Hanjabam Rajanikanta Sharma
Continued from prev issue
It is used in Semi quantitative detection of Beta Coronavirus (Sarbeco), RNA in human oropharyngeal and nasopharyngeal swab specimen. Betacoronaviruses (â-CoVs or Beta-CoVs) are one of four genera (Alpha-, Beta-, Gamma-, and Delta-) of coronaviruses. They are enveloped, positive-sense, single-stranded RNA viruses that infect human and mammals.
From the betacoronaviruses, greatest clinical importance concerning humans are OC43 and HKU1 (which can cause the common cold) of lineage A, SARS-CoV and SARS-CoV-2 (which causes the disease COVID-19) of lineage B and MERS-CoV of lineage C.
The test is recommended for use as a first line screening test for COVID-19. TrueNat machine can detect an enzyme (called RdRp) found in the RNA of the virus. RNA dependent RNA polymerase (RdRp) is one of the most versatile enzymes of RNA viruses that is indispensable for replicating the genome as well as for carrying out transcription. Samples testing positive by Truenat Beta CoVshould be confirmed using confirmatory tests for SARS CoV 2.
4. Antibody Tests (Serological Testing)
Antibody testing (or serological testing) is an examination of proteins in the bloodstream, to find out whether an individual has been infected with COVID-19. An infected person will have specific antibodies to pathogens they have been exposed to. The immune system produces antibodies as part of a larger process to defend itself from an infection.
That said, antibody tests may not be able to show whether the virus is currently infecting the body. Unlike a nasal or throat swab test, which looks for genetic signatures of the virus in the body, an antibody test looks for traces of the body’s response to the virus.
Antibodies are abundant in the blood, so a sample of blood is collected by either a finger prick or a blood sample drawn with a needle. Two specific antibody types are sought out in an antibody test:
i) IgM antibodies against SARS-CoV-2, which develops early on in an infection.
ii) IgG antibodies against SARS-CoV-2, which are mostly found after someone has recovered from the infection.
This test have high margin of error as of now. It is mainly used for research and surveillance purposes.
(Former intern at IIT Delhi, the author did his BS-MS (Bio Major) from Indian Institute of Science Education and Research (IISER), Mohali. He can be reached at [email protected]