PREPARATION OF SAMPLE FOR DIAGNOSTIC TEST BASED ON NUCLEIC ACID

PROBLEM TO BE SOLVED: To provide a new method for preparing a sample in which a liquid biological material is pooled, enabling to enhance the sensitivity of the diagnostic test based on nucleic acid. SOLUTION: A precipitating agent (e.g. polyethylene glycol, dextral sulfate or ammonium sulfate) is added to selectively precipitate nucleic acid, thereby improving the sensitivity of the diagnostic test for detecting the nucleic acid of an infectious substance in a sample in which a liquid biological material is pooled. A preferable precipitating agent is polyethylene glycol(PEG) having a mol.wt. range of 1,000-10,000 and having a final concentration of 1-5%(w/v). A monovalent or divalent salt, preferably the monovalent salt, is further added to accelerate the precipitation of the uncleic acid, The monovalent salt is preferably NaCl or KCl. The amount of the salt to be added depends on the concentration of a salt already existing in the biological sample, and is commonly about 145 mM salt which is a physiological salt concentration. The final salt concentration of the mixture is preferably 200-450 mM, most preferably 270-325 mM.