Efficient algorithm for pcr testing of blood samples

Abstract

Systems, processes, and devices are provided which are useful for testing blood or plasma donations to detect those specific donations which are contaminated by a virus above a predetermined level. Samples are formed into pools which are subsequently tested for virus contamination by a high-sensitivity test such as PCR. The pools are tested in accordance with an algorithm by which a sample from each donation is mapped to each element of an N-dimensional matrix or grid. Each element of the matrix is identified by a matrix identifier, X rcs , where rcs defines the dimensional index. An aliquot is taken from each sample, and subpools are formed, each subpool comprising aliquots of samples in which one dimensional index is fixed. All of the subpools are tested in one PCR test cycle. The dimensional indicia of each positive subpool is evaluated mathematically in accordance with a reduction by the method of minors, thereby unambiguously identifying a unique element in the grid, thereby unambiguously identifying a uniquely positive blood or plasma donation.

1 . A method for forming subpools for use in detecting the presence of a viral contamination in a set of fluid samples prior to or after antibody accumulation against the viral contaminant using high-sensitivity PCR tests, the method comprising the operations of:
 (a) associating each of the fluid samples with a unique matrix element of an N-dimensional matrix, each of the matrix elements being identified by values of N indices, the N indices corresponding one-to-one to the N dimensions of the matrix;   (b) taking a single aliquot from each of the multiplicity of fluid donations and combining said aliquots into a single master pool;   (c) testing the master pool for the viral contamination using a high-sensitivity PCR test;   (d) providing an indication to a user as to whether the master pool contains a viral positive sample;   (e) forming N aliquots from each of the fluid samples;   (f) combining aliquots to form the subpools such that each of the subpools comprises one of the N aliquots taken exclusively from each of the fluid samples associated with matrix elements that have an identical value for one of the N indices;   (g) testing each of the subpools for the viral contamination using a high-sensitivity PCR test;   (h) producing a positive indication for each of the subpools in which the viral contamination is detected   (i) combining the positive identifications on the matrix to locate the fluid samples at the intersecting positive subpools; and   (j) where positive indications are provided in more than one subpool in more than one dimensional index of the matrix then directly testing each of the potentially positive samples with a high-sensitivity PCR test to detect the presence of the viral contamination, and producing a positive indication when the sample containing the presence of the viral contamination is detected.   
   
   
       2 . The method of  claim 1 , wherein the N indices have an identical range. 
   
   
       3 . The method of  claim 1 , wherein N is equal to 3. 
   
   
       4 . The method of  claim 1 , wherein the high-sensitivity PCR test is a test for detecting at least one form of HIV. 
   
   
       5 . The method of  claim 1 , wherein N is equal to 3 and there are 3 sets of said subpools corresponding to the 3 indices, each subpool of the 3 sets of subpools being identified by a specific value of a corresponding one of the N indices.