It's an RNA virus, so you start by isolating RNA and then using a reverse transcription reaction to make cDNA from the RNA. Then you use viral-specific primers in a traditional PCR. Most of the tests that I've seen presented have then be real-time qPCR tests as opposed to gels, but for the most part, you're not far off. Also, restriction digests aren't required.
Note: I haven't seen any of the protocols, just what I've been able to learn from press reports.
And to add Wikipedia's page on real-time PCR (not to be confused with RT-PCR, which is also used here): https://en.wikipedia.org/wiki/Real-time_polymerase_chain_rea... . However, the crux of it is that the reaction contains a chemical that fluoresces in the presence of double-stranded DNA. As the PCR reaction progresses, if there is a valid template in the original mixture (i.e. if there is virus present), then there will be a detectable amount of DNA present after a number of PCR cycles. The lower the number of PCR cycles required to detect this fluorescence, the more viral RNA was present in the initial sample.
This isn't sequencing... you'd use sequencing to identify novel mutations or strains of the virus. This is a set of known PCR primers that amplify the virus's RNA. You could (in theory) also use a similar approach to identify specific strains of the virus, but this shouldn't be the priority at the moment.
While you could have an assay that used sequencing, it wouldn't be nearly as fast or cost efficient.
This CDC document was an interesting read. I found this part particularly fascinating.
>RNA isolated and purified from upper and lower respiratory specimens is reverse transcribed to cDNA
and subsequently amplified in the Applied Biosystems 7500 Fast Dx Real-Time PCR Instrument with SDS
version 1.4 software. In the process, the probe anneals to a specific target sequence located between
the forward and reverse primers. During the extension phase of the PCR cycle, the 5’ nuclease activity
of Taq polymerase degrades the probe, causing the reporter dye to separate from the quencher dye,
generating a fluorescent signal. With each cycle, additional reporter dye molecules are cleaved from
their respective probes, increasing the fluorescence intensity. Fluorescence intensity is monitored at
each PCR cycle by Applied Biosystems 7500 Fast Dx Real-Time PCR System with SDS version 1.4
software.
I can't tell if you're being sarcastic or not, but 20 years is a very short amount of time if you look back on the history of the advancement of engineering and our understanding of the world. It's very exciting, especially when you look at how little the basic operating concept of computers has changed in the same timeframe.
As someone outside the industry it _appears_ [emphasis there] to have gone from "we can take a few weeks and test you for a specific disease susceptibility" to "place your finger here and then grab a coffee ... sorry for the wait, OK we have details on 100 different diseases now" in a matter of 2 or 3 years.
Note: I haven't seen any of the protocols, just what I've been able to learn from press reports.
Edit: Here's a link to the CDC's panel protocol: https://www.fda.gov/media/134922/download
And to add Wikipedia's page on real-time PCR (not to be confused with RT-PCR, which is also used here): https://en.wikipedia.org/wiki/Real-time_polymerase_chain_rea... . However, the crux of it is that the reaction contains a chemical that fluoresces in the presence of double-stranded DNA. As the PCR reaction progresses, if there is a valid template in the original mixture (i.e. if there is virus present), then there will be a detectable amount of DNA present after a number of PCR cycles. The lower the number of PCR cycles required to detect this fluorescence, the more viral RNA was present in the initial sample.