A nucleotide probe permitting the detection of nucleic acids and constituted of a labeled nucleotide strand having three fragments: a first fragment having a first closing sequence, a second fragment, all or part of which has a recognition sequence for the molecular recognition of the target nucleic acid and a third fragment having a second closing sequence, and at least two markers, one of the ends of the strand of the detection probe being free of any marker, in which, when the two closing sequences are hybridized together, the detection probe has a completely circular shape, the closing sequences thus maintaining the probe in a conformation that cannot be detected in the absence of the target nucleic acid.