2. ELISA: Enzyme-Linked Immunosorbent Assay
2
ELISA detects substances with antigenic
properties (mainly proteins)
Based on enzymatic color-reaction
3. Basic principle of ELISA
3
Enzyme is used to detect the binding of Antibody - Antigen
Enzyme converts colorless substrate into colored product, indicating
the presence of Antibody - Antigen complex
ELISA can be used to detect either presence of Antigens or Antibodies
26. Direct vs. Indirect ELISA
26
Quick methodology – only one AB
Advantages of Indirect ELISA:
Immunoreactivity of primary
antibody is not affected by labeling
Cross-reactivity of second AB
eliminated
Wide variety of secondary
antibodies available on the market
Signal amplification (several epitopes)
EEE
Advantages of Direct ELISA:
EEE
27. Immobilized Antigen vs. Sandwich
27
Mainly used for antigen
detection
Mainly used for antibody
detection
Immobilized
Antigen:
Sandwich
ELISA:
EEE
EEE
28. Competitive ELISA
28
Step 1:
Add sample
Step 2:
Add antibodys
E
Step 3:
Washing
E
Step 4:
Add substrate
E
Quick methodology – just one washing step
29. Applications
29
Medical diagnostic to detect presence of antibodies in patient
Detection of potential allergens in food
HIV Test
But: high material costs
Drug tests
West Nile Virus
Test kits for eggs and peanuts
Slides by Mathias Bader and Simon Loew