Health

Omicron has mutations detected in earlier variants


“Based on the data available to date, we believe that currently available vaccines are indeed effective against all variants of the virus,” said Ricardo Dures-Carvalho. university’s medical school (EPM-UNIFESP) and was the final author of the paper, and he received a scholarship from FAPESP.

Another study led by Dures-Carvalho described some mutations shared by several variants in October 2021, even before the World Health Organization (WHO) recognized the occurrence of omicron.

The team studied more than 200,000 genes of SARS-CoV-2 and other coronaviruses that infect humans. They found similar mutations in different strains that could be targets for future vaccination.

“Omicron corroborates our study. Of the 35 mutations in the variant’s mutant protein (used by SARS-CoV-2 to bind to a specific receptor when infecting human cells) , only one mutation was unidentified.25 was in RBD (domain receptor binding) 15 and RBM (receptor binding motif) 10, regions of the virus that bind to human cells and thus it’s a potential target for neutralizing antibodies,” says Dures-Carvalho.

“That may explain why vaccinations have so far been effective even though there are no vaccines on the market specifically designed for omicrons. They don’t prevent transmission, but they do. severe cases and deaths, as can be seen by comparing this new wave Robert Andreata-Santos, postdoctoral fellow at EPM-UNIFESP with fellowship from FAPESP and first author of the Letter sent to editors of previous batches that occurred before a vaccine became available or when a smaller percentage of the population was fully immunized. JMV.

The researchers emphasize that this study builds on existing data on omicrons and on the genomes of other variants sequenced to date. As the pandemic progresses and more data is collected, their hypothesis may be confirmed.

Shared mutations

In research posted to the preprint platform in October, Dures-Carvalho and various co-authors analyzed the virus’ transmission dynamics and evolution over time in Brazil, the United States, and India, over a period of time from February to August 2021.

The analysis revealed an increase in the number of mutational sites in the viral genome, above all in the mutant protein, configuring what the researchers call convergent evolution, which means different variations. Each other undergoes identical mutations that confer advantages such as evading the host immune system or binding more efficiently to human cells.

“We show that the majority of mutations are due to this phenomenon,” said Carla Torres Braconi, professor at EPM-UNIFESP and co-principal investigator of the 2021 study. Braconi is associated with a group of researchers who are working on a project supported by FAPESP and led by Luiz Mrio Ramos Janini, a professor at EPM-UNIFESP and other co-author of the study. JMV posts.

Nine directional spike mutation sites were detected before February 2021, followed by 14 sites between then and July. With the spread of delta variation, more mutant protein mutations were detected. observed, as well as signs of recombination, one of the factors that can lead to the emergence of new variants.

Recombination is the rearrangement of genetic material, especially by joining fragments of DNA from different strains. Signs of omicron-associated recombination were also observed.

In December, researchers analyzed 146 omicron whole-genome sequences from Australia, Austria, Belgium, Botswana, Canada, UK, Germany, Hong Kong, Israel, Italy and South Africa. Evidence of recombination was found when the sequences from beta, delta and omicron were aligned, suggesting that co-circulation of some variants may enhance recombination events.

“Increased viral circulation increases the infectivity of the same individual by different variants, leading to an increase in viral transmission,” said Dr. Danilo Rosa Nunes at EPM-UNIFESP, first author of the 2021 paper. exchange of genetic material between variants.

The researchers now plan to investigate how serum and plasma from vaccinated patients respond to different variants of the mutations they have identified. “We wanted to use seroprevention tests to find out if these individuals could neutralize different variants, including omicrons,” says Braconi.

Another possible next step is to use computational models to predict what each mutation in the mutant protein changes and its ability to invade human cells. By combining the results of these experiments, the researchers were able to clarify the impact of these mutations, shared by several variants, so that they could become targets for vaccines. -Please be more efficient in the future.

As the researchers admit, it is not yet certain that existing vaccines will work against new strains of SARS-CoV-2 in the future, so it is essential to maintain social distancing. society, wear an effective face covering, and complete internal immunizations to slow virus evolution and reduce the risk of new mutations that favor immune evasion.

Source: Medindia



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