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HIV/AIDS 101: The Three and Four Letter Acronyms

November/December 2004

We have been living with bacteria and viruses since before homo became erectus. In fact, some bacteria are healthy and necessary for us to survive, like the ones that live in our stomachs and lower intestines that are helpful to our daily living.

Then we have the bad bugs. We have endured polio, Legionnaire's disease, West Nile virus, smallpox and the yearly flu, to name a few. However, in the early 1980s a new disease was killing people by the hundreds and then thousands, and after some years, science came up with the terms HIV -- Human Immunodeficiency Virus -- the name of the virus, and AIDS -- Acquired Immunodeficiency Syndrome, the name of the condition that eventually ensues when HIV is left untreated.


What Does AIDS Mean?

Acquired, which means you catch it, Immune Deficiency, which means your immune system is weakened and can no longer fight off bacteria and diseases, and Syndrome, a combination of symptoms that indicates a particular disorder. If left untreated, AIDS may lead to death. Nobody dies from AIDS itself, but from the illnesses that can develop due to AIDS.


What if I Test Positive for HIV?

If you have a positive result for HIV, take a deep breath and be glad that it is 2004, because there have been many advances in treatment and it is no longer a death sentence. It used to be. In the early 1980s when patients tested positive all they were given was an amount of time to prepare for death. And unfortunately, even today some people find out that they are HIV-positive only when they end up in the emergency room of a hospital, and have come down with one or more of the opportunistic infections brought on by a weakened immune system and are less likely to respond to treatment. Many people these days test positive and do not need to go on medications because science is now more sophisticated, and we know that a person with over 500 T-cells and a very low viral load (such as under 500 copies) does not need to start therapy. U.S. HIV treatment guidelines suggest that a person consider starting HAART (highly active antiretroviral therapy) when their T-cell count is below 350, or their viral load is above 30,000 by the bDNA test or 55,000 by the PCR test. If someone knows they are HIV-positive, their health and quality of life can be manageable if they empower themselves to learn about the virus, how it works and how it impacts their body.

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How Does HIV Work?

There are five basic steps to the life cycle of HIV. These are the steps scientists use to develop drugs -- fighting HIV every step of the way, as it were.

  1. Attachment, Fusion and Entry

  2. HIV attaches itself to the body's CD4 cells (also called T-cells). The virus does this by using receptors on the surface of the cell. Next, HIV fuses (or melts) into the surface of the cell. When all the separate steps of fusion take place, like arms reaching out and completing a handshake, HIV is pulled inside the cell. (By the way, the virus also infects other cells of the body, such as the lymph nodes or the brain. Sometimes it just sits there instead of going through the steps below. But the CD4s, which are immune system cells, are its favorite target.) There are several key receptors that affect cell attachment and fusion. Science knows of two types of receptors, the CD4 receptor and the chemokine co-receptor.

  3. Reverse Transcription

  4. Once inside the cell, HIV uses its transcriptase enzyme to change itself in preparation for becoming part of the body's genetic code. When that happens, the body will be forced to produce HIV like it does anything else -- tears, new liver cells, etc. Because HIV works backwards compared to most viruses (making it a "retrovirus"), this is called a "reverse transcriptase" enzyme. (Enzymes are proteins that cause substances to change.) The RT enzyme changes HIV's genetic material from RNA to DNA. (To put it simply, RNA and DNA are part of our genetic structure, which form the blueprints for all of the body's functions. HIV has its own genetics.)

  5. Integration

  6. The HIV DNA then enters the nucleus, the command center of the cell. Once inside the nucleus, HIV uses another enzyme, integrase, to re-program the cell, integrating the virus with the cell's DNA.

  7. Cutting and Assembly

  8. Every time the T-cells become activated due to an immune response -- for example, you catch a flu virus and T-cells come to fight the flu out of your system -- spare parts of the HIV DNA separate and form what is called a messenger RNA. The messenger RNA leaves the center of the cell and forms a long chain of instructions to make new HIV particles, like a parent would leave a list of instructions for a babysitter. Then an enzyme called protease comes to play. This is why we have protease inhibitors, which inhibit this part of the HIV life cycle. The protease enzyme cuts the long list of instructions into separate parts that assemble and come together to form a new HIV particle.

  9. Budding

  10. The new HIV particle moves out of the cell through a process called budding, because its action is like a blooming flower. The HIV particle pushes through the cell wall, taking parts of the cell's covering to form the new coat of HIV. The HIV particles are constantly maturing and growing, or blooming, from the time it becomes the messenger piece of information to the time it buds from the cell.


Got a comment on this article? Write to us at publications@tpan.com.


  
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This article was provided by Positively Aware. It is a part of the publication Positively Aware. Visit Positively Aware's website to find out more about the publication.
 
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