<ol>
	<li>. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Prevention+and+control+of+seasonal+influenza+with+vaccines.+Recommendations+of+the+Advisory+Committee+on+Immunization+Practices--United+States,+2013-2014.">Prevention and control of seasonal influenza with vaccines. Recommendations of the Advisory Committee on Immunization Practices--United States, 2013-2014.</a> MMWR Recomm Rep. 62, 1-43 (2013).</li><li>Dominguez-Cherit, G., 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=Critically+Ill+patients+with+2009+influenza+A(H1N1)+in+Mexico.">Critically Ill patients with 2009 influenza A(H1N1) in Mexico.</a> JAMA. 302 (17), 1880-1887 (2009).</li><li>Fox, B. D., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Pandemic+influenza+(H1N1):+impact+on+lung+transplant+recipients+and+candidates.">Pandemic influenza (H1N1): impact on lung transplant recipients and candidates.</a> J Heart Lung Transplant. 29 (9), 1034-1038 (2010).</li><li>Piercy, J., Miles, A., Krankheiten, S. B. f. G. S. V., Values, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=.">.</a> The Economic Impact of Influenza in Switzerland: Interpandemic Situation. , (2003).</li><li>Barclay, V. C., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Positive+network+assortativity+of+influenza+vaccination+at+a+high+school:+implications+for+outbreak+risk+and+herd+immunity.">Positive network assortativity of influenza vaccination at a high school: implications for outbreak risk and herd immunity.</a> PLoS One. 9 (2), 87042 (2014).</li><li>Baluch, A., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Randomized+controlled+trial+of+high-dose+intradermal+versus+standard-dose+intramuscular+influenza+vaccine+in+organ+transplant+recipients.">Randomized controlled trial of high-dose intradermal versus standard-dose intramuscular influenza vaccine in organ transplant recipients.</a> Am J Transplant. 13 (4), 1026-1033 (2013).</li><li>Haralambieva, I. H., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+Impact+of+Immunosenescence+on+Humoral+Immune+Response+Variation+after+Influenza+A/H1N1+Vaccination+in+Older+Subjects.">The Impact of Immunosenescence on Humoral Immune Response Variation after Influenza A/H1N1 Vaccination in Older Subjects.</a> PLoS One. 10 (3), 0122282 (2015).</li><li>Egli, A., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Vaccine+adjuvants--understanding+molecular+mechanisms+to+improve+vaccines.">Vaccine adjuvants--understanding molecular mechanisms to improve vaccines.</a> Swiss Med Wkly. 144, 13940 (2014).</li><li>O'Shea, D., Widmer, L. A., Stelling, J., Egli, A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Changing+face+of+vaccination+in+immunocompromised+hosts.">Changing face of vaccination in immunocompromised hosts.</a> Curr Infect Dis Rep. 16 (9), 420 (2014).</li><li>Meulemans, G., Carlier, M. C., Gonze, M., Petit, P. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Comparison+of+hemagglutination-inhibition,+agar+gel+precipitin,+and+enzyme-linked+immunosorbent+assay+for+measuring+antibodies+against+influenza+viruses+in+chickens.">Comparison of hemagglutination-inhibition, agar gel precipitin, and enzyme-linked immunosorbent assay for measuring antibodies against influenza viruses in chickens.</a> Avian Dis. 31 (3), 560-563 (1987).</li><li>Martins, T. B. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Development+of+internal+controls+for+the+Luminex+instrument+as+part+of+a+multiplex+seven-analyte+viral+respiratory+antibody+profile.">Development of internal controls for the Luminex instrument as part of a multiplex seven-analyte viral respiratory antibody profile.</a> Clin Diagn Lab Immunol. 9 (1), 41-45 (2002).</li><li>Webster, R., Cox, N., St&#246;hr, K. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=WHO+Animal+Influenza+Manual.">WHO Animal Influenza Manual.</a> WHO/CDS/CSR/NCS. 2002.5, 1-99 (2002).</li><li>Mittelholzer, C. M., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Human+cell+lines+used+in+a+micro+neutralization+test+for+measuring+influenza-neutralizing+antibodies.">Human cell lines used in a micro neutralization test for measuring influenza-neutralizing antibodies.</a> Scand J Immunol. 63 (4), 257-263 (2006).</li><li>Hamilton, R. S., Gravell, M., Major, E. O. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Comparison+of+antibody+titers+determined+by+hemagglutination+inhibition+and+enzyme+immunoassay+for+JC+virus+and+BK+virus.">Comparison of antibody titers determined by hemagglutination inhibition and enzyme immunoassay for JC virus and BK virus.</a> J Clin Microbiol. 38 (1), 105-109 (2000).</li><li>Kumakura, S., 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=Comparison+of+hemagglutination+inhibition+assay+and+enzyme+immunoassay+for+determination+of+mumps+and+rubella+immune+status+in+health+care+personnel.">Comparison of hemagglutination inhibition assay and enzyme immunoassay for determination of mumps and rubella immune status in health care personnel.</a> J Clin Lab Anal. 27 (5), 418-421 (2013).</li><li>Ogundiji, O. T., Okonko, I. O., Adu, F. D. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Determination+of+measles+hemagglutination+inhibiting+antibody+levels+among+school+children+in+Ibadan,+Nigeria.">Determination of measles hemagglutination inhibiting antibody levels among school children in Ibadan, Nigeria.</a> J Immunoassay Immunochem. 34 (2), 208-217 (2013).</li><li>Cwach, K. T., Sandbulte, H. R., Klonoski, J. M., Huber, V. C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Contribution+of+murine+innate+serum+inhibitors+toward+interference+within+influenza+virus+immune+assay.">Contribution of murine innate serum inhibitors toward interference within influenza virus immune assay.</a> Influenza Other Respir Viruses. 6 (2), 127-135 (2012).</li><li>Lee, P. S., 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=Receptor+mimicry+by+antibody+F045-092+facilitates+universal+binding+to+the+H3+subtype+of+influenza+virus.">Receptor mimicry by antibody F045-092 facilitates universal binding to the H3 subtype of influenza virus.</a> Nat Commun. 5, 3614 (2014).</li><li>Blumel, B., 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=Age-related+prevalence+of+cross-reactive+antibodies+against+influenza+A(H3N2)+variant+virus,+Germany,+2003+to+2010.">Age-related prevalence of cross-reactive antibodies against influenza A(H3N2) variant virus, Germany, 2003 to 2010.</a> Euro Surveill. 20 (32), 16-24 (2015).</li><li>Reber, A. 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=Seasonal+Influenza+Vaccination+of+Children+Induces+Humoral+and+Cell-Mediated+Immunity+Beyond+the+Current+Season:+Cross-reactivity+with+Past+and+Future+Strains.">Seasonal Influenza Vaccination of Children Induces Humoral and Cell-Mediated Immunity Beyond the Current Season: Cross-reactivity with Past and Future Strains.</a> J Infect Dis. , (2016).</li></ol>

