R-t-p-c-r Reamplification
R-t-p-c-r Reamplification - Related Videos
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Source: Laboratories of Dr. Ian Pepper and Dr. Charles Gerba - The University of Arizona Demonstrating Author: Bradley Schmitz Reverse transcription-polymerase chain reaction (RT-PCR) involves the same process as conventional PCR — cycling temperature to amplify nucleic acids. However, while conventional PCR only amplifies deoxyribonucleic acids (DNA), RT-PCR enables the amplification of ribonucleic acids (RNA) through the formation of complementary DNA (cDNA). This enables RNA-based organisms...
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FAQs
The second amplification acts on an already enriched target rather than starting with RNA. In the first stage, reverse transcription creates complementary DNA from RNA, and the initial primer pair amplifies the selected sequence. An aliquot transfers that product into a new PCR, where the same or alternative primers can further increase target yield.
Its main analytical advantage is greater detectability when the transcript begins at low abundance. Repeated amplification can produce enough target material for sequencing, cloning, or other downstream analysis. The gain comes with a tradeoff: each additional amplification can favor some products over others and increase nonspecific products, so a stronger signal is not automatically a more representative result.
Using the same primers in both rounds maintains targeting of the initially amplified sequence. Choosing alternative primers changes how the second PCR engages that product and may support a different downstream analysis requirement. Regardless of the primer choice, the additional amplification does not eliminate the need to monitor nonspecific products, which can become more prominent after reamplification.
Careful controls help distinguish a true target signal from unintended amplification, while contamination-prevention practices reduce the chance that extraneous nucleic acid enters either stage. Because the second-stage PCR can magnify whatever is present in its aliquot, contamination or nonspecific products may become more prominent in the final result, especially when detecting low-abundance transcripts.
Begin with RNA as the starting material for reverse transcription and the first PCR amplification. Next, transfer an aliquot of that initial product into a second PCR using either the original primers or an alternative primer set. Keeping the stages conceptually separate helps track where the target was generated and where nonspecific product or contamination could have been introduced.
It is useful when the first amplification does not provide enough detectable or usable target from a low-abundance transcript. The additional product can support sequencing, cloning, or other downstream analysis that requires more material than the initial reaction supplies. Thus, the technique serves both a detection role and a preparation role, depending on whether the goal is observing or further analyzing the transcript.
Interpret results alongside the method’s known amplification limits. A stronger final product indicates that target material was increased, but it can also reflect nonspecific amplification or amplification bias introduced during repeated PCR. For that reason, low-abundance transcript detection should be supported by careful controls and contamination-prevention practices, particularly when the product will be used for sequencing, cloning, or other downstream work.