What is the basic principle underlying ELISA assays?

What is the basic principle underlying ELISA assays?

• A. It relies on nucleic acid hybridization to detect proteins
• B. It measures cell viability by dye uptake
• C. It uses antibody-antigen binding with an enzyme readout
• D. It sequences proteins by mass spectrometry

Answer: (C)

ELISA works because it relies on the specific binding between an antibody and its target antigen, with an enzyme attached to that binding event providing the detectable signal. In a typical ELISA, the target molecule is captured on a solid surface, an antibody binds specifically to it, and a second antibody that carries an enzyme binds to the first antibody. When a suitable substrate is added, the enzyme catalyzes a reaction that produces a color, light, or fluorescence. The signal magnitude reflects how much target is present, allowing either quantitative or qualitative assessment. This approach is distinct from other methods: nucleic acid hybridization detects DNA or RNA rather than proteins; dye uptake assays measure cell viability rather than specific antibody–antigen interactions; and mass spectrometry analyzes protein identity or sequence rather than providing a reporter signal from an enzyme linked to binding.

ELISA works because it relies on the specific binding between an antibody and its target antigen, with an enzyme attached to that binding event providing the detectable signal. In a typical ELISA, the target molecule is captured on a solid surface, an antibody binds specifically to it, and a second antibody that carries an enzyme binds to the first antibody. When a suitable substrate is added, the enzyme catalyzes a reaction that produces a color, light, or fluorescence. The signal magnitude reflects how much target is present, allowing either quantitative or qualitative assessment.

This approach is distinct from other methods: nucleic acid hybridization detects DNA or RNA rather than proteins; dye uptake assays measure cell viability rather than specific antibody–antigen interactions; and mass spectrometry analyzes protein identity or sequence rather than providing a reporter signal from an enzyme linked to binding.