Elisa vs Western Blot
HIV AIDS has become a global problem and the incidence of this dreaded disease has increased alarmingly in the last few decades. There are many techniques of knowing the presence of the virus in human body and out of them ELISA and Western Blot are very popular today. There are many similarities in these two types of testing. However, there are also many differences that will be discussed in this article.
What is ELISA?
It stands for enzyme linked immunosorbent assay, and was the first test designed primarily for HIV detection. ELISA is known for its high sensitivity. In this test, a patient’s serum is diluted greatly (400 times) and placed on a plate on which HIV antigens are already present. If the serum contains antibodies for HIV, they stick to these antigens. The plate is then washed to remove all other components of patient’s serum and another specially prepared antibody is applied to the plate. This antibody binds to human antibodies and is linked to an enzyme. A substrate for enzyme is applied and the color change because of catalysis of enzyme gives out the results of the test. This test gives results in numbers.
What is Western Blot?
This is also an antibody detection procedure. In contrast to ELISA, viral proteins are separated and immobilized beforehand and visualization of serum antibodies to particular HIV proteins is done. This causes the cells that are infected with HIV to open. Their proteins are collected into a slab of gel and an electric current is passed through them. Different proteins, depending upon their size move at different velocities. These proteins are separated and passed on to a membrane after which the procedure continues much like ELISA.
What is the difference between Elisa and Western Blot?
Both ELISA and Western Blot are called indirect tests as they measure the immune system’s response to an infectious agent rather than looking for the components of the agent itself. Since ELISA detects HIV antibodies which the body starts to produce between 2-12 weeks after becoming infected with HIV, experts say that one should wait for at least 3 months after unprotected test to confirm for HIV AIDS. Western Blot is the most common method of testing to confirm positive results from ELISA test. Western Blot is used more as a confirmatory test as it is difficult to perform and requires high skills. One advantage of Western Blot is that it is less likely to give false positive results as it can effectively distinguish between HIV antibodies and other antibodies.
Elisa vs Western Blot Summary
• ELISA was the first test designed for detection of HIV AIDS
• To confirm the results of ELISA test, Western Blot test is preferred
• Both ELISA and Western Blot are considered indirect methods for detection of HIV AIDS.