X-Message-Number: 22240
Date: Tue, 22 Jul 2003 18:13:13 -0400
From: Francois <>
Subject: Inquiry about prions

If I am not mistaken, prions are mishaped versions of normal brain proteins.
When they come in contact with their normal versions, they cause them to
refold themselves to the prion state, thus triggering a chain reaction that
ends with the death of the "infected" individual. The mad cow disease crisis
in England, as well as exotic human diseases like Kuru, demonstrate that
eating prion contaminated food can spread the disease. However, I don't
understand how this is possible. First, most protein based foods are cooked,
which denatures proteins. Then, the consumed proteins are digested and
broken down to their constituant amino acids. Third, those proteins that
escape digestion will no easily go throught the gut's lining and enter the
blood stream. And fourth, even if some protein molecules manage to get into
the blood, the brain blood barrier will not allow them through. In view of
all those obstacles, I find it remarkable that prion based desease can be so
easily transmitted. There is obviously some other mecanism at work here and
I would very much appreciate it if someone could tell me what it is.

Francois
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