The hallmark behavior of both prion types is a promiscuous shape change: Once a normal prion protein adopts an abnormal shape, it will induce other proteins of the same type to do the same, causing them all to clump as insoluble aggregates.
A set of roughly 300 differentially expressed genes (DEGs) that were common to different experimental conditions (mouse strains and prion types) was identified from these analyses.
For a comparative molecular study of prion typing, frozen brains were collected by the NPDPSC from genetic prion disease (gPrD) E200K-129 V (n = 4), E200K-129M (n = 3), sCJDMM1 (n = 1) and sCJDVV2 (n = 1).
The two types of fibrils apparently represented distinct conformers of aggregated α-synuclein, and their different effects in terms of the stimulation of tau aggregation may be indicative of analogies to phenomena observed in the context of prion strains or prion types.
On this basis, phenotypically distinct prion agents that are made up of PrP with an identical amino acid and referred to as prion "types" or "strains" can exist and propagate in vivo in the form of different PrP conformers [ 14, 45, 94].
Proteins showing prion-type behavior are also found in some fungi, which has been useful in helping to understand mammalian prions.
Sup35p can exist in an aggregated prion form in S. cerevisiae [13], however, the strain used in this study has no such prion-type aggregates (data not shown).
There is also evidence that Aβ and neurofibrillary tangle pathologies can spread in a similar prion-type mechanism as α-synuclein and that α-synuclein may cross-seed both of these pathologies [ 15], but in this review we will focus only on the findings directly involving α-synuclein.
Unlike many diseases, C.J.D. is caused not by a virus or bacteria but by a misformed prion (a type of protein) that no longer performs its proper function in the body.
Scientists have created an artificial prion, a type of protein whose misshapen version is implicated as the cause of several fatal and infectious conditions, including "mad cow disease" and human Creutzfeldt-Jakob disease.
As it has now become clear that prion strain type, host genetic makeup and numerous other factors may significantly influence prion disease phenotype, it is expected that the actual number of distinct human prion strains may be far less than the number of identified phenotypes.
