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Omicron strains are evolving new ways to escape antibodies and vaccines
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Science: Omicron mutant strains are evolving new ways to escape antibodies and vaccines.
With the large-scale epidemic of the virus, new virus mutant strains continue to appear, Alpha, Beta, Gamma, Delta, Omicron, etc., some of which have stronger infection ability or stronger immune escape ability.
At present, the most concerned about the world is undoubtedly the Omicron mutant strain .
The Omicron mutant strain was discovered in South Africa recently and has spread to 29 countries.
Preliminary data and analysis obtained from the local area show that the epidemic in South Africa will increase exponentially, and Omicron seems to be able to reinfect survivors who have been infected with other strains of the new coronavirus.
On December 2, 2021, researchers from Harvard University Medical School in the United States published a research paper titled: Structural basis for continued antibody evasion by the SARS-CoV-2 receptor binding domain in the top international academic journal Science .
The study predicted the future evolution strategy of SARS-CoV-2 and found several possible mutations that allow the virus to evade immune defenses, including natural immunity obtained through infection or vaccination, and antibody-based treatments.
When the study was published, a new variant called Omicron swept through, and it was later discovered that Omicron contained several antibody-evading mutations that the researchers predicted in the study. This means that Omicron may evolve the ability to evade immune defenses.
The researchers said that the findings are not directly applicable to Omicron, because this particular variant will depend on the interaction between its own unique set of mutations (at least 30) . Nonetheless, the research provides important clues in specific areas related to Omicron and serves as a guide for other mutations that may occur in the future.
The results of the study indicate that special attention should be paid to Omicron mutations, because these mutations have been shown to avoid antibodies used to treat newly infected patients and antibodies from mRNA vaccines. The researchers did not study the virus defense against antibodies produced by non-mRNA vaccines.
In this study, in order to estimate how the virus might transform itself next, the researchers followed the clues of the chemical and physical structure of the virus, and looked for rare mutations in immunocompromised individuals and global virus sequence databases. In laboratory studies using non-infectious virus-like particles, researchers have discovered a combination of multiple complex mutations that allow the virus to infect human cells while reducing or neutralizing the protective ability of antibodies.
The researchers focused on the coronavirus spike protein, called the receptor binding domain, which the virus uses to bind to human cells. The spike protein allows the virus to enter human cells, where it initiates self-replication and ultimately leads to infection.
Most antibodies work by locking the same position on the receptor binding domain of the viral spike protein to prevent it from binding to cells and causing infection.
In order to prove that the virus can produce a large number of escape mutations, the researchers constructed a virus model, which is a combination of harmless non-infectious virus-like particles and SARS-CoV-2 spike protein fragments containing suspected escape mutations. of.
Escape from therapeutic antibodies and mRNA vaccine serum
Studies have found that models containing up to 7 of these escape mutations can resist the neutralization of therapeutic antibodies and serum from mRNA vaccine recipients.
With the emergence of Omicron variants, the researchers said that this level of complex mutations in the receptor binding domain is no longer a hypothesis. The Delta variant has only two mutations in its receptor binding domain. How many models are under study Up to 7 mutations, but Omicron has 15, including several specific mutations analyzed by the researchers.
In a series of experiments, the researchers conducted biochemical analysis and model tests to understand how antibodies bind to spike proteins that contain escape mutations. Some of these mutations, including those found in Omicron, allow the model to completely evade therapeutic antibodies.
In addition, the researchers also discovered an antibody that can effectively neutralize all tested variants. However, if a single mutation occurs in the spike protein and a sugar molecule is added to the position where the antibody binds to the virus, the virus will be able to evade the antibody.
Add sugar molecules to the position where the antibody binds to the virus to drive neutralization and escape
Researchers’ previous results on variants with fewer mutations have shown that these new, highly mutated variants can also cleverly evade antibodies acquired through natural infections.
In another experiment, these models were exposed to the serum of individuals who had received mRNA vaccines. For some highly mutated variants, the serum of single-dose vaccine recipients completely loses the ability to neutralize the virus. In the samples collected from people who had received the second dose of the vaccine, they maintained a certain degree of efficacy against all variants, including some widely mutated pseudotypes.
With the tremendous structural flexibility seen in the SARS-CoV-2 spike protein in this study, Omicron is unlikely to be the end of this virus. Therefore, continued attention and vigilance are needed for the emergence of new mutant strains.
Omicron strains are evolving new ways to escape antibodies and vaccines.
(source:internet, reference only)