ELISA is based on the principle of -

The correct answer is Option (4) → Antibody-antigen interaction

ELISA (Enzyme Linked Immuno-Sorbent Assay) is a test for molecular diagnosis. An antibody binds only to its own antigen. ELISA uses this specific binding. It can detect an infection by finding either the antigens of the pathogen (such as proteins or glycoproteins) or the antibodies that the body has made against it.

(1) Antibody-antibody interaction — Incorrect. Antibodies do not bind to one another in this test.

(2) Antigen-antigen interaction — Incorrect. Antigens do not bind to one another in this test.

(3) Antibody-lymphocyte interaction — Incorrect. Lymphocytes are the cells that make antibodies. ELISA does not test their binding.

(4) Antibody-antigen interaction — Correct. ELISA is based on the antigen-antibody interaction.

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NCERT Extract:
Molecular Diagnosis – …