CA2236161A1 - Unimolecular segment amplification and detection - Google Patents

Abstract

Disclosed are compositions and a method for amplification of and multiplex detection of molecules of interest involving rolling circle replication. The method is useful for simultaneously detecting multiple specific nucleic acids in a sample with high specificity and sensitivity. The method also has an inherently low level of background signal.
A preferred form of the method consists of an association operation, an amplification operation, and a detection operation. The association operation involves association of one ore more specially designed probe molecules, either wholly or partly nucleic acid, to target molecules of interest. This operation associates the probe molecules to a target molecule present in a sample. The amplification operation is rolling circle replication of circular nucleic acid molecules, termed amplification target circles, that are either a part of, or hybridized to, the probe molecules. A single round of amplification using rolling circle replication results in a large amplification of the amplification target circles. Following rolling circle replication, the amplified sequences are detected using combinatorial multicolor coding probes that allow separate, simultaneous, and quantitative detection of multiple different amplified target circles representing multiple different target molecules.
Since the amplified product is directly proportional to the amount of target sequence present in a sample, quantitative measurements reliably represent the amount of a target sequence in a sample. Major advantages of this method are that a large number of distinct target molecules can be detected simultaneously, and that differences in the amounts of the various target molecules in a sample can be accurately quantified. It is also advantageous that the DNA replication step is isothermal, and that signals are strictly quantitative because the amplification reaction is linear and is catalyzed by a highly processive enzyme.