Compared to other immunoassay methods, there are many advantages of ELISA. ELISA tests are more accurate. They are considered highly sensitive, specific and compare favorably with other methods used to detect substances in the body, such as radioimmune assay (RIA) tests. ELISA possesses the added advantages of not needing radioisotopes (radioactive substances) or a costly radiation counter (a radiation-counting apparatus).
The high sensitivity of ELISA, comes from the enzyme as a reporting group. As is known to all, the enzyme is an organic catalyst, a small amount of which could induce a large span of catalytic reactions to produce observable chromogenic reaction phenomenon.
Therefore, this system is often taken as the amplification system of enzyme. By ELISA, a tracer of the antigen or antibody is achieved in the cell or subcellular level, also, antigen or antibody quantification can be done in the microgram or even nanogram levels.
Specificity of ELISA is because of the selectivity of the antibody or antigen. Actually, the binding of antigen or antibody only occurs in the epitope of an antigen or antigen-binding site of an antibody.
Since, there is a complementary relationship between epitope and antigen-binding site both in chemical structure and spatial configuration, the reaction between antigen and antibody shows a strong specifity.
These advantages of ELISA make it an useful biotechnical tool with many appllicaitons, either in scientific research or clinical diagnosis of diseases or conditions.