A.E. was supported by a research grants from the "SNSF Ambizione Score" program (PZ00P3_154709), "Forschungsfond, F&#246;rderung strategischer Projekte" University of Basel, Stiftungsinfektionskrankheiten Basel, and Bangeter Rhyner Stiftung. L.K. was supported by a grant of the Technical University of Graz, Austria. J.L. acknowledges support by an iPhD fellowship of the SystemsX.ch initiative in systems biology program (9th call).

Quantification of pre- and post-vaccination influenza virus specific antibody titers is an important tool necessary for vaccine studies. Based on the surrogate measures of protection against virus infection, such as seroprotection (&#62;1:40) or seroconversion (4-fold titer increase), vaccination strategies can be optimized9. Using the provided protocols can determine: (i) the hemagglutination potential of a particular virus, and (ii) the antibody titers for a virus of interest.
<p class="jove...

Infection with influenza virus is associated with considerable morbidity, mortality, and high healthcare costs1,2,3,4. In particular, elderly, newborns, pregnant women, and patients with chronic disease are at risk for more severe clinical outcomes. Therefore, vaccination against circulating influenza virus strains is the primary measure to decrease the burden of disease in these high-risk populations. The increase of the individual immune response after vaccination, e.g., influenza-specific antibodies above a protective threshold, reduces the individual risk of infection and in general the likelihood of viral transmission within a population5. A detailed understanding of the vaccine-induced humoral immune response in different populations and across various age groups is a key element to answer important clinical questions6,7,8,9, such as: Why do some elderly patients have infections despite previous vaccination? What is a &#34;good&#34; and &#34;sufficient&#34; vaccine-induced protection? How often should a vaccine be applied to an immunosuppressed patient to reach protective titers? What is the most effective dosage? What is the impact of a novel adjuvant on post-vaccination antibody titers? The measurement of the vaccine-specific antibody production may help answer these important questions and improve vaccination outcomes.
The quantification of virus-specific antibody titers can be performed with various immunological methods. This includes solid-phase10 or bead-based ELISA11 assays, the HI assay12, and neutralizing assays13. ELISA-based methods allow the screening of relatively large amounts of serum samples against various antigens. Also, pathogen-specific Immunoglobulin (Ig)M and IgG can be separately explored. Although the characteristics of an antigen, e.g., the linear amino acid sequence or virus-like particle may influence the binding of antibodies, the spectrum of potential epitopes is very broad and does not provide information on whether an antibody response has functional relevance.
In contrast, the neutralization assay determines the potential of antibodies to functionally inhibit the infection of cells and therefore reflects the neutralization potential. However, this method is very labor intensive, requires culturing of specific cell lines and live viruses, and therefore, it is time-consuming, expensive, and requires special equipment.
This article describes a step-by-step the World Health Organization (WHO)-based HI protocol12 to quantify influenza-specific antibody titers. Hemagglutination is a characteristic effect of some viruses leading to the agglutination of erythrocytes. The inhibition of this effect with patient sera allows the measurement of inhibitory antibody concentrations, which reflects a neutralizing effect.
We have modified the workflow of the WHO-protocol to allow a more efficient handling of multiple samples at the same time and thereby reducing the required time. The first protocol describes the determination of the agglutination potential of a particular influenza antigen. In doing so, the correct influenza antigen concentration is determined for the second protocol. This part should be repeated with every new viral antigen, as well as each batch of blood.
The second protocol describes the determination of influenza-specific antibody titers. The presented protocols are optimized for the investigation of influenza virus and human serum samples however, it can also be applied for mouse serum samples or cell-culture supernatants from stimulated immune cells, e.g., virus-specific B-cells. Results can be determined as absolute measured titers. In many vaccine studies, the geometric mean titers and the 95% confidence interval are shown for each particular population. For interpretation, seroprotection or seroconversion are often used to describe the susceptibility of a population to a certain virus. Seroprotection is defined as a titer of &#8805;1:40, and seroconversion as a more than 4-fold titer increase with achievement of seroprotective titers between two time points (most commonly pre-vaccination and 30 days post-vaccination are used).
Both protocols are easy to use and they can be adapted to a broad range of research questions. In particular, they can be used to determine reliably and quickly&#160;the antibody titers against various other viruses with the capacity for hemagglutination, such as measles, polyomaviruses, mumps, or rubella14,15,16.

