What is the principle of the sandwich ELISA oral exam?
Answer:
As you probably know, ELISA stands for "Enzyme-Linked ImmunoSorbent Assay", and is a common theory test used to detect the presence and/or concentration of either antibodies or antigens.
Assume you want to theory test for a particular antigen. Fundamentally, the experiment would proceed as follows. Take the solution (e.g. the serum of a patient) that may or may not contain the antigen, and pour it over some sort of solid support (like a special plate) so that any antigen is immoblised (bound).
Wash off any unbound stuff, and afterwards add a solution containing the antiBODY to the antiGEN that you're looking for. Obviously, if in attendance is any antigen in the solution, the antibody will bind to it. Also, the amount of antibodies that bind communicate you how MUCH antigen there is. What you obligation now is some channel of signalling this (antibodies are way too small to see!).
Usually, the antibody that you give is modified to contain an enzyme - and the enzyme does something that can be measured. For example, it could change the colour of the solution. In this example, the greater the colour vary, the greater the enzyme concentration would have to be. And , since the intact chain is connected (antigen-to-antibody-to-enzyme... a greater concentration of enzyme implies a greater concentration of the antibody that you be searching for.
Whew! Right, in a minute for the "sandwich" part. The problem near the above is that the antigen binding to the plate is non-specific. That is, any old protein will bind to it, and this might mingy that not enough space is moved out for all the actual antigen to bind. Since anything not bound is wash away after the first step, less antigen will be tested, and the result will be too low.
To cope next to this, one can adopt the sandwich technique. In this, the plate is first lined next to antiBODIES to the antigen that you want to test for. This process that when the solution is pored over, ONLY antigen is bound - the binding is thus specific, since all other proteins are not bound by the antibody and are wash away. The rest of the test proceeds as above - the subsequent step is to add the antibodies to the desired antigen, which bind to the antigen as usual from the 'other side'. Thus, the antigen is 'sandwiched'.
Sorry for the long detailed answer, but the subject business is unfortunately pretty detailed. Take a look at the picture here (http://users.rcn.com/jkimball.ma.ultrane... which offers a graphical representation of what I've freshly said. Hope that helps!
The medication and health information post by website user , ByeDR.com not guarantee correctness , is for informational purposes with the sole purpose and is not a substitute for medical advice or treatment for any medical conditions.