VarelisA Test Principle

The VarelisA test is an enzyme linked immuno sorbent assay (ELISA) and is designed as a sandwich immunoassay.

A well is coated with the antigen recognized by the target antibody, which is specific for a particular autoimmune disease. If this specific antibody is present in the patient’s blood sample, it will bind to the antigen. In the subsequent reaction step, an enzyme-conjugated secondary antibody binds to the target antibody. Because of the enzyme, the substrate is transformed into a coloured substance. Comparing the colour intensity generated by the test sample with that of standards of known concentrations enables the antibody concentration in the test sample to be determined.

The antigen of interest, coated to the solid phase, binds the specific antibodies (e.g. of IgG class) in the patient sample.
After unbound, non-specific antibodies have been washed away, enzyme-labelled antibodies against the target antibody (e.g. of IgG class) are added to form a complex.
After incubation, unbound enzyme-labelled antibodies are washed away, and the bound complex is then incubated with an enzyme substrate.
Because of the enzyme, the substrate is transformed into a coloured product. After this reaction has been stopped, the colour intensity of the sample is measured. The more intense the colour, the more specific antibodies (e.g. of IgG class) are present in the sample.