Enzyme-linked Immunosorbent Assay (ELISA)
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ELISA theory overview
Enzyme-linked immunosorbent assay (ELISA) is widely used in immunology to detect the presence of proteins or other antibodies in a sample. For instance, it is used as an initial detection tool for HIV, based on the interaction of an antibody with antigen presented by the virus. There are several different ELISA methods: indirect ELISA, sandwich ELISA and competitive ELISA are the most commonly applied.
All three methods have similar steps:
1) attach antigens or primary antibodies or their complexes to a solid surface;
2) wash away unbound substances;
3) block exposed sites on the solid surface;
4) add detection antibodies and/or enzyme-conjugated secondary antibodies;
5) develop color by adding substrates that react with the enzymes.
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