ELISA

Question 1

What are ELISAs used for in veterinary medicine

Answer 1

Disease detection
Detection of illegal drugs
Detection of hormones

Question 2

Explain direct ELISA

Answer 2

Detects presence of antigen in sample

Antigen is immobilised on solid surface & incubated with labeled specific antibody

Antibody detected by measuring enzyme activity of label

Question 3

Explain indirect ELISA

Answer 3

Detects presence of specific antibody in sample

Antigen immobilised on solid surface & incubated with sample containing antibody

Labeled secondary antibody that specifically binds to primary antibody is added & label detected by measuring enzyme activity

Question 4

Explain sandwich ELISA

Answer 4

Detects antigen in sample

Antigen captured by first antibody that is immobilised on plate

2nd labeled antibody that specifically binds to different epitope on antigen added & label detected by measuring enzyme activity

Question 5

Explain competitive ELISA

Answer 5

Measures concentration of antigen in sample

Labeled antigen incubated with sample containing known amount of antigen of interest & fixed amount of unlabeled antibody

Amount of labeled antigen that binds to solid surface is inversely proportional to concentration of antigen in sample

Question 6

Explain importance of positive & negative controls in ELISAs

Answer 6

For any immunoassay to be valid it must include positive & negative controls

Positive control:
Confirms if procedure is performing as intended
Allows for confidence in diagnostic test results
Confirms that negative results are accurate

Negative control:
Adds validity to positive results
Will show if any solutions of assay are contaminated

Question 7

What is the difference between serology and serotyping

Answer 7

Serotyping uses antibodies
Serology measures antibodies