Este projecto foi financiado em parte com fundos federais do Instituto Nacional de alergia e doenças infecciosas, National Institutes of Health, departamento de saúde e serviços humanos, sob CEIRS P01AI097092-04S1 (P.E.L.) do contrato.

Os experimentos pré-formado neste manuscrito foram feitos institucional código do seguir Icahn da faculdade de medicina de ética e regulamentação.
1. expressão de hemaglutinina do vírus da gripe através de transfeccao ou infecção
Transfecção:
<ol><li>Células de rim humano embrionário (HEK 293T) placa em uma densidade de 2 x 104 células/poço em cultura de tecido branca trataram placa de 96 poços e deixem descansar por 4 horas em uma incubadora de 37 °C (com 5% CO2).</li>
	<li>Transfect células com 100 ng de DNA que codifica para a hemaglutinina viral e 0,2 µ l de reagente de transfeccao por bem em um volume total de 50 μL. Nota: Ambos reagente do plasmídeo e transfectant são diluídos em 1 x Opti-mínimo essencial Media (MEM) reduzida média de soro.</li>
	<li>Incubar as placas em uma incubadora de 37 °C com 5% de CO2 para 18 h, depois de remover mídia do transfection.</li>
</ol>2. infecção
<ol><li>Células de rim canino A549 placa ou Madin Darby em uma densidade de 2 x 104 células/poço em cultura de tecido branca trataram placa de 96 poços e crescerem pelo menos 18 h numa incubadora 37 °C com 5% de CO2.</li>
	<li>Vírus diluído em 1 x MEM e infectar células em uma multiplicidade de infecção de 0,33 por 1h em uma incubadora de 37 °C com 5% de CO2, 1 ou 3. Volume total deve ser igual 100 μL. Nota: 10 x MEM é diluída com água para fazer um estoque de trabalho MEM para diluição de vírus mencionada acima de 1x.</li>
	<li>Após a infecção, remover o inóculo e adicionar 100 μL de 1 x MEM na placa na ausência de tripsina.</li>
	<li>Cresce células infectadas por 18 a 24 h em uma incubadora de 37 °C com 5% de CO2.</li>
</ol>3. avaliação da ativação FcRg/NFAT-mediada de Luciferase atividade por anticorpos monoclonais ou Sera
<ol><li>Primeiro, substitua a mídia de crescimento das células transfectadas ou infectadas com 25 µ l de mídia do ensaio (1 x RPMI 1640 suplementado com 4% (vol/vol) baixa IgG fetal bovino soros).</li>
	<li>Em uma placa de 96 poços separada, realize quatro diluições dos anticorpos de interesse começando em 30 μg/mL, utilizando o meio de ensaio. Realizar diluições em triplica e um layout de placa de exemplo está ilustrado na figura 1A. Certifique-se de incluir um controle que exclui o anticorpo (sem controle de anticorpo) bem como um controle de fundo (buffer de ensaio sozinho). Nota: para ambos os 'sem anticorpos' e controles de fundo, adicione 25 µ l de tampão de ensaio em vez de anticorpo.</li>
	<li>Transferi 25 μL dos anticorpos serialmente diluídos de passo 3.2 para poços correspondentes na placa de células transfectadas ou células infectadas.</li>
	<li>Incube a placa em uma incubadora de 37 °C (com 5% CO2) por 15 min.</li>
	<li>Adicione 25 μL da célula apropriada effector modificados Jurkat expressando murino FcgRIV ou FcgRIIIa humano (75.000 células/poço). Volume total para cada bem deve ser 75 µ l e a concentração inicial e final do anticorpo é a 10 µ g/mL (figura 1B). Nota: Para o controle de fundo, adicione 25 µ l de buffer de ensaio em vez de células efetoras. Para examinar a fagocitose de mediada por células dependente de anticorpo, uma célula modificada de Jurkat expressando a FcgRIIa humana pode ser usada.</li>
	<li>Incube a placa em uma incubadora de 37 ° C com 5% de CO2 para 6 h.</li>
	<li>Degelo e tampão de substrato luciferase quente em uma água de 37 °C por cerca de 1h antes da utilização. Nota: Para fazer o tampão de substrato de luciferase, reconstitua o liofilizado luciferase ensaio substrato no buffer de ensaio fornecido. O tampão de substrato reconstituído pode ser armazenado a-30 °C até-10 °C por até seis semanas.</li>
	<li>Adicione 75 μL/poço do tampão de substrato de luciferase para todos os poços excepto o controle de fundo.</li>
	<li>Ler um luminómetro.</li>
	<li>Calcular a indução de dobra com a seguinte equação: dobre a indução = (valor de valor-Background induzida) / (nenhum valor de valor-fundo de mAb).</li>
</ol>

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Os autores declaram não há conflitos de interesse.

