On 8 Oct 1997, Ed Rybicki wrote:
> > From: Leonard Pattenden <ddlpatte at mailbox.uq.edu.au>
> > Subject: Re: viruses, evolution, and net traffic
>> > My understanding of Viral evolution - as a protein chemist working in HIV
> > - is that viruses are escaped genes. Thus - for example - in many
> > retroviruses we see the aspartyl protease which cleaves the GAG-POL
> > smaller homodimeric protease we see today. The implication of my beliefs
> > to your suggestions, is that propensities for particular viral types must
> > reflect the availability of the machinery within the cell. Ie if a plant
> > cell can produce reverse transcriptase which could be incorporated
> > somehow into a virus, then the feasability of an RNA virus is
>> Okayeeee...first problem: not all viruses can be boxed with
> retroviruses as "escaped genes", at least, not as RECENTLY escaped
Fair enough, but the point is still valid, retroviruses was an example.
In fact, there are no classical retroviruses (except maybe
> some retrotransposons which turn out to be infectious) in plants;
> only pararetroviruses of presumably ancient lineages (in that ALL
> retroviruses look MUCH more like each other than badna- and
> caulimoviruses look like each other).
Interesting, but the arguement still stands.
>> Second problem: you will find some mammal-infecting viruses in the
> same superfamilies (based on polymerase homologies) as plant
> viruses...seeing as land plants and mammals diverged some 10exp9
> years ago...see what I mean?
Yes. I understand your point. Quite frankly, how much faith would you
hold to polymerase homology in light of the size of a viral genome and the
period of time you have put forward for divergence?