<table style="border-collapse:collapse;width:716pt" width="955">
	<colgroup>
		<col style="width:263pt" width="351" />
		<col style="width:100pt" width="133" />
		<col style="width:85pt" width="113" />
		<col style="width:269pt" width="358" />
	</colgroup>
	<tbody>
		<tr height="21" style="height:15.75pt">
			<td class="xl67" height="21" style="width:263pt;height:15.75pt" width="351">25 ml Disposable Multichannel Pipette Reservoirs</td>
			<td class="xl67" style="width:100pt" width="133">Integra</td>
			<td class="xl67" style="width:85pt" width="113">4312</td>
			<td class="xl68" style="width:269pt" width="358"></td>
		</tr>
		<tr height="21" style="height:15.75pt">
			<td class="xl63" height="21" style="width:263pt;height:15.75pt" width="351">8-well PCR tubes</td>
			<td class="xl63" style="width:100pt" width="133">Brand GMBH</td>
			<td class="xl63" style="width:85pt" width="113">781332</td>
			<td class="xl66">For serum aliquots</td>
		</tr>
		<tr height="21" style="height:15.75pt">
			<td class="xl63" height="21" style="width:263pt;height:15.75pt" width="351">96-well microtiter plate, U-shaped</td>
			<td class="xl63" style="width:100pt" width="133">TPP</td>
			<td class="xl63" style="width:85pt" width="113">92097</td>
			<td class="xl66">For HI assay when using mammalian RBCs</td>
		</tr>
		<tr height="21" style="height:15.75pt">
			<td class="xl63" height="21" style="width:263pt;height:15.75pt" width="351">96-well microtiter plate, V-shaped</td>
			<td class="xl63" style="width:100pt" width="133">Corning Costar</td>
			<td class="xl63" style="width:85pt" width="113">3897</td>
			<td class="xl66">For HI assay when using avian RBCs</td>
		</tr>
		<tr height="21" style="height:15.75pt">
			<td class="xl63" height="21" style="width:263pt;height:15.75pt" width="351">Aqua ad iniect. Steril</td>
			<td class="xl63" style="width:100pt" width="133">Bichsel AG</td>
			<td align="right" class="xl63" style="width:85pt" width="113">1000004</td>
			<td class="xl66">For preparing influenza antigen and cholera filtrate solutions</td>
		</tr>
		<tr height="21" style="height:15.75pt">
			<td class="xl63" height="21" style="width:263pt;height:15.75pt" width="351">Chicken RBC (10%)</td>
			<td class="xl63" style="width:100pt" width="133">Cedarlane</td>
			<td class="xl63" style="width:85pt" width="113">CLC8800</td>
			<td class="xl66">10% suspension of chicken red blood cells in Alsever&#39;s solution</td>
		</tr>
		<tr height="21" style="height:15.75pt">
			<td class="xl63" height="21" style="width:263pt;height:15.75pt" width="351">Cholera filtrate</td>
			<td class="xl63" style="width:100pt" width="133">Sigma-Aldrich</td>
			<td class="xl63" style="width:85pt" width="113">C8772</td>
			<td class="xl66">Used as receptor destroying enzyme (RDE)</td>
		</tr>
		<tr height="21" style="height:15.75pt">
			<td class="xl63" height="21" style="width:263pt;height:15.75pt" width="351">Dulbecco&#39;s PBS</td>
			<td class="xl63" style="width:100pt" width="133">Sigma-Aldrich</td>
			<td class="xl63" style="width:85pt" width="113">D8537</td>
			<td class="xl66">For diluting the serum samples, RBCs and antigens</td>
		</tr>
		<tr height="42" style="height:31.5pt">
			<td class="xl63" height="42" style="width:263pt;height:31.5pt" width="351">Eppendorf Multichannel pipette, 12-channel, 10-100 &#181;l</td>
			<td class="xl63" style="width:100pt" width="133">Sigma-Aldrich</td>
			<td class="xl67" style="width:85pt" width="113">Z683949</td>
			<td class="xl66"></td>
		</tr>
		<tr height="42" style="height:31.5pt">
			<td class="xl63" height="42" style="width:263pt;height:31.5pt" width="351">Eppendorf Multichannel pipette, 8-channel, 10-100 &#181;l</td>
			<td class="xl63" style="width:100pt" width="133">Sigma-Aldrich</td>
			<td class="xl67" style="width:85pt" width="113">Z683930</td>
			<td class="xl66"></td>
		</tr>
		<tr height="21" style="height:15.75pt">
			<td class="xl63" height="21" style="width:263pt;height:15.75pt" width="351">Guinea Pig RBC (10%)</td>
			<td class="xl63" style="width:100pt" width="133">Cedarlane</td>
			<td class="xl67" style="width:85pt" width="113">CLC1800</td>
			<td class="xl66">10% suspension of guinea pig red blood cells in Alsever&#39;s solution</td>
		</tr>
		<tr height="21" style="height:15.75pt">
			<td class="xl63" height="21" style="width:263pt;height:15.75pt" width="351">Influenza Anti-A/California/7/09 HA serum&#160;</td>
			<td class="xl63" style="width:100pt" width="133">NIBSC</td>
			<td class="xl67" style="width:85pt" width="113">14/134&#160;</td>
			<td class="xl66">Used as positive control at the HI assay</td>
		</tr>
		<tr height="42" style="height:31.5pt">
			<td class="xl63" height="42" style="width:263pt;height:31.5pt" width="351">Influenza Anti-A/Switzerland/9715293/2013-like HA serum&#160;</td>
			<td class="xl63" style="width:100pt" width="133">NIBSC</td>
			<td class="xl67" style="width:85pt" width="113">14/272</td>