O método descrito aqui permite que o usuário medir a capacidade de um anticorpo monoclonal de HA-específicas para envolver o FcγRIV murino. O antígeno alvo, hemaglutinina do vírus da gripe, é expressa na superfície das células após a infecção por vírus ou transfeccao de Plasmideo DNA. O ensaio é mais ameno com diferentes proteínas virais superfície-expresso em combinação com outros FcγRs (humanos ou murino). Além disso, nós usamos amostras de soros para avaliar a capacidade de anticorpos em um contex...

Imunidade fornecida pela vacina contra a gripe sazonal tradicionalmente tenha sido avaliada pela hemaglutinação (HI) de inibição do ensaio1, que mede a presença de anticorpos que visam o sítio de ligação do receptor da hemaglutinina. Estes anticorpos HI-ativo podem conferir imunidade esterilizante, mas são geralmente estreitos em sua amplitude de proteção, oferecendo imunidade para apenas um seleto poucos estirpes do vírus gripe. O isolamento e caracterização de amplamente reativos anticorpos monoclonais que reconhecem a hemaglutinina (HA) sugerem que o desenvolvimento de uma vacina universal da gripe está ao alcance de3,2,4, 5 , 6 , 7 , 8. um dos objectivos principais de uma vacina universal da gripe é induzir uma resposta do anticorpo forte em direção as regiões conservadas do vírus da gripe9,10,11,12 , 13 , 14 , 15 , 16. amplamente reativos anticorpos que reconhecem estes resumos conservados, composto de neutralizantes e não-neutralizando anticorpos17,18, foram mostrados para exigir Fc-FcγR interações para ideal proteção na vivo e destacar a contribuição da imunidade mediada por Fc para a resposta imune geral a gripe vírus19,20.
Correlações de proteção são cruciais na avaliação de imunidade à infecção. Essas métricas permitem que os cientistas e médicos estimar a eficácia das vacinas, o significado dos dados e o curso do tratamento. O único estabelecido correlato de proteção contra a infecção pelo vírus da gripe é o ensaio de inibição da hemaglutinação. Um título de 01:40 é associado com uma redução de 50% no risco de doença1,21 – e reflete a presença de anticorpos que inibem a aglutinação alvejando o receptor binding site localizado na cabeça globular do HA. No entanto, também deve ser notado que respostas de células T podem ser uma melhor correlação de proteção contra a infecção pelo vírus da gripe em idosos. Curiosamente, um relatório recente sugere que a atividade de inibição de neuraminidase pode ser um melhor preditor de imunidade à gripe22. Felizmente, típico em vitro ensaios tais como ensaios de inibição de neutralização ou neuraminidase podem medir os anticorpos de talo ou neuraminidase-específicos HA. A maioria destes ensaios convencionais em vitro , no entanto, só leva em conta a função da região de ligação do antígeno do anticorpo e não meça o papel da região de Fc. Além disso, a contribuição dos anticorpos não neutralizantes que proteger via Fc receptor noivado na vivo não são detectados17,18. Para medir a proteção conferida pelos anticorpos que induzem a imunidade mediada por Fc como citotoxicidade mediada de célula dependente de anticorpo (ADCC), é necessário um ensaio robusto em vitro .
O método descrito abaixo avalia a capacidade de murino anticorpos monoclonais para induzir funções Fc-mediada através da utilização de uma linhagem de células Jurkat geneticamente modificada expressando uma ativando murino digite 1 FcR, FcγRIV. Noivado de anticorpo da FcγR transduces esse fator nuclear de gatilhos de atividade luciferase mediada por células T ativadas de sinalização intracelular. O ensaio tem várias vantagens sobre as técnicas tradicionais que exigem isolamento e cultura de células efetoras primário e o uso da citometria de fluxo para detectar a ativação do efetor mediada por Fc funções19,23,24 ,25,26. Em primeiro lugar, o protocolo descrito aqui pode ser facilmente adaptado para incorporar diferentes alvos virais, FcγRs e anticorpos de diferentes espécies (humanos e murino). Em segundo lugar, o uso de um modificado células Jurkat linha expressando uma FcγR com um gene do repórter do luciferase sob um fator nuclear das células T ativadas (NFAT) permite a um ensaio de grande formato que pode ser facilmente analisado usando um leitor de placa medindo luminescência. Aqui, a tradicional ativação de células efetoras primário é substituída com a indução do NFAT-luciferase sobre noivado de anticorpo de um FcγR na superfície da célula Jurkat. Este ensaio de formato de placa de 96 poços permite a medição de até quatro diferentes amostras em triplica com sete diluições – um número de amostras que poderia ser complicado usando técnicas tradicionais. Existem pontos adicionais a serem considerados com este ensaio que pode afetar o projeto de experimentos e interpretação de dados. O alvo viral deve ser expressos na superfície da pilha em ordem para reconhecimento de anticorpos. Para atenuar isso, o antígeno alvo (por exemplo, uma proteína viral interna) pode ser revestido diretamente na superfície de uma placa. No entanto, isto não ainda foi rigorosamente testado. Além disso, a linhagem de células Jurkat modificada expressa apenas um tipo de ativação FcγR e não expressa qualquer FcγRs inibitório, enquanto linhas de célula primária expressam todos os receptores em um contexto fisiológico.
Utilizámos anteriormente neste ensaio para demonstrar que o epítopo especificidade em um contexto de polyclonal desempenha um papel crucial na regulação de funções efetoras mediada por Fc e que ideal ativação da resposta de mediada por células dependente de anticorpo requer dois pontos de contato27,28. Aqui, descrevemos um método que avalia a capacidade dos anticorpos monoclonais específicos do talo para engajar e ativar o murino ativando FcγRIV. Embora haja exceções29,30, um grande número de anticorpos reativos amplamente região da haste antigenicamente conservada a hemaglutinina de destino e, portanto, desempenhar um papel importante no desenvolvimento de uma gripe universal vacina.

