Signal mediated amplification of RNA technology
Signal mediated amplification of RNA technology (SMART) has been developed by Cytocell. The assay consists of two oligonucleotide probes that hybridize to a specific target sequence and, only then, to each other forming a three-way junction. One probe (template for the RNA signal) contains a non-functional single-stranded T7 RNA polymerase promoter sequence. This promoter sequence is made double-stranded (hence functional) by DNA polymerase, allowing T7 RNA polymerase to generate a target-dependent RNA signal which is measured by an enzyme-linked oligosorbent assay. This method also enables the generation of signals from E. coli samples without prior extraction of nucleic acid, showing that for some targets, sample purification may not be required. The assay will be quantitative for infectious disease agents: the level of signal relates directly to the amount of target and therefore to the number of organisms in the original sample. Currently the assay requires no thermal cycling, and can be carried out in a single well. Finally, the assay will be relatively easy to automate, making it suitable for high throughput screening for detection of multiple genetic variants with known sequences. This makes it ideal for pharmacogenomic applications where large numbers of patients are required to be genotyped in clinical trials or in a clinical laboratory where an automatable assay is disease detection is needed.
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