ELISA is used to detect viruses, where the key reagent is :-
- Alkaline phosphatase
- RNase
- DNA probes
- Catalase
Answer
(1) Alkaline phosphatase
Solution
As per NCERT, ELISA is based on the principle of antigen–antibody interaction; infection by a pathogen can be detected by the presence of antigens or of antibodies synthesised against the pathogen.
⇒ In ELISA the detecting antibody is linked to an enzyme; on adding its substrate, the enzyme gives a coloured product whose intensity shows the amount of antigen.
⇒ The commonly used enzymes are alkaline phosphatase and horseradish peroxidase.
∴ The key reagent is alkaline phosphatase. (DNA probes are used in hybridisation methods, not in ELISA.)
Answer: (1)