<table><tbody><tr><td>A549 cells&amp;nbsp;</td><td>ATCC</td><td>CCL-185</td><td>Adenocarcinomic human alveolar basal epithelial cells</td></tr><tr><td>HEK 293T cells</td><td>ATCC</td><td>CRL-3216</td><td>Human embryonic kidney cells</td></tr><tr><td>Lipofectamine 2000</td><td>Life Technologies&amp;nbsp;</td><td>11668019</td><td>Transfection reagent</td></tr><tr><td>1X Opti-MEM Reduced Serum Medium</td><td>ThermoFisher Scientific</td><td>51985-034</td><td></td></tr><tr><td>White tissue culture treated 96-well plate</td><td>Corning, Inc.&amp;nbsp;</td><td>3917</td><td>Assay plates</td></tr><tr><td>10X MEM</td><td>Gibco</td><td>11430-030</td><td></td></tr><tr><td>Jurkat cell expressing murine FcgRIV</td><td>Promega</td><td>M1201</td><td>Kit provides includes cells, Bio-Glo Luciferase assay system, 1X RPMI and low IgG serum</td></tr><tr><td>Jurkat cell expressing human FcgRIIIa</td><td>Promega</td><td>G7010</td><td>Kit provides includes cells, Bio-Glo Luciferase assay system, 1X RPMI and low IgG serum</td></tr><tr><td>Jurkat cell expressing human FcgRIIa</td><td>Promega</td><td>G9901</td><td>Kit provides includes cells, Bio-Glo Luciferase assay system, 1X RPMI and low IgG serum</td></tr><tr><td>Luminometer</td><td>BioTek</td><td>Synergy H1 Multi-Mode reader</td><td>Luminescence plate reader</td></tr><tr><td>Bio-Glo Luciferase Assay System</td><td>Promega</td><td>G7940</td><td>Contains luciferase assay buffer and luciferase assay substrate</td></tr><tr><td>Madin Darby canine kidney cells</td><td>ATCC</td><td>CCL-34</td><td>Canine kidney cells</td></tr></tbody></table>

a method to assess fc-mediated effector functions induced by influenza hemagglutinin specific antibodies

