Fundamentals of Nursing Q 515
The ELISA test is used to:
A. Screen blood donors for antibodies to human immunodeficiency virus (HIV).
B. Test blood to be used for transfusion for HIV antibodies.
C. Aid in diagnosing a patient with AIDS.
D. All of the above.
Correct Answer: D. All of the above.
The ELISA test of venous blood is used to assess blood and potential blood donors to human immunodeficiency virus (HIV). A positive ELISA test combined with various signs and symptoms helps to diagnose acquired immunodeficiency syndrome (AIDS). Enzyme-linked immunosorbent assay (ELISA) is a labeled immunoassay that is considered the gold standard of immunoassays. This immunological test is very sensitive and is used to detect and quantify substances, including antibodies, antigens, proteins, glycoproteins, and hormones. The detection of these products is accomplished by the complexing of antibodies and antigens to produce a measurable result.
Option A: ELISAs are performed in polystyrene plates, typically in 96-well plates that are coated to bind protein very strongly. Depending on the ELISA type, testing requires a primary and/or secondary detection antibody, analyte/antigen, coating antibody/antigen, buffer, wash, and substrate/chromogen. The primary detection antibody is a specific antibody that only binds to the protein of interest, while a secondary detection antibody is a second enzyme-conjugated antibody that binds a primary antibody that is not enzyme-conjugated.
Option B: In HIV testing, a blood or saliva specimen is collected for testing typically by the use of indirect ELISA-based tests. The ELISA is a screening tool for HIV detection, but not diagnostic. Diagnosis requires further testing by Western blot due to potential false positives. Another virus, Molluscum contagiosum virus (MCV) that commonly infects the skin of children and young adults, can be detected by ELISA testing. ELISA testing in this setting is currently being evaluated for the assessment of global MCV seroprevalence.
Option C: ELISA testing is used in the diagnosis of HIV infection, pregnancy tests, and blood typing, among others. The first ELISA methodology involved chromogenic reporter molecules and substrates to generate observable color change that monitors the presence of antigen. Further advancement in the ELISA technique leads to the development of fluorogenic, quantitative PCR, and electrochemiluminescent reporters to generate signals. However, some of these techniques do not rely on using enzyme-linked substrates but non-enzymatic reporters that utilize the principle of ELISA.