Background: The current diagnostic test to detect whether someone is infected with the Wuhan virus is something called RT-PCR. PCR, or polymerase chain reaction, is a way to amplify a DNA sequence that is present in low abundance. It was developed in the mid 80s by Kerry Mullins and it revolutionized DNA cloning and diagnostics. It now is a widespread technology that you can find in about every bio lab in the world. For that, Kerry (who was a collaborator of mine) was awarded a Nobel Prize.
But, coronaviruses have an RNA, not a DNA genome so, since PCR only amplifies DNA, Mullins’ technology would not work to detect coronavirus. This is where the RT part comes in. RT stands for reverse transcriptase. Back in the 50s-70s, the "central dogma" of molecular biology was that DNA makes RNA which then makes proteins. That was believed to be a one-way pathway. Then Howard Temin came along and found chicken tumor viruses that had an RNA genome, but somehow were able to insert a copy of that RNA genome as DNA into the cellular genomes of the tumor cells. Somehow the viral RNA was made into DNA. He was widely disbelieved and even ridiculed, until he, and an MIT scientist, David Baltimore, purified the enzyme reverse transcriptase and directly demonstrated that it could copy an RNA sequence into DNA. That revolutionized molecular biology and for that, they shared a Nobel Prize.
So, they use RT to copy the Wuhan viral RNA into DNA and then do the PCR reaction on the DNA to detect the presence of the virus in a throat swab.
I am descended from the David Baltimore scientific lineage, having done my post-doc work at UCLA with a scientist who was a post-doc in Baltimore’s lab at MIT. And Howard Temin was a colleague and mentor of mine as a faculty member at the University of Wisconsin until he passed away in the mid-90s.
And now the interesting factoid. In the late 80s while at UCLA, we published the first paper to describe RT-PCR. We weren’t trying to detect viruses, but developed the technology to detect very rare leukemia cells in the blood of patients after marrow transplants to see if we could identify very early cases of post-transplant leukemia relapse.