Os anticorpos desempenham um papel crucial no acoplamento as respostas imune inatas e adaptativas contra patógenos virais através dos seus domínios de ligação do antígeno e Fc-regiões. Aqui, descrevemos como medir a ativação do Fc funções efetoras por anticorpos monoclonais visando a hemaglutinina do vírus da gripe com o uso de uma linhagem de células Jurkat geneticamente expressando uma ativação tipo Fc 1-FcγR. usando esse método, o contribuição de interações específicas de Fc-FcγR conferidos por imunoglobulinas pode ser determinada usando um ensaio em vitro .

Demonstrámos que um talo específicos mAb, 6F12, mas não específicos cabeça um cabeça específicos mAb, PY102, era capaz de ativar células primárias de assassinas naturais por estrogenos CD107a e interferon γ19. Para modelar a capacidade de um anticorpo específico de talo de ativar pilhas NK humanas primárias, mostramos que um mAb talo-específicas, 6F12, robustamente pode ativar a célula Jurkat modificada, expressando o murino FcγRIV por ~ 14-fold. Por outro lado, o mAb específico ca...

Watch this Scientific Journal Video about A Method to Assess Fc-mediated Effector Functions Induced by Influenza Hemagglutinin Specific Antibodies at JoVE.com

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

Nós descrevemos um método para medir a ativação das funções efetoras Fc-mediada por anticorpos que visam a hemaglutinina do vírus da gripe. Este ensaio também pode ser adaptado para avaliar a capacidade dos anticorpos monoclonais ou policlonais soros visando outras glicoproteínas de superfície virais para induzir imunidade mediada por Fc.

Um método para avaliar funções efetoras mediada por Fc induzidas por anticorpos específicos de hemaglutinina de gripe

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

a-method-to-assess-fc-mediated-effector-functions-induced-influenza

Universidad de Cartagena UDEC

Research

JoVE Journal

Immunology and Infection

7.6K visualizações.  Icahn School of Medicine at Mount Sinai. Nós descrevemos um método para medir a ativação das funções efetoras Fc-mediada por anticorpos que visam a hemaglutinina do vírus da gripe. Este ensaio também pode ser adaptado para avaliar a capacidade dos anticorpos monoclonais ou policlonais soros visando outras glicoproteínas de superfície virais para induzir imunidade mediada por Fc.

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

Quantitative Analyses of all Influenza Type A Viral Hemagglutinins and Neuraminidases using Universal Antibodies in Simple Slot Blot Assays

Hemagglutinin (HA) and neuraminidase (NA) are two surface proteins of influenza viruses which are known to play important roles in the viral life cycle and the induction of protective immune responses1,2. As the main target for neutralizing antibodies, HA is currently used as the influenza vaccine potency marker and is measured by single radial immunodiffusion (SRID)3. However, the dependence of SRID on the availability of the corresponding subtype-specific antisera causes a minimum of 2-3 months delay for the release of every new vaccine. Moreover, despite evidence that NA also induces protective immunity4, the amount of NA in influenza vaccines is not yet standardized due to a lack of appropriate reagents or analytical method5. Thus, simple alternative methods capable of quantifying HA and NA antigens are desirable for rapid release and better quality control of influenza vaccines.
Universally conserved regions in all available influenza A HA and NA sequences were identified by bioinformatics analyses6-7. One sequence (designated as Uni-1) was identified in the only universally conserved epitope of HA, the fusion peptide6, while two conserved sequences were identified in neuraminidases, one close to the enzymatic active site (designated as HCA-2) and the other close to the N-terminus (designated as HCA-3)7. Peptides with these amino acid sequences were synthesized and used to immunize rabbits for the production of antibodies. The antibody against the Uni-1 epitope of HA was able to bind to 13 subtypes of influenza A HA (H1-H13) while the antibodies against the HCA-2 and HCA-3 regions of NA were capable of binding all 9 NA subtypes. All antibodies showed remarkable specificity against the viral sequences as evidenced by the observation that no cross-reactivity to allantoic proteins was detected. These universal antibodies were then used to develop slot blot assays to quantify HA and NA in influenza A vaccines without the need for specific antisera7,8. Vaccine samples were applied onto a PVDF membrane using a slot blot apparatus along with reference standards diluted to various concentrations. For the detection of HA, samples and standard were first diluted in Tris-buffered saline (TBS) containing 4M urea while for the measurement of NA they were diluted in TBS containing 0.01% Zwittergent as these conditions significantly improved the detection sensitivity. Following the detection of the HA and NA antigens by immunoblotting with their respective universal antibodies, signal intensities were quantified by densitometry. Amounts of HA and NA in the vaccines were then calculated using a standard curve established with the signal intensities of the various concentrations of the references used. 
Given that these antibodies bind to universal epitopes in HA or NA, interested investigators could use them as research tools in immunoassays other than the slot blot only.

