ELISA Test
எலைசா சோதனை
Do not confuse ELISA with PCR. PCR detects viral genetic material, while ELISA detects the host's immune response. In NEET, this distinction is the difference between a correct answer and a negative mark.
The idea
ELISA stands for Enzyme-Linked Immuno-Sorbent Assay. It is a diagnostic technique based on the principle of antigen-antibody interaction. It detects the presence of HIV by identifying specific antibodies produced by the host or viral antigens. It is the primary screening test for AIDS.
Why it matters
It provides a sensitive and specific method to identify the presence of viral proteins or host antibodies in blood samples, allowing for early diagnosis.
NEET lens
NEET focuses on the full form and the underlying principle: antigen-antibody interaction. Expect questions asking to distinguish between screening tests like ELISA and confirmatory tests like Western Blot. Memorize that ELISA is the standard screening tool for AIDS. Do not overcomplicate the mechanism; stick to the NCERT definition.
Clinical significance
ELISA is critical for early detection of HIV infection before clinical symptoms of AIDS manifest. If this test fails, the patient remains undiagnosed, leading to the progression of the disease and potential transmission to others. It is the gatekeeper of public health surveillance for retroviral infections.
Introduction
ELISA (Enzyme Linked Immuno-Sorbent Assay) is a widely used test to diagnose infections such as HIV/AIDS. It is based on the principle of antigen-antibody interaction.
Core concept
Principle: ELISA detects either the antigen (proteins, glycoproteins of the pathogen) or the antibodies produced against the pathogen, using an enzyme-linked reaction that produces a visible signal. It is the widely used diagnostic test for AIDS. NCERT lists ELISA among molecular diagnosis techniques with PCR and recombinant DNA technology; early diagnosis allows timely treatment. PCR can detect very low amounts of DNA of pathogens even before symptoms appear, and is routinely used to detect HIV in suspected AIDS patients and mutations in genes of suspected cancer patients.
Go deeper
Because ELISA can detect either antigens or antibodies, it is versatile — used for HIV, hepatitis and many other infections.
From Class 10
A blood test that checks for the presence of a virus or the body's antibodies against it — ELISA is one such test, often used for HIV.