A method for detecting a target nucleic acid sequence, the method comprising the steps of: (a) hybridizing the target nucleic acid sequence with a PTO (Probing and Tagging Oligonucleotide); the PTO comprising (i) a targeting portion comprising a nucleotide sequence substantially complementary to the target nucleic acid sequence, and (ii) a Melting Temperature Deciding Region (MTDR), comprising a nucleotide sequence non-complementary to the target nucleic acid sequence, and (iii) at least one set of interactive labels comprising at least one fluorophore and at least one quencher; (b) hybridizing said PTO with a CQO (Capturing and Quenching Oligonucleotide); wherein the CQO comprises (i) a capturing portion comprising a nucleotide sequence which is reverse complementary to the MTDR of the PTO and (ii) at least one quenching molecule; wherein the MTDR of the PTO is configured to hybridize with the capturing portion of the CQO to form a Tag Duplex; (c) contacting the Tag Duplex with an enzyme having nuclease activity; wherein the enzyme having nuclease activity induces cleavage of the Tag Duplex when the Tag Duplex is hybridized with the target nucleic acid sequence thereby releasing an activated Tag Duplex fragment comprising a PTO fragment comprising the MTDR hybridized to the capturing portion of the CQO and the at least one fluorophore; (d) melting and/or hybridizing said activated Tag Duplex fragment to obtain a signal from the at least one fluorophore, and (e) detecting the activated Tag Duplex fragment by measuring the signal from the at least one fluorophore; wherein the signal is indicative of the presence of the target nucleic acid sequence. (a) hybridizing the target nucleic acid sequence with a PTO (Probing and Tagging Oligonucleotide); the PTO comprising (i) a targeting portion comprising a nucleotide sequence substantially complementary to the target nucleic acid sequence, and (ii) a Melting Temperature Deciding Region (MTDR), comprising a nucleotide sequence non-complementary to the target nucleic acid sequence, and (iii) at least one set of interactive labels comprising at least one fluorophore and at least one quencher; (b) hybridizing said PTO with a CQO (Capturing and Quenching Oligonucleotide); wherein the CQO comprises (i) a capturing portion comprising a nucleotide sequence which is reverse complementary to the MTDR of the PTO and (ii) at least one quenching molecule; wherein the MTDR of the PTO is configured to hybridize with the capturing portion of the CQO to form a Tag Duplex; (c) contacting the Tag Duplex with an enzyme having nuclease activity; wherein the enzyme having nuclease activity induces cleavage of the Tag Duplex when the Tag Duplex is hybridized with the target nucleic acid sequence thereby releasing an activated Tag Duplex fragment comprising a PTO fragment comprising the MTDR hybridized to the capturing portion of the CQO and the at least one fluorophore; (d) melting and/or hybridizing said activated Tag Duplex fragment to obtain a signal from the at least one fluorophore, and (e) detecting the activated Tag Duplex fragment by measuring the signal from the at least one fluorophore; wherein the signal is indicative of the presence of the target nucleic acid sequence. <EOS>