9.2.1. Normal ELISA
In conventional ELISA, the sample is adsorbed
directly into the wells, to be detected by the specific antibody. This antibody
is either conjugated directly to an enzyme (Fig. 4A), usually either horse
radish peroxidase or alkaline phosphatase, or more commonly is detected in a
subsequent incubation by a commercial enzyme-conjugated protein that recognizes
antibodies in general (Fig. 4B).
Fig. 4. Different types of ELISA, depending on whether the antigen1 is adsorbed directly onto the assay well (A & B) or is captured by the Fab fragment of a specific antibody4 or the full antibody5 (sandwich ELISA; C & D) and whether the detection system involves an enzyme reporter conjugated directly to the detecting antibody6 (A & C) or a reporter conjugated to a generic antibody-recognizing protein3 recognizing the detecting antibody2 (B & D). Adapted from de Miranda (2008).