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My biology teacher told me that if one caught HIV, they cannot be cured because it was near to impossible to be completely virus-free. She said this was because HIV keeps on changing its glycoprotein coat.

Can someone please explain what she meant by "keeps on changing its glycoprotein coat" to me?

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  • $\begingroup$ I have an exam tomorrow and i am thoroughly confused. $\endgroup$ – Tusky Oct 5 '15 at 16:48
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    $\begingroup$ There is a huge difference between "not cured yet" and "incurable." Have you done any research to answer this question yourself? $\endgroup$ – MattDMo Oct 5 '15 at 17:31
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    $\begingroup$ Seems a bit harsh to down vote a question coming from someone's teacher. The student can't really be held responsible for using the teacher's bad wording. At least they're seeking the right answer. $\endgroup$ – Nathan Oct 5 '15 at 20:08
  • $\begingroup$ I think this is a valuable, albeit broad, question. @Amory has answered the question well with an appropriate amount of detail. $\endgroup$ – James Oct 5 '15 at 21:39
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    $\begingroup$ @MattDMo, if you want to nitpick about not cured yet versus incurable, then I think Amory's point that incurable is a misnomer is valid. You cannot cure a virus. You can cure the infection that they virus causes by neutralizing the virus, but it isn't the virus that is being cured, it is the infection. So the title should really read, Why is an HIV infection incurable? Actually would be is probably better. So Why would an HIV infection be incurable? And the biology teacher is probably just hedging her statement because of The Berlin Patient. Actually I will edit for accuracy. $\endgroup$ – AMR Oct 6 '15 at 2:45
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The reasons why HIV is "incurable" (a misnomer) are legion:

  • HIV is a retrovirus, which means it inserts its own genome into the host cell's genome. You must therefore kill each and every infected cell to rid the body of the virus.
  • HIV is a lentivirus, which means it has a long incubation period, so it can "lay low" before symptoms are readily detected.
  • HIV infects CD4+ helper T-cells, macrophages, and dendritic cells, which are responsible for mediating the host immune response. Thus, it infects specifically the cells we need to fight an infection.
  • HIV drastically reduces the number of CD4+ T-cells.
  • HIV has a number of viral proteins that prevent some of the body's antiviral mechanisms
  • HIV can infect via cell-free (large number of particles, low infection rate) or cell-to-cell (low number of particles, high infection rate) routes.
  • HIV is wildly variable. It has a small RNA genome (about 10kb) that mutates very rapidly. Given the number of viral particles produced each day during infection — well over 1 billion — every single base is mutated every day.

I'm simplifying matters a bit — you should just read the en.Wikipedia article for your own research — but that's a rundown of some of the reasons why.

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    $\begingroup$ This is a very neat answer for quite a complex question. Very nice! $\endgroup$ – James Oct 5 '15 at 21:30
  • $\begingroup$ Nice answer. Your first two points answer the question. A few things you can add. Dendritic cells are the only APCs that can activate naive T-Cells (your cell-to-cell route) but the fact that it is in DCs makes it more insidious. HIV can cause CD4 death in 3 major ways. 1)Apoptosis. integrase causes ds breaks which triggers cell death. 2)Recognition by CD8 cells. 3)Though lysogenic, with enough budding, infected cells will not have enough membrane and they lyse. Also the variability you mention often changes tropism and allows gp120 to have affinity for coreceptors other than CCR5 and CXCL4. $\endgroup$ – AMR Oct 6 '15 at 2:33
  • $\begingroup$ @AMR "Simplifying matters a bit" ;-) $\endgroup$ – Amory Oct 6 '15 at 13:16
  • $\begingroup$ It is good enough to be a reference answer, so I thought might as well make it more complete. $\endgroup$ – AMR Oct 6 '15 at 13:41
  • $\begingroup$ I think the second bullet point suggests a conclusion that may not be readily apparent to a lay reader: a second sentence to the effect of “Thus, there are already a lot of cells to kill even if treatment begins as soon as symptoms appear.” The second-to-last bullet also seems like it needs to state what its significance is: is one or both of these routes unusual or particularly problematic, or is it just that having both in one virus that is notable? $\endgroup$ – KRyan Apr 4 '16 at 20:34
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  1. HI virus attaches itself to the CD4 cells making it diffuclt for the body to destory it own cells.
  2. the virus mutates faster and keep changing it shape
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