What happens in a ELISA Test?

-Antibodies will be used against the Pathogen's Antigens -Antibodies have Enzymes, which react with a Substrate to make a Colour Change -Antibodies simply are Added into the Sample being Used, and then Washed Off - however, if the Antibodies have Bind on, they will Stay in the Sample -If a Colour Change happens when the Substrate has been Added, then the Antigen, [Pathogen therefore] is Existing in the Sample