Antigen Test

There are different tests that can be used for detecting the existence of HIV. These tests involve antibody test, P24 antigen test and PCR test. CD4 test and viral load test are used after a person has been diagnosed with the virus. P24 antigen test is also known as p24 capsid or core antigen as well as p24 antigen capture assay.

How p24 antigen is used?

It may be carried out for the diagnosis of early HIV infection. p24 antigen levels get higher extensively at about one to three weeks after initial infection. It occurs during the time frame before HIV antibody is formed. The test is useful during this time for the detection of HIV. Almost two-eight weeks after revelation, HIV antibodies are created and they can be detectable in response to the infection. Performing the antibody test is the most useful way for diagnosing the infection.

When is it ordered?

If the result of HIV antibody test is negative and you have a recent exposure to HIV, then a p24 test may be used to detect the infection. Nevertheless since the tests that can detect the HIV RNA early in the infections have widely used because of that the test is not ordered as often.

What does the test result mean?

If a result of the test is positive then you are infected with HIV. On the other hand if the result is negative, it may mean that you are not infected with HIV. If you are not sure about the test results then go through the other testing i.e. HIV antibody test that is recommended for that reason.

It is one of the earlier tests that are developed to detect HIV infection. However, the utility of the test is limited as it detects the virus during a short window of time. Nevertheless, it can be used if other tests are not available.

The process of the test

HIV viral protein in blood can be detected in this test. It is normally positive from almost one week to three-four weeks after the HIV infection. The presence of the virus can not be detected till almost a week after the infection of HIV. The reason is that the virus takes certain time to develop and multiple itself to sufficient numbers. The HIV antibodies are produced about two to eight weeks after the initial exposure of HIV. Once the antibodies are created to respond to HIV infection, the result of this test normally is negative even though a person may be infected with HIV. The antibodies are bound to the p24 protein so the p24 antigen remains undetectable in the blood. At this time the HIV antibody test that is usually used for routine screening will be positive. The p24 protein levels can be detected in the blood if the infection is not treated in the course of time.

However, the use of the test is reduced in some extent as the other tests are used for the purpose. Nevertheless, the test is more often used in the areas where the resources are limited and muscular tests are not available. Occasionally, this test can be used with the HIV antibody test for detecting the HIV infection in early stages.

How the sample of the test is collected?

The blood sample is taken from the arm by using needle.

P24 antigen is a test that is used for detecting the HIV infection. The provided information would help you to learn about the test and its usages.