a molecular evolution question re ebola

[Michael L. Perdue]

On 24 May 1995 bhjelle at unm.edu wrote:

> In article <3pu9ke$59f at agate.berkeley.edu>,
>  <salamon at allele5.berkeley.edu> wrote:
> >
> >
> 
> >Where could this virus have been where it did not experience
> >much genetic drift?  Any ideas?
> 
> 
> This question reflects a misconception about the stability
> of the genomes of RNA viruses in nature. Given a host in
> which the virus is comfortable, whether that be monkeys,
> rodents, or plants, genetic drift is really minimal.

Sorry to be late in responding to this, I'd planned to earlier and forgot, 
then I heard Laurie Garrett yesterday on the radio program "Fresh Air" 
and it brought it all back.  Ms. Garrett made the bold statement that it 
would be in the "best interest" of viruses to become attenuated and 
less lethal in it's new host.  You say if a virus is 
"comfortable" in its host, genetic drift is minimal. Influenza viruses 
have apparently not gotten the word on either of these two points, since 
in humans the viruses have certainly been circulating for quite a while 
and for some reason?? aren't satisfied with their own amino acids!  Also 
recent AI outbreaks in poultry have headed in just the opposite direction 
from Ms. Garretts prediction.  Particularly the 1983 US outbreak and the 
recent Mexican outbreak of avian influenza in which the virus began as a 
mild version and wasn't "happy" so it "mutated" to become lethal.  
Perhaps the virus "felt" as though its host was just a little too 
complacent and wanted to shake it up a bit?  I realize we use these terms 
to more easily describe what we percieve as directional evolution of viruses 
but I'm not at all convinced that viruses evolve anyway. Certainly they 
adapt, but they have no "best interest" to become "comfortable" in 
anything do they?? ( I know we've had these discussions before, but I do 
get a little stimulated when I hear a Journalist (albeit a damned gutsy 
journalist) make "definitive" statements about how viruses work).

Mike Perdue