Balloons: Courtesy Wikipedia ImagesELISA (enzyme-linked immunosorbent assay) celebrated its 35th Anniversary on Monday, May 22nd, 2006. Developed in 1971, by Eva Engvall and Peter Perlman, the ELISA test revolutionized medicine. It is the most widely used enzyme immunoassay test.

The ELISA test is a group of serological tests using enzyme reactions as indicators. Enzyme labels are used because of stability, reproducibility, safety, ease of detection and they are cost effective. The enzymes horseradish peroxidase and alkaline phosphatase are most commonly used. When the appropriate substrate is added, enzyme reaction occurs with the substrate yielding a colored product. This colored product either can be detected visually or with a spectrophotometer. The amount of product produced is proportional to the amount of enzyme and therefore, antibody or antigen. ELISA procedures are popular because they require little interpretive skill to analyze and the results tend to be clearly positive or clearly negative.

There are two main versions of ELISA tests: direct ELISA detects antigens and the indirect ELISA test detects antibodies. Commonly, the direct ELISA test is used to detect the presence of drugs in urine and is also used in home pregnancy tests. An example of an indirect ELISA test includes the test for HIV antibodies.

Happy 35th Anniversary ELISA and keep up the good work!

Source: Tortora, G., Funke, B. & Case, C. (2004). Microbiology: An Introduction; 8th Ed. Pearson; San Fransico, CA.

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