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How prions propogate
25 February 2011
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A new model of prion disease may represent a paradigm shift in
the mechanisms thought to underlie these infectious, neurodegenerative
disorders.
Prion diseases, such as Creutzfeldt-Jacob disease, have a
clinically silent incubation period that can go on for years or decades,
followed by an aggressive, short clinical phase.
The new model, based on
mouse studies, indicates that the spread of prions in the brain occurs in two
distinct phases. In the first, longer, clinically silent phase, non-neurotoxic
prions multiply exponentially until a defined limit is reached. Then the second,
shorter plateau phase sees the amassed prions catalyse the formation of toxic
prion particles. And whereas the length of the infectious phase is not dependent
on prion concentration, the time it takes for the mouse to succumb after the
plateau of infectivity is reached is inversely correlated with the amount of
prion protein that it produces.
The model, proposed by John Collinge and
colleagues from the IoN Department of Neurodegenerative Disease, and the MRC
Prion Unit in this week's Nature, hints that prion infectivity and toxicity are
separate processes and, remarkably, that infectious and toxic particles may not
be the same.
reference >> Prion propagation and toxicity in vivo occur in two distinct
mechanistic phases
Malin K. Sandberg, Huda Al-Doujaily, Bernadette
Sharps, Anthony R. Clarke & John Collinge
Nature 2011: 470, 540-542
Text courtesy of Nature
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