			<td class="xl66">Used as positive control at the HI assay</td>
		</tr>
		<tr height="21" style="height:15.75pt">
			<td class="xl63" height="21" style="width:263pt;height:15.75pt" width="351">Influenza Anti-A/Texas/50/2012-Like HA Serum&#160;</td>
			<td class="xl63" style="width:100pt" width="133">NIBSC</td>
			<td class="xl63" style="width:85pt" width="113">13/178</td>
			<td class="xl66">Used as positive control at the HI assay</td>
		</tr>
		<tr height="21" style="height:15.75pt">
			<td class="xl63" height="21" style="width:263pt;height:15.75pt" width="351">Influenza Anti-B/Brisbane/60/2008-HA serum&#160;</td>
			<td class="xl63" style="width:100pt" width="133">NIBSC</td>
			<td class="xl63" style="width:85pt" width="113">13/254&#160;</td>
			<td class="xl66">Used as positive control at the HI assay</td>
		</tr>
		<tr height="21" style="height:15.75pt">
			<td class="xl63" height="21" style="width:263pt;height:15.75pt" width="351">Influenza Anti-B/Massachusetts/02/2012 HA serum&#160;</td>
			<td class="xl63" style="width:100pt" width="133">NIBSC</td>
			<td class="xl63" style="width:85pt" width="113">13/182</td>
			<td class="xl66">Used as positive control at the HI assay</td>
		</tr>
		<tr height="42" style="height:31.5pt">
			<td class="xl63" height="42" style="width:263pt;height:31.5pt" width="351">Influenza antigen A/California/7/09 (H1N1)(NYMC-X181)&#160;</td>
			<td class="xl63" style="width:100pt" width="133">NIBSC</td>
			<td class="xl63" style="width:85pt" width="113">12/168</td>
			<td class="xl66">Inactivated, partially purified A/California/7/09 (H1N1)(NYMC-X181)&#160; virus (ca. 46&#181;gHA/ml)</td>
		</tr>
		<tr height="42" style="height:31.5pt">
			<td class="xl63" height="42" style="width:263pt;height:31.5pt" width="351">Influenza antigen A/Switzerland/9715293/2013 (NIB88)</td>
			<td class="xl63" style="width:100pt" width="133">NIBSC</td>
			<td class="xl63" style="width:85pt" width="113">14/254</td>
			<td class="xl66">Inactivated, partially purified A/Switzerland/9715293/2013 (NIB88) virus (ca. 55&#181;gHA/ml)</td>
		</tr>
		<tr height="42" style="height:31.5pt">
			<td class="xl63" height="42" style="width:263pt;height:31.5pt" width="351">Influenza antigen A/Texas/50/2012 (H3N2)(NYMCX-223)</td>
			<td class="xl63" style="width:100pt" width="133">NIBSC</td>
			<td class="xl63" style="width:85pt" width="113">13/112</td>
			<td class="xl66">Inactivated, partially purified A/Texas/50/2012 (H3N2)(NYMCX-223) virus (ca. 74&#181;gHA/ml)</td>
		</tr>
		<tr height="21" style="height:15.75pt">
			<td class="xl63" height="21" style="width:263pt;height:15.75pt" width="351">Influenza antigen B/Brisbane/60/2008</td>
			<td class="xl63" style="width:100pt" width="133">NIBSC</td>
			<td class="xl63" style="width:85pt" width="113">13/234</td>
			<td class="xl66">Inactivated, partially purified B/Brisbane/60/2008 virus (ca. 42&#181;gHA/ml)</td>
		</tr>
		<tr height="21" style="height:15.75pt">
			<td class="xl63" height="21" style="width:263pt;height:15.75pt" width="351">Influenza antigen B/Massachusetts/02/2012</td>
			<td class="xl63" style="width:100pt" width="133">NIBSC</td>
			<td class="xl63" style="width:85pt" width="113">13/134</td>
			<td class="xl66">Inactivated, partially purified B/Massachusetts/02/2012 virus (ca. 35&#181;gHA/ml)</td>
		</tr>
		<tr height="42" style="height:31.5pt">
			<td class="xl63" height="42" style="width:263pt;height:31.5pt" width="351">Serum-Tubes</td>
			<td class="xl75" style="width:100pt" width="133">S-Monovette, Sardstedt</td>
			<td class="xl63" style="width:85pt" width="113">01.1601.100</td>
			<td class="xl66">For serum extraction with clotting activator</td>
		</tr>
		<tr height="42" style="height:31.5pt">
			<td class="xl63" height="42" style="width:263pt;height:31.5pt" width="351">Single Donor Human RBC, Type 0</td>
			<td class="xl63" style="width:100pt" width="133">Innovative Research</td>
			<td class="xl63" style="width:85pt" width="113">IPLA-WB3&#160;</td>
			<td class="xl66">Suspension of single donor human red blood cells in Alsever&#39;s solution (ca. 26%)</td>
		</tr>
		<tr height="21" style="height:15.75pt">
			<td class="xl63" height="21" style="width:263pt;height:15.75pt" width="351">Turkey RBC (10%)</td>
			<td class="xl63" style="width:100pt" width="133">Cedarlane</td>
			<td class="xl63" style="width:85pt" width="113">CLC1180</td>
			<td class="xl66">10% suspension of turkey red blood cells in Alsever&#39;s solution</td>
		</tr>
		<tr height="21" style="height:15.75pt">
			<td class="xl63" height="21" style="width:263pt;height:15.75pt" width="351">Phosphate Buffered Saline (PBS)</td>
			<td class="xl63" style="width:100pt" width="133">Gibco</td>
			<td class="xl63" style="width:85pt" width="113"></td>
			<td class="xl66"></td>
		</tr>
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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.

