Viruses also "roll inside"? The "stealth variant" of Omicron gradually became mainstream

◎ Science and Technology Daily reporter Hu Dingkun

A few days ago, a number of Israeli media reported that at least 20 cases of infection with the BA.2 variant of the new coronavirus Omilton strain were found in the country, which has more mutations than the original Omiljun strain, which has caused some experts to worry. Coincidentally, in recent days, multiple researchers tracking the evolution of the new crown virus have warned on social media that the BA.2 variant of the Omiljun strain is emerging in many countries and has even begun to gradually replace the earlier BA.1 variant. This "inner volume" shows that the BA.2 variant may be more contagious.

Image source: Visual China

According to the new coronavirus genome data uploaded by countries to the GISAID platform, the BA.2 variant was very rare before mid-December, but the number has risen rapidly since then. In Denmark, from December 30 to January 2, the ba.2 variant increased from 14.1% to 30% of the total number of coronavirus samples uploaded in the country, while the proportion of BA.1 variants fell from 76.6% to 65.1%, and in India, from December 30 to January 5, the proportion of BA.2 rose from 12.1% to 46.38%, and the proportion of BA.1 variants fell from 58% to 37.68%. In addition, dozens of countries around the world, such as the United Kingdom, the Philippines, Canada, and Germany, have found the existence of ba.2 variants.

According to a related article published in China's Guangdong Provincial Center for Disease Control and Prevention researchers in the "China Cdcover Weekly" on January 3, the world's earliest BA.2 variant sample was found in South Africa on November 27, 2021, and on December 28, the Guangdong Provincial Center for Disease Control and Prevention found that an imported case was infected with the BA.2 variant, and the gene sequencing analysis believed that the variant had 67 nucleotide mutation sites, 49 amino acid mutation sites and 9 amino acid deletions at the protein level. There are about 50 variations at the level of the BA.1 variant protein, which is slightly less than the BA.2 variant.

Of particular note is the off-target (SGTF) of the BA.1 variant in PCR testing, which is an important feature that distinguishes it from strains such as Delta and is therefore easier to detect. However, the BA.2 variant genome does not have the characteristic deletion that causes the spike protein gene to off-target, and PCR detection is difficult to distinguish between the variant and other strains, requiring more complex and time-consuming means such as gene sequencing to be clear, so the BA.2 variant is also known as "stealthYomikron".

In fact, the Omiljung strain also has a BA.3 variant, but the number is so small that only 33 samples have been found worldwide. At present, researchers in Israel and other countries are closely tracking the spread of the BA.2 variant of the Omiljung strain, and its infectious and pathogenic characteristics are still being studied.

Source: Science and Technology Daily

Editor: Wang Yu

Review: Wang Xiaolong

Final Judge: He Yi