The western blot test is a laboratory test that detects antibodies to HIV infection in blood or saliva. Antibodies are proteins the body makes when fighting foreign substances such as bacteria or viruses. The Western blot test is used to confirm a positive result of an enzyme-linked immunosorbent assay (ELISA) test for HIV and sometimes also used as part of the initial testing process.
The western blot test, also known as an immunoblot test, is often used to confirm a positive result of an enzyme-linked immunosorbent assay (ELISA) test for the human immunodeficiency virus (HIV). An ELISA is a laboratory procedure that measures circulating antibodies in the blood. The presence of these antibodies indicates that the body has mounted an immune response.against a particular infection.
In order to serve as confirmation that your sample contains HIV antibodies and not other proteins present in your blood, there are three important steps involved: First, a sample from you must be tested with an ELISA; second, this sample must be confirmed by testing it with a western blot; thirdly, if both of these tests yield positive results then you are considered to have HIV infection.
The ELISA and the western blot tests can detect antibodies to HIV in blood or saliva.
The ELISA test is a screening test that looks for an immune response. It is more sensitive than the western blot, but it also has false positives. The results of an ELISA are reported as either positive or negative; if your result is negative, it means you do not have HIV antibodies in your sample at this time. A negative result does not mean you don't have HIV; it only means that the sample did not react with any proteins from the virus during testing. If you receive a positive result on an ELISAscreening test, then follow up with a confirmatory test like Western Blotting which will determine whether your antibody levels are high enough to require antiretroviral treatment
Antibodies are proteins the body makes when fighting a foreign substance such as a bacteria or virus. Antibodies are produced by white blood cells called B lymphocytes, which live in your bone marrow and other organs.
The Western blot test is often used in combination with the ELISA test to confirm a positive result. The body takes about 2 to 12 weeks to produce enough HIV antibodies for HIV tests to detect them in people who are newly infected with HIV. This period is called the "window period." During this time, it's possible to have HIV and not test positive for it.
Both the ELISA and western blot test require a blood sample. The ELISA test is done first. It takes about 2 to 12 weeks for enough HIV antibodies to develop in your body, which is necessary for the second test (western blot) to be able to detect them.
If the ELISA test is positive, a health care provider will repeat it to make sure the results are accurate. If it's still positive, the western blot test will be performed.
Western blot is more specific than ELISA because it can determine if there are antibodies against HIV or other pathogens that have similar antigens to those of HIV (the proteins on the outside of viruses). For example, people who have been vaccinated against measles develop antibodies that attack both measles and mumps viruses. But when a person has contracted either illness and developed protective immunity, their antibody response would be specific only to those particular pathogens—not both nor any other common pathogen in the same family as measles-mumps (paramyxoviruses). Because western blotting uses an electrophoretic technique to separate out different types of proteins by their size and electrical charge—either positive (+) or negative (-)—it can detect these differences more precisely than ELISA does.
If both of these tests are positive, it means that there is a very high likelihood that a person has HIV. If either test is negative, there’s no need to worry about contracting the virus.If your western blot test results come back positive and you want to confirm that they are accurate, it’s possible to do so with a second ELISA test (known as “repeat testing”).
If you've been exposed to HIV within the past 3 months and you're thinking about getting tested, there's a chance that your body hasn't produced enough antibodies to be detected by the ELISA test. If this happens, then a positive result on both tests means that you may have been infected with HIV.
In general, people who have only been exposed to HIV have an average of 7 days between infection and producing antibodies. It can take anywhere from 2 weeks to 6 months for someone's immune system to produce enough antibodies for detection by an ELISA test; this is called "the window period." The exact length of time it takes depends on several factors: how much virus was shed during exposure (if any), whether or not the person has previously been exposed or vaccinated against HIV, and other unknown factors in individual biology.
The window period refers to the time during which you can have been exposed to HIV and it will not show up on a test. Everyone's window period is different, based on when they were infected and how much virus was in their body at that moment. The average length of the window period is 20 days (range: 10-120 days).
If you want to be sure that you're negative, it's recommended that you wait until after your window period has passed before assuming your results are negative. If there's reason to believe that exposure could have happened within 3 months before testing, health care providers recommend retesting again after 3 months.
Healthcare providers usually order this test as part of an initial HIV screening test or as part of a standard panel of tests done after someone has tested positive for HIV antibodies in an ELISA (enzyme-linked immunosorbent assay) test but needs further confirmation with a western blot (WB) because their results were unexpected or questionable considering their circumstances and risk factors for contracting HIV infection; however, it may also be ordered as part of routine monitoring if getting tested regularly, especially if there are other tests being conducted at the same time such as CD4 cell counts and viral load levels
The western blot test is a very accurate test that can confirm or rule out HIV infection. It's important to know that this test is only used when ELISA testing has been positive. This means that if you receive a negative result on both tests, it's very likely that you don't have HIV.