The Enzyme-Linked ImmunoSorbent Assay or ELISA and the Lateral-Flow test, also known as the dipstick or rapid test, currently are the two predominant formats in immunodiagnostics.
The ELISA (sometimes also called an EIA) is a sensitive, inexpensive assay technique involving the use of antibodies coupled with indicators (eg, enzymes linked to dyes) to detect the presence of specific substances, such as enzymes, viruses, or bacteria. While there are several different types, basically ELISAs are created by coating a suitable plastic (the solid phase) with an antibody. To complete the reaction, a sample believed to contain the antigen of interest is added to the solid phase. Then a second antibody coupled with an enzyme is used followed by the addition of a color-forming substrate specific to the antibody.