- Its simple ,nearly as sensitive as radioimmunoassay
- It has wide range of application
- Used for detection of specific antigen/antibody
- Enzyme is used to detect antigen antibody reaction
- Colour change is the indication for detection
- Its carried in polyvinyl plates ,polystyrene plate.
1) SANDWICH ELISA:
- In a microtitre plate ,wells are coated with specific antibody eg- e.coli -antigen test,specific antibody is placed.
- Specimen to be tested is added
- If the specimen contains suspected antigen (antigen-antibody reaction)
- to detect this reaction ,anti-serum conjugated with an enzyme is added it binds to antigen that's already attached to antibody
- Enzyme+antiserum act on substrate produce colour that's read by elisa reader.
2) INDIRECT ELISA:
- Microtitre plate wall coated with specific antigen that help in detection of antibody
- If positive antigen -antibody reaction occur
- Substrate: antibody to antigen conjugated , enzyme is added
- Substrate is added to detect colour change positive
3) COMPETITIVE ELISA:
- No colour change -positive
- colour change - negative
- HIV antibodies are checked through competitive elisa
- Titre coated with HIV antigen
- Serum to be tested is added
- If it contains its specific antigen,antigen to antibody reaction takes place
- In previous positive reaction there is no antigen that's left over for these to react with it therefore removed while washing away
- When substrate are added ,no enzyme labelled antibodies are left over to react as they are washed away
- Therefore no colour change
- Serum positive - no free antigen for these enzyme labelled antibodies to react
- Detection of HIV antibodies,HBV marker in serum
- Detection of Rotavirus and enterotoxin of E.coli in faeces
- Detection of mycobacterial antibodies in tuberculosis.
AIM OF THIS POST:
Today we started with what a elisa is ,principle,types of elisa in detail with easy diagrams . Yes,this is a very short post but i hope the core concepts were explained clearly .If you like this post do let me know in the comment section below .
Here at stencildent we are celebrating this week as #classification week
Day 1- classification of composite
Day 2- types of immunity-covid 19
Today being day 4 we have discussed about different types of elisa.
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