ELISA

Howdie guys, Toshlan.
What is that?
I don't know:p I guess it's a hello or welcome...in Swedish.
-_-
Let's get back to the point before we get off topic.
Today we will be learning about ELISA. You can check her at Instagram @elisaimmunomedicotechniconaruto..
Will You shut up.
Sorry, let's begin. Go.



What is ELISA?

ELISA is an abbreviation for Enzyme Linked Immuno Sorbent Assay. It is a qualitative and quantitative method to determine presence of a particular substance (Mostly antigens or antibodies) in a liquid sample (mostly serum). It is also called an wet analysis because it is...wet, that's what she said.

What is the test? (Principle)

Well, the test basically revolves around antigen-antibody specific interactions. An enzyme

conjugated with an antibody reacts with a colorless substrate to generate a colored reaction product. Such a substrate is called a chromogenic substrate. The qualitative results are based on the production of a color reaction. To quantify, you can carry out a series of dilution of the standard and test and then measure the color spectrophotometrically. Here in direct E#LISA we mostly measure antigen, whereas in indirect ELISA antibody is measured.

How is the test carried out? (Procedure).

The whole blood is the main sample to obtain the antigens. 

1. The wells of 96 wells microtitre plate is preconditioned with the buffered antigen sample, so that they are well attached to the wall of the wells.
2. This step is optional and can be done for a more sensitive quantitative analysis. In this step, a non reacting protein is added in the well to fill up any remaining spaces where the antigens are not attached.
3. An antibody (linked to an enzyme) specific to the antigen is added to well and allowed to bind to the antigen. 
4. In this step, a chromogenic substrate that is specific to the enzyme is added which on binding to the enzyme will produce the color. The more the antibodies bind to the antigen, the faster the color develops. Alternately, chemiluminiscence can also be used as a detection method in which luminiscence is observed when the substrate binds to the enzyme.

If the suspected antigen is missing in the sample, then antgen-antibody binding will not occur. Thus failing to show a colored reaction.

What are it's applications?

Mostly, ELISA is used for detection of HIV antibodies in the serum, or HCG to determine pregnancies. It is also useful in detection of various enterotoxins and certain markers in viruses.

Here's an image for explanation :D

I hope this explanation helps.

High six.

-Staph.