Patent ID: 7256020

Claim:
A method for detecting a target sequence, comprising: a) providing a sample containing nucleic acid suspected of containing a target sequence; b) generating an amplification product from said target nucleic acid, wherein said generating comprises formation of a circular nucleic acid by i) annealing a probe oligonucleotide that forms a first invasive cleavage structure in the presence of said target sequence, ii) cleaving said first invasive cleavage structure to form an annealed gapped structure, iii) ligating said annealed gapped structure to form a circular nucleic acid; c) treating said circular nucleic acid to amplification reaction conditions to produce an amplification product comprising no more than 8 contiguous bases that identically match said target sequence or its complement, and d) exposing said amplification product to oligonucleotides capable of forming a second invasive cleavage structure with said amplification product and an agent for detecting the presence of said second invasive cleavage structure.