17 Biosafety Issues in Prion Diseases

Biosafety relevant to prions has been addressed in several guidelines and recommendations published by health authorities in an attempt to limit the potential risk associated with prion contamination in laboratory studies as well as in foods and medicinal products. Unfortunately, these issues are not always considered within the context of prion pathobiology and epidemiology. Instead, prion diseases still are treated as viral-like diseases, and this can result in erroneous assumptions and misguided regulations. Of the many distinctive features that separate prion diseases from viral, bacterial, fungal, and parasitic disorders, the most remarkable is that prion diseases can be manifest as infectious, inherited, and sporadic illnesses. Familial Creutzfeldt-Jakob disease (CJD), Gerstmann-Straussler-Scheinker syndrome (GSS), and fatal familial insomnia (FFI) are all dominantly inherited prion diseases; five different mutations of the PrP gene have been shown to be genetically linked to the development of inherited prion disease. Prions from many cases of inherited prion disease have been transmitted to apes, monkeys, and mice carrying human PrP transgenes (Brown et al. 1994a; Telling et al. 1995, 1996). In all three manifestations of prion disease, infectious prions are generated in the brains of afflicted individuals, and these prions are composed of the disease-causing isoform (PrP Sc ) of the prion protein (PrP) with the amino acid sequence encoded by the PrP gene of the affected host. When prions are passaged into the brain of a different host species, a “species barrier,” related primarily to interspecies differences in PrP sequences and, in some instances, to prion strain, is...