Pre- and post-vaccination induced antibody response against Influenza A H3N2 
The vaccine-induced antibody response was assessed in 26 healthy volunteers who received an inactivated trivalent subunit influenza vaccine containing Influenza A/H1N1/California/2009, A/H3N2/Texas/2012, and B/Massachusetts/02/2012 prior to the 2014/2015 influenza season. Figure 6 shows a representative example of 2 vaccine recipients. Interestingly, during tha...

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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.

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 ...

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Universidad de Cartagena UDEC

Research

JoVE Journal

Medicine

35.7K Views.  University of Basel. 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. 

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

Methods to Quantify Pharmacologically Induced Alterations in Motor Function in Human Incomplete SCI

Spinal cord injury (SCI) is a debilitating disorder, which produces profound deficits in volitional motor control. Following medical stabilization, recovery from SCI typically involves long term rehabilitation. While recovery of walking ability is a primary goal in many patients early after injury, those with a motor incomplete SCI, indicating partial preservation of volitional control, may have the sufficient residual descending pathways necessary to attain this goal. However, despite physical interventions, motor impairments including weakness, and the manifestation of abnormal involuntary reflex activity, called spasticity or spasms, are thought to contribute to reduced walking recovery. Doctrinaire thought suggests that remediation of this abnormal motor reflexes associated with SCI will produce functional benefits to the patient. For example, physicians and therapists will provide specific pharmacological or physical interventions directed towards reducing spasticity or spasms, although there continues to be little empirical data suggesting that these strategies improve walking ability.
In the past few decades, accumulating data has suggested that specific neuromodulatory agents, including agents which mimic or facilitate the actions of the monoamines, including serotonin (5HT) and norepinephrine (NE), can initiate or augment walking behaviors in animal models of SCI. Interestingly, many of these agents, particularly 5HTergic agonists, can markedly increase spinal excitability, which in turn also increases reflex activity in these animals. Counterintuitive to traditional theories of recovery following human SCI, the empirical evidence from basic science experiments suggest that this reflex hyper excitability and generation of locomotor behaviors are driven in parallel by neuromodulatory inputs (5HT) and may be necessary for functional recovery following SCI. 
The application of this novel concept derived from basic scientific studies to promote recovery following human SCI would appear to be seamless, although the direct translation of the findings can be extremely challenging. Specifically, in the animal models, an implanted catheter facilitates delivery of very specific 5HT agonist compounds directly onto the spinal circuitry. The translation of this technique to humans is hindered by the lack of specific surgical techniques or available pharmacological agents directed towards 5HT receptor subtypes that are safe and effective for human clinical trials. However, oral administration of commonly available 5HTergic agents, such as selective serotonin reuptake inhibitors (SSRIs), may be a viable option to increase central 5HT concentrations in order to facilitate walking recovery in humans. Systematic quantification of how these SSRIs modulate human motor behaviors following SCI, with a specific focus on strength, reflexes, and the recovery of walking ability, are missing.
This video demonstration is a progressive attempt to systematically and quantitatively assess the modulation of reflex activity, volitional strength and ambulation following the acute oral administration of an SSRI in human SCI. Agents are applied on single days to assess the immediate effects on motor function in this patient population, with long-term studies involving repeated drug administration combined with intensive physical interventions.

This video demonstrates modulation of reflex activity, volitional strength and ambulation through clinical and quantitative assessments in individuals with motor incomplete SCI as a result of acute oral administration of a serotonin reuptake inhibitor (SSRI).

Spinal cord injury (SCI) is a debilitating disorder, which produces profound deficits in volitional motor control. Following medical stabilization, ...

