What is reverse transcription PCR?

Reverse transcription PCR, also known as RT-PCR, is a technique combining reverse transcription of RNA into DNA and amplification of specific target DNA sequences using polymerase chain reaction (PCR). The main difference between RT-PCR and conventional PCR is that in RT-PCR, the template sequence is RNA whereas in conventional PCR, DNA is the template. Therefore, reverse transcriptase is required in RT-PCR to first convert RNA into its complementary DNA (cDNA), after which the exponential amplification of the cDNA can be achieved by PCR. RT-PCR is routinely combined with qPCR for analysis of gene expression and quantification of viral RNA in research, which is often termed as qRT-PCR.