Does a Western Blot HIV Test Work?

September 21, 2018

HIV testing is generally a multi-step process. The initial test used is normally a high sensitivity test. High sensitivity tests are designed to detect as many potential HIV infections as possible. That first test is then followed up by a couple of highly specific tests to rule out potential false positive HIV diagnoses. Historically, the most common of this highly specific tests used in confirmatory testing is that the Western blot test.

But, there are additional confirmatory tests which can act also. 

How can the Western blot test function?

Western blots tests are also called protein immunoblots. These tests are utilized to detect certain proteins within a sample. The basic technique of a Western blot entails sorting proteins by length on a gel. Then that grid is probed with antibodies that respond to the specific proteins which are being searched for.

But, when Western blots are used for HIV testing, then this process is actually done in reverse. Normally, in a Western blot test, unknown proteins have been searched for with known antibodies. However, for an HIV Western blot test, scientists operate with prepared samples of HIV proteins and also look to find out if there are any antibodies in a individual’s blood that stick to them.

Western blot HIV tests generally look for antibodies against the following HIV proteins:

  • Proteins from the HIV envelope: gp41, and gp120/gp160.
  • Proteins from the Center of the virus: p17, p24, p55
  • Enzymes which HIV uses from the process of disease: p31, p51, p66

For a individual to be considered HIV positive, they need to have both antibodies from one of the envelope proteins and one of those core proteins, or against one of the enzymes.

If a person has antibodies which are against another mixture of proteins, their outcomes are usually considered to be indeterminate. The precise algorithm for announcing a result indeterminate changes for each particular Western blot test. On the other hand, the objective is always to reduce the risk of a false positive test that disturbs someone for no reason. 

Indeterminate Western blot effects may be a indication of a new HIV disease. These evaluation results may also happen when individuals have been exposed to or infected with other retroviruses, such as HTLV. Generally, if a individual who has an indeterminate Western blot HIV test is really HIV positive, their Western blot test will become certainly optimistic after more time has passed.

Western blot tests serve as confirmatory tests as opposed to as primary tests, since they are less sensitive than first-round ELISA tests or RNA detection tests. That means they are not as likely to discover an infection. However, Western blot tests are also less inclined to provide a false positive test result when used to confirm an initial positive test. 

Should You Are Told You Have An Indeterminate Western Blot Test

Being told a Western blot test is indeterminate can be extremely stressful for men and women that are undergoing HIV testing.

There are a range of reasons unrelated to HIV exposure that can cause such a outcome. But, people with indeterminate Western blots are usually advised to seek repeat testing, either immediately or after some time has passed.

Immediate retesting checks to find out whether there was a defect in how the Western blot was conducted. In contrast, waiting a month or longer before retesting allows a person’s immune system time to produce extra antibodies from HIV antigens, should they actually have been infected with HIV.

Retesting will frequently solve an indeterminate Western blot test to a clearly negative or positive result.

However, if repeated tests are still send confusing signals, physicians might want to switch to using other ways of ascertaining whether you have an HIV infection. No single HIV test is perfect in every circumstance.