As the coronavirus spread around the world, it picked up random changes in its genetic sequence. Like meaningless typos in a script, most of these changes do not affect the behavior of the virus.
But a change near the onset of the epidemic made a difference, suggesting several new findings, helping the virus spread easily from person to person and making it harder for the epidemic to stop.
The transformation, known as 614G, was first seen in eastern China in January and then quickly spread throughout Europe and New York City. Within months, the variable took over most of the world, displacing other types.
For months, scientists have been debating why. Researchers at the Los Alamos National Laboratory argued in May that the variable might develop the ability to infect people more effectively. Many were skeptical, arguing that the variant could only be lucky, often appearing by chance in major epidemics, such as in northern Italy, where another disease had erupted elsewhere.
But many groups of new research – including close genetic analysis of outbreaks with hamster and human lung tissue – have backed the view that the mutated virus has a distinct advantage, infecting people more easily than the original variant found in Wuhan. , China.
There is no evidence that 614G mutated coronavirus causes more severe symptoms, kills more people or complicates the development of vaccines. That findings do not change the reality that locations have performed better than those that lock down quickly and aggressively and encourage measures such as social distance and masks.
But David Engelthaler, a geneticist at the Arizona Translational Genomics Research Institute, said microscopic mutations in the virus’s genome have had an impact on the big wave. “When all is said and done, it may be that the epidemic was caused by this change.”
Most researchers, including Dr. Mut Angelther, believe that the first outbreak of the virus would have occurred even without mutations, worldwide. He said the original type spotted in Wuhan, China in late 2019 was already highly contagious. But the epidemic seems to have spread more and more quickly because of the change.
Scientists are especially cautious in the field of virology.
Lab studies have found that mutations in the Ebola virus, which began in West Africa in 2013, have led to an increase in tissue culture infections. But that conclusion does not translate to the increasing transmission of lab studies with animals. And some experts say the impact of the 614G transformation may be more general than other factors such as the social distance rate.
But new evidence from research groups in the United Kingdom and the United States has changed the minds of many scientists who were initially skeptical.
One study found that outbreaks in communities in the United Kingdom have grown faster than those produced by its Wuhan ancestors through the 614G variant. Others have reported that hamsters infect each other more quickly when exposed to variants. And in the third part, in the dish of cell-culture a variety of infected human trachea and nasal tissues in a more efficient way than its ancestor.
Trevor Bedford, an associate professor at the Fred Hutchinson Cancer Research Center and the University of Washington, said he had won by collecting findings from different lines of research.
Dr. Bedford said, “The only thing I’m convinced of is seeing it over and over again.” “I think it’s real at the moment.”
Despite being impressed by the new work, Dr. Bed. Bedford and other scientists said it was still unclear if the main cause of global domination was an inherent advantage.
Christian Anderson, a Scripps researcher, a La Jolla geneticist, said research shows that variables are more transmissible, but he believes the difference is subtle.
However, Dr. And. Andersen said the variable transmissibility of the variable could help explain why some countries that initially managed to contain the virus later became susceptible to it. He said the virus “could be more difficult than the first time around.”
Dr. “What you do may not be enough to control it,” Andersen said. “Don’t expect the enemy from two months ago to be next to you.”
Worldwide, the emergence of the 614G could generate both serious scientific debate and largely political blaming. Government officials in Vietnam and Thailand, who did a good job of keeping the ancestral strain despite the influx of Chinese visitors earlier this year, have suggested that a subsequent outbreak could be partly the result of the 614G virus.
Thira Vuranrat, an associate professor in the medical faculty at Chulalongkorn University in Bangkok, said Thailand has controlled both types of the virus in the past year through strict security of returnees, foreign tourists, masks and other measures. Still, he said, resurgence in the region is relevant.
“We’ve seen some countries like Vietnam, South Korea and Japan seem to be under its control,” Dr. Thira said. “But then came another wave.”
In Vietnam, he said, the virus with the 614G mutation was confirmed about 100 days later, in the central coastal city of Danang, with no reports of local transmission. The outbreak spread rapidly to 10 cities and provinces. In Singapore, he said, mutations spread the virus in crowded bedrooms for migrant workers.
“When the mutated virus lives in large groups, it spreads faster and makes it more difficult to control,” he said.
But other researchers say the lack of solutions, not of change, is largely responsible for the outbreak of regeneration.
The reason is spreading because people are not taking enough action in place, said Kari Stephenson, founder and chief executive of Decode Genetics, a leading Iceland-based genome analysis firm. “There seems to be an extraordinarily weak politics blaming imperfections on the virus. They should not pick this small virus but someone on their own size. “
In one of the new studies, a British team of researchers found an advantage shared by others: they were able to draw the world’s largest national database of coronavirus genome sequences. Researchers gathered new evidence that, at least in the United Kingdom, the variant took over because it spreads really fast.
Eric M., a researcher and study leader at the Center for Global Infectious Diseases Analysis at the Medical Research Council Center at Imperial College London. “When we look at clusters, the G-variant grows faster,” Wallace said.
Data collected by the Covid-19 Genomics UK consortium allowed the team to observe the growth of infected clusters as a kind of horse race. Also, did the clusters of 614G infection develop faster than the ancestral type of infection?
The analysis found that the 614G variant clearly won the race. The exact rate remains uncertain, but the potential value gives the 614G an advantage of about 20 percent over its growth rate.
Associate Professor of Biology at Emory University, Katherine V. “This is exactly the kind of analysis that needs to be done, and it provides more support for G to become more transmissible,” said Coyle, an associate professor of biology at Emory University.
In a separate series of studies, a team led by Ralph Barrick at the University of North Carolina tested a live virus comparing the 614G variant with the ancestral version. In one, the team found that the 614G virus is more contagious in human bronchial and nasal tissue samples, which is a potential source of the virus infecting others.
Another study, published in Science, found that this type of hamster was more easily transmissible when infected animals came within a few inches of each other. Scientists see the mutation as a crucial step in testing animal experiments to see if mutations, which make the virus more contagious in lab dishes, do the same in living populations.
Dr. Barrick’s team placed an infected hamster in a cage, next to an unaffected cage; The cages were several inches apart, so the animals could not touch each other. Any transmission can only be from air, droplets or aerosols.
Two days later, five of the eight hamsters with the 614G variant infected his pair. No one with the ancestral virus did that.
“When you take all the data together, everything is compatible with the system which increases contagion and transmissibility,” said Dr. Said Barrick.
Dr. The Angelthaler said that the virus would be constantly changing, and that most of the changes would be just typhoid, some could be more meaningful. “There will likely be additional changes that change the nature of the epidemic.”
Already, D En. Engelthaler said he has seen a wide range of spreads in Arizona and has seen strong signs of such a change in his unpublished data.
“We have to listen to what the virus tells us,” he said.
Mukita Suharto contributed to the report.
