RT PCR TEST

Subject : Science & tech

Context : Maharashtra says fortnightly RT-PCR tests not mandatory for those delivering essential services.

Concept :

RT-PCR Test:

Normally DNA holds information about ingredients that make up a living being. The information coded in the DNA is converted into functional proteins in a living being which is called as gene expression.
The process of gene expression happens in 2 processes namely transcription and translation.
In the 1st step the information coded in the DNA is transcripted on to an RNA in the nucleus. The job of copying this information onto RNA is done by an enzyme in the nucleus called RNA polymerase.

PCR technique

Kary Mullis, an American biochemist invented the PCR technique. He was awarded the Nobel Prize for Chemistry in 1993.Under this, copies of a segment of DNA (deoxyribonucleic acid) are created using an enzyme called Polymerase.The ‘chain reaction’ signifies how the DNA fragments are copied, exponentially — one is copied into two, the two are copied into four, and so on.
So the DNA from the patient’s sample is collected and multiplied manifold using PCR which is then detected by a probe.’’
However, coronavirus is made of RNA (ribonucleic acid). They cannot be replicated directly using PCR. Therefore to detect coronavirus, RNA is converted into DNA using a technique called reverse transcription.
A ‘reverse transcriptase’ enzyme converts the RNA into DNA. Copies of the DNA are then made and amplified.

Advantage of PCR Test over Rapid-Antibody Testing

In case of PCR tests, it is the presence of an antigen in the infected patient that is tested for instead of the presence of antibodies which is done in case of Rapid Antibody testing
Thus, detecting the presence of pathogen in the body before body’s antibodies form can detect the infection early.