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AScientists are trying to track the spread of a new, more infectious coronavirus variant around the world – finding more cases in the United States and elsewhere this week – they’re also keeping an eye out for a different mutation with potentially bigger implications for the disease. quality of Covid- 19 vaccines work.
The mutation, identified in a variant first seen in South Africa and seen separately in another variant in Brazil, changes part of the virus that the antibodies in your immune system learn to recognize after being infected or vaccinated. Laboratory studies show that the change could make human antibodies less effective at neutralizing the virus. The mutation appears to help the virus mask part of its signature appearance, so the pathogen may have an easier time evading immune protection.
It’s not that the mutation will render existing vaccines useless, scientists point out. The vaccines approved so far and those in development produce what is called a polyclonal response, generating many antibodies that focus on different parts of the virus. Changes to any of these target sites raise the possibility that the vaccines are less effective, not that they will not work at all.
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“With one mutation or even three mutations, antibodies are expected to always recognize this variant, although they might not recognize it as well as other variants,” said Ramón Lorenzo-Redondo, molecular virologist at the Feinberg School of Medicine at Northwestern University.
Essentially, the mutation is gaining attention because it seems more likely to have an effect on vaccines than other mutations that have emerged, although scientists are still trying to test this hypothesis. The most contagious variant that sets off global alarms, which was first seen in the UK and called B.1.1.7, is unlikely to have mutations that will greatly affect vaccines, evidence so far shows .
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“We need to watch for these mutations,” said Jesse Bloom, an evolutionary virologist at the Fred Hutchinson Cancer Research Center, who with his colleagues published a paper on this specific mutation, known as E484K, this week.
But Bloom added that he believed the virus would have to detect several mutations – and particular mutations in specific places, not just any alterations – to have a serious effect on the effectiveness of the vaccine, which will likely take some time. time.
“I’m pretty optimistic that even with these mutations, immunity isn’t going to suddenly fail on us,” Bloom said. “It could be gradually eroded, but it won’t fail for us, at least in the short term.”
Scientists believe that the coronavirus could possibly change so much that the immunity provided by vaccines will be threatened, a process that will increase as the number of people protected against the virus – whether through vaccination or infection – increases and the evolutionary pressure increases in turn. But they still predict that it could take years, and when that happens, vaccine makers will be able to modify their designs to match the new variant, a process some companies said would only take weeks.
The SARS-CoV-2 coronavirus, which causes Covid-19, mutated as it spread, just like other viruses. Many mutations do nothing, and some could even hinder the virus’s quest to replicate and spread. But every now and then a random mutation gives the virus an evolutionary advantage, and that variant can then become dominant. At the start of the pandemic, a mutation known as D614G helped the coronavirus to spread more easily, and variants with this mutation quickly overtook others around the world.
B.1.1.7, which has since spread to other parts of the world, appears to be even more contagious, with some estimates indicating that it is 50% more transmissible. One of its mutations, called N501Y, improves the ability of the spike protein of the virus to bind to a receptor called ACE2 on human cells, which increases the likelihood that the virus will successfully infect cells and the virus passes from person to person.
The same N501Y mutation is also present in the variant identified in South Africa, although the two variants have evolved independently. (Public health authorities try to dissuade people from using terms such as “British variant” or “South African variant”, just as they discourage people from linking SARS-2 by name to China or China. Wuhan. “We have to use the names appropriately because we don’t want to stigmatize where these variants have been identified,” Maria Van Kerkhove of the World Health Organization said Tuesday. “That’s true for any virus identified. ”)
The inclusion of N501Y also appears to help the variant in South Africa to spread faster, but the variant also has the E484K mutation, unlike the variant which first appeared in the UK. mutations in the same part of the virus have appeared previously during the pandemic, the E484K specific mutation is attracting more interest now in part because it is in this variant that is spreading across South Africa and, through travelers, has started to appear elsewhere, including in Japan, Norway and the UK.
The E484K change occurs on a part of the spike protein called the receptor binding domain, which plays a crucial role because the virus binds to ACE2 and is a key target for antibodies. As lab studies have shown, antibodies do not recognize E484K variants as well as other forms.
The research by Bloom and his colleagues this week has further added to this evidence. In their study, which involved mapping how the antibodies of people who had recovered from Covid-19 behaved against different variants, the scientists found that mutations like E484K had the greatest impact on the ability of antibodies to block the virus, with some people experiencing more than a 10-fold decrease in neutralization compared to the variant. The researchers called the location of the E484K mutation “the site of most concern for viral mutations.” (There was variability among the samples, however; some people were able to neutralize the variant very well, and the mutations in other places had more impact than E484K for some people.)
Bloom’s study focused on people who had recovered from infection, not those who had been vaccinated; researchers around the world are studying how well current vaccines resist different variants.
But despite what he and his colleagues found on E484K, Bloom noted that the mutation only reduced neutralizing activity and did not eliminate it. Current vaccines, on the other hand, have shown that they can generate strong immune responses. “I have no doubts that the current vaccines will be useful for some time,” Bloom wrote in a Twitter feed detailing research.
The most pressing concern at the moment, scientists say, remains the spread of B.1.1.7, the variant first seen in the UK, although it is not believed to be causing more cases. serious cases of Covid-19, if it causes more cases overall because it spreads more easily, it will lead to more hospitalizations and deaths. It is also probably more difficult to control than other variants and increases the threshold for the percentage of the population that must be protected to achieve herd immunity.
“The variant is really important,” said Marc Lipsitch, an epidemiologist at the TH Chan School of Public Health at Harvard.
Lipsitch said the United States should focus its efforts on reducing the variant, including sequencing more patient samples to identify cases and directing its contact tracing and quarantine campaigns to try to address it. ‘to jail.
“As far as we can find them and preferably stop the spread, it won’t be perfect, it will be far from perfect, but anything we can do to delay the spread of this new virus variant will make it easier to control.” and help we are in the race to get more people vaccinated before it becomes more common, ”he said.
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