A kit for detecting a target nucleic acid sequence, the kit comprising: i) an endonuclease enzyme; ii) a long probe (LP-exp) consisting of a single-stranded oligonucleotide consisting of: - a 3' sequence consisting of the target nucleic acid sequence or a portion thereof (ΔT), - an endonuclease recognition site, and - a 5' Δ1cT sequence which is complementary to a first portion of the target nucleic acid sequence to be detected; iii) a first short probe (SP1-exp) consisting of a single-stranded oligonucleotide consisting of: - a 5' Δ2cT sequence which is complementary to a second portion of the nucleic acid sequence to be detected, and - a 3' Δ1cNE sequence which is complementary to a first portion of the endonuclease recognition site; and iv) a second short probe (SP2-exp) consisting of a single-stranded oligonucleotide consisting of: - a Δ2cNE sequence which is complementary to a second portion of the endonuclease recognition site, wherein the Δ1cNE sequence of the first short probe together with the Δ2cNE sequence of the second short probe make up the complement of the whole endonuclease recognition site, wherein the Δ2cNE sequence is sufficiently short so that hybridization of the second short probe to the long probe does not occur in the absence of the target nucleic acid sequence, and wherein the kit does not comprise a polymerase enzyme. i) an endonuclease enzyme; ii) a long probe (LP-exp) consisting of a single-stranded oligonucleotide consisting of: - a 3' sequence consisting of the target nucleic acid sequence or a portion thereof (ΔT), - an endonuclease recognition site, and - a 5' Δ1cT sequence which is complementary to a first portion of the target nucleic acid sequence to be detected; - a 3' sequence consisting of the target nucleic acid sequence or a portion thereof (ΔT), - an endonuclease recognition site, and - a 5' Δ1cT sequence which is complementary to a first portion of the target nucleic acid sequence to be detected; iii) a first short probe (SP1-exp) consisting of a single-stranded oligonucleotide consisting of: - a 5' Δ2cT sequence which is complementary to a second portion of the nucleic acid sequence to be detected, and - a 3' Δ1cNE sequence which is complementary to a first portion of the endonuclease recognition site; and - a 5' Δ2cT sequence which is complementary to a second portion of the nucleic acid sequence to be detected, and - a 3' Δ1cNE sequence which is complementary to a first portion of the endonuclease recognition site; and iv) a second short probe (SP2-exp) consisting of a single-stranded oligonucleotide consisting of: - a Δ2cNE sequence which is complementary to a second portion of the endonuclease recognition site, wherein the Δ1cNE sequence of the first short probe together with the Δ2cNE sequence of the second short probe make up the complement of the whole endonuclease recognition site, wherein the Δ2cNE sequence is sufficiently short so that hybridization of the second short probe to the long probe does not occur in the absence of the target nucleic acid sequence, and wherein the kit does not comprise a polymerase enzyme. - a Δ2cNE sequence which is complementary to a second portion of the endonuclease recognition site, wherein the Δ1cNE sequence of the first short probe together with the Δ2cNE sequence of the second short probe make up the complement of the whole endonuclease recognition site, wherein the Δ2cNE sequence is sufficiently short so that hybridization of the second short probe to the long probe does not occur in the absence of the target nucleic acid sequence, and wherein the kit does not comprise a polymerase enzyme. wherein the Δ2cNE sequence is sufficiently short so that hybridization of the second short probe to the long probe does not occur in the absence of the target nucleic acid sequence, and wherein the kit does not comprise a polymerase enzyme.