LETTERS: Breathing in the BSE molecules

Sir: Dr J S Knowland's suggestion (letter, 29 March) that non- oral routes could be responsible for the transmission of BSE and other prion-based diseases appears very reasonable.

It is generally assumed that in prion diseases harmless naturally occurring protein molecules are being transformed into harmful molecules with a different configuration. It is supposed that molecules already transformed tend to act as seeds on which harmless molecules are deposited and rendered into pathogenic ones.

Airborne particles with pathogenic prion molecules at their surface when presented to endings of olfactory nerves could initiate a degenerative process which propagates along the nerve and eventually reaches the brain. The precise nature of such a process can only be understood when more is known about the function and location of natural prion protein in the nervous system.

Dr J Lucassen

Oegstgeest, The Netherlands