“The virus is always looking for the next move”: Why science remains vigilant against new variants

Follow up researchers Coronavirus mutation It took a week to carefully study the details of a new variant discovered in Botswana this month.

This is the latest of more than 1,500 recognized Sars-Cov-2 virus lineages that have emerged since the beginning of the pandemic. Out of concerns about the threat of the new variant, the United Kingdom and Israel imposed travel restrictions on a group of southern African countries on Thursday night in response to the unusually high number of spike mutations in the new B.1.1.529 strain.

Can strains that are more spreading, more deadly, and even resistant to vaccines be substituted? The dominant Delta variant, The virus that emerged in India at the end of last year kept scientists and health officials on high alert.

“Did Sars-Cov-2 tried all the techniques? You have to believe this very arrogantly,” said Gavin Scraton, an immunologist and head of the Medical Sciences Department at Oxford University.

Viruses are constantly changing: each copy brings new errors in the 30,000 nucleotide strands that make up its genome.

Under normal circumstances, these mutations will fail, but each mutation is accompanied by the possibility of the virus becoming healthier, which may cause it to produce a higher viral load, and it is easier to bind with respiratory cells or escape the body’s immunity defense.

Before Delta, the biggest threat came from Alpha variants that spread rapidly in the UK. The World Health Organization classifies more than a dozen strains as “following” or “interesting” variants, and gives the official Greek letter names. The latest is the Mu variant that appeared in Colombia in January.

Last month, the British authorities began monitoring the Delta sub-variant, and its transmission rate may increase by about 10%. Two other delta descendants recently discovered in Canada and Indonesia have similarities with this strain.

Emma Holdcroft, an evolutionary geneticist at the University of Basel, was one of the first to track mutations. She said: “Since Alpha and Delta appeared at the end of last year, basically nothing has happened.” “But the virus is always there. Look for the next move.”

Although experts agree that the global vaccination campaign helps to slow down mutations, there is no reason why there is no more dangerous mutation.

Hodcroft explained that before the vaccine was launched, the virus faced a “simpler immune environment” in which almost everyone was susceptible and “transmissibility is the easiest victory.”

Now, with the world’s first dose coverage exceeding 53% and approximately 30 million jabs performed globally every day, the next step for the virus is to “reduce cutting and drying.” “It may become more communicable, or find a way to evade our immune response-or both,” she said.

A public health digital committee warns of a worrying variant in Bolton, northwest England © Oli Scarff/AFP via Getty Images

Some people say that the transmission rate has reached its peak. Francois Balloux, director of the Institute of Genetics at University College London, said that after decades of natural selection, before SARS-Cov-2 reached the highest value of 7, the R0 of the endemic coronavirus was ——The number of reproduction in a fully exposed population.

He said that because the Delta’s R0 is between 6 and 7-which is more than twice the original Wuhan strain-the dominant variant may “not have much room for contagion in the short term,” he said.

Balloux predicts that Sars-Cov-2 will fall into a pattern in which it will “evolve slowly around the immune system” within a decade, rather than “continuously contagious jumping.” The same long evolution can be observed in influenza and seasonal coronaviruses.

But scientists are still worried about sudden viral mutations that will derail the global pandemic response and vaccination efforts.

For this reason, the B.1.1.529 strain that is circulating in South Africa and Botswana has attracted attention because many of its 32 mutations are related to the ability to evade the immune system and spread faster.

The graph shows that a new variant is spreading rapidly in South Africa, and seems to beat other variants faster than previously focused variants

According to a person familiar with the matter, the WHO has held an emergency meeting on Friday where it is expected to classify the strain as a variant of interest.

Tulio de Oliveira, director of the South Africa Epidemic Response and Innovation Center, said he was “worried” about this variant. Of the approximately 1,100 virus cases registered in Gauteng on Wednesday, approximately 90% is caused by it. He said that what is unusual is that strains can be detected by analyzing the results of conventional PCR tests without using genome sequencing.

“The key question to answer is what exactly is [variant’s] The impact on vaccines,” he added.

Slawomir Kubik, a genomics researcher at Geneva-based biotechnology company Sophia Genetics, emphasized that the “suitability” of a mutation can only be judged by its “propagation method in the real world.”

“It has to do with genes, environment, and a certain degree of luck… If you have a’favorable’ mutation but never pass it on, it will never spread,” he said.

The chart shows signs that B.1.1.529 may trigger a new wave in South Africa

Even if the pressure in Botswana disappears, others will appear. Venky Soundararajan, the chief scientist of the data analysis company Nference, worries that the role of vaccination-driven may be to force the virus into a “genetic dead end” and produce an “escape variant” that can evade the immune system.

“Vaccines are God-given ability to stop infections and serious diseases, but paradoxically, they also increase our need to monitor these very specific, targeted mutations,” he said.

Soundararajan warned that the uneven distribution of sequencing technology has created “holes” in genome monitoring. Of the 5.4 million Sars-Cov-2 genomes uploaded to the Gisaid global repository, more than 80% came from two continents: North America and Europe.

Although no one can be sure when and where a major variant will appear, the scientific community agrees that Delta will not remain dominant forever.

Kevin McCarthy, professor of microbiology and microgenetics at the University of Pittsburgh, said that the evolution of the virus is “close to a tipping point,” after which escape variants are likely to appear.

“Will we turn to places where the virus changes its antigenicity and weakens the efficacy of vaccines? I think this is likely to happen,” he said. “If the virus faces the dual choice of evolution or extinction, it will evolve.”

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