RT-PCR
Reverse transcription polymerase chain reaction
This test is helpful in detection and research of genetic diseases. And is being used in the detection of SARS-Cov-02 popularly known as corona virus.
*So let us understand how the test is done:-
1) Swabs are used to collect samples from Nose or Throat. Sometimes blood can be taken too to perform the test.
2) Swabs are then kept in virus transport medium to protect the samples. And are taken to specific laboratories which are authorized and capable of handling such viruses.
Here individual or pool testing can be done according to the requirement. Both testing follow same procedure.
3) Swab is mixed in a liquid so that the viral matter gets dispersed. Liquid is then kept for centrifugation after which the pellet of viral cells remain. Pellet is then processed to separate the RNA matter.
As RNA( Ribonucleic acid) strands are used in this method.
4) Then an enzyme called RT(Reverse transcriptase) is used to convert the single stranded RNA into DNA which is called complimentary DNA (C-DNA). As the amount of DNA is less so it is replicated to make more C-DNA.
5) Then comes the role of primers and probe.
Primers are also DNA cells designed to bind specifically to some DNA.
Probe is like a fluorescent dye.
So primers and probe is then added to the solution. And kept into PCR machine for binding.
If the sample has virus, it will bind to primers, where left primer bind to left end of DNA and right to right DNA and probe in the middle of the two.
In PCR machine when it complete one cycle the sample is given time to cool a little, then the DNA strands come closer and the dye in between is released. This process takes about 35-40 cycles and after that the amount of dye released shows the presence of virus in the sample.
And the person is declared positive.
This test does not work on recovered patients as they have antibodies in their sample and the test shows false negative result.
This is how RT-PCR test is conducted.
Source:- Wikipedia, Youtube.
– Abhay Pratap