Sludge Watch ==> New twist in tale of BSE's beginnings

[Maureen Reilly]

New twist in tale of BSE's beginnings
18.mar.07
NewScientist.com
Debora MacKenzie

The discovery that a rare brain disease in cows can mutate into BSE has, 
according to this story, given new life to the theory that mad cow disease 
started out in cattle, rather than crossing over from sheep.
The story says that the new twist to the story comes from studies of a 
disease called bovine amyloidotic spongiform encephalopathy, or BASE. It was 
discovered in 2003, when two Italian cows, out of tens of thousands of 
European cattle screened for BSE at slaughter, were found to have a prion 
disease that seemed different from BSE. The BASE prion had a lower molecular 
weight and one, rather than two, sugars bound to it. The brains of cows with 
BASE were also damaged in different places from those with BSE, and had 
dense protein deposits called amyloid that are not seen in BSE. Similar 
prions have also turned up in France, Germany and Japan.
Fabrizio Tagliavini and his colleagues at the Carlo Besta Neurological 
Institute in Milan, Italy, have now injected material from the brains of 
cows with BSE or BASE into mice. In animals genetically altered to make cow 
PrP - the normal form of the prion protein - BSE and BASE produced different 
symptoms and brain damage, confirming that BASE is a different disease.
If BASE can mutate into BSE, this could well be how mad cow disease emerged.
http://www.newscientist.com/article/dn11395-new-twist-in-tale-of-bses-beginnings.html