a "happy" virus

[asa at sirius.com]

>   pab3jam at leeds.ac.uk (J.A. May) writes:
>  I realise that by its very nature the presence of a virus will be damaging to 
>  the host, and may well ellicit antibody response, but could there have been an 
>  evolutionary path around this? Perhaps its allready happened many times before 
>  and various beneficial viruses have been incorporated into our DNA.
>  Any references appreciated - I wasn't sure where to start looking.
>         
>                                               Jake
>  
>  
>>>>
You're thinking of something like a commensal virus - commensal means 
'eating at the same table' in Greek or something.  Basically, they are viruses
that have highly evolved specific tropisms for their hosts and cause relatively little
antigenic disturbance.  

The best example of this are HERV's, or human endogenous retroviruses, which are
transmitted vertically through the germline and integrate into the host chromosome, 
picking up pieces of genes from one host and depositing them in another.
In my opinion, viruses like this probably play a critical role in the evolution of all 
life since they essentially function as 'gene exchangers.'
A good read on this is The Quarterly Review of Biology, March 1989,v64n1, Origins
and Evolutionary Relationships of Retroviruses.  Any lit search on HERV's will pull up
alot of stuff as well since these are relatively new.

Asa
@sirius.com