Prion protein standard and method of making same

Abstract

The invention provides prion protein standards for use as reference materials for prion detection. The standard may be species specific, i.e. the standard is comprised of a preparation for detection of a single strain prion or it may be prepared to allow detection of multiple prion strains simultaneously. The invention also provides methods of preparing the prion protein standards using a group of non-human host mammals which have their genome manipulated with respect to genetic material related to a PrP gene such that the mammals are susceptible to infection with a prion which generally only infects an animal which is genetically diverse from the host.

1 .- 28 . (canceled)  
     
     
         29 . A method of calibrating an assay for detecting prions, comprising: 
 using a standardized prion preparation as an assay calibration standard, wherein the preparation comprises homogenized brain tissue of a plurality of transgenic mice.    
     
     
         30 . The method of  claim 29 , wherein the preparation is characterized by containing prions (a) which infect and cause disease in a known species of animal, (b) which are of a known strain, and (c) which are present in a known amount.  
     
     
         31 . The method of  claim 29 , wherein the preparation further comprises a carrier of a known composition which is different from brain tissue of the mammal which the prions would infect in the animal's natural state.  
     
     
         32 . The method of  claim 30 , wherein the known amount is a known number of infectious units and known concentration of prions and wherein the known species is selected from the group consisting of human, cow and sheep.  
     
     
         33 . The method of  claim 29 , wherein the preparation comprises prions which infect and cause disease in a mammal selected from the group consisting of human, cow and sheep.  
     
     
         34 . The method of  claim 31 , wherein substantially all prions present in the preparation are of a single strain and wherein the carrier is comprised of water.  
     
     
         35 . The method of  claim 34 , wherein the strain is generated from a polymorphism selected from the group consisting of: human M129, human V129, human E219, human K219, sheep R171, sheep E171, sheep A136, sheep V136, a bovine 5 octarepeat polymorphism, and bovine 6 octarepeat polymorphism.  
     
     
         36 . The method of  claim 34 , wherein the strain is human and is generated from a pathogenic mutation selected from the group consisting of: a 2 octarepeat insert, a 4 octarepeat insert, a 5 octarepeat insert, a 6 octarepeat insert, a 7 octarepeat insert, an 8 octarepeat insert, a 9 octarepeat insert, P102L, P105L, A117V, D178N, V180I, F198S, E200K, V210I, D217R, M232A, codon at 145.  
     
     
         37 . The method of  claim 29 , wherein the preparation is comprised of prions of a plurality of different known strains and wherein the prions are obtained from 10 or more animals, and further wherein the prions are produced in a transgenic mouse having a genome comprising exogenous genetic material encoding at least a portion of a PrP protein.  
     
     
         38 . The method of  claim 29 , wherein the preparation is comprised of prions obtained from a mouse having an ablated endogenous PrP gene and a genome manipulated to express a high copy number of an exogenous PrP gene from a genetically diverse animal, and wherein the mouse spontaneously forms prions that normally infect the genetically diverse animal wherein the genetically diverse animal is selected from the groups consisting of a human, cow, sheep, dog, cat, goat, chicken or turkey.  
     
     
         39 . The method of  claim 29 , wherein the preparation is comprised of prions uniformly dispersed in the preparation and the prions are produced in a transgenic mouse selected from the group consisting of: Tg(HuPrP), Tg(HuPrP)/Prnp +/0  Tg(HuPrP)/Prnp 0/0 , Tg(HuPrP CJD ), Tg(HuPrP CJD )/Prnp +/0 , Tg(HuPrP CJD )/Prnp 0/0 , Tg(SHaPrP), Tg(SHaPrP +/0 )81/Prnp 0/0 , Tg(SHaPrP)/Prnp +/0 , Tg(SHaPrP)/Prnp 0/0 , Tg(ShePrP), Tg(ShePrP)/Prnp +/0 , Tg(ShePrP)/Prnp 0/0 , Tg(BovPrP), Tg(BovPrP)/Prnp +/0 , and Tg(BovPrP)/Prnp 0/0 .  
     
     
         40 . The method of  claim 29 , wherein the transgenic mouse is selected from the group consisting of: Tg(MHu2M), Tg(MHu2M)/Prnp +/0 , and Tg(MHu2M)/Prnp 0/0 .  
     
     
         41 . The method of  claim 29 , wherein the transgenic mice are selected from the group consisting of: Tg(HuPrP)/Prnp 0/0 , Tg(ShePrP)/Prnp 0/0 , and Tg(BovPrP)/Prnp 0/0 .  
     
     
         42 . A method of calibrating an assay, comprising: 
 using a standardized prion preparation comprising prions obtained from a plurality of mice which are Tg (BovPrP)Prnp 0/0  and a carrier as a calibration standard;    wherein the prions are present in a known number of infectious units and infect and cause disease in a cow and are prions of a known strain.