing assays merely provide a percentage of how many granulocytes are activated following a single, fixed length incubation. Complicating matters, most assays focus on only one aspect of function due to limitations in detection technology. This report demonstrates a technique for simultaneous measurement of granulocyte phagocytosis of bacteria and oxidative burst. By measuring both of these functions at the same time, three unique phenotypes of activated granulocytes were identified: 1) Low Activation (minimal phagocytosis, no oxidative burst), 2) Moderate Activation (moderate phagocytosis, some oxidative burst, but no co-localization of the two functional events), and 3) High Activation (high phagocytosis, high oxidative burst, co-localization of phagocytosis and oxidative burst). A fourth population that consisted of inactivated granulocytes was also identified. Using assay incubations of 10, 20, and 40-min the effect of assay incubation duration on the redistribution of activated granulocyte phenotypes was assessed. A fourth incubation was completed on ice as a control. By using serial time incubations, the assay may be able to able to detect how a treatment spatially affects granulocyte function. All samples were measured using an image-based flow cytometer equipped with a quantitative imaging (QI) option, autosampler, and multiple lasers (488, 642, and 785 nm).

Image-based Flow Cytometry Technique to Evaluate Changes in Granulocyte Function In Vitro

This method demonstrates a technique for assessing granulocyte function by simultaneously measuring phagocytosis of bacteria and oxidative burst. Image-based flow cytometry allowed for the identification of three distinct subsets of activated granulocytes that all differed in their relative functional capacity.

Baseada em imagem Técnica de Citometria de Fluxo para avaliar as mudanças na função de granulócitos<em&gt; In Vitro</em

Granulocytes play a key role in the body&#8217;s innate immune response to bacterial and viral infections. While methods exist to measure granulocyte ...

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.

Medindo Anexo e Internalização do Vírus da Influenza A em células A549 por citometria de fluxo

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.

Isolamento de neutrófilos e análise para determinar seu papel na linfoma sensibilidade das células a agentes terapêuticos

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 ...

A Simple and Efficient Approach to Construct Mutant Vaccinia Virus Vectors

The CRISPR-associated endonuclease Cas9 can edit particular genomic loci directed by a single guide RNA (gRNA). The CRISPR/Cas9 system has been successfully employed for editing genomes of various organisms. Here we describe a protocol for editing the vaccinia virus (VV) genome in the cytoplasm of VV-infected CV-1 cells using the RNA-guided Cas9. RNA-guided Cas9 induces double-stranded DNA breaks facilitating homologous recombination efficiently and specifically in the targeted site of VV and a transgene can be incorporated into these sites by homologous recombination. By using a site-specific homologous vector with transgene(s), a N1L gene-deleted VV with the red fluorescence protein (RFP) gene incorporated in this region was generated with a successful recombination efficiency 10 times greater than that obtained from the conventional homologous recombination method. This protocol demonstrates successful use of RNA-guided Cas9 system to generate mutant VVs with enhanced efficiency.

Vaccinia virus (VV) has been widely used in biomedical research and the improvement of human health. This article describes a simple, highly efficient method to edit the VV genome using a CRISPR-Cas9 system.

Uma abordagem simples e eficiente para construir vectores de vírus mutante Vaccinia

The CRISPR-associated endonuclease Cas9 can edit particular genomic loci directed by a single guide RNA (gRNA). The CRISPR/Cas9 system has been ...

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.

Virus Zika sistema de cultura celular Infecciosas e do<em&gt; In Vitro</em&gt; Efeito profilático de interferões

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

Rescue and Characterization of Recombinant Virus from a New World Zika Virus Infectious Clone

Infectious cDNA clones allow for genetic manipulation of a virus, thus facilitating work on vaccines, pathogenesis, replication, transmission and viral evolution. Here we describe the construction of an infectious clone for Zika virus (ZIKV), which is currently causing an explosive outbreak in the Americas. To prevent toxicity to bacteria that is commonly observed with flavivirus-derived plasmids, we generated a two-plasmid system which separates the genome at the NS1 gene and is more stable than full-length constructs that could not be successfully recovered without mutations. After digestion and ligation to join the two fragments, full-length viral RNA can be generated by in vitro transcription with T7 RNA polymerase. Following electroporation of transcribed RNA into cells, virus was recovered that exhibited similar in vitro growth kinetics and in vivo virulence and infection phenotypes in mice and mosquitoes, respectively.

