Assay for prions

Abstract

The invention relates to a method for detection of abnormal PrP in a sample of blood or urine, said method comprising: (a) diluting the sample with buffer to comprise final concentrations of (i) 10 mM to 500 mM buffer agent; (ii) 1% to 10% w/v bovine serum albumin; and (iii) 1% to 8% w/v CHAPS; (b) adding steel particles and incubating to allow PrP binding; (c) washing the steel particles to remove diluted sample; and (d) detecting abnormal PrP captured on the steel particles using antibody capable of binding said abnormal PrP. The invention also provides compositions and kits.

1 . A method for detection of abnormal PrP in a sample of urine, said method comprising:
 (a) diluting the urine sample with buffer to comprise final concentrations of
 (i) 10 mM to 500 mM buffer agent; 
 (ii) 1% to 10% w/v bovine serum albumin; and 
 (iii) 1% to 8% w/v 3-[(3-cholamidopropyl)dimethylammonio]-1-propanesulfonate (CHAPS); 
 wherein said buffer does not include chaotropic agents or proteinases; 
   (b) adding steel particles and incubating to allow PrP binding;   (c) washing the steel particles to remove diluted sample;   (d) subjecting the washed steel particles to a heat treatment; and   (e) detecting abnormal PrP captured on the steel particles using antibody or portion thereof capable of binding said abnormal PrP; wherein said method is practiced without use of chaotropic agents or proteinases.   
     
     
         2 . The method according to  claim 1  wherein step (a) comprises diluting the sample with buffer to comprise final concentrations of
 (i) 50 mM to 200 mM buffer agent; 
 (ii) 1% to 4% w/v bovine serum albumin; and 
 (iii) 2% to 4% w/v CHAPS. 
 
     
     
         3 . The method according to  claim 1 , wherein step (a) comprises diluting the sample with buffer to comprise final concentrations of
 (i) 100 mM buffer agent;   (ii) 2% w/v bovine serum albumin; and   (iii) 2% w/v CHAPS.   
     
     
         4 . The method according to  claim 1 , wherein the urine sample is diluted with buffer in the range of 2:1 to 1:2. 
     
     
         5 . The method according to  claim 4 , wherein the urine sample is diluted with buffer at 1:1. 
     
     
         6 . The method according to  claim 1 , wherein the buffer further comprises protease inhibitors. 
     
     
         7 . The method according to  claim 1 , wherein the antibody of step (e) is selected from the group consisting of ICSM10, ICSM18, ICSM33, ICSM35, and portions thereof. 
     
     
         8 . The method according to  claim 7 , wherein
 the sample is from a tga20 mouse and the antibody is ICSM10 or a portion thereof; or   the sample is from a CD1 mouse and the antibody is ICSM33 or a portion thereof; or   the sample is from a hamster and the antibody is ICSM18 or a portion thereof; or   the sample is from a sheep and the antibody is selected from the group consisting of ICSM10, ICSM18, ICSM33, ICSM35, and portions thereof; or   the sample is from a cow and the antibody is ICSM18 or a portion thereof; or   the sample is from a human and the antibody is ICSM18 or a portion thereof.   
     
     
         9 . The method according to  claim 1 , wherein step (d) comprises subjecting the steel particles to a heat treatment for 5 minutes. 
     
     
         10 . The method according to  claim 9 , wherein
 the sample is from a tga20 mouse and heat treatment is at 50 to 110 degrees Celsius; or   the sample is from a CD1 mouse and heat treatment is at 50 to 110 degrees Celsius; or   the sample is from a hamster and heat treatment is at 20 to 115 degrees Celsius; or   the sample is from a sheep and heat treatment is at 115 degrees Celsius; or   the sample is from a cow and heat treatment is at 120 degrees Celsius; or   the sample is from a human and heat treatment is at 50 to 115 degrees Celsius.   
     
     
         11 . The method according to  claim 10 , wherein the steel particles comprise AISI 316 stainless steel. 
     
     
         12 . The method according to  claim 1 , wherein the buffer agent is Tris. 
     
     
         13 . The method according to  claim 1 , wherein the pH is 8.4. 
     
     
         14 . The method according to  claim 1 , wherein the urine is human urine. 
     
     
         15 . Use of a dry composition comprising Tris:BSA:CHAPS in the weight ratio 1:1.65:1.65 or a solution comprising Tris:BSA:CHAPS in the molar ratio 1:0.003:0.32 for detection of abnormal PrP in a urine sample. 
     
     
         16 . A method of aiding the diagnosis of prion infection in a subject, the method comprising
 (a) providing a sample of urine from said subject; and   (b) assaying said sample of urine for abnormal PrP according to  claim 1 , wherein detection of abnormal PrP indicates an increased likelihood of prion infection in the subject.   
     
     
         17 . The method of  claim 10 , wherein the sample is from a human and the heat treatment is at 110 degrees Celsius.