The principle of conducting any EIA lies in determination of the enzymatic reactions at the study of the samples being tested in comparison with the negative and positive controls.

To detect antigens and antibodies the solid-phase (heterogenic) enzyme immunoassay is applied. The use of the solid phase allows for facilitating the process of separation of the reaction components due to the immobilization of one of the components on the solid phase and removal of those substances not participating in the reaction.

As compared with other antigen and antibody detection methods, the enzyme immunoassay has the following advantages:

— High sensitivity that allows for detecting the concentrations of up to 0.05uh/ml. Such the method sensitivity can be explained by the ability of one enzyme molecule to catalyze the transformation of the great number of the substrate’s molecules;
— An opportunity for the use of minimum volumes of the material being studied;
— A stable storage of all ingredients required for the conduct of EIA;
— Reaction conduct simplicity;
— Availability of both instrumental (both qualitative and quantitative) and visual accounting;
— An opportunity for automating all reaction stages;
— Relatively low cost of the kits of instruments for diagnosis.