Nucleic acid sequence-based amplification (NASBA) is an isothermal-based method of RNA amplification (Davey and Malek, 1989). Using this method, RNA is amplified by the action of an enzyme cocktail that includes AMV Reverse Transcriptase, T7 RNA polymerase and RNAse H at a fixed temperature (41°C; Figure 1). By pairing this technique with the ability to monitor the fluorescence signal produced from Molecular Beacon probes (Figure 2) in real time as they hybridize to the amplicon, it is possible to perform real time analysis of samples and obtain data in a matter of minutes. By coupling these technologies with a hand-held detection system, this method becomes a deployable monitoring device for onboard and remote sensing purposes.
Davey, C. and L.T. Malek. 1989. Nucleic acid amplification process. European Patent No. EP 0329822