ELISA is also referred to as the Enzyme linked immunosorbent assay. It is also known as the EIA or the enzyme immunoassay. It is the biochemical technique which is primarily used in immunology to help in detection of the presence of any antibodies or also to detect an antigen present in a given sample. The ELISA has been utilized in medicine as a diagnostic tool and also used in plant pathology. It is also used in various industries as the quality control check. Thus, very simply, in the ELISA a certain unknown quantity of eh antigen is first put on to a surface. Then a particular antibody is slashed over the surface to allow it to bind itself to that antigen. This particular antibody is then linked to the enzyme. The final step of this process involves a substance being added to the enzyme which will help to convert it to a detectable signal.
When doing an ELISA, it involves at the minimum a single antibody with specificity for a certain antigen. When the sample is taken having the unknown quantity of antigen it is immobilized on to a solid support non specificity which is normally a polystyrene microtiter plate. The other technique is by capturing another antibody which is specific to the very same antigen and is referred to as the sandwich ELISA. Post the antigen being immobilized the detection antibody is then combined, which results in the formation of a complex along with that antigen.
The indirect ELISA maintains the following mechanism wherein the antigen which needs to test for first is added on to every well of the microtiter plate. Here the charges for all the different protein conformations are found to be present. Then a solution which contains the non reactive protein like casein or the bovine serum albumin is introduced to stop any further changes that had not drawn the interest protein. Next the serum is introduced on which is known to contain the antibodies of the unknown concentration that is special only for the antigen that has been added on originally. The secondary antibody very often has the enzyme fixed to it that has no reaction on bonding characteristics of all the molecules. Then the substrate for the enzymes is added on. Quite often, the substrate changes color on reaction to the enzyme. Finally, if the serum has greater concentration of the basic antibodies, the change in color would also be great.