ELISA antibody

ELISA Applications / Applications of ELISA

ELISA test is a useful tool since either the presence of antigen or the presence of antibody in a sample can be evaluated by the application of ELISA.

ELISA can be applied to determination of serum antibody concentrations in a virus test (such as HIV testor West Nile Virus Test). Applications of ELISA have also been found in home pregnancy test, and in the food industry when detecting potential food allergens such as milk, peanuts, walnuts, almonds, and eggs. ELISA can also be used in toxicology as a rapid presumptive screen for certain classes of drugs.The ELISA was widely used in various of areas sach as Immunology , Biological Pharmacy, Diagnostic industry, and so on.

ELISA Application example

Take one of the applications of ELISA for example, indirect ELISA can be applied in the determination of antibody titer:

Absorbancer of OD450 for positive serum and nagative serum-antibody titer determination

Many types of immunoassays can be used to detect and quantitate both antigens and antibodies, but there are differences in the avidity requirements for the antibodies, the signal strengths of the labels, and the amount of background for each of these types of assays. Indirect ELISA is the most appropriate technique for measuring the titer of the antisera you have generated. The only difference from general indirect ELISA is that what need to be doubling diluted are antisera (antibodies) other than antigens. In this type of ELISA (Enzyme-Linked Immunosorbant Assay), the antigen (peptide or protein) is bound to the polystyrene microtiter plate first. The antiserum is then doubling diluted by for example, 1/200, 1/400, 1/800, 1/1600, 1/3200, 1/6400, 1/12800, 1/25600, 1/51200, and so on. The antiserum containing the anti-peptide antibody is then added to the well and allowed to bind. Note that, negative serum should also be diluted and added to the well in the same manner with antiserum at the same time. Finally, a secondary antibody, specific for the primary antibody and labeled for detection, is added to the well and allowed to bind. The secondary antibody is usually conjugated with an enzyme. This enzyme catalyzes the formation of colored substance from a colorless substrate, such as TMB. This colored substance is then quantified. The value of OD450nm of each well is measured by a microplate reader, and then, all the values of A450 for positive serum and nagative serum are recorded in the form of line chart, as is shown above. Calculate the ratio of the absorbance of the positive serum and nagative serum (P/N). If the ratio of P/N is less than 1.5, the result is taken as negative; if 1.5≤P/N＜2.1, the result is doubtful; and only when the value of P/N is more than 2.1, the result can be taken as positive. That is, as the dilutability of serum is getting larger, the dilution point when the ratio of P/N begins to get less than 2.1, is just the titer of antibody for the antiserum.

The technique of ELISA was created by Doctor Dennis E Bidwell and Alister Voller, and the first purpose was to detect various kind of diseases, such as Malaria, Chagas' disease, and Johne disease. For further detailed information about ELISA applications in disease diagnosis, please read about the section of ELISA related diseases. If you would like to know about some disease therapeutic targets, suggested here are some useful tools for research on diseases, including Cancer, Alzheimer's, Autoimmune disease, Diabetes, Heart disease, Vascular disease, Parkinson's, etc. Other applications of ELISA will be described respectively as following links.

ELISA applications

ELISA Test can be used to dignostic diseases