How does an “NAT PCR” test differ from an “RT-PCR” test?


How does an “NAT PCR” test differ from an “RT-PCR” test?

In: Biology


They are both very similar. Both of them are amplifying DNA through use of PCR. The way DNA is amplified is that DNA is put in a tube with primers (sequences of DNA you want to amplify usually sense and antisense). The PCR machine will heat up DNA so that it denatures or split from the original double helix into single stranded DNA. This is where the primers come in by binding to the single standard DNA. The machine will then cool it down so that the strands anneal again/come back together and nucleotides will fill in the rest of the strand with primers and theoretically double the amount of specific DNA sequence every time. There are lots of different variables (annealing temp, primer efficiency, amount of cycles, amount of DNA, etc) that go into play but that’s for another day.

So now we know what PCR (polymerase chain reaction) is. As far as I am understanding it, Nucleic acid test or nucleic acid amplification test seems to be encompassing reverse transcriptase PCR. So the reason why rtPCR is special is because you add an extra step. You extract RNA from specimen and reverse transcribe it into DNA through the use of a reverse transcriptase. Then it become like other DNA sample and you would do the same procedure as explained above.

The reason why we can’t just run PCR on RNA is because RNA is extremely unstable and would denature too quickly. The reason why it’s important to look into RNA is because it can show you what proteins are being made at that exact moment.

NAT (nucleic acid testing) is just a generic name for tests which detect specific genes.

PCR (polymerase chain reaction) is a type of NAT. LAMP (loop mediated isothermal amplification) is another type of NAT.

RT (reverse transcriptase) is a process to convert RNA into DNA. Nucleic acid amplification only works on DNA. So if you are testing for RNA, the first step in testing needs to be RT.

COVID-19 is caused by an RNA virus so the first step in testing is RT, then comes amplification.

RT PCR Is the most used NAT for CV19, but RT LAMP is done in some labs.