Question 1

You may have wondered what does ELISA stand for?

Accepted Answer

ELISA stands for enzyme-linked immunoassay. It is a commonly used laboratory test to detect antibodies in the blood. An antibody is a protein produced by the body's immune system when it detects harmful substances, called antigens. ELISA is an effective and widely used technique in microbiology and virology—in particular, for investigating infectious pathogens.

Question 2

What is the principle of enzyme linked immunosorbent assay?

Accepted Answer

ELISA is an abbreviation for "Enzyme Linked Immunosorbent Assay" and it is a common laboratory technique. To get the task of measuring the analyte's (antibodies or antigens most likely) concentration in solutions done, we use the ELISA technique. As an indicator to the amount of analytes exist in the original sample, a colored end product is the final result of the ELISA steps. ELISAs are typically performed in 96-well (or 384-well) polystyrene plates, which will passively bind antibodies and proteins. It is this binding and immobilization of reagents that makes ELISAs so easy to design and perform. The ELISA principle depends on having the reactants of the ELISA immobilized to the microplate surface makes it easy to separate bound from unbound material during the assay. This ability to wash away nonspecifically bound materials makes the ELISA a powerful tool for measuring specific analytes within a crude preparation.

Question 3

How does the ELISA test work?

Accepted Answer

Unless you are using a kit with a plate that is pre-coated with antibody, an ELISA begins with a coating step, in which the first layer, consisting of a target antigen or antibody, is adsorbed onto a 96-well polystyrene plate.  This is followed by a blocking step (Blocking ELISA principle: all unbound sites are coated with a blocking agent.) Following a series of washes, the plate is incubated with enzyme-conjugated antibody. Another series of washes removes all unbound antibody. A substrate is then added, producing a calorimetric signal. Finally, the plate is read.  Because the assay uses surface binding for separation, several washes are repeated in each ELISA step to remove unbound material. During this process, it is essential that excess liquid is removed in order to prevent the dilution of the solutions added in the next assay step. To ensure uniformity, specialized plate washers are often used.  ELISAs can be quite complex and include multiple intervening steps, especially when measuring protein concentration in heterogeneous samples such as blood. The most complex and varying step in the overall process is detection, where multiple layers of antibodies can be used to amplify signals.

Question 4

What is the principle of competitive ELISA technique?

Accepted Answer

, the primary antibody is incubated with the sample antigen and the resulting antibody–antigen complexes are added to wells that have been coated with the same antigen. After an incubation period, any unbound antibody is washed off. The more antigens in the sample, the more primary antibodies will be bound to the sample antigen.  Therefore, there will be a smaller amount of primary antibody available to bind to the antigen coated on the well, resulting in a signal reduction. The main advantage of this type of ELISA arises from its high sensitivity to compositional differences in complex antigen mixtures, even when the specific detecting antibody is present in relatively small amounts.

Question 5

What Are the 4 Steps of an ELISA Protocol?

Accepted Answer

Plate Coating, Plate Blocking, Antibody Incubation, and Detection.

Question 6

What Is the ELISA Test Used for?

Accepted Answer

This test is often used to see if you have been exposed to viruses or other substances that cause infection. It is also used to screen for current or past infections.

Question 7

How Is the ELISA Test Performed?

Accepted Answer

A blood sample is needed. Most of the time, blood is drawn from a vein located on the inside of the elbow or the back of the hand. The sample is sent to a laboratory where the targeted antibody or antigen is linked to a specific enzyme. If the target substance is in the sample, the test solution turns a different color.

Nourhan Essam