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XMVR Mutation rates and WPI decision to abandon PCR for identification

Discussion in 'XMRV Research and Replication Studies' started by gerwyn morris, Jan 18, 2010.

  1. Knackered

    Knackered Guest

    In the long run would be easier to treat? If the virus doesn't change very much, once they know how to attack it they'd be on to a winner huh?
  2. Katie

    Katie Guest

    That's my thinking. You need the right tool for the job, no good trying to put out a fire with a hammer. It also the reason a vaccine seems likely.
  3. Mithriel

    Mithriel Senior Member

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    The snag is that when the virus isn't replicating it is part of our DNA or cells so anything that attacked the virus would damage us too. This closeness to our tissue in viruses is why antibiotics for bacteria were developed in the 40s but there are still not many antivirals.

    Technology and biochemistry are developing fast though so there is hope, especially if someone can make a profit from it :Retro smile: Also if it reactivates things like EBV and enteroviruses then antivirals against them would make a big difference to us.

    I love the idea that the virus is not very active so it has all the characteristics of CFS :D

    Mithriel
  4. Gerwyn

    Gerwyn Guest

    the slow rep rate contibutes to the dodgyness of PCR assay-------Putting it in water may not do it a lot of good either its weak enough in sera----its coat may well qualify as a semi permeable membrane osmotic shock buffering etc could well be key issues
  5. natasa778

    natasa778 Senior Member

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    not necessarily, if the "attack" is carried out via epigentic means, by silencing viral gene expression etc...
  6. Cloud

    Cloud Guest

    On a more subjective note.....Dr Peterson told me that one of the good things about xmrv is that it's slow growing, which will make it much more treatable once we get the right meds. He was referring to replication, not mutation. I think the main reason to be concerned about mutation would be with the use of inadequate drug treatment. Determining the best med(s) through adequate research before treating the masses, should minimize chances of mutation significantly. I for one, would not throw AZT at this bug regardless of illness severity because the chances of causing a mutation and therefore resistance, seem huge.
  7. Parismountain

    Parismountain Senior Member

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    Dumbest biology question yet todate but here goes. When science talks of virus entering our cells, like the pathway for Xmrv I believe they mention RNA which then converts to DNA and in the slides of how this all works that I've seen the cell incorporates the DNA into our genes and oh by the way we have many many artifacts from long ago viruses from our ancestors passed down into our makeup, so here's my dumb question. If a virus like xmrv can only live in one type of body cell, say some white blood cell, since our DNA has been altered by the virus do all cells of that type now have the virus dna incorporated or are we still producing cells of the type without the affect?

    That was question 1, here's number 2. If the virus only lives in a certain cell line and we are positive for a particular virus and it corrupts our DNA will ALL cells in our body now have the altered DNA? I am so confused, I just thought though we have many cell types that our DNA if tested from any kind of cell would sequence the same as a human cell from another cell type. And if it doesn't work that way then if a virus only lives in say a white blood cell of a certain type, will some cells of that type have our original DNA and the affected cells the new DNA we have now become? I guess guessing outloud I'm using cells that have relatively short life spans, what about long living cells? What's their dna sequence look like? Brain cells don't replace right? (if they did I might not have written such a goofball question)
  8. spit

    spit Senior Member

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    parismountain -- not dumb at all. It's actually really complicated -- so this will be only mostly correct, but should clarify a bit, hopefully. I'll be really broad, because I don't know your background at all, and this is sort of a connection point for a lot of biology, so I want to try to give you something better than yes/no.

    Once something like a retrovirus incorporates its genome into that of a host cell -- it's then called a provirus -- it will be present in every daughter cell that comes from that host cell. If one cell in my big toe gets infected with Virus X that incorporates into its DNA, then every cell that comes from the splitting of that big toe cell will also have that (currently latent) provirus. If the virus is active in another cell, it will be using the machinery of the cell to pump out new copies of the virus, too. Other uninfected big toe cells will still also be dividing, so everything is happening at once -- infected cell may be splitting off into more infected cells, uninfected cells may be splitting into more uninfected cells, and active viruses may be running around infecting more cells. It's more of a balance than of a yes/no, and the reaction of your immune system makes a huge difference in trying to tip that balance toward healthy cells.

    With white blood cells specifically, they don't really divide directly from each other, though. They're produced from stem cells in your bone marrow, and once they differentiate into whatever kind of blood cell they're going to be, they generally lose the ability to self-replicate; the bone marrow keeps pumping out new ones as the old ones die off. Now, if your stem cells have the provirus, then so will the blood cells they produce.

    Add to that mishmash that we have systems designed to kill cells that have irregularities in their DNA -- the cell itself is set up to have a number of ways it may either stop replicating or kill itself if its DNA is really damaged, and there are other cells out there on the lookout for signs of infected or damaged cells, which they will then kill. In something like HIV, for example, the CD-4 cell depletion happens in part because one's own body attacks the infected CD-4 cells. Again, gets way more complicated than that, but that's sort of the basic picture.

    Damage to DNA -- whatever the source, viruses are just one -- will most often result in the death of the damaged cell, but if it doesn't, and it's an actively replicating cell, then that cell is replicating into more cells with that damage. Damage to some regions can lead to tumors this way, if the cell has damage, say, to the parts that tell it <i>not</i> to divide all willy-nilly. If it neither kills itself nor is killed by other cells, it will become a big lump of dividing whatnot. This is why we have systems for autoimmunity, which can also sometimes sadly go awry and kill perfectly healthy cells.

    It's really an oversimplification to say that every cell in your body has exactly the same genetic information. Sometimes, there are mistakes in transcription when cells divide, and sometimes cells sustain damage of various kinds that create small mistakes somewhere in the code. Cells do have mechanisms to try to repair these mistakes, but that's not perfect, either, and some may remain from time to time. Most of these are harmless and tiny, and aren't noteworthy at all when you're talking about looking across your whole genome, which is huge. When there's a change that is large enough or well-placed enough to be harmful, your body actively tries to kill the cell (if it won't kill itself).

    If these mutations happen and survive in most types of your body cells, they're not generally a big deal, and they're so small as to be insignificant for something like DNA sequencing -- they will still all be 99.999999% alike or whatever. If changes happen to the DNA in the cells that make eggs or sperm, they will be passed on to your children, should you have any, as mutations that will be in <i>all</i> of their DNA. Random mutations aren't uncommon, they increase in cells over time (this is part of aging, really), they're usually completely meaningless, and when they aren't, they're the fundamental stuff of evolution.

    Whew. Hope that wasn't too far afield and that I actually answered your question in there somewhere.
  9. Mithriel

    Mithriel Senior Member

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    Good post, thank you.

    Mithriel
  10. Parismountain

    Parismountain Senior Member

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    Wow Spit that was very understandable. Thanks.
  11. dsdmom

    dsdmom Senior Member

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    spit, thank you for the explanation. I know it's a simplified version but it's all my brain can handle. And I know I'll have to go back and reread it several times!

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