RECEPTORS

Ed Rybicki ED at micro.uct.ac.za
Tue Aug 3 02:53:53 EST 1993


> Not much out there on plant virus receptors, it seems.....
>
> Gildow's work using EM seems to be the only good evidence around
> that plant viruses can travel through insect cells by what
> looks like receptor mediated endocytosis (strictly transcytosis).
> Like the geminiviruses, they (probably) do not replicate in the
> insect vector.

And Peter Markham's crowd at the JII have done some nice EM on maize
streak monogeminivirus in its leafhopper vector, too, showing similar
sorts of specific interactions as occur with BYDV in aphids (seen at last
ICV).

> This kind of thing must happen elsewhere - do any animal
> viruses move through cells, rather than just into them? What about other,
> strictly insect viruses? How do they get in - especially how do they get
> through the gut wall before infecting cells within the host?

Like mammal enteroviruses, perchance - infect the cells of the gut
lining/epithelium and spread cell-to-cell thereafter?

> Seems to me us plant virologists could learn from our animal
> counterparts - or are animal viruses just brutes which get
> in any way they can and kill....

Er...that would be PLANT viruses, which are not particularly subtle about
getting into a plant in terms of interactions with plant cell membranes:
an analogy would be of a virus which was only transmitted to humans on axe-
blades....whoops, there goes HIV and HBV...!  No, seriously, it would
appear that most plant viruses - and especially those NOT infecting
insects or with insect vectors - get into cells via transient damage to
cell walls/membranes (see the excellent EM work of Verduin's group on
cowpea chlorotic mottle bromovirus), and NOT thru specific interactions
with cell membrane receptors.  This leaves open the q of what happens with
things like plant rhabdoviruses and plant bunyaviruses, which obviously do
have attachment proteins specific for their INSECT hosts, but have never
been shown to have the same for their PLANT hosts: do they enter cells via
transient breaches in cell membrane integrity, due to insect mouthpart
damage/piercing action, same as simple plant viruses, or is there specific
cell memb receptor interaction?  I suspect the former.

  ____________________________________________________________________
 | 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             |
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