- Direct ELISA: Involves the direct attachment of the antigen to the plate and the detection is carried out using an enzyme-labeled antibody. - Indirect ELISA: The antigen is immobilized on the plate, followed by the application of a primary antibody specific to the antigen, and then a secondary enzyme-linked antibody specific to the primary antibody. - Sandwich ELISA: Uses a capture antibody immobilized on the plate to bind the antigen, and a detection antibody also binds to the antigen forming a "sandwich" complex. - Competitive ELISA: Involves the competition between the sample antigen and a labeled antigen for a limited number of binding sites on a capture antibody.
