Explain why antibodies allow scientists to target and identify specific disease agents.

Explain why antibodies allow scientists to target and identify specific disease agents.
Antibodies is a protein that has the ability to bind to a specific structure of another protein called antigen. It can bind that specific structure because protein(like enzyme) has a complex 3D structure. That makes a slight difference in the structure of molecule will cause it unable to bind with the antibodies. This feature called  "lock and key" and used in ELISA or any test that count antibody/antigen