With this entry we conclude the series of posts where we have delved into the peculiarities of the different types of ELISA.
After knowing the rationale and procedure on which each of them is based and seeing the main characteristics that differentiate them , today we will focus on analyzing the advantages and disadvantages of the different types of ELISA .
ADVANTAGES AND DISADVANTAGES OF THE DIFFERENT TYPES OF ELISA
In order to make this entry as visual and practical as possible, we will summarize and group the main advantages and disadvantages of the different types of ELISA in the following table:
|TYPES OF ELISA||ADVANTAGE||DISADVANTAGES|
|ELISA direct||1.- The protocol is simple and fast.2.- There is no possibility of cross reactivity with the secondary antibody.3.- Less probability of error due to the use of fewer reagents and steps in the procedure.||1.- It can give more background noise, since other proteins present in the sample (in addition to the antigen of interest) can adhere to the plate.2.- There is no signal amplification since secondary antibodies are not used, which reduces the sensitivity of the assay.3.- The primary antibody must be labeled, which reduces the flexibility of the assay, and can be used to alter its immunoreactivity.|
|Indirect ELISA||1.- High sensitivity, since the use of secondary antibodies makes it possible to amplify the signal.2.- High flexibility due to the fact that the same secondary antibody can be used with different primary antibodies, which also translates into an economic benefit.3.- The primary antibody maintains its immunoreactivity intact by not being conjugated.||1.- Protocol more complex than the direct ELISA, which includes additional incubation steps with the secondary antibody.2.- The use of secondary antibodies can lead to cross reactivity.|
|ELISA sandwich||1.- High flexibility, since detection can be done both by direct and indirect procedure.2.- High sensitivity and specificity, due to the use of two antibodies against the same antigen.||1.- The antigen must be large enough to allow two antibodies to bind simultaneously.2.- It is not always easy or possible to have pairs of antibodies that work well in this type of assay.|
|Competitive ELISA||1.- High flexibility: it can be based on a direct, indirect or sandwich procedure.2.- High sensitivity, robustness and consistency.3.- It allows the detection of small size antigens and in low concentrations.4.- It does not require the previous processing of the samples to be analyzed.||1.- The protocol is relatively complex.2.- Requires the use of inhibition antigen.|
As a conclusion after analyzing the advantages and disadvantages of the different types of ELISA, we can determine the ideal use of each of them :
- Direct ELISA : it is the technique of choice to analyze the immune response to a certain antigen, for example, in the production of antibodies or in diagnostic procedures.
- Indirect ELISA : test of choice to determine the total concentration of antibodies in a certain sample.
- Sandwich ELISA : technique of choice when it comes to analyzing complex samples, without the need to purify the antigen previously.
- Competitive ELISA : ideal technique to detect antigens of small size or that are present in very low concentrations in the sample.