DNA SEQUENCING

Abigail Turner (OHS)

DNA sequencing refers to the technique which is used to determine the order of nucleotides in DNA and therefore, the base order. DNA sequencing has been one the most vital discoveries as it has helped to advance genetic research, in addition to medicine as whole. DNA sequencing is now used in medical diagnostics, virology and forensic biology amongst other things. For example, this technology can be used to compare the DNA sequence of healthy reference sections of DNA with DNA sections which are believed to contain a mutation. In this way, DNA sequencing can allow the mutation to be identified, thus allowing a diagnosis to be made.

DNA sequencing is a relatively new technology. It is believed that 1965 marked the first year for the first-generation of DNA sequencing when Robert Holley and his colleagues produced a whole nucleic acid sequence of alanine tRNA from Saccharomyces cerevisiae, which is a species of yeast. Following on from this, DNA sequencing technology rapidly improved and the ease with which it can be carried out has increased. By 1977, the most significant breakthrough in terms of DNA sequencing occurred as a result of Frederick Sanger’s work. This allowed Sanger and his team to reach a milestone step by sequencing the first full genome; a virus called phiX174. Following on from this, came a second generation or ‘revolution’ of sequencing technology. This allowed multiple DNA fragments to be sequenced at a single time, thus allowing DNA sequencing to become cost-efficient and thus more accessible. In less than 10 years, the cost of whole genome editing has decreased by a factor of 1 million and consequently, sequencing is now readily available on the market for less than £1000. It is widely believed that we are currently at the forefront of the next DNA sequencing revolution where whole genome sequencing may become commonplace in hospital setting in helping with diagnostics.

In the current COVID-19 era, DNA sequencing has been critical. In January 2020, following the discovery of an RNA virus, which was later named COVID-19, scientists immediately sequenced the genome of this virus in order to discover a virus and therefore, the characteristics of the virus. The virus was found to have a 79.0% sequence identity to SARS-CoV and an 86.7%-89% sequence identity to SARS which originates in bats. This sequencing was crucial in allowing the scientists to gain an initial idea about the infection rate and mortality rate at a time before large data sets were available to be examined. Following on from this, DNA sequencing has allowed new and potentially more infectious strains (variants) of the virus to be identified. This has allowed ‘hot-spot’ areas for virus strains to be highlighted and has thus led to extra precautions and mass testing being carried out in these areas to monitor the prevalence and reduce the spread of transmission to the wider population. Furthermore, with the increase in prevalence of these new strains, DNA sequencing has meant that these sample strains can be analysed. This has allowed scientists to predict the severity of symptoms linked with a particular strain and the speed at which the particular strain is likely to spread. Furthermore, in terms of treatment, DNA sequencing has allowed scientists to conclude which medicines would be most effective against COVID-19. For example, DNA sequencing can highlight whether a particular strain would be likely to respond to antiviral treatments and will be used to edit the vaccine structure to enable booster vaccines to be more efficacious against the emerging variant strains.

To conclude, the potentials of DNA sequencing can already be seen, and it are being utilised widely in our everyday life. There have been two main revolutions associated with DNA sequencing so far. Each one has led to huge changes in the technology related to the actual process of performing DNA sequencing, in addition to the cost and accessibility of this technology. Looking towards the future, it is likely that in the next few years, a third revolution of DNA sequencing will occur which may see everyone undergo DNA sequencing as part of a routine procedure to identify possible illnesses which a person may be prone to suffering from over their life. This would allow people to plan for their futures and plan for treatment in the future.

Bibliography

Wikipedia. (2021). DNA sequencing. <https:// en.wikipedia.org/wiki/DNA_sequencing> [accessed 19th April 2021]

Wikipedia. (2021). Daccharomyces cerevisiae. <https:// en.wikipedia.org/wiki/Saccharomyces_cerevisiae> [accessed 19th April 2021]

Chain, B. et. al. (2016). The sequence of sequencers: The history of sequencing DNA. <https://www.ncbi. nlm.nih.gov/pmc/articles/PMC4727787/> [accessed 19th April 2021]

Yourgenome. (2020). Timeline: History of genomics. <https://www.yourgenome.org/facts/timeline-historyof-genomics> [accessed 19th April 2021]

Griffiths, A.J.F. (2012). DNA sequencing. Brittanica. <https://www.britannica.com/science/DNAsequencing> [accessed 19th April 2021]

Worldometer. (2020). Coronavirus (COVID-19) Mortality Rate. <https://www.worldometers.info/ coronavirus/coronavirus-death-rate/> [accessed 19th April 2021)]

Hemarajata, P. (2020). SARS-CoV-2 Sequencing Data: The Devil Is in the Genomic Detail. <https://asm.org/ Articles/2020/October/SARS-CoV-2-SequencingData-The-Devil-Is-in-the-Gen> [accessed 19th April 2021]

NYU Langone Health. (2020). COVID-19: Sequencing the Genome [video]. <https://www.youtube.com/ watch?v=HbgPII1DOOk> [accessed 19th April 2021]

The Medical Futurist. (2018). I Got My Whole Genome Sequenced. Here’s What I Learned. <https:// medicalfuturist.com/i-got-my-whole-genomesequenced-heres-what-i-learned/> [accessed 19th April 2021]

Segata, N. et. Al. (2021). At the forefront of the sequencing revolution—notes from the RNGS19 conference. <https://genomebiology.biomedcentral. com/articles/10.1186/s13059-019-1714-3> [accessed 19th April 2021]

Mayo Clinic. (2018). What is Genomic Sequencing?. <https://www.youtube.com/watch?v=2JUu1WqidC4> [accessed 19th April 2021]