ELISA (enzyme-linked immunosorbent assay) is a technique for detecting and quantifying specific antibodies, antigens, or proteins in a sample using methods such as direct, indirect, sandwich, and competitive ELISA. The procedure involves coating a microtiter plate with antigens or antibodies, adding samples for incubation, and measuring color development from enzymatic reactions. ELISA is widely utilized in diagnostic testing, research, quality control, vaccine development, and therapeutic drug monitoring.

1. ELISA Practical
ELISA (Enzyme-Linked Immunosorbent Assay) is a laboratory
technique used to detect and quantify specific antibodies,
antigens, or proteins in a sample.
Types of ELISA:
1. Direct ELISA: Detects antibodies or antigens directly.
2.Indirect ELISA: Detects antibodies or antigens using a
secondary antibody.
3. Sandwich ELISA: Detects antigens using two
antibodies.
4.Competitive ELISA: Detects antibodies or antigens using a
competitor molecule.
Principle:
ELISA is based on the binding of antibodies to specific antigens,
followed by the detection of the bound antibodies using an
enzyme-linked secondary antibody.
Procedure:
5.Coating: Antigen or antibody is coated onto a microtiter
plate.
6.Sample addition: Sample containing the target antibody or
antigen is added.
7. Incubation: Plate is incubated to allow binding.
8.Secondary antibody: Enzyme-linked secondary antibody is
added.

2. 5. Substrate addition: Substrate for the enzyme is added.
6. Color development: Color develops due to enzyme activity.
7.Measurement: Absorbance is measured using a
spectrophotometer.
Uses:
8.Diagnostic testing: ELISA is used to diagnose various
diseases, such as HIV, hepatitis, and cancer.
9.Research: ELISA is used to study immune responses, protein
expression, and biomarker detection.
10.Quality control: ELISA is used to detect contaminants,
allergens, and residues in food and environmental samples.
11.Vaccine development: ELISA is used to monitor
immune responses to vaccines.
12.Therapeutic drug monitoring: ELISA is used to monitor
drug levels in patients.