A simple slot blot method was developed for the quantification of influenza viral hemagglutinin and neuraminidase using universal antibodies targeting their most conserved sequences identified through bioinformatics analyses. This innovative approach may provide a useful alternative to quantitative determination of all viral hemagglutinin and neuraminidase.

Análise quantitativa de todos Influenza Tipo A Hemaglutininas Virais e neuraminidases usando anticorpos Universal em Ensaios Blot simples slot

Hemagglutinin (HA) and neuraminidase (NA) are two surface proteins of influenza viruses which are known to play important roles in the viral life cycle ...

Imunologia e Infecção

Measuring Influenza Neuraminidase Inhibition Antibody Titers by Enzyme-linked Lectin Assay

Antibodies to neuraminidase (NA), the second most abundant surface protein on influenza virus, contribute toward protection against influenza. Traditional methods to measure NA inhibiting (NI) antibody titers are not practical for routine serology. This protocol describes the enzyme-linked lectin assay (ELLA), a practical alternative method to measure NI titers that is performed in 96 well plates coated with a large glycoprotein substrate, fetuin. NA cleaves terminal sialic acids from fetuin, exposing the penultimate sugar, galactose. Peanut agglutinin (PNA) is a lectin with specificity for galactose and therefore the extent of desialylation can be quantified using a PNA-horseradish peroxidase conjugate, followed by addition of a chromogenic peroxidase substrate. The optical density that is measured is proportional to NA activity. To measure NI antibody titers, serial dilutions of sera are incubated at 37 &#176;C O/N on fetuin-coated plates with a fixed amount of NA. The reciprocal of the highest serum dilution that results in &#8805;50% inhibition of NA activity is designated as the NI antibody titer. The ELLA provides a practical format for routine evaluation of human antibody responses following influenza infection or vaccination.

We describe the enzyme-linked lectin assay (ELLA) for measuring influenza neuraminidase (NA)-inhibition antibody titers in sera. The assay uses peanut agglutinin to quantify galactose residues that become accessible when NA removes sialic acid from fetuin-coated, 96-well plates.

Medição de Inibição da Neuraminidase Influenza títulos de anticorpos por Enzyme-linked Lectina Ensaio

Antibodies to neuraminidase (NA), the second most abundant surface protein on influenza virus, contribute toward protection against influenza. Traditional ...

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.

Estudos do Vírus Influenza A em um Modelo de Infecção de Camundongos

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 ...

Generation of Escape Variants of Neutralizing Influenza Virus Monoclonal Antibodies

Influenza viruses exhibit a remarkable ability to adapt and evade the host immune response. One way is through antigenic changes that occur on the surface glycoproteins of the virus. The generation of escape variants is a powerful method in elucidating how viruses escape immune detection and in identifying critical residues required for antibody binding. Here, we describe a protocol on how to generate influenza A virus escape variants by utilizing human or murine monoclonal antibodies (mAbs) directed against the viral hemagglutinin (HA). With the use of our technique, we previously characterized critical residues required for the binding of antibodies targeting either the head or stalk of the novel avian H7N9 HA. The protocol can be easily adapted for other virus systems. Analyses of escape variants are important for modeling antigenic drift, determining single nucleotide polymorphisms (SNPs) conferring resistance and virus fitness, and in the designing of vaccines and/or therapeutics.

We describe a method by which we identify critical residues required for the binding of human or murine monoclonal antibodies that target the viral hemagglutinin of influenza A viruses. The protocol can be adapted to other virus surface glycoproteins and their corresponding neutralizing antibodies.

