RTPCR Reverse Transcription Test Gold Standard Method YouTube Lecture Handouts

Glide to success with Doorsteptutor material for competitive exams : get questions, notes, tests, video lectures and more- for all subjects of your exam.

Covid-19 Tests: RT-PCR (Reverse Transcription), RADT (Rapid Antigen), Antibody - What to Know? | GS

Title: RTPCR Test

  • Used in containment zones, hotspots, hospital settings and laboratories among those who manifested one or other symptoms of the disease, influenza-like illnesses.
  • People with comorbidities who were asymptomatic and high-risk contacts of those confirmed positive.
  • Those who tested ‘negative’ and whom clinicians suspected to be harbouring the disease ought to be definitely tested sequentially by RT-PCR to rule out infection and higher chances of false negatives.
  • Those who test positive don՚t need a re-test and must be considered positive.
  • The average incubation period of SARS-CoV-2 is 5.6 days so an individual will test positive only after six days of contracting the virus. Undergoing a COVID-19 test at the initial stage when the viral load is very low can give negative results.
RTPCR Test
  • Used in containment zones, hotspots, hospital settings and laboratories among those who manifested one or other symptoms of the disease, influenza-like illnesses.
  • People with comorbidities who were asymptomatic and high-risk contacts of those confirmed positive.
  • Those who tested ‘negative’ and whom clinicians suspected to be harbouring the disease ought to be definitely tested sequentially by RT-PCR to rule out infection and higher chances of false negatives.
  • Those who test positive don՚t need a re-test and must be considered positive.
  • The average incubation period of SARS-CoV-2 is 5.6 days so an individual will test positive only after six days of contracting the virus. Undergoing a COVID-19 test at the initial stage when the viral load is very low can give negative results.
  • Kary Mullis, the 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. A fluorescent DNA binding dye called the “probe” is added to DNA, which shows the presence of the virus on a fluorometer. However, coronavirus is made of RNA (ribonucleic acid) .
  • 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.

Gold Standard Method

  • The RT-PCR test takes a minimum of 2 - 5 hours including the time taken for sample transportation. This limits the widespread use of the test and also impedes quick augmentation of testing capacity in various containment zones and hospital settings.
  • It is a test on swabbed nasal samples that detects antigens (foreign substances that induce an immune response in the body) that are found on or within the SARS-CoV-2 virus. It is a point-of-care test, performed outside the conventional laboratory setting, and is used to quickly obtain a diagnostic result. Like RT-PCR, the rapid antigen detection test too seeks to detect the virus rather than the antibodies produced by the body. While the mechanism is different, the most significant difference between the two is time. As the ICMR has pointed out, the RT-PCR test takes a minimum of 2 - 5 hours including the time taken for sample transportation. In a reliable rapid antigen detection test, the maximum duration for interpreting a positive or negative test is 30 minutes.
  • In RADT, the maximum duration for interpreting a positive or negative test is 30 minutes, thus a quicker complement to the standard RT-PCR tests
  • Inaccurate tracking and false negative results.
  • RAT detects the presence of viral proteins (antigens – attributes of the virus) in a sample from the respiratory tract of a person. However, it is capable of giving more false negatives.
  • Antibody positive does not mean COVID positive

Developed by: