All Detail about RT PCR Test
RT-PCR (reverse transcription-polymerase chain reaction) is the most sensitive technique for mRNA detection and quantitation currently available. Compared to the two other commonly used techniques for quantifying mRNA levels, Northern blot analysis and RNase protection assay, RT-PCR can be used to quantify mRNA levels from much smaller samples. In fact, this technique is sensitive enough to enable quantitation of RNA from a single cell.
This article first discusses the advantages of real-time RT-PCR compared to end-point methods. This discussion is followed by a description of the different methods for quantitating gene expression by real-time RT-PCR with respect to the different chemistries available, the quantitation methods used and the instrumentation options available. Subsequently, the “traditional” methods of quantitating gene expression by RT-PCR, i.e. end-point techniques, are presented.
Why Real-Time RT-PCR?
Over the last several years, the development of novel chemistries and instrumentation platforms enabling detection of PCR products on a real-time basis has led to widespread adoption of real-time RT-PCR as the method of choice for quantitating changes in gene expression. Furthermore, real-time RT-PCR has become the preferred method for validating results obtained from array analyses and other techniques that evaluate gene expression changes on a global scale.
To truly appreciate the benefits of real-time PCR, a review of PCR fundamentals is necessary. At the start of a PCR reaction, reagents are in excess, template and product are at low enough concentrations that product renaturation does not compete with primer binding, and amplification proceeds at a constant, exponential rate. The point at which the reaction rate ceases to be exponential and enters a linear phase of amplification is extremely variable, even among replicate samples, but it appears to be primarily due to product renaturation competing with primer binding (since adding more reagents or enzyme has little effect). At some later cycle the amplification rate drops to near zero (plateaus), and little more product is made.
What is RT-PCR test
RT-PCR (Reverse Transcription Polymers Chain Reaction) Test. In addition, rapid antigen and antibody tests are also done. If the rapid antigen test is positive, then the person is positive for corona. But if the test is negative and symptoms of corona still appear, it becomes necessary to have an RT-PCR test.
This test provides information about the virus in a person. In which the ribonucleic acid (RNA) of the virus is examined. Making RNA from deoxyribonucleic acid (DNA) is called transcription.
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What is CT value
According to the Indian Council of Medical Research (ICMR), the RT-PCR test measures SRS-CoV-2 and then measures its positivity based on the cycle threshold (CT).
Samples need cycling several times to detect how much transition there is in the individual. In these circumstances if the CT value is 35 or less then the person appears to be infected. And if this value is less than 22 then hospitalization is required. CT values 23 to 39 are considered appropriate. Even in these circumstances a CT scan is advised to find out how widespread the infection is.
When the corona needs to be tested
Corona needs to be tested when there is fever, chest pain, odor and taste, difficulty breathing.
In addition, corona tests may be performed at a distance of 6 feet if in contact with an infected person or in contact with an infected person for more than 15 minutes.