New data on "mad cow" disease

A research team at the University of Navarre has detected the presence of the prion protein in the digestive tract of three animal species: the autochthonous Pyrennean cow, in a primate and in rats. This study is the first to describe the exact location of the “healthy” form of the prion (PrPc), a protein necessary for the development of prionic diseases in these three species.

The results obtained by the Navarre researchers provide new data on the propagation of the prion and on the development of encephalopathies through the ingestion of contaminated food. It is important to underline that these discoveries could be extrapolated to other species, including the human.

As is known, the majority of cases of bovine spongiform encephalopathy (BSE) detected in Navarre province in the 2001-2004 period correspond to the Pyrennean cow breed. The pathogen prion, PrPsc, is the cause of the mad cow disease. The research into prions is still scant, although it intensified as a result of the mad cow problem.

Locating the prions – the first phase of the study

Prions are proteins that are the causal agent of transmissible spongiform encephalopathies (TSEs), a group of neurodegenerative illnesses which currently have no cure and which affect both animals and humans. Prionic illnesses are characterised by the accumulation in the brain of the pathogenic form (PrPsc) of the normal protein (PrPc), present in all mammals. In order for the disease to develop and manifest itself, the presence of the PrPc in the host tissues is indispensable. Moreover, in TSEs of infectious origin, the actual pathogenic agent enters the organism. Although there are several possible ways for the pathogen to enter, it has always been suggested that that the principal way is orally, through the ingestion of contaminated food. Once the pathogenic form has penetrated, this propagates and accumulates, transforming the PrPc present. Nevertheless, it is still unknown today how exactly this process occurs, i.e. how the protein manages to penetrate the wall of the digestive tract, make contact with the PrPc, transform it and finally recah the brain, where the damage is carried out. In order to decipher the keys to the process, it is important to know the exact location of the PrPc in the digestive tract, and this is what the research has been aimed at.