Enzyme Linked Immunosorbent Assay (ELISA)

Immunoassays continue to remain the major backbone of diagnostic industry and the most conventional of these include ELISA. Though in use from decades now, ELISA still continues to be a major support for diagnosis of infectious conditions. With the advent of dedicated commercial kits comprising of controls as well as calibrators, the sensitivity of the technique has increased manifold.
Principle
Analyzers on Floor
Instrument Images

Principle of Enzyme Linked Immunosorbent Assay (ELISA)

ELISA is an immunoassay which majorly deals with analyzing antigen-antibody complexes using enzyme labeled antibodies in a 96 well microtitre plate. The commercial plates are pre-coated with specific antigens, and on addition of patient serum, antibodies if present against the antigen, will bind and form immune complexes. Post incubation and washing, a secondary labeled antibody is added, followed by substrate to aid in color development. The intensity of the color can then be measured using an ELISA plate reader.
The main advantage of this technique is its versatility to be designed and used for diagnosing a multitude of infections. The tests can also be performed both in qualitative as well as quantitative fashion requiring simple instruments.
Chemiluminescence image