Which technique is based on the principle of antigen-antibody interaction?
Answer & explanation
Correct answer: option 2
The correct answer is Option (2) → ELISA
Some tests find a disease by its molecules rather than by symptoms. ELISA uses the fact that an antibody binds only to its own antigen. An infection can be found either by detecting the pathogen’s antigens (proteins, glycoproteins) or by detecting the antibodies the body has made against the pathogen.
Option (1) PCR — Incorrect. PCR (polymerase chain reaction) amplifies a stretch of DNA many times using primers and a heat-stable DNA polymerase. It detects the pathogen’s nucleic acid, not an antigen-antibody reaction.
Option (2) ELISA — Correct. ELISA (enzyme linked immuno-sorbent assay) is based on antigen-antibody interaction. It is used, for example, to detect infection by a pathogen in molecular diagnosis.
Option (3) Recombinant DNA technology — Incorrect. Recombinant DNA technology cuts and joins DNA from different sources and puts it into a host. It is a method of making new DNA, not a test based on antibodies.
Option (4) Gene therapy — Incorrect. Gene therapy corrects a faulty gene by putting a working gene into a person’s cells, as in ADA deficiency. It is a treatment, not a diagnostic test.
NCERT Extract:
Molecular Diagnosis – “… ELISA is based on the principle of antigen-antibody interaction. Infection by pathogen can be detected by the presence of antigens (proteins, glycoproteins, etc.) or by detecting the antibodies synthesised against the pathogen.”