Immunological Therapeutic and Imaging Approaches for Prion Disease

Currently there is no effective treatment or prophylaxis against prion diseases. Although sporadic forms of this disease are relatively rare, the incidence of the transmissible prionoses is rising as a result of the exposure of Western European populations to bovine spongiform encephalopathy. It has been recently demonstrated in animal models that active or passive immunization may delay the onset of disease or even protect from the occurrence of symptoms if started prior to prion replication involving the central nervous system. Results of these animal studies suggest that development a vaccination approach for humans is feasible within the near future. Another aspect of prion diseases, potentially limiting the practical use of the vaccine, is lack of diagnostic tests detecting infected, non-symptomatic subjects. This can partially be overcome using high field magnetic resonance imaging (MRI), which in animal models is capable of detecting signal alterations in the brain before the onset of symptoms. Another potential way to improve the sensitivity and specificity for prion infection diagnosis is using ligands specifically targeting the β-sheet structure of PrPSc or anti-PrP antibodies. These can be coupled either with paramagnetic agents or radioisotopes making PrPSc detectable using MRI or scintigraphy respectively. Successful development of such ligands has been demonstrated for Alzheimer's disease and is currently being studied for prionoses.