Enzyme-linked Immunosorbent Assay (ELISA) for the qualitative detection of antibodies against specific antigens in human serum.

The wells of the microtiter plate contain specific antigens of the respective pathogen. Antibodies bind to the fixed antigen in the well during the serum incubation. HRP-conjugate binds to this antigen-antibody complex during the conjugate incubation. The horseradish peroxidase converts the substrate and stains the solution with a blue color. The addition of stopping solution ends the reaction and the color turns from blue to yellow. The optical density of the yellow colored solution is measured at 450nm with a reference measurement at 620nm. The washing procedures between serum-, conjugate- and chromogen/substrate incubation remove unreacted reagents.