Novel coronavirus (2019-nCoV) originated in Wuhan, an inside city in China and quickly spread throughout almost all the provinces and other countries. The second case of coronavirus was confirmed in Chicago on Jan 23 in the United States. How can we confirm the diagnosis?
Real time Reverse Transcription-Polymerase Chain Reaction (rRT-PCR) is a fast and accurate diagnostic test. Firstly, a single-stranded DNA is synthesized form the RNA in virus by transcriptase. Then, reverse transcriptase primers could help DNA polymerase find DNA target regions and start DNA amplification. The primers are designed based on the RNA sequence of 2019-nCoV, which were determined by Chinese Center for Disease Control and Prevention. Finally, non-specific fluorescent dyes or sequence-specific DNA probes consisting of a fluorescent reporter permits the visible detection of all double-stranded DNA or DNA target region. Fluorescent will reflect the amount of DNA target regions in real time during amplification.
If there is no virus in a sample, primers could not find target regions to start amplification. Therefore, there will be a horizontal line in figure. On the contrary, there will be a curve. It is needed to be mentioned that different institutes may select different RNA regions to design primers.
Good method！
Why did the inventor of the PCR, Nobel prize winner Kary Mullis, say the PCR should never be used as a diagnostic tool?
“Social media users have been sharing a quote attributed to the inventor of the Polymerase Chain Reaction (PCR) test, currently being used to detect COVID-19, which says “PCR tests cannot detect free infectious viruses at all”.This quote has been falsely attributed to the inventor, Kary Mullis, and has been taken out of context to falsify its original meaning.”
“However, the quote is actually from an article written by John Lauritsen in December 1996 about HIV and AIDS, not COVID-19.”
From Fact check: Inventor of method used to test for COVID-19 didn’t say it can’t be used in virus detection