The present invention comprises a method for producing mammalian
therapeutics free from prion contamination and cells for use in such
methods. Such therapeutics are produced in somatic cells having a genome
with an artificially altered PrP gene. The PrP gene in these cells may be
ablated, or replaced by an exogenous inducible form of the PrP gene. The
endogenous gene in the host cells may be disrupted, or disrupted and
replaced by an exogenous PrP gene.
