[News] The coronavirus is mutating, what does that mean for us?

[EvKirito]

                                                                        

 

The New York Times
London, United Kingdom

 

 

Now that vaccines are beginning to give hope to emerge from the pandemic, British authorities last weekend warned of a highly contagious new variant of the coronavirus circulating in England.

 

Taking as a reference the rapid spread of the virus in and around London, Prime Minister Boris Johnson imposed the strictest blockade on the country since March.

"If the virus changes its method of attack, we must change our method of defense," he said.

 

A crowd trying to rush out of the city when the restrictions went into effect packed London's train stations. On Sunday, European countries began closing their borders to travelers from the United Kingdom, hoping to block out the new version of the pathogen.

 

In South Africa, a similar version of the virus emerged that, according to the scientists who detected it, shares one of the mutations seen in the British variant. That virus has been found in up to 90 percent of samples whose genetic sequences have been analyzed in South Africa since mid-November.

 

Scientists are concerned about these variants, but are not surprised. Researchers have recorded thousands of small modifications to the genetic material of the coronavirus as it has spread around the world.

 

Some variants become more common in a po[CENSORED]tion only by chance, not because the changes somehow overload the virus. However, as it becomes more difficult for the pathogen to survive, due to vaccines and the increasing immunity of human po[CENSORED]tions, researchers also hope that the virus will obtain useful mutations that allow it to spread more easily or escape detection. of the immune system.

 

"It's a real warning that we need to pay more attention," said Jesse Bloom, an evolutionary biologist at the Fred Hutchinson Cancer Research Center in Seattle. "Without a doubt, these mutations are going to spread, and ultimately the scientific community needs to monitor these mutations and describe which ones have effects."

 

The British variant has around twenty mutations, including several that affect the way the virus attaches to and infects human cells. These mutations may allow the variant to replicate and transmit itself more efficiently, said Muge Cevik, an infectious disease expert at the University of St. Andrew in Scotland and a scientific adviser to the British government.

 

However, the estimate of higher transmissibility (British officials said the variant was up to 70 percent more transmissible) is based on modeling and has not been confirmed in laboratory experiments, Cevik added.

 

"In general, I think we need to have a little more experimental data," he said. "We cannot entirely rule out the fact that some of this transmissibility data may be related to human behavior."

 

In South Africa, scientists were also quick to point out that human behavior was driving the epidemic, not necessarily new mutations whose effect on transmissibility has yet to be quantified.

 

The British announcement raised concerns that the virus could evolve to become resistant to the newly released vaccines. Concerns center on a couple of alterations in the virus' genetic code that could make it less vulnerable to certain antibodies.

 

However, several experts called for caution, arguing that it would take years, not months, for the virus to evolve enough to render current vaccines impotent.

 

"No one should be concerned about the possibility of a single catastrophic mutation emerging that suddenly cripples all immunity and antibodies," said Bloom. “It is going to be a process that will happen over several years and requires the accumulation of multiple viral mutations. It doesn't function as an on-off switch, ”he added.

 

The scientific nuance mattered little to the UK's neighbors. The Dutch, concerned about the possible influx of travelers carrying the variant, said they would suspend flights from the United Kingdom from Sunday, December 20, 2020 until January 1, 2021.

 

Italy also suspended air travel, and on Sunday Belgian officials enacted a 24-hour ban on arrivals from the UK by air or train. Germany is developing a regulation limiting travelers from the UK and South Africa.

 

According to local media, other countries are also considering bans, including France, Austria and Ireland. Spain has asked the European Union for a coordinated response to the ban on flights. New York Governor Andrew Cuomo asked the Donald Trump administration to consider the possibility.

 

He added that the restrictions Johnson imposed could be in effect for months.

 

Like all viruses, the coronavirus is a metamorph. Some genetic changes are inconsistent, but others can give you a head start.

 

Scientists particularly fear this last possibility. The vaccination of millions of people can force the virus to make new adaptations, mutations that help it evade or resist the immune response. There are already small changes in the virus that have arisen independently on various occasions around the world, suggesting that the mutations are useful to the pathogen.

 

The mutation that affects susceptibility to antibodies (technical name deletion 69-70, referring to missing letters in the genetic code) has been observed at least three times: in Danish mink, in people from the United Kingdom and in an immunosuppressed patient who became much less sensitive to convalescent plasma.

 

“This thing is broadcast. It's spread. It adapts all the time, ”said Ravindra Gupta, a virologist at the University of Cambridge who last week detailed the recurrent emergence and spread of the deletion. "But people don't want to hear what we say, which is that this virus will mutate," he added.

 

The new genetic deletion changes the spike protein (known as protein S) found on the surface of the coronavirus, which the virus needs to infect human cells. Variants of the virus with this elimination emerged independently in Thailand and Germany in early 2020 and became prevalent in Denmark and England in August.

 

Several recent articles have shown that the coronavirus can evolve to avoid being recognized by a single monoclonal antibody, a mixture of two antibodies, or even a convalescent serum administered to a specific individual.

 

Fortunately, the body's immune system as a whole is a much more formidable adversary.

 

The Pfizer-BioNTech and Moderna vaccines induce an immune response only to protein S located on the surface of the coronavirus. However, each infected person produces a wide, unique and complex repertoire of antibodies against this protein.

 

"Let's say we have a thousand high-caliber guns that target the virus," said Kartik Chandran, a virus expert at the Albert Einstein School of Medicine in New York. "No matter how the virus twists and turns, it is not so easy to find a genetic solution that can really combat all these different antibody specificities, not to mention the other arms of the immune response."

 

In short: it will be very difficult for the coronavirus to escape the body's defenses, despite the many variants it may adopt.

 

Escaping immunity requires a virus to accumulate a series of mutations, each of which allows the pathogen to erode the effectiveness of the body's defenses. Some viruses, such as influenza, accumulate these changes relatively quickly. But others, like the measles virus, have almost none of the alterations.

 

Even the influenza virus takes five to seven years to collect enough mutations to completely escape immune recognition, Bloom said. His lab released a new report on Friday, December 18, showing that common cold coronaviruses also evolve to escape detection by the immune system, but that happens over many years.

 

The scale of infections in this pandemic may be generating rapid diversity in the new coronavirus. Still, the vast majority of people around the world have yet to become infected, and that has given scientists hope.

 

"I would be a bit surprised if we saw active selection for immune escape," said Emma Hodcroft, a molecular public health researcher at the University of Bern in Switzerland. "The virus does not need to do that yet in a po[CENSORED]tion that has mostly not been exposed, but it is something we want to take care of in the long term, particularly when we start vaccinating more people," she explained.

 

Immunizing about 60 percent of the po[CENSORED]tion over the course of a year and keeping the number of cases low while that happens will help minimize the chances of the virus mutating significantly, Hodcroft said.

 

Still, scientists will need to closely monitor the evolution of the virus to detect mutations that could give it an advantage over vaccines.