The present invention provides antibodies that specifically bind with a
high degree of binding affinity to a native ungulate PrP.sup.C and/or a
denatured ungulate PrP.sup.Sc, but not to a native ungulate PrP.sup.Sc.
Preferred antibodies find native bovine PrP.sup.C and treated PrP.sup.Sc
but not native bovine PrP.sup.Sc and can be used in an assay to determine
if a sample is infected with infectious prions, i.e. PrP.sup.Sc.
