Method Description

Vasoactive intestinal polypeptide (VIP) enzyme-linked immunosorbent assay is a two-step competitive immunoassay. VIP in the patient sample competes with a biotin-labelled antigen for a limited number of anti-VIP antibody binding sites on the microplate wells during the first incubation. After a wash step to remove unbound and excess material the samples are incubated with a streptavidin anti horseradish peroxidase conjugate to form a biotin conjugate complex. After washing, an enzyme substrate is added and incubated. Following the incubation, the reaction is stopped by addition of a stopping solution. Antibody-analyte complex is detected by absorbance measurement at 450 nm wavelength. The absorbance measured is inversely proportional to the concentration of VIP in the samples and calibrators.(Unpublished Mayo method)