Strand displacement amplification (SDA) and transient-state fluorescence polarization detection of Mycobacterium tuberculosis DNA.

Strand displacement amplification (SDA) is an isothermal, in vitro method of amplifying a DNA sequence for diagnostic purposes. We have combined SDA with fluorescence polarization detection in a closed, homogeneous format. A fluorescently labeled oligodeoxynucleotide detector probe hybridizes to the amplification product that increases in concentration during SDA. The single- to double-stranded conversion of the probe is accompanied by an increase in fluorescence polarization values, which can be measured in real-time without physical manipulation of the sample. The probe was labeled with the near-infrared dye La Jolla Blue, and fluorescence polarization was measured on a transient-state fluorometer. We have applied this homogeneous SDA/detection system to a target DNA sequence specific for Mycobacterium tuberculosis DNA.