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Diploid Viruses?

Mark E. Brodsky markb at hook.eecs.nwu.edu
Sun Oct 23 18:35:52 EST 1994

In article <38dtp2INNecq at early-bird.think.com>,
Ian A. York <york at mbcrr.dfci.harvard.edu> wrote:
>In article <Cy24L5.H9t at eecs.nwu.edu> markb at hook.eecs.nwu.edu (Mark E. Brodsky) writes:
>>Recently, I was browsing a Virology WWW page, when I came across a
>>referance to "Diploid" viruses. It seemed to imply that these were not
>>diploid in the usual sense of the word, but the server did not
>>elaborate any more on the subject. Could someone please explain what
>>is meant by a diploid virus? Thank you.
>I'm not sure if this is what was meant, but herpes simplex virus (and 
>most of the other herpes viruses) are pseduodiploid for some of their 
>genes.  This is because their genome contains repeated regions which 
>encode a couple of genes: (ascii herpes simplex virus: not to scale)  
>  ____                                   ________                 __
> |____|---------------------------------|____|___|---------------|__|
> ^^^^^^ b                             k ^^^^^^^^^^               ^^^^
> gene a                                   a  ^^^^^               ^^^^
>                                               l   m           t   l 
>As this schematic is supposed to show, genes "a" and "l" are doploid, 
>while genes "b" to "k" and "m" to "t" are not.
Thank you. Others have written me saying that retroviruses have two
copies of their genome, such is the case with HIV for instance. Does
anyone know why this is? I thought viruses were supposed to be models
of efficiency. Aren't two copies of the same genome wasteful if the
organism doesn't reproduce sexually?
"I know that you believe you understand what you think I said, but I'm not sure
 you realize that what you heard is not what I meant."
Mark E. Brodsky					E-mail: mark-brodsky at nwu.edu
Northwestern University                         or  markb at casbah.acns.nwu.edu

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