continued

Ed Rybicki ED at micro.uct.ac.za
Fri Jun 25 03:50:49 EST 1993


> I am not so personally interested in the systematics
> as some of the other virologists, but I am interested
> in their results!!!

And people into the systematics are interested in yours potentially, too...

> It is fascinating that many of the insect and even plant
> viruses are picorna-like.  What does this say about
> a common origin???


(Sounds of a systematist getting onto hobby-horse)

Ahem...it says much about a common origin.  Consider: all the mammalian
picornaviruses (incl Hep A group) are more closely related to one another
serologically than are the insect picorna(like) viruses or plant
picornalike viruses; thus, the potential diversity among insect p-like
viruses would seem to indicate that these viruses originated in insects,
and a subset got into and have co-evolved with mammals.  Of course, there
is an unfortunate dearth of sequence for these viruses: to my knowledge
only cricket paralysis virus has even been partially sequenced, and - if
the sequence is real - it is only very distantly related to mammalian
viruses.  We have partial sequence data from a very structurally similar
aphid virus (aphid lethal paralysis) which shows no homology to anything
at all...!  The plant viruses are fascinating too, as they bear little
sequence similarity with one another or anything else, yet their overall
genetic organisation is obviously similar to picornaviruses.  Some are
trying to erect a classification scheme with the plant viruses as a
separate family with two genera; however, I think this is unjustified, as
more evidence from insect viruses is needed before a clear picture of
relationships in thie larger group of picorna-like viruses is understood.
More sequence from insect picornaviruses, people!!

  ____________________________________________________________________
 | Ed Rybicki, PhD             |       "Lord, won't you buy me        |
 | (ed at micro.uct.ac.za)        |                                      |
 | Dept Microbiology           |         A Mer-ce-des Benz..."        |
 | University of Cape Town     |                                      |
 | Private Bag, Rondebosch     |                                      |
 | 7700, South Africa          |           - Janis Joplin             |
 | fax: 27-21-650 4023         |                                      |
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