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  • HIV/AIDS has taken the lives of over 39 million people worldwide, despite our efforts to prevent, treat and better understand it.

  • But with 35 million people currently infected, what exactly is it, and are we close to a cure?

  • To contract HIV, the virus must enter the bloodstream - and it's often transmitted

  • from infected bodily fluids like blood, semen, vaginal fluids or breast milk.

  • Once inside the bloodstream, HIV targets a variety of cells, but most specifically the T-helper cells (CD4),

  • which are a type of white blood cell that play an essential role in our immune system and fighting infections.

  • The outer envelope of HIV is covered in glycoproteins

  • which mutate frequently, ultimately tricking the T-cell receptors to not recognize the virus.

  • Once attached to specific proteins on the T-cell, it begins to fuse the membranes together,

  • and eventually enters the cell where it releases 2 viral RNA strands and 3 essential replication enzymes.

  • Because HIV is a retrovirus, the RNA is transcribed into DNA, represented here by a zipper of two RNA strands transcribing into DNA.

  • This DNA is then integrated into the host cell’s genome.

  • This makes the T-cells treat the viral genes like their own, which causes

  • them to make more copies of the virus. These then leave the host cell and mature, ultimately

  • seeking more T-cells. The virus is particularly difficult to treat because its mutation rate

  • is so high. Overall the replication process creates more than 10 billion new virions each day.

  • During these initial stages of replication, called the latency period, a person may not

  • show any major symptoms for up to 8 years. If not treated, the HIV eventually kills off

  • the specific T-cells it infects. When these T-Cells fall below 200 cells per cubic millimeter of blood,

  • it becomes Acquired Immune Deficiency Syndrome or AIDS.

  • After progressing this far, the immune system becomes suppressed is much more susceptible

  • to cancers and opportunistic infections such as pneumonia. A person doesn't die from AIDS

  • they actually die from an illness that the body could not fend off.

  • Nowadays there is medicine that helps fight these opportunistic infections, like Daraprim

  • (which was recently in the news when Martin Shkreli of Turing Pharmaceutical decided to

  • raise the price from $13.50 - $750 per pill.. There are also anti-retroviral drugs that

  • slow the virus down by blocking certain enzymes which are required for the virus to multiply.

  • Similarly, those without HIV but at high risk of contracting the virus may take pre-exposure

  • prophylaxis or PrEP. This works similar to antiretroviral drugs by blocking the enzyme reverse transcriptase.

  • Thankfully there is hope for a cure - a small population of people are immune to the HIV virus

  • because of a mutation linked to the T-cells. In one case, an HIV-positive subject

  • received a bone marrow transplant, meaning they were given new stem cells that generate

  • different T-cells, and within 20 months there was no evidence of the virus in their bloodstream.

  • Though this is very indivisualized medicine, it certainly opens up the possibilities of

  • generating HIV resistant cells. Combine this with other therapies and preventative measures

  • like condoms, clean needle programs and safe blood transfusions, and HIV/AIDS may one day

  • be a thing of the past.

  • Your sharing of this video is much appreciated, in the effort to help spread knowledge and awareness.

  • Special thanks to audible for supporting this episode to give you a free 30 day trial at

  • This week we wanted to recommend the book Redefining Reality, which explores

  • what is real and what’s illusory from both a scientific and philosophical perspective,

  • through a series of really awesome lectures. You can get a free 30 day trial at

  • and choose from a massive selection! We love them as they are great when youre on the go.

  • And subscribe for more weekly science videos!

HIV/AIDS has taken the lives of over 39 million people worldwide, despite our efforts to prevent, treat and better understand it.

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The Science of HIV/AIDS

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    韓澐 posted on 2016/09/27
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