A global study has found strong evidence that a new form of the coronavirus has spread from Europe to the US The new mutation makes the virus more likely to infect people, but does not appear to make them sicker than previous variations. of the virus, an international team of researchers reported Thursday.
“It is now the dominant form that infects people,” Erica Ollmann Saphire of the La Jolla Institute of Immunology and the Coronavirus Immunotherapy Consortium, who worked on the study, told CNN.
“This is now he virus.”
The study, published in the journal Cell, builds on previous work the team did and launched on a prepress server earlier this year. Information shared about genetic sequences had indicated that a certain mutant version of the virus was taking over.
Now, the team has not only verified more genetic sequences, but has also conducted experiments on people, animals, and cells in laboratory dishes that show that the mutated version is more common and more infectious than other versions.
“We know that the new virus is in better shape. At first glance, it doesn’t seem to be any worse, ”said Saphire.
The mutation affects the spike protein, the structure the virus uses to enter the cells it infects. Now researchers are checking to see if this affects whether the virus can be controlled by a vaccine. The current vaccines being tested mainly target the spike protein, but were made using older strains of the virus.
The study, published in the journal Cell, confirms previous work suggesting that the mutation had made the new variant of the virus more common. The researchers call the new mutation G614, and show that it has almost completely replaced the first version that spread in Europe and the United States, a one called D614.
No effect on patient survival.
“Our global tracking data shows that the G614 variant on Spike has spread faster than D614,” theoretical biologist Bette Korber of the Los Alamos National Laboratory and colleagues wrote in their report. “We interpret this to mean that the virus is likely to be more infectious,” they added. “Interestingly, we found no evidence of the impact of G614 on the severity of the disease.”
This could be good news, said Lawrence Young, a professor of medical oncology at the University of Warwick in the United Kingdom, who was not involved in the study.
“Current work suggests that while the G614 variant may be more infectious, it is not more pathogenic. There is hope that as the SARS-CoV-2 infection spreads, the virus could become less pathogenic, “it said in a statement.
The team tested samples taken from patients across Europe and the US and sequenced the genomes. They compared these genome sequences with what has been shared publicly. Comparing these sequences helped them draw a map of the spread of the two forms.
“As of March 1, 2020, the G614 variant was rare outside of Europe, but by the end of March it had increased in frequency worldwide,” they wrote.
Even when the D614 form had caused widespread epidemics, in places like Wales and Nottingham in England, as well as in Washington state, they discovered that G614 took over once it appeared.
“The increase in G614 frequency often continues long after the stay-at-home orders are in place and after the two-week incubation period,” they added. There are a few exceptions, including the Santa Clara, California, and Iceland area, where the older D614 form was never replaced by the newer G variant.
Three to nine times more infectious
The new version appears to multiply faster in the upper respiratory tract, nose, sinuses and throat, which would explain why it happens more easily, the researchers said.
But tests on 1,000 hospitalized patients with coronavirus in Britain showed that those infected with the new version fared no worse than those who caught the original strain.
David Montefiore of Duke University and his colleagues tested the virus in the laboratory. “We were able to test whether the G form of the virus was more infectious than the D form,” Montefiore, director of the AIDS Vaccine Research and Development Laboratory, told CNN.
“All results agreed that Form G was three to nine times more infectious than Form D,” he added. “We now had experimental evidence that supported, in part, what Bette was seeing in her analysis of sequences around the world: Form G had an aptitude advantage in terms of infectivity.”
Laboratory tests of the virus in action confirmed what the genetic maps had shown.
“These findings suggest that the newer form of the virus can be transmitted even more easily than the original form. Regardless of whether that conclusion is confirmed or not, it highlights the value of what were already good ideas: wearing masks and maintaining social distance, ”Korber said in a statement.
Other mutations often go along with the G614 mutation, but it is unclear what effect they have. “The first sequence we detected carrying the four mutations was sampled in Italy on February 20,” they wrote. “In a matter of days, this haplotype was sampled in many countries in Europe.”
The G614 mutation can be neutralized with convalescent serum, the blood product taken from people who have recovered from a coronavirus infection, Saphire said. Her team analyzed the blood donated by six coronavirus survivors in San Diego.
“We were looking to see if the range of antibodies in people’s blood was as effective in neutralizing the new virus as the old virus was.” In fact, it was a little better, ”he said.
“That was a relief.”
The researchers were concerned that if the new mutation made the virus grow faster and at higher levels, it would take more effort from the immune system to neutralize it. “In these six San Diegans, that was not the case,” said Saphire.
More work is needed, of course, to solidify the findings and see what the changes mean for the epidemic and for patients, the researchers said.
“There are possible consequences for vaccines. We are actively investigating these possible consequences, ”said Montefiore.
And of course they are on the lookout for other mutations. “We could have dodged a bullet with this particular mutation,” said Saphire. “However, that does not mean that another mutation cannot be above this one,” he added.
“It would be in our interest to remain vigilant.”
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