In article <4h5614$knt at panix.com>, iayork at panix.com (Ian A. York) wrote:
> In article <Pine.SOL.3.91.960229145323.11886A-100000 at tam2000.tamu.edu>,
> Wade <dwl0685 at tam2000.tamu.edu> wrote:
> >I have been doing some paper research lately on picorna(esp. polio)
> >viruses and have found that an explanation for the extensive CPE
> >generated by multiplying polioviruses has yet to be explained. Many
> >suggestions exist, but I would like to see what others have to say as far
> >as information or opinions on how the host cell is destroyed so rapidly.
>> I believe that CPE, in general, is a poorly understood process, and that
> in few cases is it really clear exactly why viruses kill cells. That is,
> although there are some mechanisms which will clearly kill a cell (e.g.
> those viruses which burst the cell to exit), it's rarely clear whether
> the cell is even alive at that point, and whether that mechanism, or
> another or some combination of many, is responsible. It seems even more
> difficult to point to causes for some of the pre-death changes in the
> cells that are often seen - the rounding and clumping, vacuolation, etc -
> although in some cases it seems that disruptions in cytoskeletal networks
> and so forth are involved (though that's merely refining the description
> and doesn't really address a mechanism).
>> I'm far from an expert on this, and I'm sure that there are some cases
> where there are clearly understood mechanisms. I suspect, though, that
> these are the minority.
>> In the case of polio, one factor that seems likely to muck up an infected
> cell in a real hurry is the recently described inhibition of glycoprotein
> trasport in infected cells (Doedens, J.R. and K. Kirkegaard. 1995.
> Inhibition of cellular protein secretion by poliovirus proteins 2B and 3A.
> EMBO J.14:894-907; Barco, A. and L. Carrasco. 1995. A human virus
> protein, poliovirus protein 2BC, induces membrane proliferation and blocks
> the exocytic pathway in the yeast Saccharomyces cervisiae. EMBO
> Ian York (iayork at panix.com) <http://www.panix.com/~iayork/>
> "-but as he was a York, I am rather inclined to suppose him a
> very respectable Man." -Jane Austen, The History of England
Don't forget that Dasgupta's lab has shown that a couple of the host cell
transcription initiation factors are degraded by the viral 3C protease, I
believe it was TFIIB and TFIIIC (but I have spread faulty info in this
group before and probably will again as more neurons disconnect). In
addition, there was a period of time when there were whispers of a viral
or virally induced lysis factor that has yet to surface.
University of California - Davis