How coronavirus mutations are taking control

The more people the virus infects, the more likely it is to evolve, according to Theodora Hatziioannou, a virologist at Rockefeller University who is studying the new variants.

Since the beginning of the pandemic, scientists using samples of SARS-CoV-2 collected around the world have cataloged these genetic mutations. This allowed them to build a family tree tracing how the virus is evolving.

Here are some milestones in the evolution of the virus that causes Covid-19 and how adjustments in its genetic code have led to potentially more infectious new strains that are spreading around the world:

Decisive Mutation

At the beginning of last year, scientists detected a mutation in Europe that makes the virus more transmissible than the original versions detected in China.

The mutation, called D614G, changes the shape of the peak proteins on the virus’s surface, making it more efficient at binding and infecting cells.

Variants with the D614G mutation quickly outperformed previous versions of the virus.

“In June, he replaced the ancestral virus,” said Jeremy Luban, a virologist at the University of Massachusetts School of Medicine who studied the mutation. “Everywhere it went, it became the dominant variety.”

Summer Spread

A new variant, known as 20E (EU1), was first detected in Spain last summer.

Since then, it has spread widely across Europe.

20E (EU1) does not appear to have mutations that make it more transmissible than the initial variants. Instead, it may have been in the right place at the right time – a popular vacation destination in Europe in the height of summer. “It could be a summer trip, it could be because you got rid of all your restrictions or it could be because it is more transmissible,” said Emma Hodcroft, an epidemiologist at the University of Bern, Switzerland, who conducted a study on the variant.

The new variants

The variants recently detected in the United Kingdom and South Africa have several new changes in their peak protein genes.

Scientists believe that a mutation that these variants share could help the virus to bind and enter cells. The variant recently detected in Brazil shares a key mutation of the spike protein with that of South Africa.

“What we are seeing is exactly what we hope to see. The virus’s surface proteins are under tremendous pressure to change, ”said Sean Whelan, a virologist at the University of Washington in St. Louis. “All that the virus really matters is to multiply … If it can enter the cells of the [host] and avoid that host’s immune system, it will multiply. Whether it causes disease is a different matter. ”

Some scientists fear that the South African variant may be better at escaping antibodies produced in response to natural infection and vaccination.

Preliminary estimates suggest that the UK variant is 50% -70% more transmissible than previous versions of the virus. And UK scientists said recently that the first data suggested it could also be more deadly.

Variants found in the United Kingdom and South Africa have become the dominant types in the countries where they were first detected.

The UK variant has spread widely abroad. By the end of January, it had been reported in 70 countries and territories. The South Africa variant has been reported in more than 30.

The United Kingdom variant was detected in more than two dozen states by the end of January.

The Centers for Disease Control and Prevention projected that it could become the dominant domestic strain in mid-March, unless steps are taken to slow it down. Variants found for the first time in South Africa and Brazil have also been detected in the USA

The full extent of its spread is difficult to assess. Apart from the United Kingdom and Denmark, few countries with active outbreaks have carried out extensive genetic sequencing of the virus, said Dr. Hodcroft.

“At the moment, almost the rest of the world is a blind spot.”

Additional sources: Nextstrain (phylogenetic trees); Emma Hodcroft, University of Bern

Write to Daniela Hernandez at [email protected]