Assay involving looped nucleic acid

Abstract

Disclosed is a method of detecting the presence of a nucleic acid target sequence of interest in a sample, comprising the steps of: (a) reacting the sample containing the target sequence of interest with a first nucleic acid probe, so as to cause hybridization between complementary portions of the target and the probe, wherein the first probe comprises 5′ and 3′ portions complementary to respective, substantially adjacent portions of the target sequence and an intervening non-complementary portion which does not become hybridized to the target, thereby creating a loop region looped out from a complex formed between the first probe and the target, such that non-contiguous portions of the first probe are brought into close proximity; (b) hybridizing a second nucleic acid probe to the non-contiguous portions of the first probe, (c) initiating nucleic acid synthesis, using the first probe as template, in a manner dependent upon hybridization of the second probe to the first probe; and (d) detecting the newly synthesized nucleic-acid from step (c) above. Also disclosed are kits for performing the method of the invention.