Which description correctly characterises transcription-mediated amplification (TMA), the technology used in some blood-screening nucleic acid tests for HIV and HCV?
- A A thermal cycling method that doubles DNA target copies exponentially using Taq polymerase
- B A ligase-dependent method that joins adjacent probes only when the target sequence is perfectly matched
- C An isothermal method that uses reverse transcriptase and T7 RNA polymerase to produce RNA amplicons from an RNA target ✓
- D A signal amplification method based on branched DNA probes hybridised to the target without any enzyme-driven copying
Correct answer: C. An isothermal method that uses reverse transcriptase and T7 RNA polymerase to produce RNA amplicons from an RNA target
Explanation
TMA is an isothermal amplification in which reverse transcriptase makes a cDNA copy of the RNA target and T7 RNA polymerase then transcribes large numbers of RNA amplicons, giving rapid exponential amplification without a thermocycler. It is widely used in donor screening NAAT for HIV and HCV. Option D describes branched DNA signal amplification, and option B describes ligase chain reaction, both distinct technologies.
Reference: Koneman's Color Atlas and Textbook of Diagnostic Microbiology, 7th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
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