Sheep may not be responsible for the development of BSE, believes a research team.
The bovine epidemic BSE may have developed from a rare, naturally occurring brain disease in cows and not, as previously thought, from the sheep disease scrapie. This is indicated by the results of an international research team on mice. Were the animals infected with the causative agent of the primordial bovine phenomenon BASE, which sometimes occurs in older cattle, did they develop the symptoms characteristic of BSE under certain conditions? and not the disease symptoms typical of the course of BASE. Should this suspicion be confirmed, measures to prevent further epidemics and to protect humans would have to be reconsidered. Since the mid-1980s, the first BSE cases in cattle in Britain occurred, scientists consider contaminated feed for the epidemic triggers. According to the theory, the feed contained the remains of sheep that had been infected with the scrapie scrapie, whose pathogens then passed to the cattle and caused the typical brain damage there. However, there were doubts about this scenario from the beginning, reports the online service of the science magazine New Scientist. For example, attempts to spread scrapie to cattle failed, and moreover, there had not been BSE cases in every country where sheep cadavers were processed into feed. For this reason, scientists had long suspected that BSE could be a modification of a naturally occurring prion disease in cattle.

This suspicion is now supported by the results of Raffaella Capobianco and her team. The scientists studied the causative agents of BASE, a prion disease that was first observed in 2003 in two Italian cows and later also in Germany, France and Japan. Although the responsible proteins are also misfolded forms of the natural prion protein, their structure and their distribution in the brain differ significantly from the BSE agents. When the researchers infected their test mice with these proteins, only a single disease developed? that of BSE, not of BASE. In a second series of experiments, in which some mice were given brain material of the first group, finally all animals became ill with BSE.

Thus, BSE could actually be a modified and more aggressive variant of BASE, the researchers conclude. It may also have been a kind of intermediate host involved in this change, for example, sheep that were fed with cattle carcasses. It now needs to be carefully examined whether BASE can pass on to humans and how exactly the BSE epidemic arose to avoid further cases of contagion, they emphasize.

New Scientist, online service Original text: Raffaella Capobianco (Neurological Carlo-Besta Institute, Milan) et al .: PLoS Pathogens, DOI: 10.1371 / journal.ppat.0030031 ddp / Ilka Lehnen-Beyel advertisement


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