Home » Omicron, why is it more contagious but milder? Quick to hook cells (but less melts)

Omicron, why is it more contagious but milder? Quick to hook cells (but less melts)

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While the Omicron variant of the SarsCoV2 virus is very rapid in latching on to human cells, it does very little to fuse with them compared to the Delta variant and the native SarsCoV2 virus. This was reported by the Japanese consortium Genotype to Phenotype (G2P-Japan), specializing in genetic analysis, in an article published online before being reviewed by the scientific community. Genome analysis of the Omicron variant indicates that the Spike (S) protein, used by the virus to attach to cells, does not have a structure to facilitate the process of fusion of the virus with the human cell. In fact, the division into two sub-units, present in the Delta variant, which allowed the virus to fuse efficiently with human cells, is missing.

Omicron, studies on fusion with cells

Other tests, which the same research group subsequently conducted on hamsters, also indicate that Omicron infects the lungs less and spreads less in their cells, with the result of being less pathogenic than both the Delta and the original strain of the SarsCoV2 virus. . According to the researchers, the data suggest that the structure of protein S and its attenuated ability to fuse with human cells “are closely associated with viral pathogenicity” and suggest that the Omicron variant “has evolved towards greater transmissibility and attenuated pathogenicity. “.

The confirmations

Research conducted between Great Britain and Japan, coordinated by Ravindra K. Gupta, of the University of Cambridge, and online on the bioRxiv platform, which includes articles that do not they have yet to pass the scrutiny of the scientific community. Also in this case it is noted that the structure of the protein S of the Omicron variant is such as to make the process of fusion of the virus inside human cells less efficient.

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The difference with Delta

The tests were conducted on a pseudovirus, i.e. a virus that does not exist in nature and has the same mutations as the Omicron variant, and on human lung organoids, i.e. miniature organs grown in the laboratory from cells. It also emerged that the enzyme Tmprss2, which in the presence of the Delta favored the fusion process, in the case of Omicron has a very low efficacy. The data therefore indicate that this mechanism makes Omicron infection less efficient in cells that express the Tmprss2 enzyme, such as those of the lungs, while the new variant more easily infects the upper airways, devoid of the enzyme.

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