This protocol describes the recovery of infectious Zika virus from a two-plasmid infectious cDNA clone.

Salvamento e Caracterização do Vírus Recombinante de um Clone Infeccioso do Vírus do Novo Mundo Zika

Infectious cDNA clones allow for genetic manipulation of a virus, thus facilitating work on vaccines, pathogenesis, replication, transmission and viral ...

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.

Zika vírus específico diagnóstico 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 ...

Isolation and In Vitro Culture of Murine and Human Alveolar Macrophages

Alveolar macrophages are terminally differentiated, lung-resident macrophages of prenatal origin. Alveolar macrophages are unique in their long life and their important role in lung development and function, as well as their lung-localized responses to infection and inflammation. To date, no unified method for identification, isolation, and handling of alveolar macrophages from humans and mice exists. Such a method is needed for studies on these important innate immune cells in various experimental settings. The method described here, which can be easily adopted by any laboratory, is a simplified approach to harvesting alveolar macrophages from bronchoalveolar lavage fluid or from lung tissue and maintaining them in vitro. Because alveolar macrophages primarily occur as adherent cells in the alveoli, the focus of this method is on dislodging them prior to harvest and identification. The lung is a highly vascularized organ, and various cell types of myeloid and lymphoid origin inhabit, interact, and are influenced by the lung microenvironment. By using the set of surface markers described here, researchers can easily and unambiguously distinguish alveolar macrophages from other leukocytes, and purify them for downstream applications. The culture method developed herein supports both human and mouse alveolar macrophages for in vitro growth, and is compatible with cellular and molecular studies.

Isolation and In Vitro Culture of Murine and Human Alveolar Macrophages

This communication describes methodologies for isolation and culture of alveolar macrophages from humans and murine models for experimental purposes.

Isolamento e cultura In Vitro de macrófagos alveolares murino e humanos

Alveolar macrophages are terminally differentiated, lung-resident macrophages of prenatal origin. Alveolar macrophages are unique in their long life and ...

Rapid, Safe, and Simple Manual Bedside Nucleic Acid Extraction for the Detection of Virus in Whole Blood Samples

The rapid diagnosis of an infection is essential for the outbreak management, risk containment, and patient care. We have previously shown a method for the rapid bedside inactivation of the Ebola virus during blood sampling for safe nucleic acid (NA) tests by adding a commercial lysis/binding buffer directly into the vacuum blood collection tubes. Using this bedside inactivation approach, we have developed a safe, rapid, and simplified bedside NA extraction method for the subsequent detection of a virus in lysis/binding buffer-inactivated whole blood. The NA extraction is directly performed in the blood collection tubes and requires no equipment or electricity. 
After the blood is collected into the lysis/binding buffer, the contents are mixed by flipping the tube by hand, and the mixture is incubated for 20 min at room temperature. Magnetic glass particles (MGPs) are added to the tube, and the contents are mixed by flipping the collection tube by hand. The MGPs are then collected on the side of the blood collection tube using a magnetic holder or a magnet and a rubber band. The MGPs are washed three times, and after the addition of elution buffer directly into the collection tube, the NAs are ready for NA tests, such as qPCR or isothermal loop amplification (LAMP), without the removal of the MGPs from the reaction. The NA extraction method is not dependent on any laboratory facilities and can easily be used anywhere (e.g., in field hospitals and hospital isolation wards). When this NA extraction method is combined with LAMP and a portable instrument, a diagnosis can be obtained within 40 min of the blood collection.

Here, we present a protocol for the rapid virus nucleic acid extraction from the virus-inactivated whole blood. The extraction is performed directly in the blood collection tubes and requires no equipment or electricity. The method is not dependent on laboratory facilities and can be used anywhere (e.g., in field hospitals).

Extração rápida, segura e simples Manual cabeceira de ácidos nucleicos para a detecção de vírus em amostras de sangue total

The rapid diagnosis of an infection is essential for the outbreak management, risk containment, and patient care. We have previously shown a method for ...

A citometria de fluxo simples com base em ensaio para determinar In Vitro anticorpo dependente do realce do vírus da Dengue, usando soro convalescente vírus Zika

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