In the mutant variants, has the coronavirus shown its best tricks? – World

The rapid increase in different parts of the world of deadly and more infectious coronavirus variants that share new mutations prompts scientists to ask a crucial question: Has the SARS-CoV-2 virus shown its best cards?

New variants first detected in countries as far away as Brazil, South Africa and Britain emerged spontaneously within months late last year. All three share some of the same mutations in the important spike region of the virus used to enter and infect cells.

These include the E484k mutation, dubbed “Eek” by some scientists for its apparent ability to evade natural immunity from previous Covid-19 infection and reduce the protection offered by current vaccines – all of which target peak protein.

The appearance of similar mutations, independent of each other, appearing in different parts of the globe shows that the coronavirus is undergoing a “convergent evolution”, according to a dozen scientists interviewed by Reuters.

Although it will continue to mutate, immunologists and virologists have said they suspect this coronavirus has a fixed number of movements in its arsenal.

It remains to be seen the long-term impact on the survival of the virus and whether limiting the number of mutations makes it less dangerous.

“It’s plausible that this virus has a relatively limited number of antibody escape mutations that it can make before it has played all of its cards, so to speak,” said Shane Crotty, a virologist at the La Institute. San Diego Immunology Jolla.

This could allow drugmakers to stay on top of the virus as they develop booster vaccines directly targeting current variants, as governments struggle to tame a pandemic that has killed nearly three million people.

The idea that the virus could have a limited number of mutations has been circulating among experts since early February, and gained momentum with the publication of an article showing the spontaneous appearance of seven variants in the United States, all in the same peak region. protein.

Evolution, in real time

Central to evolutionary biology is the process of different species independently developing the same traits that improve the chances of survival. The vast extent of the coronavirus pandemic – with 127.3 million infections worldwide – allows scientists to observe it in real time.

“If you wanted to kind of write a little textbook on viral evolution, it’s happening right now,” Dr. Francis Collins, geneticist and director of the US National Institutes of Health, said in an interview.

Scientists saw the process on a smaller scale in 2018 as a dangerous H7N9 bird flu virus in China appeared to begin to adapt to human hosts. But no pathogen has evolved under such close scrutiny as SARS-CoV-2.

Wendy Barclay, a virologist and professor at Imperial College London and a member of a scientific advisory committee to the UK government, said she was struck by “the astonishing converging development we are seeing” with SARS-CoV- 2.

“There are these infamous mutations – E484K, N501Y and K417N – that the three worrisome variants are building up. That, added together, is a very strong biology that this is the best version of this virus at any given time, ”Barclay said.

It’s not that this coronavirus is particularly smart, scientists have said. Whenever it infects people it makes copies of itself, and with every copy it can make mistakes. While some errors are trivial one-off errors, those that give the coronavirus a survival advantage tend to persist.

“If this continues to happen over and over again, it must provide a real growth advantage for this virus,” Collins said.

Some scholars believe the virus may have a limited number of mutations that it can endure before compromising its physical form – or changing so much that it is no longer the same virus.

“I don’t think he’s going to reinvent himself with extra teeth,” said Ian Jones, professor of virology at the UK University of Reading.

“If there were an unlimited number of things […] we would see an unlimited number of mutants, but we don’t, ”said Michel Nussenzweig, immunologist at Rockefeller University in New York.

Cautious optimism

Scientists remain cautious, however, and say it’s difficult to predict how a virus mutates. If there are limits to how the coronavirus can evolve, that would make it easier for vaccine developers.

Novavax Inc is adapting its vaccine to target the South African variant which, in lab tests, appeared to make current vaccines less effective. Managing Director Stan Erck said the virus can only change and bind to human hosts, and hopes the vaccine “will cover the vast majority of strains circulating.”

Otherwise, Novavax can continue to match its vaccine to new variants, he said.

Researchers are tracking variants through data-sharing platforms such as the Global Avian Influenza Data Sharing Initiative, which is home to a huge mine of coronavirus genomes.

Scientists recently identified seven variants of the US coronavirus with mutations all occurring in the same place in a key part of the virus, offering more evidence of convergent evolution.

Other teams are running experiments that expose the virus to antibodies to force it to mutate. In many cases, the same mutations, including the infamous E484K, have appeared.

Such evidence adds to the cautious optimism that the mutations appear to share many of the same traits.

But the world must continue to monitor changes in the virus, experts said, and stifle its ability to mutate by reducing transmission through vaccinations and measures that limit its spread.

“It shows a very important set of opening moves,” said Vaughn Cooper, an evolutionary biologist at the University of Pittsburgh School of Medicine, of this coronavirus. “We don’t know what the end of the game will look like.”