An in vivo Assay to Test Blood Vessel Permeability

This method is based on the intravenous injection of Evans Blue in mice as the test animal model. Evans blue is a dye that binds albumin. Under physiologic conditions the endothelium is impermeable to albumin, so Evans blue bound albumin remains restricted within blood vessels. In pathologic conditions that promote increased vascular permeability endothelial cells partially lose their close contacts and the endothelium becomes permeable to small proteins such as albumin. This condition allows for extravasation of Evans Blue in tissues. A healthy endothelium prevents extravasation of the dye in the neighboring vascularized tissues. Organs with increased permeability will show significantly increased blue coloration compared to organs with intact endothelium. The level of vascular permeability can be assessed by simple visualization or by quantitative measurement of the dye incorporated per milligram of tissue of control versus experimental animal/tissue. Two powerful aspects of this assay are its simplicity and quantitative characteristics. Evans Blue dye can be extracted from tissues by incubating a specific amount of tissue in formamide. Evans Blue absorbance maximum is at 620 nm and absorbance minimum is at 740 nm. By using a standard curve for Evans Blue, optical density measurements can be converted into milligram dye captured per milligram of tissue. Statistical analysis should be used to assess significant differences in vascular permeability.

An in vivo Assay to Test Blood Vessel Permeability

We are presenting an in vivo assay to test blood vessel permeability. This assay is based on intravenous injection of a dye and subsequent visualization of its diffusion into interstitial spaces.

This method is based on the intravenous injection of Evans Blue in mice as the test animal model. Evans blue is a dye that binds albumin. Under ...

Using Quantitative Real-time PCR to Determine Donor Cell Engraftment in a Competitive Murine Bone Marrow Transplantation Model

Murine bone marrow transplantation models provide an important tool in measuring hematopoietic stem cell (HSC) functions and determining genes/molecules that regulate HSCs. In these transplant model systems, the function of HSCs is determined by the ability of these cells to engraft and reconstitute lethally irradiated recipient mice. Commonly, the donor cell contribution/engraftment is measured by antibodies to donor- specific cell surface proteins using flow cytometry. However, this method heavily depends on the specificity and the ability of the cell surface marker to differentiate donor-derived cells from recipient-originated cells, which may not be available for all mouse strains. Considering the various backgrounds of genetically modified mouse strains in the market, this cell surface/ flow cytometry-based method has significant limitations especially in mouse strains that lack well-defined surface markers to separate donor cells from congenic recipient cells. Here, we reported a PCR-based technique to determine donor cell engraftment/contribution in transplant recipient mice. We transplanted male donor bone marrow HSCs to lethally irradiated congenic female mice. Peripheral blood samples were collected at different time points post transplantation. Bone marrow samples were obtained at the end of the experiments. Genomic DNA was isolated and the Y chromosome specific gene, Zfy1, was amplified using quantitative Real time PCR. The engraftment of male donor-derived cells in the female recipient mice was calculated against standard curve with known percentage of male vs. female DNAs. Bcl2 was used as a reference gene to normalize the total DNA amount. Our data suggested that this approach reliably determines donor cell engraftment and provides a useful, yet simple method in measuring hematopoietic cell reconstitution in murine bone marrow transplantation models. Our method can be routinely performed in most laboratories because no costly equipment such as flow cytometry is required.

Determining donor cell engraftment presents a challenge in mouse bone marrow transplant models that lack well-defined phenotypical markers. We described a methodology to quantify male donor cell engraftment in female transplant recipient mice. This method can be used in all mouse strains for the study of HSC functions.

Murine bone marrow transplantation models provide an important tool in measuring hematopoietic stem cell (HSC) functions and determining genes/molecules ...

A Sensitive Method to Quantify Senescent Cancer Cells

Human cells do not indefinitely proliferate. Upon external and/or intrinsic cues, cells might die or enter a stable cell cycle arrest called senescence. Several cellular mechanisms, such as telomere shortening and abnormal expression of mitogenic oncogenes, have been shown to cause senescence. Senescence is not restricted to normal cells; cancer cells have also been reported to senesce.
	Chemotherapeutical drugs have been shown to induce senescence in cancer cells. However, it remains controversial whether senescence prevents or promotes tumorigenesis. As it might eventually be patient-specific, a rapid and sensitive method to assess senescence in cancer cell will soon be required.
	To this end, the standard &beta;-galactosidase assay, the currently used method, presents major drawbacks: it is time consuming and not sensitive. We propose here a flow cytometry-based assay to study senescence on live cells. This assay offers the advantage of being rapid, sensitive, and can be coupled to the immunolabeling of various cellular markers.

Whether senescence prevents or promotes tumorigenesis remains controversial. Since chemotherapeutical drugs can induce cancer cells to senesce, studying senescence is essential for proposing new therapies. However, the standard and broadly used &beta;-galactosidase assay presents major drawbacks. We propose here a rapid and sensitive flow cytometry-based assay to quantify senescence.

Human cells do not indefinitely proliferate. Upon external and/or intrinsic  cues, cells might die or enter a stable cell cycle arrest called senescence. ...

