Enzyme-Linked-Immunosorbent-Assay (ELISA) for the detection of antibodies against plasmid-coded secretory proteins of pathogenic Yersinia strains in human serum for the diagnosis of Arthritis.

Specific 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 TMB substrate and stains the solution with a blue color.
By stopping the reaction with 0,2 N sulfuric acid or 3 N phosphoric acid the color changes from blue to yellow. The absorption of the yellow colored solution is measured at 450 nm with a reference measurement at 620 nm.
The washing procedures between serum-, conjugate- and chromogen/substrate incubation remove unreacted reagents. The use of a calibrator control and the resulting ratio values correct variation due to environment patameters (e.g. temperature).