It turns out that when the normal prion protein is mis-folded it is capable of inducing more of the same normal protein to mis-fold in a similar fashion. What makes matters worse is that this particular mis-folded protein, unlike the normal protein, cannot be broken down and recycled by the infected cell. Thus this prion protein accumulates in a brain cell as enlarging clumps of un-digestible protein to such an extent that the infected cell ceases to work properly and ultimately dies. Worse still was our learning that prions can, on at least some occasions, become infectious for species different from that in which it originated (much as the AIDS virus did). In this way some unfortunate humans became infected with the prion causing “mad cow disease” and suffered a tragic degeneration of the brain after simply eating beef that had come from cows fed on the offal of prion-infected animals. Prevention remains our best defense as finding a treatment for prion diseases will be extremely difficult.
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