A High Throughput, Multiplexed and Targeted Proteomic CSF Assay to Quantify Neurodegenerative Biomarkers and Apolipoprotein E Isoforms Status

Many neurodegenerative diseases are&#160;still lacking effective treatments. Reliable biomarkers for identifying and classifying these diseases will be important in the development of future novel therapies. Often&#160;potential new biomarkers do not make it&#160;into the clinic&#160;due to limitations&#160;in their development and&#160;high costs.&#160;However,&#160;targeted proteomics using Multiple Reaction Monitoring Liquid Chromatography-tandem/Mass Spectrometry (MRM LC-MS/MS), specifically using triple quadrupole mass spectrometers, is one method that can be used to rapidly evaluate and validate biomarkers&#160;for clinical translation into diagnostic laboratories. Traditionally, this platform has been used extensively for measurement of small molecules&#160;in clinical laboratories, but it is the potential to analyze proteins, that makes it an attractive alternative to ELISA (Enzyme-Linked Immunosorbent Assay)-based methods. We describe here how targeted proteomics can be used to measure multiplexed markers of dementia, including the detection and quantitation of the known risk factor apolipoprotein E isoform 4 (ApoE4).
In order to make the assay suitable for translation, it is designed to be rapid, simple, highly specific and cost effective. To achieve this, every step in the development of the assay must be optimized for the individual proteins and tissues they are analyzed in. This method describes a typical workflow including various tips and tricks to developing a targeted proteomics MRM LC-MS/MS for translation.
The method development is optimized using custom synthesized versions of tryptic quantotypic peptides, which calibrate&#160;the MS for detection and then spiked into CSF to determine correct identification of the endogenous peptide in the chromatographic separation prior to analysis in the MS. To achieve absolute quantitation, stable isotope-labeled internal standard versions of the peptides with short amino acid sequence tags and containing a trypsin cleavage site, are included in the assay.

We describe a high-throughput, multiplex, and targeted proteomic cerebrospinal fluid (CSF) assay developed with potential for clinical translation. The test can quantitate potential markers and risk factors for neurodegeneration, such as the apolipoprotein E variants (E2, E3 and E4), and measure their allelic expression.

Many neurodegenerative diseases are&#160;still lacking effective treatments. Reliable biomarkers for identifying and classifying these diseases will be ...

Determination of the Relative Potency of an Anti-TNF Monoclonal Antibody (mAb) by Neutralizing TNF Using an In Vitro Bioanalytical Method

This protocol shows the measurement of the apoptotic activity neutralization of TNF&#945; in a mouse fibroblast cell model (WEHI 164) using an anti-TNF&#945; mAb. In addition, this protocol can be used to evaluate other anti-TNF&#945; molecules, such as fusion proteins. The cellular model employed here is sensitive to TNF&#945;-mediated apoptosis when an additional stress factor is induced in cell culture conditions (e.g., serum deprivation). This procedure exemplifies how to execute this analytical assay, highlighting the key operations relating to the sample preparation, cell dilution, apoptosis induction, and spectrophotometric measurements that are critical to ensure successful results. This protocol reveals the best-performance conditions relating to apoptosis induction and efficient signal recording, leading to low uncertainty values.

Determination of the Relative Potency of an Anti-TNF Monoclonal Antibody mAb by Neutralizing TNF Using an In Vitro Bioanalytical Method

A protocol for the determination of the relative anti-apoptotic activity of an anti-TNF&#945; mAb using a neutralization mechanism with WEHI 164 cells is presented here. This protocol is useful for comparing the neutralization strength of different molecules with the same biological functionality.

This protocol shows the measurement of the apoptotic activity neutralization of TNF&#945; in a mouse fibroblast cell model (WEHI 164) using an ...

An Optimized Evans Blue Protocol to Assess Vascular Leak in the Mouse

Vascular leak, or plasma extravasation, has a number of causes, and may be a serious consequence or symptom of an inflammatory response. This study may ultimately lead to new knowledge concerning the causes of or new ways to inhibit or treat plasma extravasation. It is important that researchers have the proper tools, including the best methods available, for studying plasma extravasation. In this article, we describe a protocol, using the Evans blue dye method, for assessing plasma extravasation in the organs of FVBN mice. This protocol is intentionally simple, to as great a degree as possible, but provides high quality data. Evans blue dye has been chosen primarily because it is easy for the average laboratory to use. We have used this protocol to provide evidence and support for the hypothesis that the enzyme neprilysin may protect the vasculature against plasma extravasation. However, this protocol may be experimentally used and easily adapted for use in other strains of mice or in other species, in many different organs or tissues, for studies which may involve other factors that are important in understanding, preventing, or treating plasma extravasation. This protocol has been extensively optimized and modified from existing protocols, and combines reliability, ease of use, economy, and general availability of materials and equipment, making this protocol superior for the average laboratory to use in quantifying plasma extravasation from organs.

In this article, an economical, optimized, and simple protocol is described which uses the Evans blue dye method for assessing plasma extravasation in the organs of FVBN mice that can be adapted for use in other strains, species, and other organs or tissues.

Vascular leak, or plasma extravasation, has a number of causes, and may be a serious consequence or symptom of an inflammatory response. This study may ...

Optimized Griess Reaction for UV-Vis and Naked-eye Determination of Anti-malarial Primaquine

Primaquine (PMQ), an important anti-malarial drug, has been recommended by the World Health Organization (WHO) for the treatment of life-threatening infections caused by P. vivax and ovale. However, PMQ has unwanted adverse effects that lead&#160;to acute hemolysis in patients with glucose-6-phosphate dehydrogenase (G6PD) deficiency. There is a need to develop simple and reliable methods for PMQ determination with the purpose of dosage monitoring. In early 2019, we have reported an UV-Vis and naked-eye based approach for PMQ colorimetric quantification. The detection was based on a Griess-like reaction between PMQ and anilines, which can generate colored azo products. The detection limit for direct measurement of PMQ in synthetic urine is in the nanomolar range. Moreover, this method has shown great potential for PMQ quantification from human serum samples at clinically relevant concentrations. In this protocol, we will describe the technical details regarding the syntheses and characterization of colored azo products, the reagent preparation, and the procedures for PMQ determination.

