Manage
ment responses to prion diseases of cattle, deer,and elk create a significant need for safe and effectivedisposal of infected carcasses and other
materials.Further
more, soil
may contribute to the horizontal trans
missionof sheep scrapie and cervid chronic wasting disease byserving as an environ
mental reservoir for the infectious agent.As an initial step toward understanding prion
mobility inporous
materials such as soil and landfilled waste, theinfluence of pH and ionic strength (
I) on pathogenic prionprotein (PrP
Sc) properties (viz. aggregation state and
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mages/gifchars/zeta.gif" BORDER=0 >-potential) and adsorption to quartz sand was investigated.The apparent average isoelectric point of PrP
Sc aggregateswas 4.6. PrP
Sc aggregate size was largest between pH4 and 6, and increased with increasing
I at pH 7. Adsorptionto quartz sand was
maxi
mal near the apparent isoelectricpoint of PrP
Sc aggregates and decreased as pH eitherdeclined or increased. PrP
Sc adsorption increasedas suspension
I increased, and reached an apparentplateau at
I ~ 0.1 M. While trends with pH and
I in PrP
Scattach
ment to quartz surfaces were consistent withpredictions based on Born-DLVO theory, non-DLVO forcesappeared to contribute to adsorption at pH 7 and 9 (
I =10
mM). Our findings suggest that disposal strategies thatelevate pH (e.g., burial in li
me or fly ash),
may increasePrP
Sc mobility. Si
milarly, PrP
Sc mobility
may increase as alandfill ages, due to increases in pH and decreases in
Iof the leachate.