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HIV and AIDS: Mechanisms and Diseases of the Retroviridae Virus Family

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  • 0:05 The Retroviridae Virus Family
  • 2:55 Human Immunodeficiency Virus
  • 5:08 Acquired…
  • 6:56 Lesson Summary
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Lesson Transcript
Instructor: Artem Cheprasov
Learn about one of the most famous viruses in the world: HIV. We'll also delve into a condition you've almost certainly heard of: AIDS. Finally, we'll discuss the mechanisms of how viruses in this family cause so much damage and if there's anything you can do about it.

The Retroviridae Virus Family

Despite the fact that you've almost certainly heard of viruses and conditions covered in this lesson, I'm more than sure you'll learn a few new facts along the way. Regardless, the main virus we'll cover in this lesson is one of the most deceitful and terrible viruses known to humankind. Massive efforts are underway to try and get rid of it once and for all, but so far, our big brains are no match for this microscopic terror.

Retroviridae Structure and Transmission

The viruses in this family have a single-stranded RNA genome that is enclosed in an essentially helical protein capsid. This capsid is itself enclosed by an envelope obtained when this virus buds away from its host cell. Depending on which virus in this family that we're talking about, these viruses can spread through contaminated fluids such as blood, semen, vaginal fluids and breast milk, the respiratory route, or by way of direct cell-to-cell spread once they are inside of your body.

Regardless of those methods of transmission, there are two important things to keep in mind for this group of viruses. That's because we will be discussing their important roles in another lesson when we deal with the treatment options available for one very famous virus of this family. The first term to keep in mind is something known as reverse transcriptase. This is an enzyme used for replication by viruses of the Retroviridae family.

This enzyme allows the virus to essentially switch its RNA into DNA once it is inside the cell. This newly manufactured DNA genome can then incorporate into the animal's DNA genome. This will then allow the virus to take over the cell it has infected, like a virus would take over a computer if it were to incorporate itself into the computer's hard drive, which is like an animal cell's genome. Once the viral DNA is inserted into the host DNA, it can then use the cell however it wants to, especially for the purposes of replication.

One thing to keep in mind is that reverse transcriptase isn't limited to viruses of the Retroviridae family. In fact, DNA viruses, notably those of the Hepadnaviridae family, which includes the Hepatitis B virus, use reverse transcriptase as well. In any case, the other important enzyme involved in this viral family is known as a protease, which is an enzyme that breaks apart a protein into smaller components. In the case of the specific retrovirus we're going to talk about next, this protease is critical in allowing the virus to properly mature and become infectious.

Human Immunodeficiency Virus

The virus I'm most concerned about with respect to this lesson, the reverse transcriptase and protease I mentioned, is known as HIV. This is more formally known as the human immunodeficiency virus. Contrary to popular belief, this is a virus that has been around for a lot longer than previously suspected. In fact, some scientists have suggested it's been around for over 100 years. Unfortunately, even though this virus has been around for a long time, it has only come to light in the recent past and an effective vaccine or cure has yet to be developed.

This is quite disconcerting, as HIV causes a life-long infection that will eventually lead to death, especially if not treated. All over the world, millions of people get infected and die every single year due to the issues this virus causes. You see, when a person is first infected with HIV, they may have absolutely no symptoms at all or they may experience flu-like symptoms that they will often ignore as just another flu. This is a problem because this virus loves to lay low, or go latent that is. This means that it may stay inside of the person for 10 or more years before it comes back with a massive vengeance, at which point it may be too late to save the person.

That's because HIV loves to attack white blood cells, called CD4+ T cells, which are critical for your immune system. When these and other immune cells die in large numbers due to HIV, your body has no army left to fight off an intruder such as a virus, bacteria, fungus or parasite. Even relatively harmless viruses that would cause nothing more than a short cold in a healthy person can end up killing a person with this advanced most stage of HIV infection that is more commonly referred to as AIDS.

Acquired Immunodeficiency Syndrome

AIDS is more formally known as the acquired immunodeficiency syndrome. People with this syndrome are susceptible to the opportunistic infections I implied before. These are infections caused by pathogens that take advantage of a host's weakened state. In a healthy host, these pathogens would cause little or no damage at all. But, when they recognize that in a person with AIDS there is no standing army of immune cells left to fear, they pounce, attacking the body like crazy with severe and deadly consequences. If left untreated, people who have AIDS and are suffering from an opportunistic infection may have less than one year to live.

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