Who is ELISA?

In this case, rather than a ‘who,’ ELISA is a ‘what,’ and it refers to an abbreviation which stands for “enzyme-linked immunosorbent assay.”


What is this test?

The ELISA test utilizes components that belong to the immune system together with chemicals which work to determine responses of immunity in the body, for example, immunity to infectious microbes.

The test involves an enzyme, which in effect, is a protein that brings about the catalyzing of a biochemical reaction. Further, it also involves an antigen or antibody, which are immunologic molecules.


What is the use of the test?

ELISA tests are frequently used as a way of detecting substances which have antigenic properties. These substances are primarily proteins, and can include bacterial antigens, antibodies, and hormones. The test can be used to diagnose:

  • Lyme disease
  • HIV
  • Rocky Mountain spotted fever
  • Pernicious anemia
  • Toxoplasmosis
  • Rotavirus
  • Syphilis
  • Squamous cell carcinoma
  • Varicella zoster virus (the cause of shingles and chickenpox)

If it’s found that your blood contains antibodies to any one of these conditions, it’s more than likely that you either have had it recently or you currently have it.

Frequently, ELISA is used as a quick screening tool prior to other tests, which are more in-depth, being ordered.


How does the test work?

There are numerous variations of the ELISA test, though, in its most basic form, it consists of a solid surface and an antibody which is attached to it.

The antibody has an affinity for the particular substance of interest. As an example, the commonly measured protein, human chorionic gonadotropin (HCG), which indicates pregnancy.

A blend of purified HCG which is linked to an enzyme as well as the test sample, be that urine or blood, are then added to the test sample. In the test sample, if no HCG is present, then the only binding agent will be the enzyme-linked HCG.

The substance which has brought about a reaction by the enzyme is then added and in some way, the amount of product is measured. This can be something like a measure of the change in color of the solution.


And the Advantages of ELISA are?

These are, albeit relatively basic, in general pretty accurate tests. They are seen to be specific and highly sensitive, and they compare favorably with a number of other methods which are used to detect substances that reside in the body, for example, radioimmune assay (RIA) tests.

They have further advantages. They don’t require radioisotopes, which are radioactive substances. Nor do they need a costly radiation counter – radiation-counting apparatus.