HIV/AIDS is a worldwide pandemic disease, but I would wager that few people (even among our esteemed readers) really understand it at all. You may be aware that Acquired Immunodeficiency Syndrome (or AIDS) is a disease that results from an HIV infection. To most, HIV/AIDS is a frightening scourge that notably affected the gay community in the 1980’s and then spread to most other population groups in America. Now the largest concerns lie in Africa, where the virus runs rampant.
Having recently taken a number of courses about HIV, I thought I would share some information. As a biologist, my primary area of knowledge centers around the virus itself and how it infects the body. It would be difficult to cover both the biology and the socio-political implications of HIV in one article, so I will stick to the former, but keep in mind that the science will aid you should you wish to learn about the latter as well.
Human Immunodeficiency Virus (or HIV) is a staggeringly simple virus, containing only 9 genes and a relatively small number of viral components. What makes HIV so formidable is its ability to make the most of each protein and systematically invade your body’s cells.
Leaving genetics out of it for the moment, the most useful things to know about the HIV particle (called a “particle” because it is a virus and therefore not a “cell”) are its targets and its structure.
Targets of HIV
HIV tends to go after helper T cells (CD4+ is another name). While HIV infects other cells, such as the big macrophages that digest foreign material in the body, most research focuses on helper T cells because the progression of the disease is believed to be most heavily linked with these types of cells.
It is difficult to explain the roll of the helper T cell without delving into immunology, but essentially the body has many different tools with which to fight the disease and helper T’s crucially regulate these tools. Not only do these cells activate or suppress the immune response as needed, but they also influence which parts are right for each job.
After HIV has taken over and destroyed almost all of the body’s helper T’s, it is very hard for the body to mount an immune response to even seemingly harmless diseases like the common cold. This state or syndrome is called AIDS. Preventing the final stage of AIDS (and hopefully even the initial infection) is a major research target.
Structure of HIV
Working our way in, the exterior of the virus consists of a lipid membrane, similar to that of a human cell’s membrane. The reason for this is that HIV steals the membrane of its host as it leaves old, infected cells. But we’re getting ahead of ourselves…just remember that this stolen membrane is called the “viral envelope.”
Around the outside of the envelope are proteins called Env proteins (gp120 and gp41). These are some of the most important viral proteins because they allow docking with human cells. As the video below points out, interrupting the fusion of the viral envelope with the cell membrane (with drugs called “fusion inhibitors”) is a very active area of research.
Within the viral envelope lies the core of the virus, the capsid. After the virus enters the cell, the outer layer becomes absorbed into the cell membrane and only the capsid remains. For this reason, everything of import for re-creating the virus lies within the capsid. These components consist of two single strands of RNA, reverse transcriptase, integrase, and protease. Don’t get too hung up on the big words. Watch the following video (*wheels in TV cart*) and check back in with me afterward:
There was a lot going on in that video, to be sure, but here are the key points:
- Once inside the cell, the HIV RNA (a molecule similar to DNA that can carry genetic information) is converted into double stranded DNA by reverse transcriptase. This new DNA strand is very similar to the DNA found in human genomes.
- The viral DNA is carried into the cell nucleus by integrase and added to the genome of the cell. When done en masse, the viral genes can be considered part of the body’s overall genome. Once this occurs it’s very difficult to remove it or stop viral products from being produced.
- Lastly, the cell translates the viral genes into viral proteins which are created by the cell’s own machinery outside the nucleus. The proteins are briefly modified by protease and begin to assemble themselves into new viral particles, eventually bursting from the cell.
After learning all about HIV, you may be thinking, as I once did, that HIV will never be cured. It uses the body in such a cunning way (destroying the defenses that might be used to stop it) that scientists must truly think outside the box. Fortunately, I know first-hand that there are a great number of people working tirelessly to treat and cure the infection and the disease. Speaking of treatments and cures, let’s briefly discuss the differences between the two.
Treatments vs. Cures
While all research grows knowledge, when it comes to HIV research there are generally two paths for a project to take. Treatments are conceptually easier to understand because (as the video points out) any active step in the HIV replication process is a potential drug target. If a drug was 100% effective, the disease would stop in its tracks, but any damage might be lasting and the virus would probably persist in the genome of the patient.
Thus far, most research that has moved into clinical trials has been treatment research. Thanks to this branch of experimentation, many HIV patients have been able to control their disease and prevent its devastating effects. Drug treatments are a double-edged sword, though, as the side effects are often harsh on the patient.
If you recall my previous article, The Cure for Cancer, I described cancer as a phenomenon that will not be solved with a magic bullet. HIV on the other hand, while by no means an easy target, might be susceptible to such an approach. The virus has the ability to mutate and evade the body’s defenses, but there are certain core facts about the virus that will not likely change. Attacking cells that have been infected but ignoring all others, for instance, might be an approach for clearing one’s genome of the viral DNA. The trick is, how might this be accomplished? Also, a vaccine preventing initial viral infection would be wonderful, but the nature of the virus makes a vaccine unlikely. Engineering either a vaccine or a cure will undoubtedly be the most challenging part of this research.
One Word of Warning…
Hopefully some who read this article will not feel satisfied with the simple overview given above and seek out more knowledge. During your intellectual journey you may discover people who claim any or all of the following:
- HIV does not exist.
- HIV may or may not exist, but it does not cause AIDS.
- AIDS is a gay disease (yes, there are still some who believe this)
- AIDS medication only hurts patients and does absolutely no good (the suggested alternatives are decidedly more new-age)
These statements are generally circulated by “HIV Deniers:” people who for some reason or another believe scientists are either stupid, wrong, or part of a plot with the government. You can make up your own mind, of course, but if this stuff is true, what keeps my friends in virology so busy then?
Does the above information affect your understanding of HIV? Have any questions or comments? Leave them below or chat with me via Twitter!
- NIAID’s Informational Website on HIV/AIDS (Part of the NIH)
- HIV on Wikipedia
- ERV, a blog about retroviral research
["Human Immunodeficency Virus - stylized rendering" from Los Alamos National Laboratory (Public Domain) | "Diagram of the HIV virus" from the US National Institute of Health (Public Domain)]