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Amplification of target nucleic acids using gap filling ligase chain reaction

  • US 5,427,930 A
  • Filed: 06/28/1991
  • Issued: 06/27/1995
  • Est. Priority Date: 01/26/1990
  • Status: Expired due to Term
First Claim
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1. A method for detecting the presence of a target nucleic acid in a sample, said method employing a ligase chain reaction to create geometrically increasing numbers of reorganized probe molecules in the presence of said target nucleic acid, said method comprising:

  • a) providing a sample suspected to contain nucleic acid, the nucleic acid having a target sequence of the formula;

    5'"'"'-(N)h XEp Fq Z(N)k -3'"'"' or its complement 3'"'"'-(N'"'"')h X'"'"'E'"'"'p F'"'"'q Z'"'"'(N'"'"')k -5'"'"', wherein E represents any base, E'"'"' is the complement of E, F represents any base except E, F'"'"' is the complement of F, p and q are independently integers from 1 to about 10, X represents any base except E or F'"'"', X'"'"' is the complement of X, Z represents any base except F or E'"'"', Z'"'"'is the complement of Z, N represents any base, and h and k are independently integers from 5 to 100, provided (p+h) and (q+k) each are greater than 10, wherein (N)h and (N)k represent sequences that are characteristic for the target sought to be detected;

    b) providing a plurality of each of four probes having the formulas;

    
    
    space="preserve" listing-type="equation">5'"'"'-(N).sub.h X E.sub.p -3'"'"' A
    
    
    space="preserve" listing-type="equation">3'"'"'-(N'"'"').sub.h X'"'"'-5'"'"' A'"'"'
    
    
    space="preserve" listing-type="equation">5'"'"'-Z(N).sub.k -3'"'"' B
    
    
    space="preserve" listing-type="equation">3'"'"'-F'"'"'.sub.q Z'"'"'(N'"'"').sub.k -5'"'"'wherein N, N'"'"', X, X'"'"', Z, Z'"'"'E, F'"'"', h, p, k and q are defined above, except that A and A'"'"' or B and B'"'"' need not be identical in length, and wherein at least one of the probes is labeled with a moiety capable of detection; and

    also providing deoxyribonucleotide triphosphates of E'"'"' and F, a polymerase reagent and a ligase reagent;

    c) performing the following cycle at least once;

    i) mixing said probes with said sample under hybridizing conditions to allow probes to hybridize to the target sequence and its complement if present, or to reorganized probes created therefrom;

    ii) using target sequence or reorganized probes created therefrom as template, extending probe A with said polymerase reagent by adding F deoxyribonucleotide triphosphates to its 3'"'"' end, and extending probe B'"'"' with said polymerase reagent by adding E'"'"' deoxyribonucleotide triphosphates to its 3'"'"' endiii) ligating extended probe A to probe B, and extended probe B'"'"' to probe A'"'"', using said ligase reagent to form reorganized probe molecules; and

    iv) providing denaturing conditions to separate said reorganized probe molecules from said template;

    d) separating reorganized probe molecules from unreorganized labeled probes; and

    e) detecting the presence of said labeled probes in the reorganized or unreorganized fraction as a measure of the presence of the target sequence.

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