Science

Genomic Sequencing: How Researchers Identify COVID-19 Variants Like Delta and Omicron

Genomic Sequencing: How Researchers Identify COVID-19 Variants Like Delta and Omicron

DNA Genetic Analysis Concept

How enact scientists detect unique variants of the virus that causes




The first human genome took two many years to sequence. With advances in technology, scientists are now ready to sequence DNA in a topic of hours.

How are genomes sequenced?

Even handed one of many earliest ideas scientists feeble in the 1970s and 1980s used to be Sanger sequencing, which entails lowering up DNA into short fragments and adding radioactive or fluorescent tags to title each and each nucleotide. The fragments are then place thru an electrical sieve that kinds them by dimension. In comparison with newer ideas, Sanger sequencing is slack and could per chance moreover path of easiest rather short stretches of DNA. Despite these limitations, it offers extremely merely data, and a few researchers are restful actively the utilize of this procedure to sequence SARS-CoV-2 samples.

For the reason that slack 1990s, next-generation sequencing has revolutionized how researchers receive data on and perceive genomes. Known as NGS, these technologies are ready to path of much greater volumes of DNA on the identical time, vastly lowering the amount of time it takes to sequence a genome.

There are two predominant forms of NGS platforms: 2d-generation and third-generation sequencers.




2d-generation sequencing marks each and each nucleotide with a selected coloration.

2d-generation technologies are ready to learn DNA right away. After DNA is lower up into fragments, short stretches of genetic cloth known as adapters are added to present each and each nucleotide a special coloration. For instance, adenine is coloured blue and cytosine is coloured red. In a roundabout procedure, these DNA fragments are fed right into a laptop and reassembled into your complete genomic sequence.

Third-generation technologies cherish the Nanopore MinIon right away sequence DNA by passing your complete DNA molecule thru an electrical pore in the sequencer. On memoir of every and each pair of nucleotides disrupts the electrical most up-to-date in a selected procedure, the sequencer can learn these modifications and add them right away to a laptop. This enables clinicians to sequence samples at point-of-care clinical and treatment products and services. Nonetheless, Nanopore sequences smaller volumes of DNA compared with other NGS platforms.




Third-generation sequencing detects modifications in an electrical most up-to-date to title nucleotides.

Though each and each class of sequencer processes DNA in a special procedure, they’ll all document the millions or billions of organising blocks that perform up genomes in a temporary time – from a few hours to some days. For instance, the Illumina NovaSeq can sequence roughly 150 billion nucleotides, the the same of 48 human genomes, in only three days.

Using sequencing data to battle coronavirus

So why is genomic sequencing this kind of wanted instrument in combating the spread of SARS-CoV-2?

Snappily public nicely being responses to SARS-CoV-2 require intimate data of how the virus is changing over time. Scientists earn been the utilize of genome sequencing to be conscious SARS-CoV-2 nearly in true time because the starting up of the pandemic. Thousands and thousands of particular person SARS-CoV-2 genomes earn been sequenced and housed in diversified public repositories cherish the Global Initiative on Sharing Avian Influenza Files and the Nationwide Middle for Biotechnology Files.

DNA Sequence

Sequencing the genome of a virus offers researchers data on how mutations can earn an affect on its transmissibility and virulence.

Genomic surveillance has guided public nicely being choices as each and each unique variant has emerged. For instance, sequencing the genome of the omicron variant allowed researchers to detect over 30 mutations in the spike protein that permits the virus to bind to cells in the human body. This makes omicron a variant of disaster, as these mutations are identified to make a contribution to the virus’s skill to spread. Researchers are restful discovering out about how these mutations will earn an affect on the severity of the infections omicron causes, and how nicely it’s ready to evade most up-to-date vaccines.

Sequencing moreover has helped researchers title variants that spread to unique areas. Upon receiving a SARS-CoV-2 pattern accrued from a traveler who returned from South Africa on Nov. 22, 2021, researchers on the University of California, San Francisco, earn been ready to detect omicron’s presence in five hours and had on the topic of your complete genome sequenced in eight. Since then, the Centers for Disease Take watch over and Prevention has been monitoring omicron’s spread and advising the authorities on ways to stop frequent neighborhood transmission.

The short detection of omicron worldwide emphasizes the power of sturdy genomic surveillance and the price of sharing genomic data in the course of the globe. Working out the genetic makeup of the virus and its variants offers researchers and public nicely being officers insights into ideas to easiest replace public nicely being pointers and maximize useful resource allocation for vaccine and drug pattern. By offering a must-earn data on ideas to curb the spread of contemporary variants, genomic sequencing has saved and could per chance moreover proceed to put limitless lives over the path of the pandemic.

Written by:

  • Andre Hudson, Professor and Head of the Thomas H. Gosnell College of Lifestyles Sciences, Rochester Institute of Technology
  • Crista Wadsworth, Assistant Professor in the Thomas H. Gosnell College of Lifestyles Sciences, Rochester Institute of Technology

This article used to be first printed in The Conversation.The Conversation