Spreading faster! Beware of the "second-generation variant" of Omicron, cases have appeared in many countries

Recently, a new variant of the Omicron virus, numbered "BA.2.75", has attracted great attention from scientists in Israel and other countries. This variant evolved from the BA.2 variant of the Omicron virus and is called the "second-generation variant". It has many "unusual" mutations, which may break through the immune barrier constructed by existing vaccines and strain infections, and is highly contagious. Cases have appeared in many countries, including India, Japan, and the United States. Relevant experts are worried that this variant may replace existing variants such as BA.2 and BA.4, and set off a new peak of the epidemic around the world.

New variant mutations raise concerns

As of July 2, researchers from various countries have found 85 gene sequences of the BA.2.75 variant in international coronavirus genome databases such as GISAID. The variant first appeared in gene sequences from India in early June, and then quickly appeared in seven other countries including the United Kingdom, the United States, Japan, Canada, Australia, New Zealand, and Germany. Since the number of coronavirus genomes shared by various countries is only the "tip of the iceberg" of the number of global coronavirus cases, the actual number of people infected with the BA.2.75 variant is far more than 85.

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Dr. Shay Fleisch, an expert at the Central Virus Laboratory of the Israeli Ministry of Health, said on a social media platform that the emergence of BA.2.75 is "worrying." It is a "second-generation variant" evolved from the BA.2 variant. Compared with BA.2, it has 16 new mutations, 8 of which are located in the spike protein gene region.

The American Bloom Laboratory stated on the social media platform that compared with its BA.2, this variant has two key mutations, G446S and R493Q. G446S will cause changes in antigenic characteristics, helping the virus break through the immune barriers constructed by existing vaccines, while R493Q increases the ability of the virus to enter human cells. Therefore, BA.2.75 is very worthy of further tracking.

British virology expert Tom Peacock said that BA.2.75 has a large number of spike protein mutations, belongs to the "second-generation variant", and has a fast transmission speed and wide geographical distribution, and needs to be closely monitored.

BA.2.75 may become the first successful "second generation variant"

According to Shay Fleischon, Tom Peacock and others, the so-called "second-generation variant" refers to a variant that evolved from the "first-generation variant" but has more mutations and is significantly different from the first-generation variant. For the Omicron strain, variants such as BA.1, BA.2, BA.3, BA.4, and BA.5 belong to the "first-generation variant", while BA.2.75 may become the first successful "second-generation variant".

Shay Fleisch said that before BA.2.75, researchers had discovered many "second-generation variants" of the new coronavirus - "these samples can be found every day", but the variants discovered before have not been able to spread widely, and the sample size is very small, while BA.2.75 has spread in many different countries, and there are already dozens of sample sizes, and it seems to have succeeded. BA.2.75 is only the first "successful solution", representing the "next step" in the evolution of the Omicron strain (that is, the production of more "second-generation variants"), and more complex genetic changes may appear in the future.

Tom Peacock said that "second-generation variants" evolved from existing and successful variants that already have "nasty" antigenicity, transmissibility and other characteristics, which may mean that they are more likely to acquire more threatening mutation combinations.

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New epidemics may occur in the future

Studies have shown that the BA.2 variant of the Omicron virus is more contagious than the earlier BA.1 variant. At the end of last year, after the Omicron virus appeared, the BA.1 variant first triggered an unprecedented peak of the epidemic around the world; in March and April this year, BA.2 gradually "replaced" BA.1, causing the United States, Europe and other countries to enter another round of epidemics; after entering June, the spread of BA.4 and BA.5 variants caused the epidemic in Europe, Israel and other places to intensify again.

Many experts believe that BA.2.75 is likely to have a competitive advantage over other variants.

Australian data processing expert Mike Honey believes that BA.2.75 spreads extremely quickly. Between June 15 and 30, the proportion of this variant in genome samples uploaded by India quickly increased from less than 5% to 18%, indicating that it is replacing other variants and its spread seems to be faster than the BA.2 and BA.5 variants.

Raj Rajnarayanan, associate professor of biology at New York Institute of Technology, also believes that BA.2.75 has the potential to replace BA.5, BA.4 and other spreading BA.2 variants. There is currently too little data to draw reliable results, and its growth advantage may become apparent within a few weeks.

Tom Wenslers, professor of biology at the University of Leuven in Belgium, also said that he was certain that the growth advantage of BA.2.75 over BA.5 was real.

Ulrich Eling, a researcher at the Institute of Molecular Biotechnology of the Austrian Academy of Sciences, said that before we get through the BA.5 wave, we may have already prepared for the next wave. BA.2.75 and BA.5 have 11 mutations in the spike protein gene region. The immune barrier produced by BA.5 infection may not be able to protect against BA.2.75, leading to a new peak of infection.

Author: Hu Dingkun

Source: Science and Technology Daily

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