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Nucleic acid sequence amplification methods

  • US 5,399,491 A
  • Filed: 03/19/1992
  • Issued: 03/21/1995
  • Est. Priority Date: 07/11/1989
  • Status: Expired due to Term
First Claim
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1. A method of synthesizing multiple copies of a target nucleic acid sequence which consists essentially of:

  • (a) treating a nucleic acid which comprises an RNA target sequence with a first oligonucleotide which comprises a first primer which has a hybridizing sequence sufficiently complementary to a 3'"'"'-terminal portion of the target sequence to hybridize therewith and which optionally has a sequence 5'"'"' to the hybridizing sequence which includes a promoter for an RNA polymerase, under conditions whereby an oligonucleotide/target sequence hybrid is formed and DNA synthesis may be initiated;

    (b) extending the primer in an extension reaction using the target as a template to give a DNA primer extension product complementary to the RNA target;

    (c) separating the DNA primer extension product from the RNA target using an enzyme which selectively degrades the RNA target;

    (d) treating the DNA primer extension product with a second oligonucleotide which comprises a primer or a splice template and which has a hybridizing sequence sufficiently complementary to the 3'"'"'-terminal portion of the target sequence to hybridize therewith, under conditions whereby an oligonucleotide/target sequence hybrid is formed and DNA synthesis may be initiated, provided that if the first oligonucleotide does not have a promoter, then the second oligonucleotide is a splice template which has a sequence 5'"'"' to the hybridizing sequence which includes a promoter for an RNA polymerase;

    (e) extending the 3'"'"'-terminus of either the second oligonucleotide or the first primer extension product, or both, in a DNA extension reaction to produce a template for an RNA polymerase; and

    (f) using the template of step (e) to produce multiple RNA copies of the target sequence using an RNA polymerase which recognizes the promoter sequence;

    wherein said method is conducted under conditions of constant temperature and wherein a reverse transcriptase comprising RNase H activity is used in the method, and no other enzyme comprising RNAse H activity is used in the method.

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