This protocol describes a novel colorimetric method for antimalarial primaquine (PMQ) detection in synthetic urines and human serums.

Primaquine (PMQ), an important anti-malarial drug, has been recommended by the World Health Organization (WHO) for the treatment of life-threatening ...

A Simple Pit Assay Protocol to Visualize and Quantify Osteoclastic Resorption In Vitro

Mature osteoclasts are multinucleated cells that can degrade bone through the secretion of acids and enzymes. They play a crucial role in various diseases (e.g., osteoporosis and bone cancer) and are therefore important objects of research. In vitro, their activity can be analyzed by the formation of resorption pits. In this protocol, we describe a simple pit assay method using calcium phosphate (CaP) coated cell culture plates, which can be easily visualized and quantified. Osteoclast precursors derived from human peripheral blood mononuclear cells (PBMCs) were cultured on the coated plates in the presence of osteoclastogenic stimuli. After 9 days of incubation, osteoclasts were fixed and stained for fluorescence imaging while the CaP coating was counterstained by calcein. To quantify the resorbed area, the CaP coating on plates was stained with 5% AgNO3 and visualized by brightfield imaging. The resorption pit area was quantified using ImageJ.

A Simple Pit Assay Protocol to Visualize and Quantify Osteoclastic Resorption In Vitro

Here, we present a simple and effective assay procedure for resorption pit assays using calcium phosphate coated cell culture plates.

Mature osteoclasts are multinucleated cells that can degrade bone through the secretion of acids and enzymes. They play a crucial role in various diseases ...

Endothelial Cell Transcytosis Assay as an In Vitro Model to Evaluate Inner Blood-Retinal Barrier Permeability

Dysfunction of the blood-retinal barrier (BRB) contributes to the pathophysiology of several vascular eye diseases, often resulting in retinal edema and subsequent vision loss. The inner blood-retinal barrier (iBRB) is mainly composed of retinal vascular endothelium with low permeability under physiological conditions. This feature of low permeability is tightly regulated and maintained by low rates of paracellular transport between adjacent retinal microvascular endothelial cells, as well as transcellular transport (transcytosis) through them. The assessment of retinal transcellular barrier permeability may provide fundamental insights into iBRB integrity in health and disease. In this study, we describe an endothelial cell (EC) transcytosis assay, as an in vitro model for evaluating iBRB permeability, using human retinal microvascular endothelial cells (HRMECs). This assay assesses the ability of HRMECs to transport transferrin and horseradish peroxidase (HRP) in receptor- and caveolae-mediated transcellular transport processes, respectively. Fully confluent HRMECs cultured on porous membrane were incubated with fluorescent-tagged transferrin (clathrin-dependent transcytosis) or HRP (caveolae-mediated transcytosis) to measure the levels of transferrin or HRP transferred to the bottom chamber, indicative of transcytosis levels across the EC monolayer. Wnt signaling, a known pathway regulating iBRB, was modulated to demonstrate the caveolae-mediated HRP-based transcytosis assay method. The EC transcytosis assay described here may provide a useful tool for investigating the molecular regulators of EC permeability and iBRB integrity in vascular pathologies and for screening drug delivery systems.

Endothelial Cell Transcytosis Assay as an In Vitro Model to Evaluate Inner Blood-Retinal Barrier Permeability

This protocol illustrates an in vitro endothelial cell transcytosis assay as a model to evaluate inner blood-retinal barrier permeability by measuring the ability of human retinal microvascular endothelial cells to transport horseradish peroxidase across cells in caveolae-mediated transcellular transport processes.

Dysfunction of the blood-retinal barrier (BRB) contributes to the pathophysiology of several vascular eye diseases, often resulting in retinal edema and ...

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

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Chapters in this video

Methods to Quantify Pharmacologically Induced Alterations in Motor Function in Human Incomplete SCI

An in vivo Assay to Test Blood Vessel Permeability

Using Quantitative Real-time PCR to Determine Donor Cell Engraftment in a Competitive Murine Bone Marrow Transplantation Model

A Sensitive Method to Quantify Senescent Cancer Cells

A High Throughput, Multiplexed and Targeted Proteomic CSF Assay to Quantify Neurodegenerative Biomarkers and Apolipoprotein E Isoforms Status

Determination of the Relative Potency of an Anti-TNF Monoclonal Antibody (mAb) by Neutralizing TNF Using an In Vitro Bioanalytical Method

An Optimized Evans Blue Protocol to Assess Vascular Leak in the Mouse

Optimized Griess Reaction for UV-Vis and Naked-eye Determination of Anti-malarial Primaquine

A Simple Pit Assay Protocol to Visualize and Quantify Osteoclastic Resorption In Vitro

Endothelial Cell Transcytosis Assay as an In Vitro Model to Evaluate Inner Blood-Retinal Barrier Permeability