Which of the following process involves the theory of antigen-antibody interaction?
Answer & explanation
Correct answer: option 2
The correct answer is Option (2) → ELISA
Option (1) PCR — Incorrect. The polymerase chain reaction makes millions of copies of a DNA segment using primers and a heat-stable DNA polymerase. It works on DNA, not on antigens and antibodies.
Option (2) ELISA — Correct. ELISA (Enzyme Linked Immuno-Sorbent Assay) detects an infection by finding the antigens of the pathogen, or the antibodies the body has made against it. An antibody binds only its own antigen, and the test uses this binding.
Option (3) Gene Therapy — Incorrect. Gene therapy corrects a gene defect by putting a normal gene into a person’s cells, as in ADA deficiency. It is a treatment, not a test.
Option (4) Gel electrophoresis — Incorrect. Gel electrophoresis separates DNA fragments by size as they move through agarose gel towards the anode.
NCERT Extract:
Molecular Diagnosis – “… Recombinant DNA technology, Polymerase Chain Reaction (PCR) and Enzyme Linked Immuno-sorbent Assay (ELISA) are some of the techniques that serve the purpose of early 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.”