HIV-1 vs HIV-2

mperdue at mperdue at
Fri Mar 17 08:52:22 EST 1995


I just wanted to make a short comment on the discussion that brought flu 
in as an example.  I don't think you can place viruses into a specific 
host-parasite relationship that says that the virus will "evolve" in one 
direction or the other.  Mostly because you are not looking at anything 
close to what we have known as "evolution" or species differentiation.  
While virus adaptation to hosts certainly uses similar basic mechanisms 
namely nucleotide change followed by selective pressure it is occuring at 
such a rate and with so many fewer external variables than evolution of 
higher organisms that it sort of falls into its own category.  Attempting 
to place behavioral characteristics on a virus or virus populations like 
you would say a finch population responding to environment variables, 
really stretches the imagination I think.  My point is that in 
considering the adaptation of virus to hosts I don't believe a set 
paradigm will evolve.  Adaptation of a mouse virus to a rabbit host for 
example may involve a different set of variables and go in a completely 
different direction (virulence wise) than say adaptation of a monkey 
virus to humans. With regard to the flu pandemic of 1918, theories 
abound as to the mechanisms of development of pathogenicity, but in 
reality given the mutation rate, the reassortment rate of its 8 RNA 
segments and particularly given the relatively SHORT period of time which 
we have been able to track the virus molecularly, we could never have  a 
similar pandemic, or it could be starting tomorrow!

Mike Perdue
SEPRL
mperdue at asrr.arsusda.gov




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