17 Biosafety Issues in Prion Diseases

Abstract

Biosafety relevant to prions has been addressed in several guidelines, and recommendations have been 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 often are not considered within the context of prion pathobiology and epidemiology. Instead, prion diseases 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. Yet in all three manifestations of prion disease, infectious prions are generated in the brains of afflicted individuals, and these prions are composed of PrP^Sc molecules 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 is responsible for inefficient infection (Pattison 1965; Scott et al. 1989; Telling et al. 1995). If interspecies transmission does occur, then the prions generated in the brain of the alternate host carry the amino acid sequence encoded by the PrP gene of that particular species and not the PrP sequence found in the original inoculum. In other words, in interspecies infection, such as from sheep to cattle or from cattle to humans, the prions that replicate in the host brain are...