NASBA (molecular biology)
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Nucleic Acid Sequence Based Amplification (NASBA) is a relatively new method in molecular biology which is used to amplify RNA sequences.
Although the same can be done with PCR using a reverse transcriptase (in order to synthesize a complementary DNA strand as a template), NASBA's main advantage is that it works at isothermic conditions - at a temperature of constantly 41° C.
NASBA has been introduced into medical diagnostics, where it has been shown to give quicker results than PCR, and it is also more sensitive.[1]
Explained briefly, NASBA works as follows:
- RNA template is given to the reaction mixture, the first primer attaches to its complementary site at the 3' end of the template
- Reverse transcriptase synthesizes the opposite, complementary DNA strand
- RNAse H destroys the RNA template (RNAse H only destroys RNA in RNA-DNA hybrids, but not single-stranded RNA)
- the second primer attaches to the 5' end of the DNA strand
- T7 RNA polymerase produces a complementary RNA strand which can be used again in step 1, so this reaction is cyclic.
[edit] Weblinks
[edit] References
- ^ For example Petra Schneider et al. in "Real-Time Nucleic Acid Sequence-Based Amplification is more convenient than Real-Time PCR for quantification of Plasmodium falciparum", Journal of Clinical Microbiology, Jan. 2005, pp. 402-405
