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A vaccine candidate developed by scientists in the United States performed well in an experiment that pitched it against the most common mutation of the coronavirus, according to a new study. The product, manufactured by Moderna, a biotechnology company based in Massachusetts, was tested on a modified strain that simulated the D614G mutation of the coronavirus. Research has shown this is present in more than 70 per cent of the confirmed infections around the world, and in close to 100 per cent in some European countries. Compared to other strains, D614G produces more viral copies in the respiratory tract and spreads more efficiently from person to person. What the US researchers, led by Professor Drew Weissman from the University of Pennsylvania, sought to find out was if the mutation could evade a vaccine-induced immune response.
Their methodology involved injecting the Moderna vaccine into humans, monkeys and mice, then collecting blood samples a few weeks later, after antibodies had been produced. What they found was that the antibodies were up to four times more likely to bind to the pseudovirus if it had the D614G gene than if it did not. “This is not an escape mutation that would impede current vaccines,” the researchers in a paper published on Friday on the preprint website Medrxiv.org, which means it has not been peer-reviewed. But they said they were not surprised by the results. That is because, according to the study, the mutation makes a subtle change to the virus’ spike protein, which makes it easier to bind with a receptor on the host cell. But that also increases the chances of antibodies binding with the virus. “The gain in infectivity provided by D614G comes at the cost [to the pathogen] of making the virus more vulnerable to neutralising antibodies,” Weissman said. His collaborators were from Duke University, Harvard Medical School and Los Alamos National Laboratory.
Preprint available at medRxiv (July 24, 2020):
