Question

What is meant by ELISA test?

Answer 1

Hint: ELISA stands for enzyme- linked immunosorbent assay. It is a test to diagnose antibodies in the blood, it is performed in the laboratory. Antibody is a protein that is produced by the immune system of the body when any harmful substances are detected in the body known as antigens.

Complete answer:
There is no special preparation required for this test. ELISA test is used to check whether your body has any antibodies related to some certain infectious conditions or not.

Principle: ELISA works on the principle that specific antibodies bind to the target antigen and detects the presence and quantity binding antigen.

Procedure: In ELISA test first of all a person’s blood/ serum is taken for sample and is sent to laboratory for further process. The sample taken is diluted 400 times first, and then it is applied to a plate to which antigens are attached against which we need to check the antibodies. For example, let's take an example of HIV antigens. After diluting when a sample is applied to the plate or tray where HIV antigens are attached, if antibodies to HIV antigens are present in the sample we took it will bind to the HIV antigens present on the testing plate. This results in the color change or any detectable signal comes up. This is how we perform it.

There are otherwise four Main protocols to be followed for this test these are;
1. Bind the samples to support
2. Add substrate
3. Add Primary antibody and wash
4. Add secondary antibody- enzyme conjugate and wash

Note: Application of ELISA test are; in detection of Ebola, Pernicious anaemia, AIDS, Rotavirus, Lyme disease, Syphilis, Toxoplasmosis, Carcinoma etc. there are many more. Frequently there are 3 types of ELISA test;
> Indirect ELISA
> Sandwich ELISA
> Competitive ELISA