Currently, there is no effective treatment for prion diseases. To date, hundreds of chemical compounds have been identified that antagonize prion propagation in vitro in cell culture-based assays and/or in vivo in animal studies [39] [40] [41] [42] [43] . Unfortunately, many compounds efficient in in vitro studies were only effective in animal models if treatment was begun before or close to the time of inoculation with the infectious agent [44] . Furthermore, many of the candidate compounds have limited usefulness clinically due to toxicity or their inability to cross the bloodbrain barrier [e.g. Congo red [45] , iododoxorubicin, b-sheet breakers].