Types of HIV Tests

Human Immunodeficiency Virus (HIV) is a deadly virus that is well-known for its adverse effect on the body's immune system. This virus spreads through sexual contact with an infected person. HIV could also get transmitted through transfusion of blood that is contaminated with this virus or use of infected syringes. This virus can also get transmitted from a pregnant woman to her unborn child. Once this virus enters the body, it targets the immune system, thereby making one highly susceptible to infections and diseases. The immune system of the body comprises specialized cells and structures that respond to the presence of disease-causing agents or anything that it perceived as foreign. In the first stage of this infection, the immune system detects the presence of this virus, and responds by producing antibodies. The development of HIV antibodies is medically referred to as seroconversion. Unless the process of seroconversion is over, an infected person would not test positive for HIV. These days, various types of HIV tests are being used for diagnosing this serious disease. Here's some information on these tests.

Diagnostic Tests for HIV

As mentioned earlier, detection of HIV antibodies is one of the commonly used methods for detecting the presence of this virus. While blood samples are mostly used to test for HIV, at times, the pathologist may take urine or oral fluid samples for the same purpose. Scroll down if you wish to know more about the tests that are commonly used as diagnostic tools.

Antibody Tests: More often than not, individuals infected with HIV, develop antibodies within three to four months, however, for some people, the process of seroconversion may last longer. It is therefore essential, that antibody tests are conducted at regular intervals. Enzyme-Linked Immunosorbent Assay (ELISA) is one such HIV screening test that is commonly conducted for the detection of antibodies. The pathologist may collect blood, urine or oral fluid samples. In this test, HIV antigens are coated on the ELISA plate and the patient's blood is then added. If the patient's serum contains the antibodies, these will bind to the antigens. The next step involves washing or rinsing the plate to get rid of any other particles that may be present on the plate. A secondary antibody which is linked to an enzyme is then added to the plate. When the substrate for the enzyme is added, the reaction between the substrate and enzyme would cause a change in the color if the blood sample contains the virus. The results of Rapid HIV testing are available within 10 to 20 minutes. OraQuick Advanced Rapid HIV-1/2 Antibody Test, Reveal G2 HIV-1 Antibody Test and Multispot HIV-1/2 are some of the tests that are categorized under rapid HIV testing. If one tests positive, then confirmatory tests such as Western blot test or Indirect Fluorescent Antibody (IFA) test may also be conducted.

Antigen Test: An antigen is a substance that react with an antibody and trigger an immune response. In case of HIV, p24 protein, which is a protein and is present in the core of this virus, acts as the antigen. Though antibody tests are more commonly used for the diagnosis of HIV infection, doctors may order a p24 antigen test. While antibody test results can provide accurate results only after the seroconversion process is complete, p24 antigen test may help in the diagnosis. However, it must be conducted in the first few weeks after one may have been infected. The levels of p24 antigen increase in the couple of weeks after one has been exposed to this virus, and only during this time, the patient's serum can be tested for checking the levels of p24 antigen. This test involves mixing monoclonal antibodies that are specific to this protein to the blood sample. If p24 protein in present in the sample, it will bind to the antibody. Adding an enzyme-linked antibody to the monoclonal antibodies would bring about a color change.

PCR Test: PCR stands for Polymerase Chain Reaction test. PCR test, which is also known as viral load test, is used for measuring the amount of HIV in the blood sample. Unlike the aforementioned tests that are used for testing for antigens or antibodies, this test is used for detecting the genetic material of the human immunodeficiency virus. DNA/RNA amplification tests or qualitative PCR test may be used for testing infants born to women infected with HIV.

AIDS is a life-threatening disease, that makes one susceptible to recurring infections and surely affect one's quality of life. Thus, one must take all possible precautionary measures to prevent this disease. Those who feel that they may have been exposed to this virus must get themselves tested for HIV. Those who test positive, must go for regular checkups and comply with the guidelines given by the doctors.