Opinions on the CPE of Polio

[ijiwaru at wheel.dcn.davis.ca.us]

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
> J.14:3349-3364). 
> 
> Ian
> -- 
>       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.

Lyle Najita
Plant Pathology
University of California - Davis