Patent ID: 6916613

Claim:
A composition for determining the presence or absence of a target molecule comprising a first ribonucleic acid (RNA) molecule, said first RNA molecule binds a target molecule and has the following formula: 5′-A-B-C-D-E-3′; wherein A is a section of the RNA molecule having 10-100,000 nucleotides which section is, with another RNA sequence, E, replicated by an RNA replicase, the letter “B” denotes a section of the RNA molecule having approximately 1 to 50000 nucleotides which section, with another sequence D, binds the target molecule under binding conditions, wherein said target is a small or large organic molecule selected from the group consisting of a peptide, protein, and derivatives thereof, the letter “C” denotes a section of the RNA molecule having approximately 1 to 10000 nucleotides which section is capable preventing the replication of the first molecule by the RNA replicase, the letter “D” denotes a section of the RNA molecule having approximately 1 to 50000 nucleotides which section, with another sequence B, binds the target molecule under binding conditions, the sections B and D, in combination, comprise in total at least 10 nucleotides, the first RNA molecule, with sections B and D bound to target, is acted upon by the RNA replicase to form a second RNA molecule, said second RNA molecule has the following formula: 5′-E′-X-A′-3′; wherein, E′ is the complement to E, and A′ is the complement to A, and the letter “X” denotes the complement of parts of the sections B and D which may be replicated, or the letter denotes the direct bond between sections E′ and A′, and said second RNA molecule is replicated by the RNA replicase under replicating conditions.