ELISA test

• the first step in an ELISA test is antigens of the pathogen to be identified are secured to the bottom of a dish. the blood of the individual is placed into the dish and any antibodies to the pathogen bind to the antigens.

  
• in step 2 the blood is washed away with distilled water to remove any extra antibodies. anti-antibodies with enzymes are introduced and bind to the antibodies.

  
• any spare anti-antibodies are washed away with distilled water.

  
• in the fourth step a substrate is introduced that reacts with the enzymes. so if any enzymes are present, the substrate undergoes a colour change.