Ha Assay
Ha Assay - Related Videos
03:03
Measuring the Activation of Fc-Mediated Effector Functions by HA Antibodies
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2025
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...
06:08
Application of Ha-CoV-2 Pseudovirus for Rapid Quantification of SARS-CoV-2 Variants and Neutralizing Antibodies
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2023
This protocol describes the application of a novel hybrid alphavirus-SARS-CoV-2 pseudovirus (Ha-CoV-2) as a platform for rapid quantification of infectivity of SARS-CoV-2 variants and their sensitivity to neutralizing antibodies.
13:12
Quantitative Analyses of all Influenza Type A Viral Hemagglutinins and Neuraminidases using Universal Antibodies in Simple Slot Blot Assays
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Cited by 19 •
2011
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.
14:32
Deacetylation Assays to Unravel the Interplay between Sirtuins (SIRT2) and Specific Protein-substrates
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Cited by 1 •
2016
This protocol describes the required steps to execute in vitro and in vivo deacetylation assays in order to establish the role of proteins as specific deacetylation substrates for sirtuins and further study the role of reversible - lysine acetylation as a post-translational modification.
08:12
The TUNEL Assay
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2023
One of the hallmarks of apoptosis is the nuclear DNA fragmentation by nucleases. These enzymes are activated by caspases, the family of proteins that execute the cell death program. TUNEL assay is a method that takes advantage of this feature to detect apoptotic cells. In this assay, an enzyme called terminal deoxynucleotidyl transferase catalyzes the addition of dUTP nucleotides to the free 3’ ends of fragmented DNA. By using dUTPs that are labeled with chemical tags that can produce...
FAQs
Particles carrying hemagglutinating surface proteins bind multiple red blood cells and cross-link them into a visible lattice. This dispersed network prevents the cells from collecting as a compact pellet, creating the agglutinated pattern used for interpretation. The endpoint therefore reflects whether the sample retains detectable cell-cross-linking activity at a particular dilution.
Serial dilution shows how far the sample can be diluted while still producing visible agglutination. The highest dilution that maintains this pattern is recorded as the hemagglutination titer. Because samples are assessed across the same dilution series, the assay supports quantitative comparison of their hemagglutinating activity rather than providing only a positive or negative result.
Agglutination appears as a spread-out lattice of red blood cells, whereas a nonagglutinating sample allows the cells to settle into a compact pellet. Reading this physical pattern across the dilution series identifies the transition between detectable and undetectable activity. Accurate distinction is essential because that transition determines the reported titer.
A typical workflow begins by preparing serial dilutions of the sample, then mixing each dilution with red blood cells. After the mixture is assessed for its visible pattern, wells or samples showing lattice formation are distinguished from those forming compact pellets. The highest dilution with agglutination is then used to estimate the hemagglutination titer.
The assay is useful when investigators need to detect or compare particles with hemagglutinating activity, especially viruses bearing hemagglutinating surface proteins. Its dilution-based readout supports viral detection and quantitative comparison of samples. In infection research, it can therefore provide a practical measure for examining differences in hemagglutination across tested preparations.
Differences in hemagglutination titers can contribute to antigenic characterization by showing how samples compare in their ability to agglutinate red blood cells. The method also supports evaluation of procedures involving hemagglutinating pathogens. In both settings, the visible endpoint and its position within the dilution series provide the measured outcome for comparison.