HIV evolving 'into milder form'

  • Posted by a hidden member.
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    Dec 02, 2014 5:45 PM GMT
    HIV is evolving to become less deadly and less infectious, according to a major scientific study.

    The team at the University of Oxford shows the virus is being "watered down" as it adapts to our immune systems.

    It said it was taking longer for HIV infection to cause Aids and that the changes in the virus may help efforts to contain the pandemic.

    Some virologists suggest the virus may eventually become "almost harmless" as it continues to evolve.

    http://www.bbc.co.uk/news/health-30254697

    Encouraging news (unless, of course, you are one of RJ's own little band of HIV doom-mongers).
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    Dec 02, 2014 9:25 PM GMT
    That is as predicted, scientifically. However, it could be a very long time (centuries) before it becomes clinically relevant.

    Generally, diseases are at their most deadly just after they make the jump to a new host animal. But that's not really a good strategy for a parasite - if the host immediately dies (e.g. Hanta or Ebola) the parasite will not persist in that population. If the virulence factors become attenuated, the parasite can persist in the host and reproduce over a long period of time (e.g. Salmonella.) And might even eventually become a symbiote.

    HIV is a bit of a different story, since it doesn't kill outright. I haven't seen the original paper that the story is about, but the theory seems to be that it's a response to a human mutation in a particular African population that increases fitness but reduces virulence within that population that has the mutation. The story also doesn't say which strain of HIV that they're talking about.

    BTW: One of the ways that the earliest vaccines were made was to infect mice with human pathogens, through several generations, to come up with "attenuated" strains. These vaccine strains had then lost their virulence factors but could still raise an immune response. It didn't always work.
  • HottJoe

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    Dec 02, 2014 9:29 PM GMT
    It seems ebola is also much less deadly than it was when it was first discovered.
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    Dec 03, 2014 4:05 AM GMT
    HottJoe saidIt seems ebola is also much less deadly than it was when it was first discovered.
    There are 5 strains of Ebola. The Zaire and Sudan strains are the most deadly (Zaire was the first one discovered). Those still have a 90% fatality rate, but that also makes it harder for them to spread.
  • bro4bro

    Posts: 1034

    Dec 03, 2014 4:19 AM GMT
    Yes, the data indicates HIV takes 12.5 years to kill you now, instead of 10. That, apparently, is what's meant by "less deadly".

    So... how will you spend your extra 2.5 years?
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    Dec 03, 2014 8:07 AM GMT
    bro4bro saidYes, the data indicates HIV takes 12.5 years to kill you now, instead of 10. That, apparently, is what's meant by "less deadly".

    So... how will you spend your extra 2.5 years?


    That's still not bad, given the relatively short period HIV has been identified in the human population. It's not going to go away tomorrow, but if it is becoming less deadly at that pace, it is good news.
  • Rhi_Bran

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    Dec 16, 2014 12:32 AM GMT
    That's how viruses work. Killing your host is NOT an adaptive trait. The viral infections we survive and fight off today are the ones that have been infecting us since antiquity - rhinoviruses, flu viruses, noroviruses, etc. Unsurprisingly, these are the viruses that have adapted to both spread and mutate rapidly in order to propogate, or trick our immune systems so they can lie dormant in our bodies for our entire lives without murdering us outright while still being contagious (like herpes zoster, or cytomegalovirus).
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    Dec 16, 2014 1:10 PM GMT
    This is true of all biotrophic pathogens (obviously not the case for a necrotroph!).

    I think an important thing to remember about a virus is that it really has limited control over itself. Technically a virus isn't a living organism! In that regard, the biggest variable is probably host selection variables.

    While not everyone presents symptoms when they are initially HIV infected; an individual that does present is more likely to go to the doctor, catch the disease, and get treatment sooner. So in that regard being a less virulent strain means possibly missing detection more. Also the longer living the host, the more likely to spread transmission!

    So the virus really has nothing to do with it, its all about our interactions.
  • Rhi_Bran

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    Dec 18, 2014 4:24 AM GMT
    sftgfop saidWhile not everyone presents symptoms when they are initially HIV infected; an individual that does present is more likely to go to the doctor, catch the disease, and get treatment sooner. So in that regard being a less virulent strain means possibly missing detection more.


    Unfortunately that is not necessarily the case. Not everyone makes the link between immune-mediated responses to viral infection (aka flu-like illness) and sexually transmitted infections. Even if someone presents with symptoms, they may not experience ALL of the known symptoms of acute HIV, or they may present with atypical symptoms. Honestly the only time someone will get themselves checked because they're experiencing symptoms is if they know about these relations and if they're worried about disease. Many people don't know anything about the immune system and will just assume that they just got the flu.

    Now, it might be different if the doctor inquires into a patient's sexual history, but then that relies on the patient being totally honest.

    This is why statistics about symptoms are hazy and not at all narrowly constrained - people will get diagnosed years after being infected, and won't know exactly when they got infected or if any symptoms they may have had were the result of infection with HIV, or something more benign.