| abstract |
The present invention provides a method for detecting or enriching for a target deoxyribonucleic acid (DNA) present in a nucleic acid sample, said method comprising: (a) fragmenting a nucleic acid sample to generate nucleic acid fragments including a target fragment containing said target DNA; (b) rendering said fragments, including said target fragment, at least partially single-stranded, wherein the single-stranded portion includes an end portion and wherein the length of said single-stranded portion is sufficient to allow hybridisation of at least part of the single-stranded portion of said target fragment to the probe of step (c); (c) contacting the at least partially single-stranded fragments of step (b) with oligonucleotides A and B of a single target-specific nucleic acid probe, wherein: (i) oligonucleotide A is a single-stranded oligonucleotide comprising at one end a first target-specific part comprising at least 10 nucleotides complementary in sequence to at least part of said single-stranded portion of said target fragment, and comprising at the other end a second non-target-specific part which comprises a nucleotide sequence complementary to at least a portion, including one end, of oligonucleotide B of the probe, and (ii) oligonucleotide B is a single-stranded oligonucleotide which may contain or carry at least one element for detection and/or enrichment of said target fragment, and of which at least a portion, including one end, is complementary in sequence to the second non-target-specific part of oligonucleotide A, such that said target fragment becomes annealed to said probe through hybridisation to the first target-specific part of oligonucleotide A resulting in only one target-specific probe-binding event per target fragment; (d) ligating oligonucleotide B of said probe to the part of the single-stranded portion of said target fragment which is hybridised to oligonucleotide A of said probe to produce a probe-target fragment hybrid; and (e) detecting or enriching for said probe-target fragment hybrid. Kits for use in the method of the invention are also provided. |