Prion transmissibility

Ian A. York york at mbcrr.dfci.harvard.edu
Thu Jul 13 10:25:23 EST 1995


In article <3u3b7d$2b9 at tali.hsc.colorado.edu> ak961 at freenet.HSC.Colorado.EDU (Prateek K. Lala) writes:
>
>In a previous article, umfunk15 at cc.umanitoba.ca (Duane James Funk) says:
>
>>3. Finally, and most importantly, this business about blood 
>>transmission.  From the papers I have read I think to myself 'Not Bloody 
>>Likely' (Pun intended).  Aren't prions transmitted primarily in neural 
>>tissue.
>
>   As you say, prions are primarily transmitted through neural tissue
>(neurosurgery, pituitary hormone transfusion, etc), but they are also
>supposedly transmitted by corneal transplants.  How do the proteins end up
>in the cornea?  Perhaps by traveling from the brain through the
>vasculature (just a guess).  Blood transfusion doesn't seem all that
>far-fetched to me, particularly in view of the fact that we don't really
>know all that much about modes of transmission of prions.

It's been some time now, but I recall a seminar on scrapie,  discussing 
the course of infection in hamsters (?mice?).  If I remember this 
correctly, they were able to pull fairly high titres of scrapie agent out 
of spleens early on in the infection, and this eventually disappeared and 
then the brain became positive.  If I have this right (and it's been a 
while) then it seems likely that there is some blood-borne transmission 
with at least one prion.  

I also recall that there were absolutely massive amounts of the agent, 
and that the speaker was tossing around number like 10^11 infectious 
particles in his preps.  If one infectious particle is infectious (by 
definition, I suppose) then it wouldn't take a lot of tissue damage to 
allow this extremely stable agent to be continuously shedd into the 
peripheral circulation and potentially be infection there.  

Ian
-- 
Ian York   (york at mbcrr.harvard.edu)
Dana-Farber Cancer Institute, 44 Binney St., Boston MA 02115
Phone (617)-632-3921     Fax  (617)-632-2627




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