ELISA

ELISA or Enzyme-Linked Immunosorbent Assay is a popular laboratory technique used in immunology. It is used to detect the presence of antibodies or antigens in a sample. The technique is named for the enzymes used to detect the target molecule.

History

The ELISA technique was first developed in the early 1970s by two independent research groups: one led by Peter Perlmann and Eva Engvall at Stockholm University in Sweden, and the other by Anton Schuurs and Bauke van Weemen in The Netherlands.

Principle

The ELISA test begins by coating a surface with a sample containing the target antigen. An antibody is then applied to the surface, which will bind to the antigen. The 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 solution.

Types of ELISA

There are four primary types of ELISA:

• Direct ELISA: The antigen is immobilized by direct adsorption to the assay plate. The detection antibody is then added, followed by the enzyme-linked secondary antibody.

• Indirect ELISA: Similar to the direct ELISA, but with an added step. After the antigen is immobilized, a primary antibody is added, followed by an enzyme-linked secondary antibody.

• Sandwich ELISA: This method requires two antibodies that are specific to the antigen. The first antibody is coated on the plate, and the antigen is then added. After washing, the second antibody is added, which has been linked to an enzyme.

• Competitive ELISA: The antigen is mixed with an enzyme-linked antibody and added to an antigen-coated plate. The more antigen in the sample, the less antibody will be able to bind to the antigen in the plate, thus giving a reverse result.

Applications

ELISA is used in both diagnostic and research settings. It is a common diagnostic tool in medicine, plant pathology, and biotechnology. In research, it is often used to measure protein concentrations in samples.

Advantages and Limitabilities

ELISA is a highly sensitive and specific method, capable of detecting small amounts of antigen or antibody. However, it requires careful sample preparation and specific antibodies, which can be expensive and time-consuming to produce.

See Also

• Immunology
• Antibody
• Antigen
• Enzyme

ELISA Resources
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