Lab work: Detection of antibodies using ELISA test

Official Transcript:
12th Grade Science: Adaptive immunity, extension of innate immunity (3-A-2)
- Design and conduct an experiment to characterize the specificity of molecules involved in adaptive immunity.
- Design and conduct experiments to demonstrate the presence of immunoglobulins during the immune response.
12th Grade STL: Antibodies can be used in vitro for diagnostic applications.

Scientific Issue:
Upon the introduction of an antigen into the body, the immune system produces a specific antibody in response to this initial contact. Upon subsequent exposure, the immune response is more massive and almost immediate, as if the organism had memorized the characteristics of the antigen.
Vaccination exploits this property by inducing the 'memory' of an antigen corresponding to a pathogen one aims to protect against. How can one determine an individual's immune status through a simple test? In other words, how can one verify that an individual's vaccination is still effective by evaluating the quantity of specific antibodies in their serum?

Procedure:
The goal is to detect the presence of a specific antibody in the serum of a test subject and to measure the concentration of this antibody. To achieve this, students will use an ELISA test (Enzyme-Linked Immunosorbent Assay). A common immuno-enzymatic detection technique, the ELISA test allows for the visualization of an antigen-antibody reaction through a colored reaction produced by an enzyme that reacts with a chromogenic substrate. This enzyme (in this case, peroxidase) is linked to the tracer antibody (secondary antibody) which can specifically bind to the primary antibody being measured.
The antigen is fixed on the walls of wells in a microtiter plate. The enzymatic reaction produces a blue compound, and the intensity of the coloration is proportional to the number of secondary antibodies bound to the primary antibody. In this protocol, the aim is to measure the quantity of anti-BSA antibodies (bovine serum albumin) in the serum of an immunized rabbit (presenting Ac1 anti-BSA). These activities provide students with the opportunity to practice developing a colorimetric assay protocol applied to life sciences.