The Human Immunodeficiency Virus
By: Jeffrey Xu
General
-”HIV is today’s best known but least understood virus” (Lloyd 18).
-After some time, an HIV infection becomes the acquired immunodeficiency syndrome, or AIDS for short.
-There is no sign of a permanent cure, even though it is one of the fastest-spreading diseases (Bivona).
-Despite the fact that there is no permanent cure for HIV/AIDS, there are still many medications that can be used to slow down its effects.
Why is HIV so well known?
-AIDS is one of the world’s top incurable diseases (enkivillage.org).
-HIV defies the understanding of modern evolutionary biology. Instead of competition, it’s more like teamwork (Lloyd 19).
Origins
-HIV originated in South Africa.
-The virus skipped across the species border from monkeys to humans (Lloyd).
-South Africa now has around 5.7 million infectants, which is about 15% of the population.
Wikimedia Commons
Transmission
-HIV can only be spread through bodily fluids including:
-semen & preseminal fluids
-breastmilk
-vaginal & anal fluids
-blood
(Rothwell)
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Targeting the Immune System
-The primary target of HIV are T-cells, or white blood cells, which protect the body from infectious diseases.
-By weakening these defenses, other pathogens like the virus for the common cold can have a much more severe effect.
-A person has AIDS when the number of T-cells per cubic millimeter of blood drops below 200. Normally the concentration is from 4,300 to 10,800 cells per cubic mm.
Invading and Taking Over a Host Cell
-HIV is a retrovirus, meaning it has single-stranded RNA.
-HIV injects its own RNA into the host cell and uses reverse transcriptase to incorporate its own genetic sequence within the host cell’s DNA. This viral DNA is known as a provirus.
-When normal transcription and translation occur within the host cell, mRNA that is translated by the cell’s ribosomes code for the virus’s proteins, which help in the assembly of new viruses. So far, it is a lysogenic infection.
Takeover and Destruction
-After a while, the cell will try to cut out the provirus from the host cell DNA.
-The virus will then enter the lytic infection cycle, making copies of its nucleic acids, synthesizing proteins using the host cell’s ribosomes to make the capsid and viral envelope, and will eventually cause the cell to lyse, destroying it.
-As more and more white blood cells are used and destroyed, HIV symptoms begin to occur.
Symptoms
-Early symptoms of HIV share many in common with the flu such as fevers, sore throats, rashes, and fatigue.
-However, when this progresses to AIDS, the symptoms will increase in severity: rapid weight loss, extreme tiredness, diarrhea that lasts more than a week, mouth and genital sores, memory loss, and depression (Baker).
Impact
-More than 70 million people have been infected with HIV and over 35 million have already died. (aids.gov)
-Because of the virus’s insanely fast RNA replication speed, mutation rate is really high as well, which prevents makes it very difficult for scientists to keep up with the new strains.
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Speculation for the Future
-Despite the seeming impossibility of combatting HIV, there is still hope.
-According to a study, about 10 percent of Europeans are naturally immune to HIV due to the exposure of their ancestors to the Bubonic Plague (Lloyd 19).
-I think that with more research and field-testing scientists will find a way to genetically engineer a cure for HIV.
Bibliography
Lloyd, Christopher, and Andy Forshaw. What on Earth Evolved?: 100 Species That Changed the World.
New York: Bloomsbury, 2009. Print.
Baker, Paige. "Symptoms of HIV." AIDS.gov. SMAIF, 31 Dec. 2015. Web. 20 Apr. 2017.
Bivona, Stephanie. "The Evolving Genetics of HIV." Understanding Genetics. The Tech Museum of
Innovation, 3 Feb. 2005. Web. 20 Apr. 2017.
Rothwell, Charles J. "HIV/AIDS." Centers for Disease Control and Prevention. Centers for Disease
Control and Prevention, 21 Dec. 2016. Web. 20 Apr. 2017.