Cross-species transmission of CWD prions

Assessment of the PrP c Amino-Terminal Domain in Prion Species Barriers

“…A favored interpretation of these data describes a steric zipper, wherein very few amino acid changes can severely disrupt the tertiary structure. Several polymorphisms between human and WTD PrP c s exist in this region, which may explain the apparent resistance of humans to CWD (39,40). However, our data indicate that the variation in the ␤2-␣2 loop does not prevent in vitro conversion, which suggests that factors in addition to the PrP c -PrP Sc interactions we modeled in vitro must influence in vivo conversion.…”

“…Despite these reports, prion species barriers remain mostly empirical. While the most important known factor in transspecies transmission is the compatibility of the PrP c amino acid sequences, there is evidence that the tertiary and quaternary structures of PrP Sc also influence prion transmission (36)(37)(38)(39).…”

Chronic Wasting Disease: Neuro-infectivity as a Result of Oral-fecal Transmission by a Prion

“…Reports [2] have shown CWD (prions) exist in muscle of infected organisms. This suggests risk is low regarding transmission and possibly due to genetic differences may actually not be transmittable to man (cross-species transmission) [2,6,7]. Protection of man from CWD may be due to requirements for transmission occurring only when certain genetic polymorphisms exist allowing change of the PRPc to the infectious form [6,7,19,20].…”

“…This suggests risk is low regarding transmission and possibly due to genetic differences may actually not be transmittable to man (cross-species transmission) [2,6,7]. Protection of man from CWD may be due to requirements for transmission occurring only when certain genetic polymorphisms exist allowing change of the PRPc to the infectious form [6,7,19,20]. Based on amino acid evidence (structural determinants) of CWD and human PrP it appears there is a substantial barrier for disease transmission of this agent to humans [6,7,19,20].…”

“…However, the structure of the CWD prion may be the primary reason why this "disease" has not been reported in man; although, consumption of contaminated meat commonly occurs [6]. Amino acid differences may act as a barrier in transferring CWD (PrP CWD ) to other species, most notably man and cattle [7].…”