Abstract: The invention includes an artificial PrP gene, a transgenic animal containing a PrP gene of another animal or the artificial PrP gene, a hybrid non-human mammal with an ablated endogenous prion gene and exogenous prion gene and assay methodology which uses the animals to detect pathogenic prions in a sample or diagnose a cause of death. The artificial gene includes a sequence such that when it is inserted into the genome of a host animal (such as a mouse), the animal is rendered susceptible to infection with prions which normally would infect only a genetically diverse test animal (such as human, cow or sheep). The artificial PrP gene may be comprised of a completely artificial polynucleotide sequence. Alternatively, the artificial gene may be comprised of the codon sequence of a host animal with one or more codon substitutions being made wherein the substitutions are preferably corresponding PrP gene codons from a genetically diverse test animal.

Abstract: Prions are protein based infectious material that cause of variety of diseases such as Scrapie, bovine spongiform encephalopathy (also known as "Mad Cow" disease), Creutzfeldt Jakob Disease, Kuru, and fatal familial insomnia. The invention is directed to artificial prion genes that are made up of elements of the prion genes of a host and test species. When these artificial prion genes are inserted into a transgenic mouse, the resultant mouse becomes susceptible to infection with prions that infect the test species but do not normally infect mice. The transgenic animals are useful for testing for the presence of prions in a sample.