A virus is a microscopic package of genetic material surrounded by a molecular envelope. The genetic material can be either DNA or RNA.
DNA is a two-strand molecule that is found in all organisms, such as animals, plants, and viruses, and it holds the genetic code, or blueprint, for how these organisms are made and develop.
RNA is generally a one-strand molecule that copies, transcribes and transmits parts of the genetic code to proteins so they can synthetize and carry out functions that keep organisms alive and developing. There are different variations of RNA that do the copying, transcribing and transmitting.
Some viruses such as the coronavirus (SARS-Cov2) only contain RNA, which means they rely on infiltrating healthy cells to multiply and survive. Once inside the cell, the virus uses its own genetic code — RNA in the case of the coronavirus — to take control of and ‘reprogramme’ the cells so that they become virus-making factories.
In order for a virus like the coronavirus to be detected early in the body using real time RT-PCR, scientists need to convert the RNA to DNA. This is a process called ‘reverse transcription’. They do this because only DNA can be copied — or amplified — which is a key part of the real time RT-PCR process for detecting viruses.
Scientists amplify a specific part of the transcribed viral DNA hundreds of thousands of times. Amplification is important so that instead of trying to spot a minuscule amount of the virus among millions of strands of genetic information, scientists have a large enough quantity of the target sections of viral DNA to accurately confirm that the virus is present.