Table 1.

Potential candidate disease-associated transmissible proteins.

Disease	Protein (location)	Experimental Transmission	Natural Transmission	References*
Prion diseases	PrPSc (extracellular)	Infectious in diverse animal species by various routes	Infectious in diverse species by various routes	(Prusiner, 1998; Aguzzi and Calella, 2009)
Alzheimer's disease	Aβ (extracellular)	Induction of pathology in transgenic mice by intracerebral and intraperiotoneal inoculation	Not shown	(Kane et al., 2000; Meyer-Luehmann et al., 2006; Eisele et al., 2010; Morales et al., 2011)
Parkinson's disease	α-synuclein (cytoplasmatic)	Cell-to-cell and host-to-graft spreading in animal models	Host-to-graft spreading in humans	(Desplats et al., 2009; Luk et al., 2009; Volpicelli-Daley et al., 2011; Mougenot et al., 2011; Hansen et al., 2011)
Huntington's disease	Huntingtin (nuclear)	Cell-to-cell spreading in culture	Not shown	(Ren et al., 2009)
Tauopathies	Tau (cytoplasmatic)	Cell-to-cell spreading in culture and transmission in transgenic mice by intracerebral inoculation	Not shown	(Clavaguera et al., 2009; Frost et al., 2009; Nonaka et al., 2010; Guo and Lee, 2011)
Secondary amyloidosis	Amyloid-A (extracellular)	Acceleration of pathology in mice by various routes of administration	Possible transmission to captive cheetah	(Lundmark et al., 2002; Zhang et al., 2008)
Mouse senile amyloidosis	Apolipoprotein A (extracellular)	Acceleration of pathology in mice by various routes of administration	Transmission to mice in the same cage by feces consumption	(Xing et al., 2001; Korenaga et al., 2006)

^*There are several more references that could have been cited, but for space constraints only the most relevant articles are listed.