Enzyme-linked immunosorbent assays specificity

Watanabe et al. developed an enzyme-linked immunosorbent assay (ELISA) for the detection of inabenfide, a plant growth regulator, in rice. Specific monoclonal antibody (MAB) is used for this method. The effects of rice matrices on the sensitivity of ELISA can be reduced by adding 0.1% Tween 20. Good reproducibility and accuracy of the proposed ELISA were obtained for rice samples and the recovery was 92% at a fortification level of 5-500 xgkg . ... 

Even though stool examination for ova and parasites has remained the major means of diagnosis, other diagnostic tests include enzyme-linked immunosorbent assay (ELISA), which is considered to be between 85% to 98% sensitive and almost 100% specific (ProSpecT, Giardia Microplate Assay, Remel, Lenexa, KS). 

In order to measure the exact amount of a specific protein (analyte) by IHC signal intensity, a critical requirement is the availability of a standard reference material (present in a known amount by weight) that can be used to calibrate the assay (IHC stain). It is then possible to determine the amount of test analyte (protein) by a translation process from the intensity of IHC signals. In this respect it is helpful to consider the IHC stain as a tissue based ELISA assay (Enzyme Linked ImmunoSorbent Assay), noting that ELISA is used in the clinical laboratory as a standard quantitative method for measuring protein by weight in fluids, by reference to a calibrating reference standard. 

In order to compare the specific activity of plant-derived C5-1 to that of the hybridoma-derived antibody, the antigen-binding capacity of antibodies produced in each system was assayed by enzyme-linked immunosorbent assay (ELISA). As shown in Table 1.2, antibodies from both sources demonstrated similar binding characteristics against human IgGs [8]. Furthermore, the stability of alfalfa-derived C5-1 in the blood stream of Balb/c mice was comparable to that of the hybridoma-derived IgG [8]. 

The most commonly used screening method for HIV is an enzyme-linked immunosorbent assay, which detects antibodies against HIV-1 and is both highly sensitive and specific. False positives can occur in multiparous women in recent recipients of hepatitis B, HIV, influenza, or rabies vaccine following multiple blood transfusions and in those with liver disease or renal failure, or undergoing chronic hemodialysis. False negatives may occur if the patient is newly infected and the test is performed before antibody production is adequate. The minimum time to develop antibodies is 3 to 4 weeks from initial exposure. 

A classical approach is the enzyme linked immunosorbent assay (ELISA), where the antigen (e.g., the protein to be quantified) is immobilized on the surface of a well. A first antigen-specific antibody is applied to occupy all antigens, before a second antibody binds all primary antibodies on the well. The second antibody carries an enzyme, which now catalyzes a color reaction. If the substrate of the enzyme is given in high excess, the enzyme is saturated and the production of product is linear with time and concentration of second antibody and antigen (Fig. 8). 

King, D.P. et al., The use of monoclonal antibodies specific for seal immunoglobulins in an enzyme-linked immunosorbent assay to detect canine distemper virus-specific immunoglobulin in seal plasma samples, J. Immuno. Methods, 160, 163, 1993. 

Biological techniques, e.g., immunoassays, are among the most sensitive analytical methods, but are limited by the availability of the specific antisera and are subject to cross-reactivity. Huang et al. [36] employed an enzyme-linked immunosorbent assay (ELISA) for determination of estradiol, its conjugates, and ethynylestradiol in wastewaster treatment plant effluents (see Table 4). The reported limit of detection (LOD) of 0.1 ng L 1 reflects the sen-... 

Diagnosis If signs and symptoms spelled out above are noted in large numbers of geographically clustered patients, exposure to aerosolized ricin is the suggested cause. The rapid time course of severe symptoms and death would be unusual for infectious agents. Laboratory findings are nonspecific except for specific serum ELISA (enzyme-linked immunosorbent assay). Acute and convalescent sera (plural of serum ) should be collected. 

The model immunoassay is the enzyme-linked immunosorbent assay (ELISA) in which a non-specific capture antibody is bound to a surface, such as a multi-well plate or small tube [13]. In the basic form of ELISA, a second antibody tagged with an enzyme interacts specifically with the analyte. The enzyme assay produces a colored product that is read with a spectrophotometer. There are many variations on the basic immunoassay format that serve to increase sensitivity, specificity, linear range, and speed. Many commercial instruments have been developed to take advantage of various technologies for reporter molecules. The immunoassay may be coupled to an electronic sensor and transducer, such as a surface acoustical wave (SAW) sensor. Electrochemiluminescence (ECL) is a method in which the detector antibody is tagged with a ruthenium-containing chelate [13-15]. When the tag is... 

Positive clones A phrase usually used to describe those hybridoma clones which bind reasonably to their respective hapten in an enzyme-linked immunosorbent assay, thereby eliminating non-specific antibodies raised to different epitopes of the hapten/carrier conjugate. 

Enzyme-linked immunosorbent assay (ELISA) is based on the specific reaction between an antibody and an antigen. One of the reagents in the reaction is labeled with an enzyme that generates a colorimetric product that can be measured with a spectrophotometric device. The color intensity correlates with the concentration of specific antibody and the respective antigen. The reaction can be formatted in various ways in a multiwell plate (microtiter plate) with the common formats being the sandwich assay, the competitive assay, and the direct assay. (See Figure 11.1.)... 

After incubation, the supernatants of the ceU cultures can be used for the cytokine assay by capture enzyme-linked immunosorbent assay (ELISA) using specific antibody pairs and recombinant cytokine standards and ELISA plates. 

Engvall, E. and Perlman, P. (1972) Enzyme-linked immunosorbant assay, ELISA. Quantitation of specific antibodies by enzyme-labeled anti-immunoglobulin in antigen-coated tubes. J. Immunol. 109,129. 

Currently there are few methods for specific investigation of immunotoxic effects, which are regarded as sufficiently validated for routine use (EC 2003). The plaque forming assay or the equivalent using the ELISA method (Enzyme-linked Immunosorbent Assay) are recommended to identify altered T-cell-dependent humoral responses. Of particular value for hazard assessment are the so-called host resistance models, in which the clinical relevance of immunotoxicity can be evaluated. Other methods may also be of value to provide information on the mode of immunotoxic action, e.g., mitogen stimulation tests and leucocyte phenotyping. However, further work is needed on standardization and validation of these test methods. 

There are several important advantages RPMAs have over antibody arrays and other proteomic techniques such as immunohis-tochemistry or tissue arrays. Antibody arrays usually require a second specific antibody, made in a different species, for each captured protein to be visualized in a manner analogous to enzyme-linked immunosorbent assays (ELISA). Therefore, it becomes difficult to simultaneously optimize the antibody-antigen hybridization conditions for so many antibodies at once present on antibody arrays while minimizing nonspecific cross-reactivity and ensuring that proteins over a wide range of concentrations can be quantitated in a linear fashion (14). Antibody arrays also consume or require much higher inputs of protein than reverse phase arrays. With antibody arrays. 

Enzyme-linked immunosorbent assay (ELISA) is a new method in alkaloid studies. The application of ELISA to alkaloid study is based on antibody incubations. It differs from classical precipitation-based methods in that specific antigen-antibody interactions are recognized by assaying an enzyme label conjugated to one reactant, usually an antibody. Because of the sensitivity with which enzyme... 

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