Amirabad Pathobiology and Virology Laboratory


Everything about the HIV virus

Date: 2 سال قبل

author: AmirAbad

HIV (human immunodeficiency virus) is a virus that attacks cells that help the body fight infection, making a person more vulnerable to other infections and diseases. It is spread by contact with certain bodily fluids of a person with HIV, most commonly during unprotected sex (sex without a condom or HIV medicine to prevent or treat HIV), or through sharing injection drug equipment.
If left untreated, HIV can lead to the disease AIDS (acquired immunodeficiency syndrome).
The human body can’t get rid of HIV and no effective HIV cure exists. So, once you have HIV, you have it for life.
However, by taking HIV medicine (called antiretroviral therapy or ART), people with HIV can live long and healthy lives and prevent transmitting HIV to their sexual partners. In addition, there are effective methods to prevent getting HIV through sex or drug use, including pre-exposure prophylaxis (PrEP) and post-exposure prophylaxis (PEP).
First identified in 1981, HIV is the cause of one of humanity’s deadliest and most persistent epidemics.
What Is AIDS?
AIDS is the late stage of HIV infection that occurs when the body’s immune system is badly damaged because of the virus.
In the U.S., most people with HIV do not develop AIDS because taking HIV medicine every day as prescribed stops the progression of the disease.
A person with HIV is considered to have progressed to AIDS when:
  • the number of their CD4 cells falls below 200 cells per cubic millimeter of blood (200 cells/mm3). (In someone with a healthy immune system, CD4 counts are between 500 and 1,600 cells/mm3.) OR
  • they develop one or more opportunistic infections regardless of their CD4 count.
Without HIV medicine, people with AIDS typically survive about 3 years. Once someone has a dangerous opportunistic illness, life expectancy without treatment falls to about 1 year. HIV medicine can still help people at this stage of HIV infection, and it can even be lifesaving. But people who start ART soon after they get HIV experience more benefits—that’s why HIV testing is so important.
How Do I Know If I Have HIV?
The only way to know for sure if you have HIV is to get tested. Testing is relatively simple. You can ask virology labs for advice on HIV testing.
In general, there are three main groups of tests used to diagnose HIV / AIDS:
·       Antibody test (antibody)
·       Antigen test
·       PCR test
In an antibody test, the presence of antibodies produced and secreted into the blood by the white blood cells of the immune system is checked.
 In an antigen test, the blood is tested for the presence of the virus itself. Antigen tests are also divided into two groups: RT-PCR and P24.
PCR tests the virus genome in a person's blood and is slightly more expensive.
In most HIV-infected people, a series of specific antibodies develop within three to 12 weeks after the initial infection. The initial diagnosis of HIV before antibody change is made by measuring HIV-RNA or P24 antigen. Positive results obtained by antibody or polymerase chain reaction (PCR) test are confirmed by PCR or another antibody.

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