ELISA Test Principles and Concepts

Study Notes

Key Components of the ELISA Test

ELISA (Enzyme-Linked Immunosorbent Assay) detects proteins, antibodies, or hormones in a sample.
Key components include:
- Wells coated with antigens or antibodies specific to the target.
- Sample containing antibodies (or antigens) to be tested.
- Secondary antibody linked to an enzyme for signal generation.
- Enzyme substrate that produces a measurable signal, often in the form of color change.

Difference Between Direct and Indirect ELISA

Direct ELISA:
- Involves a single step assay using a labeled primary antibody that directly binds to the target antigen.
- Results in a faster process but less signal amplification.
Indirect ELISA:
- Uses an unlabeled primary antibody followed by a labeled secondary antibody that binds to the primary.
- Allows for greater signal amplification and increased sensitivity but requires more steps.

Applications of Indirect ELISA

Commonly used for detecting antibodies in serum and plasma.
Utilized in diagnostic labs for infectious diseases (e.g., HIV, hepatitis).
Employed in vaccine development to measure antibody response.
Useful in research for quantifying protein levels and studying immune responses.

Main Purpose of Measuring Antibody Levels Using ELISA

Assesses immune response in individuals by determining antibody concentration.
Essential for diagnostics, monitoring disease progression, and evaluating vaccine efficacy.
Aids in identifying previous exposure to pathogens by analyzing historical antibody levels.

Disadvantages of ELISA

Potential for cross-reactivity leading to false-positive results.
Requires careful handling and processing of samples to prevent degradation.
Limited ability to identify specific antibody subclasses without additional assays.
Can be time-consuming and labor-intensive with multiple processing steps.

Description

This quiz covers the principles and concepts of the ELISA test, including the introduction, the principle of the test, basic immunology response, and key concepts like antigens and antibodies. It also includes information on enzyme conjugate substrates, non-competitive ELISA, direct and indirect ELISA.