How the Coronavirus Mutates

Explaining how the coronavirus mutates and why it is important to understand and track these mutations

Vedika Harnathka

Published on:

May 2, 2020

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The novel coronavirus, SARS-CoV-2, is an RNA virus with its genetic material packed inside a protein envelope. Once it infects a cell, the genetic information tells the virus how to make copies of itself. This way the virus - and thus the infection - spreads.

However, while making copies of itself, viruses tend to make mistakes in their genomes. These mistakes, or mutations, are inherited by future copies of the virus, and cause the virus to transform away from its original form.

Scientists have mixed opinions regarding the rate of mutation of SARS-CoV-2. The virus has the ability to proofread its genome, so when it recognises an incorrect base pair, the virus can delete it and re-insert the correct base, minimising mutations. Because of this, some say that the virus mutates at a lower rate than the flu, at a rate of about

25 mutations per year⁠

Understanding how fast the virus mutates, and where in the genome it does so, is useful for drug design, predicting the effectiveness of a vaccine, and predicting the possible effects of the mutation.

Today, scientists all over the world are working together to track the genetic changes of the virus.

Nextstrain⁠

collates data from researches across the world to create a phylogenetic tree, which maps how the virus is mutating in different parts of the world. This helps understand how the disease is being transmitted from country to country, as shown in the image below.

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Screen Shot 2020-04-24 at 1.30.39 PM.png

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Researchers at the

University of Cambridge⁠

have found that there are three distinct ‘variants’ of SARS-CoV-2, each variant containing closely related viruses of closely related genomes. They’re labeled ‘A’, ‘B’, and ‘C’.

The virus most closely related to the one found in bats, type ‘A’, is the one thought to be the original virus. This was present in Wuhan, China (where the virus first originated), and has been found in large numbers in the US and in Australia.

The predominant virus type in Wuhan and East Asia - type ‘B’ - has not spread to other parts of the world, suggesting resistance against this type outside of this region. Type ‘C’ is predominant in Europe, found in France, Italy, Sweden and England. It has also been seen in Singapore, Hong Kong, and South Korea. Examination of the genetic codes of the three types has shown that type B was derived from type A, and type C was derived from type B.

These different types of the novel coronavirus could explain why the symptoms and severity of the virus in different parts of the world are so different. Understanding the mutations of the virus can explain how it spread, showing connections between different cases, and may also help scientists in predicting future hotspots of the virus, in identifying the number of separate outbreaks in a community, and in judging the effectiveness of measures like social distancing.

Sources:

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https://www.ncbi.nlm.nih.gov/pubmed/21593585⁠

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https://www.cam.ac.uk/research/news/covid-19-genetic-network-analysis-provides-snapshot-of-pandemic-origins⁠

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https://www.nationalgeographic.com/science/2020/03/how-coronavirus-mutations-can-track-its-spread-and-disprove-conspiracies/⁠

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https://nextstrain.org/ncov/global⁠

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https://www.livescience.com/coronavirus-mutation-rate.html⁠

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