Coronavirus Mutations: What We Have Learned | The Human World

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Along Lucy van Dolpe, UCL

In early January, the first genomic sequence of Sars-CoV-2 (the virus that causes Covid-19) was released under the name “Wuhan-1”. This 30,000-character string (the genetic code A, T, C, G) marked the first day of the race to understand the genetics of this newly discovered coronavirus. Currently, an additional 100,000 coronavirus genomes sampled from Covid-19 patients in more than 100 countries have been added to Wuhan-1. Geneticists around the world are mining data to get answers. Where did Sars-CoV-2 come from? When did you start infecting humans? How is the virus mutated, and is it important? Sars-CoV-2 genomics has grown and become global, just like the virus itself.

The term mutation tends to remind us of the image of a dangerous new virus with enhanced ability to dominate the entire globe. And while mutations constantly appear and sometimes wipe out, early mutations in Sars-CoV-2 spread around the world as the virus spread almost unnoticed. Mutations are a completely natural part of any organism, including viruses. The overwhelming majority do not affect the ability of the virus to spread or cause the disease.

Mutations simply mean a difference. Changes in the characters of the genome. Although the Sars-CoV-2 population was genetically essentially unchanged when it jumped into the first human host In late 2019More than 13,000 of these changes are found in the 100,000 Sars-CoV-2 sequenced so far.Still, any two viruses from any two patients worldwide are slightly different on average. 10 characters.. This means that it is a small part of the virus’s genetic code totaling 30,000 characters, and that all circulating Sars-CoV-2 can be considered part of a single clonal lineage.

Mutate slowly

It will take some time for the virus to acquire substantial genetic diversity. Sars-CoV-2 mutates fairly slowly against the virus in all strains Some changes every month; 2-6 times lower More than the number of mutations acquired by the influenza virus during the same period.

Nevertheless, mutations are the basis on which natural selection can act. The most common mutations do not make the virus work or have no effect. Nevertheless, there is a possibility that mutations may affect the infectivity of Sars-CoV-2 in the new human host. As a result, since the first Sars-CoV-2 genome was sequenced in Wuhan, if there is an identifiable mutation, it is eager to determine if it can significantly alter viral function. Efforts have been made.

A notorious mutation in this context is an amino acid change in the Sars-CoV-2 spike protein. This protein gives the coronavirus a characteristic coronary process and allows it to attach to host cells.This single letter change in the viral genome-called D614G – There is no measurable effect on the severity of the disease, but it has been shown to increase the viral infectivity of cells grown in the laboratory. This mutation is found almost systematically with the other three mutations, but all four are found in about 80% of the sequenced Sars-CoV-2 and are the most frequent set of mutations in the cycle. It has become.

The challenge for D614G, like any other mutation, is to unravel whether the frequency has increased due to the accidental presence of the virus responsible for the early successful sowing of the outbreak, or whether they have occurred. Really give benefits In their career.Genomics works on UK datasets, but suggests a subtle role for the D614G in growth Strain growth rate Carry it and you can find our own job No measurable effect At the time of transmission.

Easy to carry

D614G is not the only mutation found frequently. Strings of three mutations in the Sars-CoV-2 protein shell are also increasingly appearing in sequence data and are now found in one-third of viruses. A single change at position 57 of the Orf3a protein, a known immunogenic region, occurs in a quarter.Other mutations are present in spike proteins, but a myriad of other mutations appear to have been induced by our activity. Own immune response.. At the same time, there remains no consensus that these or others significantly alter the infectivity or pathogenicity of the virus. Most mutations are simply carried because Sars-CoV-2 continues to spread successfully.

However, replacement is not the only small edit that can affect Sars-CoV-2. Deletion of the Sars-CoV-2 accessory gene Orf7b / Orf8 Reduce pathogenicity Sars-CoV-2 can cause mild infections in patients.A similar Delete May have worked with Same way In Sars-CoV-1, the associated coronavirus SARS Outbreak in 2002-04. Deletions of Orf8 have been present since the early stages of the pandemic and appear to have not increased in frequency, but progress towards less toxic Sars-CoV-2 is welcome news.

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Adaptive changes can still occur, but all data available at this stage suggests that they have faced the same virus since the onset of the pandemic. Chris WhittiThe UK Chief Health Officer was right to pour cold water on the idea that the virus has Mutant to a milder one Than what caused Britain to impose a blockade in March. The potential for reduced severity of symptoms seen in summer is probably the result of improved infections, containment measures (such as social distance), and treatment, rather than changes in the virus itself. However, while Sars-CoV-2 hasn’t changed significantly so far, we’ve extended the tools to track and track its evolution and keep pace.

Lucy van Dolpe, Microbial Genomics, Senior Research Fellow, UCL

This article will be republished from conversation Under a Creative Commons license.Read Original work..

Conclusion: What science knows about mutations in the Covid-19 virus.