Views: 0 Author: Site Editor Publish Time: 2022-05-13 Origin: Site
Since South African researchers reported new subtypes BA.4 and BA.5 of the mutated new coronavirus Omicron strain, the United States reported another new subtype of the strain, BA.2.12.1, leading to an increase in infections. Omicron's continuous "evolution" is troubling. This strain is frequently mutated. What impact does it have on vaccines and drugs?
According to the weekly report on the new crown epidemic released by the World Health Organization on April 27, the Ormicron strain is the mainstream variant of the global epidemic. Among the more than 250,000 new coronavirus sequences uploaded to the Global Influenza Shared Database (GISAID) in the past 30 days, 99.7% is Omicron.
Since its emergence in November 2021, the Omicron strain has evolved numerous subtypes and recombinant strains, including early BA.1, BA.2, BA.3, and more recently BA.4, BA.5 and BA.2.12.1, and the recombinant strain XD of the delta strain subtypes AY.4 and BA.1, and the recombinant strain XE of BA.1 and BA.2, and the delta strain and BA.1 The recombinant strain XF. Among them, the BA.2 subtype strain is currently the most prevalent in the world.
Trevor Bedford, a professor in the Division of Vaccines and Infectious Diseases at the Fred Hutchinson Cancer Research Center in the United States, recently released a molecular epidemiological analysis of multiple subtypes of Omicron through social media. He said the study found that BA.2 gradually replaced BA.1 between January and April this year and dominated the global epidemic of new coronavirus strains due to faster transmission.
Why did the Ormicron strain evolve such a "variety" of subtype variants? WHO experts say the genetic diversification of Omicron shows that the new coronavirus continues to face natural selection pressure in an attempt to adapt to its host and environment.
Although the severity of the pathogenicity of the Omicron strain is lower than that of the delta strain, its unique "advantage" makes it ultimately "beat" the delta strain to become the mainstream strain in the world. Studies have shown that in addition to the fast transmission speed, Omicron has a significant immune escape ability, which can escape the humoral immune barrier established by vaccines or other variants of the new coronavirus before infection.
The three newly emerged Omicron subtypes - BA.2.12.1, BA.4 and BA.5 have strong immune escape ability. On May 2, the team of Professor Xie Xiaoliang of the Institute of Frontier Interdisciplinary Studies of Peking University published an article on bioRxiv, a biomedical preprint website, evaluating the immune escape of the above three new subtype strains. The study found that all three strains had the L452 mutation on the spike protein, which is key to their immune escape.
The L452 mutation is also a key mutation in the delta strain. Bedford previously predicted that strains such as BA.2.12.1, BA.4, and BA.5 with L452 mutations superimpose the mutations of Omicron and Delta, which have more transmission advantages and may become the main epidemic mutations in the future. strains.
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