Many scientists and medical technicians use the ELISA kit on a regular basis. ELISA stands for enzyme-linked immunosorbent assay. This is an assay technique that uses a plate. It is useful in detecting and giving the number of substances such as antibodies, hormones, peptides, and proteins. There is another kit called the EIA or enzyme immunoassay that uses the same technique as the ELISA kit does. With the ELISA, the antigen has to be placed on a surface or well to immobilize it; then it is treated with an antibody that can link to an enzyme. It is then incubated using a substrate, and the results are measured. This specific antigen-antibody interaction is the most crucial thing in the detection process.
Typically the ELISA kit contains either a 96, 192 or a 384 well plate ( usually the 96 well) made of polystyrene. This will bond the proteins and the antibodies. When the reactants of the ELISA kit are immobilized makes it easier to perform the next stage of the process. That is to separate the bound from the non-bound material.
One advantage to using the ELISA test is the fact that you can get an accurate result rather quickly. Generally, it is done with a simple blood sample taken either from the patient’s finger or their arm. The ELISA kit is very versatile and a valuable tool for the doctors, labs and other medical professionals. In addition to it being widely used in the medical industry, the ELISA kit is also used in the food industry to detect allergens for example. Some of the allergens it will identify are peanuts, milk almonds, walnuts, and eggs. These can be crucial for the patient with severe allergies to any of these products. Elisa is also used in toxicology to screen for certain kinds of drugs. One of the most significant advantages is that the ELISA kit is very sensitive and more cost-effective than other tests. Now the ELISA kit is being used as a convenient test for HIV.
Formats for the ELISA kit
The ELISA kit comes in four main formats. They are the direct, indirect, sandwich and competitive.
In a direct detection strategy, the plate is coated with the antigen. This method uses a labeled primary antibody. This antibody and antigen directly react to each other. This method is not widely used in the ELISA but is mostly used as a way to stain the cells and tissues.
In the indirect detection strategy, a secondary labeled antibody is introduced and used for detection. This is the most common assay format that is used for the ELISA. The two labeled antibodies are the capture antibody (the first one added) and the primary antibody.
In the sandwich ELISA test, the secondary antibody absolutely must be specific for the detection of the primary antibody and not the capture antibody. This is done by using two different hosts such as the mouse or goat.
Finally in the Competitive ELISA is mostly used when the antigen is small and only one antibody binding site can be detected. A labeled purified antigen is used, and an unlabeled antigen is used, The two ultimately compete to see which one binds to the capture antibody. When this happens, the signal from the purified antigen decreases, making it easier to separate.