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How is reverse transcriptase used in reverse transcription-polymerase chain reaction?

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Diagram illustrating the process of retrovirus infection and reverse transcription, showing a retrovirus entering a host cell, releasing viral RNA, reverse transcriptase converting RNA to DNA, integration into the host genome, transcription of new viral RNA, assembly of new virions, and budding from the cell. — Reverse transcriptase After a retrovirus infects a cell, an enzyme known as reverse transcriptase converts viral RNA into proviral DNA in the cytoplasm. Proviral DNA then enters the nucleus, where it is incorporated into the host cell's DNA.

In the laboratory technique known as reverse transcription-polymerase chain reaction (RT-PCR), reverse transcriptase is used to convert fragile RNA into a more stable form for analysis.1

Because RNA is difficult to study directly, the enzyme catalyzes the synthesis of a strand of complementary DNA (cDNA) using the RNA as a template. Once this cDNA is generated, it can be amplified through the polymerase chain reaction process, allowing researchers to quantify the amount of messenger RNA present in a sample. This procedure serves as a powerful tool in scientific research and the diagnosis of various diseases, including cancer.1