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:

  1. RNA template is given to the reaction mixture, the first primer attaches to its complementary site at the 3' end of the template
  2. Reverse transcriptase synthesizes the opposite, complementary DNA strand
  3. RNAse H destroys the RNA template (RNAse H only destroys RNA in RNA-DNA hybrids, but not single-stranded RNA)
  4. the second primer attaches to the 5' end of the DNA strand
  5. 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

  1. ^ 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
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