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Thread: A question about viruses

  1. #1 A question about viruses 
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    Hi,

    this question just came to me just yesterday as I was listening to a podcast, and I really can't get it out of my head.

    i am wondering, is it possible for the same virus to develop different symptoms in its victims based on the different ecological region which they live? For example two men contract the exact same virus, but have a few different symptoms from each other because lets say one lives in a very hot climate as opposed to the other's colder climate?

    would this happen as a result of the virus evolving into two unique but related or sub categories of the main family of the virus, to better find and spread in its hosts based on where they live?

    Thanks for anyone who can help me out.


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    Forum Masters Degree Implicate Order's Avatar
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    Hi CatholicFaithful75.

    You might have been hearing a podcast relating to epigenetics and effects of viruses. As you probably are aware a virus comprises a nucleic acid, a coat of protein and a lipid membrane..that's about it. They contain instructions but not the machinery to carry out those instructions. A virus uses a host cell to employ the cells machinery to make more viruses. It does so by merging it's genetic instructions (genes) into the host cell's DNA (genes) thereby utililising the host cells infected genome to instruct the cell to make more viruses. Now it is only when the resulting cell's infected genes are active that these instructions get processed by the host cell by its machinery. If the gene is 'switched off' then the code lies dormant and is not expressed by the host cell.

    Epigenetics relate to heritable changes that are not caused by changes in the DNA sequence. A good example of epigenetics at work on cells with the same exact genetic code is during ontogeny. During embryonic growth, it is epigenetics that causes cells to differentiate despite possessing identical DNA due to the surrounding chemistry of the cell switching on (thereby expressing the gene) and switching off (suppression of the expression) certain genes.

    We can see epigenetics at work with certain viruses such as the herpes virus. The disease is caused by a virus that infects nerve cells. If the virus is inactive, it's genes are not expressed and there are no associated symptoms.

    Work on bacteriophages (viruses that infect bacteria) demonstrate that when the virus is active and expresses its genes, more viruses are produced by the host cell. Sometimes however the viral genes are not expressed but they get transferred in this dormant state as the cells multiply. Later the virus genes may be 'turned on' to then make viral progeny many generations later.

    The important thing to remember here is that the code doesn't change but the epigenetic state may. This has now been associated with the chemistry surrounding the DNA and more importantly the presence or absence of methyl groups. When methyl groups are present, genes are silenced. When absent, genes are expressed.

    Now the altered chemistry surrounding the DNA opens the door to possible external environmental influences such as diet, stress etc. being ultimately responsible for the altered chemistry.

    .....epigenetics is a very recent field and is still in its infancy. It is still too early to draw long bows and attribute everything to epigenetics but it certainly is an active area of research and stay tuned for more interesting findings.

    Now........I am hoping that your enquiry was a valid one and that there is no 'bias' lurking there (given your avatar) seeking to dispatch Darwinian evolution. Epigenetics works hand in hand with Darwinian Evolution and in no way replaces it.


    Last edited by Implicate Order; July 31st, 2014 at 09:20 AM.
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    Thank you for the information.

    I'll start off by saying that no, the podcast wasn't anything to do with epigenitics. It had to do with something else entirely, but still was dealing with viruses. And no I was no bias at all against evolution. I can't say I completely agree with evolution, but I wo t deny it in its entirety either.

    If I am understanding in basic layman's terms, the virus itself doesn't so much evolve, as it's affected by the, let's say, evolutionary elements within the host cell, and as such, because of the. Genetics within the host cell, one might find, though similarity in the virus itself, different symptoms in the infected individual? Is this correct?

    If I missed the mark on that, I deeply apologize.
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    Forum Masters Degree Implicate Order's Avatar
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    No probs CF75. Your understanding is correct. Symptoms of underlying ailments vary from host to host as organisms are complex creatures containing systems within systems or system dependencies upon system dependencies. The information injected by the virus may be the same but the way this information is 'expressed' in the host can be very complex attributed to the composition of the hosts genome as well as the way the host's system responds to the information in the genome. The combination of these factors produce an array of different symptoms that may vary between hosts.
    Last edited by Implicate Order; July 31st, 2014 at 06:26 PM.
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  6. #5  
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    Okay thank you very much, I appreciate it.
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    Hi Implicate Order, just an aside question, as you seem to be familiar with epigenetics. Do you know if it's always the case that for euchromatin, when it is unmethylated, it is acetylated, and vice versa for heterochromatin?
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    Quote Originally Posted by Curiosity View Post
    Hi Implicate Order, just an aside question, as you seem to be familiar with epigenetics. Do you know if it's always the case that for euchromatin, when it is unmethylated, it is acetylated, and vice versa for heterochromatin?
    Hi Curiosity. *waves towards Melbourne and shivers*

    I wish I knew. I am no expert in biochemistry. You will need assistance from others on acetylation and deacetylation. :-))
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    Ahaha it's been a bit chilly down here of late :P fair enough then
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