The ELISA (Enzyme Linked Immunosorbent Assay) is an immunoassay, which is particularly suited to the determination of antibodies in the field of infectious serology. The reaction is based on the specific interaction of antibodies with their corresponding antigen. To this end, the test strips of the SERION ELISA classic microtiter plate are coated with specific antigens of the pathogen of interest. If antibodies in the patient serum sample are present, they bind to the fixed antigen. A secondary antibody, which has been conjugated with the enzyme alkaline phosphatase, detects the immune complexes. The colourless substrate p-nitrophenylphosphate is then converted into the coloured product p-nitrophenol. The signal intensity of the reaction product is proportional to the concentration of the analyte in the sample and is measured photometrically.