Prion Disinfection

Abstract

The invention relates to a methods and compositions for treating a surface, suspension or solution contaminated with a PrP Sc prion protein or a surrogate thereof. The methods and compositions employ a combination of one or more enzymes effective to cleave a prion protein to fragments having a non-infective molecular weight, and one or more agents selected to favour conformational unfolding of the PrP Sc prion protein while not denaturing the one or more enzymes.

1 - 21 . (canceled) 
     
     
         22 . A method of disinfection comprising the steps of treating a surface, suspension, or solution contaminated with a PrP Sc  prion protein simultaneously 5 with a combination comprising:
 (1) one or more enzymes effective to cleave a PrP Sc  prion protein to fragments having a non-infective molecular weight;   (2) an anionic surfactant selected to favor conformational unfolding of the PrP Sc  prion protein while not denaturing the one or more enzymes; and   (3) one or more agents selected to promote or protect folding of the one or more enzymes, without preventing cleavage of the PrP Sc  prion protein, and   (4) wherein the conditions are selected to favor unfolding over refolding and wherein the combination of the enzyme, the anionic surfactant and the one or more agents is selected so as to effectively cleave a prion surrogate which is a protein with a high degree of sheeting.   
     
     
         23 . A method according to  claim 22  wherein the treatment is selected so as to result after cleavage in a predetermined percentage of the protein fragments having a molecular weight of less than a predetermined molecular weight. 
     
     
         23 . A method according to  claim 22  wherein at least 90% of the protein fragments after cleavage have a molecular weight of less than 27 kDa 
     
     
         25 . A method according to  claim 22  wherein at least 90% of the protein fragments after cleavage have a molecular weight of less than 25 kDa. 
     
     
         26 . A method according to  claim 22  wherein at least 90% of the protein fragments after cleavage have a molecular weight of less than 23 kDa. 
     
     
         27 . A method according to  claim 23  or  26 , wherein the conditions are selected to protect or refold the one or more enzymes while irreversibly unfolding or at least opening the prion sufficiently for access by the enzyme. 
     
     
         28 . A method according to  claim 22  further including in the combination one or more agents selected from the group consisting of irradiation, electric field, magnetic field, energetic vibration and combinations thereof. 
     
     
         29 . A method according to  claim 28  wherein the energetic vibration is one or more of ultrasound, electromagnetic or mechanical vibration. 
     
     
         30 . A method according to  claim 22  wherein the one or more enzymes are selected from serine proteinases, aspartic acid proteinases, metalloproteinases, keratinises, collegenases and enzymes possessing proteolytic activity. 
     
     
         31 . A method according to  claim 22  further including in the combination one or more agents selected to promote unfolding from the group consisting of heat, pH, organic solvents of the kind which tend to denature proteins, chaotropic agents, surfactants tending to bind proteins, inorganic salts which are strong denaturants of proteins, agents which cause S—S bond scission, substances having a strong affinity for hydrophilic residues of amino acids, substances having a strong affinity for hydrophobic residues of amino acids, substances promoting adsorption on surfaces, anionic surfactants and combinations of the foregoing. 
     
     
         32 . A method according to  claim 22  wherein the one or more agents selected to promote or protect folding of the one or more enzymes is selected from the group consisting of nucleophilic solvents, weakly protic stabilizing solvents, non ionic surfactants, ionic surfactants, zwitterionic and amphoteric surfactants, buffers, surface active homo-co- or block copolymers, sulphated compounds, deoxycholate, glycosaminoglycans and combinations of the foregoing. 
     
     
         33 . A composition for treating a surface contaminated with a PrP Sc  prion protein or a surrogate thereof comprising:
 (1) one or more enzymes effective to cleave a PrP Sc  prion protein to fragments having a non-infective molecular weight;   (2) an anionic surfactant selected to favor conformational unfolding of the PrP Sc  prion protein while not denaturing the one or more enzymes; and   (3) one or more agents selected to promote or protect folding of the one or more enzymes, without preventing cleavage of the PrP Sc  prion protein, and   (4) wherein the conditions are selected to favor unfolding over refolding and wherein the combination of the enzyme, the anionic surfactant and the one or more agents is selected so as to effectively cleave a prion surrogate which is a protein with a high degree of sheeting.   
     
     
         34 . A composition according to  claim 33  wherein the anionic surfactant and one or more agents are selected so as to result after cleavage in a predetermined percentage of the protein fragments having a molecular weight of less than a predetermined molecular weight. 
     
     
         35 . A composition according to  claim 33  wherein the anionic surfactant and one or more agents is selected so as to result after cleavage in at least 90% of the protein fragments after cleavage having a molecular weight of less than 27 kDa. 
     
     
         36 . A composition according to  claim 34  wherein the anionic surfactant and the one or more agents is selected so as to result after cleavage in at least 90% of the protein fragments having a molecular weight of less than 25 kDa. 
     
     
         37 . A composition according to  claim 33  wherein the anionic surfactant and the one or more agents is selected so as to result after cleavage in at least 90% of the protein fragments having a molecular weight of less than 23 kDa. 
     
     
         38 . A method of treating a surface contaminated with a PrP Sc  prion protein or a surrogate thereof wherein the surface is treated with a composition according to any one of  claims 33 - 37 . 
     
     
         39 . A method according to  claim 38  wherein the surface is the surface of a medical or surgical instrument. 
     
     
         40 . A method according to  claim 38  wherein the surface is a food preparation or hospital work surface.