Giardia ELISA

The Giardia ELISA employs specific antibodies in a sandwich-type method. Giardia-specific antibodies to the specific antigens of Guardia lamblia cysts and trophozoites are attached to the well surface of the microwell plate. A pipette is used to place a suspension of the stool sample as well as control samples into the well of the microwell plate together with biotinylated anti-giardia antibodies (Conjugate 1) for incubation at room temperature (20–25 °C). After a wash step, streptavidin poly-peroxidase conjugate (Conjugate 2) is added, and the plate is incubated again at room temperature (20–25 °C). With the presence of the Giardia lamblia antigen in a sample, the immobilized antibody, the Giardia lamblia antigen, and the conjugated antibody form a sandwich complex. Another wash step removes the unattached streptavidin poly-peroxidase conjugate. After adding substrate, the attached enzyme changes the color of the previously colorless solution in the wells of the microplate to blue if the test is positive. Addition of a stop reagent changes the color from blue to yellow. The extinction is proportional to the concentration of Giardia lamblia antigens in the sample.