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HIV 101

by Dr. Jason Faulhaber
Fenway Community Health Center, Boston MA
EDGE Medical Correspondent

What Is HIV?

The Human Immunodeficiency Virus (HIV) is a microscopic particle that, once it gets into your body, can make you sick. HIV renders your body susceptible to other infections and illnesses by undermining your immune system.

How Do You Get HIV?

Simply put, you can get HIV through unprotected sex or via other risky activities such as sharing needles for injecting drugs. The virus is transmitted from person to person through contaminated fluids, notably blood, sexual bodily fluids (including vaginal secretions, pre-ejaculate, and ejaculate), and breast milk. Certain factors increase the risk of infection, including actively having a sexually transmitted infection (such as herpes or syphilis), the amount of HIV present in the contaminated fluid, and the length of time of exposure.

How Do You NOT Get HIV?

Tears, saliva, and intact skin are not capable of transmitting the virus from one person to another. The contaminated fluid needs to gain access into the body, typically through a mucous membrane (such as the rectum or vagina) or directly into the bloodstream (such as by sharing needles).

How Do I Know If I Have HIV?

There is only one way to know if you have HIV: get an HIV test. While some people exhibit symptoms shortly after being infected (usually described as flu-like), many people stay infected for ten years or more without being symptomatic in any way.

If I Have HIV, How Long Will I Live?

Thanks to a variety of medicines available to infected individuals, HIV-positive people can expect to live almost as long as their HIV-negative peers. Living with HIV involves taking your HIV medicines property in order to keep your CD4 count up and your viral load down, as well as living a generally healthy lifestyle.

How Many People Have HIV?

HIV has a worldwide distribution with an estimated 34 million people currently living with the infection. HIV affects everyone regardless of gender, race, sexual orientation, or socioeconomic status. Despite public health initiatives, new infections continue to occur, and no cure has been discovered yet. The field of HIV medicine is vast and continues to evolve, but there is much known about its life cycle and ways to prevent its spread.

Meet the HIV virus. [Source: Wikipedia]

OK Really: How Does HIV Work?

HIV is in the family of viruses called Retrovirus. Its genetic information is in the form of RNA instead of DNA. In order for HIV to infect human cells and cause destruction, the HIV RNA must be transformed into DNA. It can do this with the help of an enzyme called reverse transcriptase (RT). Without this enzyme, the HIV cannot make new copies of itself. HIV looks like a ball with an inner core, which contains the RNA and the necessary enzymes that we do not have in our cells. The virus is not “alive” per se; it requires the resources of our cells in order to replicate (make more of itself). If the virus cannot penetrate into our cells, then it cannot survive. It would continue circulating around our body trying to find a way to make more copies, but ultimately our immune system would take care of it.

Once HIV enters into the body, it has to dock onto one of our cells to actually cause infection. The HIV docking is specific, notably to cells that contain a complementary receptor called CD4. There are different types of cells that contain CD4, including a part of your immune system called helper T-cells. These cells act like whistleblowers, calling in the heavy-duty cells of your immune system in order to attack foreign invaders and control infection. HIV enters into the cells and then, once in the form of DNA, integrates into the DNA of our cells. It then hijacks the cell and forces it to become a factory designed to produce new HIV particles. Through several biological processes, new HIV copies are made and are then released into the bloodstream allowing the ability for new CD4 cells to become infected. This cycle ultimately kills the CD4 cells.

Every day, millions of CD4 cells in the body are destroyed, releasing billions of HIV particles into the bloodstream; however, your body is hard at work making millions more new CD4 cells which aid in destroying billions of HIV particles. Soon after initial infection, this back-and-forth process of killing and making new CD4 cells and virus can cause acute symptoms, similar to having a bad flu-like illness. This can last days to weeks before a balance is struck between destruction and regeneration. This seesaw battle can persist for years, and it typically is not associated with any symptoms such as fever, fatigue, or weight loss. Over time, though, the body cannot keep pace with replenishing the CD4 cells, and the numbers continue to decrease. As a result, the number of HIV particles increases. This imbalance continues, favoring the HIV, until there is so much destruction of the immune system that it can no longer fight off certain infections like it used to. These infections now have the opportunity to cause disease because the weakened immune system cannot control them. These are called opportunistic infections, and they serve as a hallmark of severe immunodeficiency, or AIDS (Acquired Immune Deficiency Syndrome). Without intervention or treatment, the body will succumb to the overwhelming infection.

The virus is rather careless when it is trying to make copies of itself, and it often makes mistakes (mutations). Sometimes, the mutations are self-destructive, thereby preventing further replication. Other times, the mistakes may be fortuitous, rendering the virus resistant to certain medications. The more resistant mutations that are present, the fewer medications that can be used to treat the virus.

Not all immune systems work the same. Some people may have a genetic alteration in their CD4 dock; consequently, it will be more difficult for HIV to penetrate into these cells. If the virus cannot enter the cell, then it cannot replicate. These individuals tend to have a slower course of infection, and often can be found to have a stable immune system for decades. Certain factors can impact negatively on the immune system, including substance use (e.g., crystal meth), poor nutrition, steroid use, and other infections or illnesses (e.g., Hepatitis or cancer). This could cause a more rapid course of decline, with symptoms and opportunistic infections appearing earlier.