What immunologic test detects antibodies against specific proteins by antigen-antibody binding and a colorimetric readout in patient serum?

What immunologic test detects antibodies against specific proteins by antigen-antibody binding and a colorimetric readout in patient serum?

• A. Western blot
• B. ELISA (enzyme-linked immunosorbent assay)
• C. Immunofluorescence assay
• D. Agglutination assay

Answer: (B)

Enzyme-linked immunosorbent assay detects antibodies in patient serum through antigen binding and a color change produced by an enzyme-substrate reaction. In an indirect ELISA, wells are coated with the target protein. If the serum contains antibodies against that protein, they bind to the antigen. A secondary antibody that recognizes human antibodies and carries an enzyme is added, linking to the bound antibodies. When substrate is introduced, the enzyme catalyzes a reaction that yields a colored product; the color intensity reflects the amount of specific antibody present. This colorimetric readout is the defining feature of ELISA, setting it apart from methods like Western blot, immunofluorescence, or agglutination, which rely on different detection principles.

Enzyme-linked immunosorbent assay detects antibodies in patient serum through antigen binding and a color change produced by an enzyme-substrate reaction. In an indirect ELISA, wells are coated with the target protein. If the serum contains antibodies against that protein, they bind to the antigen. A secondary antibody that recognizes human antibodies and carries an enzyme is added, linking to the bound antibodies. When substrate is introduced, the enzyme catalyzes a reaction that yields a colored product; the color intensity reflects the amount of specific antibody present. This colorimetric readout is the defining feature of ELISA, setting it apart from methods like Western blot, immunofluorescence, or agglutination, which rely on different detection principles.