With the need to identify and keep cases of Omicron variant in check, genome sequencing has become critical in the current phase of the pandemic.
With Omicron cases rapidly rising in India, the central and state governments are on high alert against widespread transmission of the new variant of concern. The centre recently shared an advisory with states, noting that Omicron is three times as infectious as the Delta variant which was behind the devastating second wave of the pandemic in India. States have been asked to impose night curfews, strict restrictions on gatherings, activate war rooms, emergency operation centres.
To aid the check of Omicron spread, genome sequencing has been increased. The Delhi government has announced that all COVID-19 positive cases will be sent for genome sequencing. The activity is not just crucial to detect and curb Omicron spread but also to detect new mutated strains. The Omicron strain and all earlier COVID-19 strains including Delta were discovered using the same method of genome sequencing. Here’s all you need to know about the process of genome sequencing and how it helps discover which variant is behind an individual COVID-19 infection or community spread.
What is genome sequencing?
The technique refers to the process used to extract the genetic information from an RNA molecule. It gives important information about the type of virus, its mutations, mode of attack and transmissibility.
To understand the technique, one must first understand how infection happens in the body. Just like DNA molecules make up the body, infection is also made of DNA or RNA, with the COVID-19 virus being an RNA virus.
How different COVID-19 variants are detected?
An individual is first tested for COVID-19 positivity with the help of the RT-PCR test. The Test sample is sent to a Biosafety level three facility (BSL 3) lab for testing. The RNA is extracted from the sample for genome sequencing. The RNA is kept at minus 80 degrees Celsius to prevent degradation. The RNA is then processed in the lab where it is converted into DNA. This is done because RNA is highly unstable compared to DNA which can keep the information content of the sample stable. The DNA is then put into PCR amplification before being forwarded for a technique called fragmentation. The DNA strands are broken into pieces as a complete DNA is too long to be sequenced. Each fragmented sample is then tagged individually.
The sample is then fed into a machine to test its quantity and quality. After this a ready sample is sent to a DNA sequencer machine where it is mixed with different chemicals and the samples nucleic acid sequence is determined to find out the variant to which it belongs.
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 "Explainer: What is genome sequencing? Know how Omicron, other COVID-19 variants are detected")
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