Geração de variantes de fuga de neutralizar os anticorpos monoclonais de vírus da gripe

Influenza viruses exhibit a remarkable ability to adapt and evade the host immune response. One way is through antigenic changes that occur on the surface ...

Measuring Influenza Neutralizing Antibody Responses to A(H3N2) Viruses in Human Sera by Microneutralization Assays Using MDCK-SIAT1 Cells

Neutralizing antibodies against hemagglutinin (HA) of influenza viruses are considered the main immune mechanism that correlates with protection for influenza infections. Microneutralization (MN) assays are often used to measure neutralizing antibody responses in human sera after influenza vaccination or infection. Madine Darby Canine Kidney (MDCK) cells are the commonly used cell substrate for MN assays. However, currently circulating 3C.2a and 3C.3a A(H3N2) influenza viruses have acquired altered receptor binding specificity. The MDCK-SIAT1 cell line with increased &#945;-2,6 sialic galactose moieties on the surface has proven to provide improved infectivity and more faithful replications than conventional MDCK cells for these contemporary A(H3N2) viruses. Here, we describe a MN assay using MDCK-SIAT1 cells that has been optimized to quantify neutralizing antibody titers to these contemporary A(H3N2) viruses. In this protocol, heat inactivated sera containing neutralizing antibodies are first serially diluted, then incubated with 100 TCID50/well of influenza A(H3N2) viruses to allow antibodies in the sera to bind to the viruses. MDCK-SIAT1 cells are then added to the virus-antibody mixture, and incubated for 18 - 20 h at 37 &#176;C, 5% CO2 to allow A(H3N2) viruses to infect MDCK-SIAT1 cells. After overnight incubation, plates are fixed and the amount of virus in each well is quantified by an enzyme-linked immunosorbent assay (ELISA) using anti-influenza A nucleoprotein (NP) monoclonal antibodies. Neutralizing antibody titer is defined as the reciprocal of the highest serum dilution that provides &#8805;50% inhibition of virus infectivity.

Measuring Influenza Neutralizing Antibody Responses to AH3N2 Viruses in Human Sera by Microneutralization Assays Using MDCK-SIAT1 Cells

Influenza neutralizing antibodies correlate with protection of influenza infections. Microneutralization assays measure neutralizing antibodies in human sera and are often used for influenza human serology. We describe a microneutralization assay using MDCK-SIAT1 cells to measure neutralizing antibody titers to contemporary 3C.2a and 3C.3a A(H3N2) viruses following influenza vaccination or infection.

Medição da gripe neutralizando Antibody Responses to A(H3N2) vírus em soros humanos por Microneutralization ensaios usando as células MDCK-SIAT1

Neutralizing antibodies against hemagglutinin (HA) of influenza viruses are considered the main immune mechanism that correlates with protection for ...

An Optimized Hemagglutination Inhibition (HI) Assay to Quantify Influenza-specific Antibody Titers

Antibody titers are commonly used as surrogate markers for serological protection against influenza and other pathogens. Detailed knowledge of antibody production pre- and post-vaccination is required to understand vaccine-induced immunity. This article describes a reliable point-by-point protocol to determine influenza-specific antibody titers. The first protocol describes a method to specify the antigen amounts required for hemagglutination, which standardizes the concentrations for subsequent usage in the second protocol (hemagglutination assay, HA assay). The second protocol describes the quantification of influenza-specific antibody titers against different viral strains by using a serial dilution of human serum or cell culture supernatants (hemagglutination inhibition assay, HI assay).
As an applied example, we show the antibody response of a healthy cohort, which received a trivalent inactivated influenza vaccine. Additionally, the cross-reactivity between the different influenza viruses is shown and methods to minimize cross-reactivity by using different types of animal red blood cells (RBCs) are explained. The discussion highlights advantages and disadvantages of the presented assays and how the determination of influenza-specific antibody titers can improve the understanding of vaccine-related immunity.

An Optimized Hemagglutination Inhibition HI Assay to Quantify Influenza-specific Antibody Titers

The presented protocols describe how to perform a hemagglutination inhibition assay to quantify influenza-specific antibody titers from serum samples of influenza vaccine recipients. The first assay determines optimal viral antigen concentrations by hemagglutination. The second assay quantifies influenza-specific antibody titers by hemagglutination inhibition.

