Elisa is a very important method of detecting virus. Enzyme-linked immunosorbent assay (ELISA), is a popular format that uses one sub-type to detect the presence of a substance, usually is in a liquid sample or wet sample.
The ELISA has been used as a diagnostic tool in medicine and plant, as well as a quality-control check in various industries. It is to detect the presence of the antigen in the sample proceeds as follows: Antigens from the sample are attached to a surface. Then a further specific antibody is applied over the surface so that it can bind to the antigen. This antibody is linked to an enzyme, and, in the final step, a substance containing the enzyme's substrate is added. The subsequent reaction produces a detectable signal, most commonly a color change in the substrate.
Performing an ELISA involves at least one antibody with specificity for a particular antigen. The sample with an unknown amount of antigen is on a solid support either non-specifically or specifically. After the antigen is immobilized, the detection antibody is added, forming a complex with the antigen. The detection antibody can be linked to an enzyme, or can itself be detected by a secondary antibody that is linked to an enzyme through it. Between each step, the plate is typically washed with a mild detergent solution to remove any proteins or antibodies that are not specifically bound. After the final wash step, the plate is developed by adding an enzymatic substrate to produce a visible signal, which indicates the quantity of antigen in the sample.
The technique essentially requires any reagent that can be immobilized on the solid phase along with a detection reagent that will bind specifically and use an enzyme to generate a signal that can be properly quantified. In between the washes only the ligand and its specific substance remain specifically bound or by antigen-antibody interactions to the solid phase, while the nonspecific or unbound components are washed away. Unlike other spectrophotometric wet lab assay formats where the same reaction well can be reused after washing, the ELISA plates have the reaction products on the solid phase which is part of the plate and thus are not easily substance.
Article : From Perlong medical (http://www.pl999.net/) Attention:If you want to copy, please attach the website.
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