Specificity Assays
Specificity Assays - Related Videos
07:08
High-Density Lipoprotein-Specific Phospholipid Efflux Assay
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2025
Herein, we describe the protocols to measure the amount of fluorescent phospholipid specifically removed from lipid donor particles by high-density lipoprotein (HDL) present in whole human plasma or serum. We have shown that this metric of HDL functionality predicts incident cardiovascular disease.
10:49
Assays for the Specific Growth Rate and Cell-binding Ability of Rotavirus
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Cited by 4 •
2019
Here we present two protocols, one for measuring the specific growth rate and the other for the cell-binding ability of rotavirus using the plaque assay and RT-qPCR. These protocols are available for confirming the differences in phenotypes between rotavirus strains.
11:37
Sigma's Non-specific Protease Activity Assay - Casein as a Substrate
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Cited by 440 •
2008
Proteases break peptide bonds. In the lab, it is often necessary to measure and/or compare the activity of proteases. Sigma's non-specific protease activity assay may be used as a standardized procedure to determine the activity of proteases.
06:11
A High-throughput Shigella-specific Bactericidal Assay
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Cited by 7 •
2019
Here we present a protocol to measure Shigellacidal activity of antibodies in serum. Serum is mixed with bacteria and exogenous complement, incubated, and the reaction mixture is plated on agar plates. Viable bacteria form colonies which are counted, using an automated colony enumerator, and used to determine the bactericidal titer.
10:17
An Allele-specific Gene Expression Assay to Test the Functional Basis of Genetic Associations
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Cited by 2 •
2010
Genetic associations often remain unexplained at a functional level. This method aims to assess the effect of phenotype-associated genetic markers on gene expression by analyzing cells heterozygous for transcribed SNPs. The technology allows accurate measurement by MALDI-TOF mass spectrometry to quantify allele-specific primer extension products.
FAQs
Specificity assays distinguish true target recognition from signal caused by related materials. The key comparison places the intended target alongside potential interferents, such as related molecules, cells, or pathogens, and examines whether the assay signal changes selectively. This comparison helps determine whether observed antibody binding, antigen detection, or cellular response reflects the intended interaction rather than nonspecific reactivity.
Cross-reactivity becomes apparent when an immune reagent or diagnostic method produces a measurable response to related molecules, cells, or pathogens in addition to the intended target. Comparing these responses shows whether the assay recognizes the target selectively or reacts more broadly. This distinction is important when interpreting pathogen-related measurements or separating specific immune responses from unrelated reactivity.
Controlled conditions make comparisons between the intended target and potential interferents more meaningful. Keeping the assay context consistent helps link differences in antibody binding, antigen detection, or cellular responses to the tested material rather than to changing experimental circumstances. As a result, researchers can interpret selective signals with greater confidence during assay development and diagnostic evaluation.
A basic workflow exposes the assay system to the intended target and to selected potential interferents, then measures the resulting signal for each condition. Depending on the assay, the readout may involve antibody binding, antigen detection, or a cellular response. Comparing these measurements indicates whether the method responds selectively and identifies evidence of cross-reactivity or nonspecific reactivity.
Specificity assays can examine several forms of measurable response, including antibody binding, antigen detection, and cellular responses. The appropriate readout depends on what the immune reagent or diagnostic method is designed to detect. Examining these signals against both the target and related materials helps researchers judge whether the observed result supports a pathogen-specific or otherwise intended interpretation.
In immunology and infection research, these assays help validate antibody and antigen tests, assess cross-reactivity, and distinguish pathogen-specific immune responses from nonspecific reactivity. They also support assay development by showing whether a method behaves selectively under controlled comparisons. This information strengthens diagnostic interpretation and improves confidence when studying host-pathogen interactions.