HIV For Dummies

Here’s How HIV Does Its Thing

The Human Immunodeficiency Virus

The Human Immunodeficiency Virus stalks a very specific type of lymphocyte, or white blood cell, called the Helper T-Cell or CD4+ cell. It is this type of cell’s job to course through our bodies looking for microbial invaders that don’t belong there, and, upon finding one, to call in the cavalry, so to speak, by signaling other lymphocytes to come and destroy it. While the Helper T-cell attempts to probe the virus to identify it as an antigen, the HIV virus latches onto the T-Cell and inserts its own RNA through the cell’s membrane and into the cell where it combines with the T-Cell’s own RNA to create a copy of the HIV virus. The T-Cell is now a factory for HIV, churning out copies until it dies.

 

 

 

As the virus continues to attack and kill CD4+ cells, the immune system becomes less and less able to identify antigens in the bloodstream, opening the body up to a host of opportunistic infections it would normally be able to fight off and resist. Anti-Retroviral Therapies (ART) attempt to suppress the virus’ ability to invade

 

 

CD4+ cells, thereby cutting off its means of reproduction while allowing the immune system to replenish the number of Helper T-Cells it needs to function normally. This is why it is important to monitor the specific number of healthy CD4+ cells in people living with HIV.

 

Typical lab tests for monitoring a person’s HIV therapy include:

 

A Helper T-Cell Lymphocyte (CD4+)

CD4 Cell Count

The number of CD4 cells (Helper T-Cells) per cubic millimeter of blood. As HIV disease progresses, the CD4 cells fall from a normal count of 500-1500 down to as low as zero. When the CD4-cell count goes below 200, there is an increased risk of opportunistic infections, and when the CD4-cell count drops below 50, the risk rises dramatically.
My Absolute CD4+ Count
DATE LYMPHOCYTE COUNT STATUS NORMAL RANGE
11/18/2016: Absolute CD4 Helper 132 Low 359-1519 /µL
01/30/2017: Absolute CD4 Helper 138 Low 359-1519 /µL
04/20/2017: Absolute CD4 Helper 172 Low 359-1519 /µL

A Helper T-Cell Lymphocyte (CD4+)CD8 Cell Count

The number of CD8 cells (Killer T-Cells) per cubic millimeter of blood. Even though most test results refer to these as Suppressor cells, the count actually includes both Suppressor and Killer T-cells (see definitions above). The CD8 cell count is usually elevated in people infected by HIV, but since little is known as to why this is, the test result is rarely used in making treatment decisions.
My Absolute CD8 Suppressor/Killer T-cells Count
DATE LYMPHOCYTE COUNT NORMAL RANGE
11/18/2016: Abs. CD 8 Suppressor 721 109-897 //µL
01/30/2017: Abs. CD 8 Suppressor 662 109-897 //µL
04/20/2017: Abs. CD 8 Suppressor 861 109-897 //µL

A Helper T-Cell Lymphocyte (CD4+)

A Helper T-Cell Lymphocyte (CD4+)

CD-Cell Ratio

The CD4 count divided by the CD8 count. Since the CD4 count is usually lower than normal in people living with HIV, and the CD8 count is usually higher, the ratio is usually much lower than normal. A normal ratio is usually between 0.9 and 6.0. Like the CD8 cell count, nobody really knows what this low number means. However, most experts agree that once antiretroviral treatment is started, an increase in the CD-cell ratio (i.e. a rising CD4 count and a falling CD8 count) is a sign that treatment is working.
My CD4/CD8 Ratio
DATE LYMPHOCYTE COUNT STATUS NORMAL RANGE
11/18/2016: CD4/CD8 Ratio 0.18 Low 0.92-3.72
01/30/2017: CD4/CD8 Ratio 0.21 Low 0.92-3.72
04/20/2017: CD4/CD8 Ratio 0.20 Low 0.92-3.72

The Human Immunodeficiency VirusViral Load Count

A test known as a viral load count, a viral burden count, or a HIV RNA count, measures the amount of HIV in a drop of blood. If only a small amount of virus is present (say, less than 50-200 copies depending on the test), then the test cannot detect the virus. This is what is meant when a viral load count comes back with a result of “undetectable.” It doesn’t mean that there is no virus present, but that the amount is so low that the test cannot measure it.

 

As HIV disease progresses, the viral load count tends to rise, so that someone who starts with a very low viral load count (say 5,000 copies of virus per drop) may rise to a very high viral load count (say, several hundred thousand or even more than a million copies of virus per drop of blood). While it is sometimes used to determine if antiretroviral therapy should be started—HIV-positive patients with higher viral loads may progress quickly to AIDS without antiretroviral treatment—viral load is most often employed while a person is on therapy to make sure that the medications are working correctly.

 

When using HIV medications, the ultimate goal is to make the viral load go undetectable. If your viral load becomes detectable or continues increasing while you’re on treatment, it may be necessary to switch your regimen to control the virus and to protect your CD4 cells and health.

 

There are actually two types of viral load tests. A viral load report—sent to your doctor after blood samples have been collected and sent to a lab—will specify which test was used. Typically, labs use either the Amplicor polymerase chain reaction (PCR) test, or either the Quantiplex or Versant branched DNA (bDNA) tests. Just look for “PCR” or “bDNA” on your lab results, and you’ll know which one was used.

 

Each test uses a different technique to measure the amount of virus, but their results tell you the same thing—the amount of HIV in your blood. It’s important to use just one of these tests over time, and not switch between the two. PCR values are approximately twice those measured by bDNA (i.e., 20,000 copies using PCR is equal to 10,000 copies using bDNA).

 

There is no “normal” amount of HIV, since it is not normally present in the body. Your viral load lab report will list the lowest amount of virus that the particular test can detect. Most commercially available versions of viral load tests measure down to between 40 and 75 copies of virus accurately.

 

While taking therapy, your viral load lab report might show that HIV can no longer be detected. This is known as having an “undetectable” viral load. However, this does not mean that HIV is no longer present in your body since less than 5 percent of HIV in the body can be found in the blood. It is also important to keep in mind that even the newest versions of PCR and bDNA cannot detect very small amounts of HIV that may be present in the blood. But, in terms of figuring out how to treat HIV based on these results, the goal is simple: to keep the amount of HIV in your blood as low as possible.

 

HIV-1 RNA, PCR

This is your viral load count. HIV-1 is the most common type of HIV outside of Africa (where HIV-2 is most prevalent). RNA is the virus’s genetic material, which the test looks for. PCR tells you that in this case, this is the Amplicor test. If you saw bDNA in the test name, then it would be the Quantiplex test. This is not the same as the HIV antibody test that is used to identify the presence of HIV in a person’s blood. Antibodies for HIV continue to exist even when no detectable virus copies remain in the body. (see HIV Antibody and HIV Antigen)
My Viral Load 
DATE TEST RESULT
11/18/2016 HIV-1 RNA by PCR   13,600 copies/mL
01/30/2017 HIV-1 RNA by PCR   30 copies/mL
04/20/2017 HIV-1 RNA by PCR <20 copies/mL (Undetectable)
(Comment: The reportable range for this assay is 20 to 10,000,000 copies HIV-1 RNA/mL.)

Lymphocyte Encountering Antigens

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