Um ensaio de inibição (HI) de hemaglutinação otimizado para quantificar os anticorpos específicos de gripe

Antibody titers are commonly used as surrogate markers for serological protection against influenza and other pathogens. Detailed knowledge of antibody ...

Medicina

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

T Follicular Helper (Tfh) cells are an independent CD4+&#160;T cell subset specialized in providing help for germinal center (GC) development and generation of high-affinity antibodies. In influenza virus infection, robust Tfh and GC B cell responses are induced to facilitate effective virus eradication, which confers a qualified mouse model for Tfh-associated study. In this paper, we described protocols in detection of basic Tfh-associated immune response during influenza virus infection in mice. These protocols include: intranasal inoculation of influenza virus; flow cytometry staining and analysis of polyclonal and antigen-specific Tfh cells, GC B cells and plasma cells; immunofluorescence detection of GCs; enzyme-linked immunosorbent assay (ELISA) of influenza virus-specific antibody in serum. These assays basically quantify the differentiation and function of Tfh cells in influenza virus infection, thus providing help for studies in elucidating differentiation mechanism and manipulation strategy.

This paper describes protocols of evaluating Tfh and GC B response in mouse model of influenza virus infection.

Avaliação de células auxiliares tolas e resposta do centro germinal durante a infecção pelo vírus da influenza A em camundongos

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

Measuring the Activation of Fc-Mediated Effector Functions by HA Antibodies

Source: Bailey, M. J., et al. <a href="https://appjove.unicartagenaproxy.elogim.com/v/56256">A Method to Assess Fc-mediated Effector Functions Induced by Influenza Hemagglutinin Specific Antibodies.</a> J. Vis. Exp. (2018).
This video demonstrates an assay measuring the antibody-mediated activation of T cell effector functions. Adding an influenza virus hemagglutinin (HA)-specific monoclonal antibody to transfected mammalian cells expressing HA results in the formation of immune complexes with HA. Upon introducing engineered T cells expressing Fc receptors and a luciferase reporter, the T cells are activated by the antibody-HA complexes, and this activation is detected by adding a luciferase substrate and measuring the produced bioluminescence.

Medindo a ativação de funções efetoras mediadas por Fc por anticorpos HA

1. Expression of Influenza Virus Hemagglutinin via Transfection

	Plate Human Embryonic Kidney (HEK 293T) cells at a density of 2 x 104 cells/well in a ...

JoVE Encyclopedia of Experiments

Imunologia

Antibody-Based Technologies

Characterization and Functional Analysis

Generation of Influenza Virus Escape Variants against Neutralizing Antibodies

Source: Leon, P. E., et al. <a href="https://appjove.unicartagenaproxy.elogim.com/v/56067">Generation of Escape Variants of Neutralizing Influenza Virus Monoclonal Antibodies.</a> J. Vis. Exp. (2017).
This video demonstrates a technique for generating escape variants of neutralizing influenza virus monoclonal antibodies. Antibody-neutralized virus suspension is injected into embryonated chicken eggs to propagate escape variants selectively. This results in a virus population predominantly of escape variants, confirmed via a Hemagglutination assay.

Geração de variantes de escape do vírus influenza contra anticorpos neutralizantes

NOTE: HA-specific antibodies that inhibit viral replication can generally be categorized into i) ones that bind on or adjacent of the receptor binding ...

The Hemagglutination Inhibition Assay to Detect Serum Antibodies Against a Target Antigen

Source: Kaufmann, L. et al., <a href="https://appjove.unicartagenaproxy.elogim.com/v/55833">An Optimized Hemagglutination Inhibition (HI) Assay to Quantify Influenza-specific Antibody Titers.</a> J. Vis. Exp. (2017)
The video demonstrates a hemagglutination inhibition assay for detecting serum antibodies against specific antigens. Confirmation of hemagglutination inhibition in the test well and hemagglutination in the control well is achieved through distinct visual patterns. This assay plays a crucial role in assessing immune response, vaccine effectiveness, and studying viral infections in virology and immunology.

O ensaio de inibição da hemaglutinação para detectar anticorpos séricos contra um antígeno alvo

All procedures involving human participants have been performed in compliance with the institutional, national, and international guidelines for human ...