What is ELISA Technique? – Types of Elisa Test, Uses
Origin of Elisa Technique
The Enzyme-Linked Immunosorbent Assay, or ELISA, technique was first introduced in the early 1970s as a revolutionary method for detecting and quantifying biological substances. This groundbreaking technique quickly gained popularity due to its simplicity, sensitivity, and versatility.
What is Elisa Technique?
ELISA is a powerful biochemical technique used to detect the presence of an antigen or antibody in a sample. It relies on an enzyme and substrate interaction to produce a measurable signal. This method has become an essential tool in various fields, including clinical diagnostics, research laboratories, and the pharmaceutical industry.
Principle of ELISA
The principle behind ELISA is based on the specific binding of an antigen and an antibody. The antigen of interest is immobilized on a solid surface, such as a microplate. Subsequently, an enzyme-linked antibody is added, which binds to the antigen forming an antigen-antibody complex. The enzyme substrate is then added, resulting in a color change that can be quantified using a spectrophotometer.
Types of Elisa Test
ELISA assays can be classified into three main types based on the method of detection: indirect ELISA, sandwich ELISA, and competitive ELISA. Each type has its unique advantages and applications in various fields of research and diagnostics.
Indirect ELISA
Indirect ELISA is a commonly used method for detecting antibodies in a sample. In this technique, the antigen is immobilized onto a solid surface, and the sample containing antibodies is added. If antibodies specific to the antigen are present in the sample, they bind to the immobilized antigen. Then, a secondary antibody labeled with an enzyme is added, which binds to the bound antibodies, forming a complex. The enzyme activity is detected using a substrate, indicating the presence of antibodies in the sample.
Sandwich ELISA
Sandwich ELISA is highly sensitive and specific for detecting and quantifying antigens in a sample. In this technique, a capture antibody is immobilized onto a solid surface, and the sample containing the antigen is added. If the antigen is present, it binds to the capture antibody. Then, a detection antibody labeled with an enzyme is added, which binds to a different epitope on the antigen, forming a “sandwich” structure. The enzyme activity is detected using a substrate, indicating the presence and quantity of the antigen in the sample.
Competitive ELISA
Competitive ELISA is used for quantifying the concentration of an antigen in a sample. In this technique, the antigen of interest is immobilized onto a solid surface, and a known amount of labeled antigen (conjugate) is added to the sample. The sample containing the unlabeled antigen competes with the labeled antigen for binding to the immobilized antibody. The amount of labeled antigen bound to the antibody is inversely proportional to the concentration of the unlabeled antigen in the sample, allowing for quantitative analysis.
Complete Elisa Technique Procedure
The ELISA technique involves several key steps, including coating, blocking, incubation, washing, detection, and analysis. Here’s a brief overview of the complete procedure:
- Coat the microplate with the antigen.
- Block non-specific binding sites.
- Add the sample or standard containing the antigen.
- Wash the plate to remove unbound substances.
- Add the enzyme-linked antibody.
- Wash the plate again.
- Add the enzyme substrate to produce a measurable signal.
- Measure the color intensity using a spectrophotometer.
Diseases that can be Diagnosed Using ELISA Method
ELISA is instrumental in diagnosing various diseases, including:
- HIV/AIDS
- Hepatitis B and C
- Lyme disease
- Breast cancer
- Alzheimer’s disease
Uses of Elisa Technique
The ELISA technique has a wide range of applications, including:
- Disease diagnosis
- Monitoring of treatment efficacy
- Detection of food allergens
- Environmental monitoring
- Drug development
Conclusion
The Elisa technique revolutionized the field of biomedical research and diagnostics, providing a reliable and efficient method for detecting antigens and antibodies. With its versatility and sensitivity, ELISA continues to be a valuable tool in various scientific disciplines.
This article delves into the ELISA Technique, exploring its unique applications and complete procedure for ELISA technique. For further insights into related concepts, visit our blog section. Seeking personalized online tuition? Tutoroot offers top-notch biology tutoring tailored to your needs. Our sessions aim to clarify any doubts you may have. Click here to schedule a FREE DEMO session.
FAQs
Elisa Test Principle
The ELISA test principle is based on the specific binding of an antigen and an antibody, followed by an enzyme-substrate reaction to produce a measurable signal.
Sandwich Elisa Technique
The sandwich ELISA technique involves capturing the antigen between two antibodies, one immobilized and the other enzyme-linked, allowing for sensitive detection of antigens with multiple epitopes.
Direct Elisa Principle
The direct ELISA principle involves immobilizing the antigen on a solid surface, followed by the addition of an enzyme-linked antibody that directly binds to the antigen for signal detection.