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Original author: Max Kozlov Although patients infected with other mutant strains can develop severe lung damage, a growing number of animal studies have shown that Omicron does not easily reproduce in lung tissue
.
Preliminary indications from South Africa and the United Kingdom suggest that the new coronavirus (SARS-CoV-2) variant Omicron is less dangerous than the previous Delta variant
.
Now, multiple laboratory studies have come up with an interesting explanation for the difference: Omicron is more likely to infect cells in the upper respiratory tract and less likely to infect cells deep in the lungs
.
"This observation is intriguing and may explain some of the symptoms we see in patients," said Melanie Ott, a virologist at the Gladstone Institute of Virology in San Francisco who was not involved in the study
.
But she also noted that while Omicron causes disease Severity has decreased, but its high contagion still quickly fills hospitals
.
A doctor in Uzhhorod, Ukraine, examines the lungs of a COVID-19 patient
.
The Omicron variant may have less damage to the lungs than previous popular strains
.
Source: Serhii Hudak/Ukrinform/Barcroft Media via Getty South Africa's official body announced on December 30 that South Africa has passed its peak Omicron without a significant increase in mortality
.
A U.
K.
government report released on December 31 found that among those infected in Omicron in England, about half of those infected in Delta required hospitalization or emergency care
.
However, as the number of vaccinations and/or infections increases, the immune protection of the population itself increases
.
Therefore, it is difficult to tell whether the disease caused by Omicron is really milder than that of the previous variant
.
To find out, the researchers turned to animals and cells grown in the lab
.
University of Washington virologist Michael Diamond and colleagues infected hamsters and mice with variants such as Omicron to track the spread of the disease
.
They found a surprising difference: After a few days, the virus levels in the lungs of animals infected with Omicron were at least 10 times lower than those infected with the other variants [1]
.
Other teams have also noted that Omicron levels are lower in lung tissue than in previous variants [2,3]
.
Diamond said he was particularly surprised to see animals infected with Omicron lose almost no weight, while animals infected with other mutant strains lost weight rapidly, because rapid weight loss means that the infection caused very serious disease
.
"All variants of SARS-CoV-2 infected hamsters easily and at high levels," he said, "but obviously the hamsters infected with Omicron were slightly different
.
" The lung is where the virus causes the most damage, and a lung infection can Triggers an inflammatory immune response that destroys infected and uninfected cells, leading to tissue scarring and hypoxia
.
Fewer infected cells in the lungs may mean less disease
.
Another team found that Omicron was significantly inferior in infecting lung cells and lung organoids (mini-lung models) [4]
.
The experiments also uncovered a possible factor in the difference—the TMPRSS2 protein, which grows prominently on the surface of cells in organs such as the lungs, but is barely present on most cells in the nose and throat
.
Previous variants used this protein to infect cells (see: How does the new coronavirus infect cells? Why is Delta so toxic? | Long article in Nature), but the researchers found that Omicron was unable to bind tightly to TMPRSS2, and was more likely to be Into cells during cellular uptake [5,6]
.
In love with the respiratory tract Ravindra Gupta, a virologist at the University of Cambridge in the United Kingdom and co-author of one of the TMPRSS2 studies [4], said the difficulty in accessing lung cells may help explain why Omicron is more "well-rounded" in the upper respiratory tract rather than in the lungs
.
The theory might also explain why, in some ways, Omicron is nearly as infectious as measles, which has long been seen as a benchmark for high infectivity, Diamond said
.
If Omicron remains stuck in the upper respiratory tract, Gupta says, viral particles can "hide on a ride": They can attach to material exhaled from the nose and mouth and find new hosts
.
Other data provide direct evidence that Omicron replicates much more readily in the upper airways than in the lungs [2,5]
.
The latest results, Ott said, may mean that "Omicrons are less likely to establish local infections in the upper respiratory tract, making them less likely to get into the lungs and wreak havoc
.
" That may be good news, but the host's immune response plays a role in determining the severity of the disease also plays a key role, and scientists need more clinical data to explain how the basic biology of Omicron affects the disease progression it causes in humans
.
Audrey John, a pediatric infectious disease specialist at the Children's Hospital of Philadelphia, said that Omicron's infection method may also have lessons for children (see: What's the secret to children being less susceptible to the new crown? | Long article in Nature)
.
The nasal passages of young children are relatively small, and infants can only breathe through the nose
.
These factors can cause children to have more severe upper respiratory symptoms than adults, John said
.
But she added that she has yet to see a surge in the number of children hospitalized for conditions such as croup, which can indicate a serious upper airway infection
.
While we don't know enough about Omicron yet, Gupta says the alarm raised in late November by the discovery of a large number of mutations in the Omicron genome has not yet been lifted (see: Omicron variants that alarm scientists)
.
The earliest warnings, he said, seemed to warn us that it was difficult to infer from the genetic sequence of a virus how it would infect life
.
References: 1.
Diamond, M.
et al.
Preprint at Research Square https://doi.
org/10.
21203/rs.
3.
rs-1211792/v1 (2021).
2.
McMahan, K.
et al.
Preprint at bioRxiv https://doi.
org/10.
1101/2022.
01.
02.
474743 (2022).
3.
Bentley, EG et al.
Preprint at bioRxiv https://doi.
org/10.
1101/2021.
12.
26.
474085 (2021).
4.
Meng, B.
et al.
Preprint at bioRxiv https://doi.
org/10.
1101/2021.
12.
17.
473248 (2021).
5.
Peacock, TP et al.
Preprint at bioRxiv https://doi.
org/10.
1101/2021.
12.
31.
474653 ( 2022.
On the news section of Nature on January 5 © naturedoi: 10.
1038/d41586-022-00007-8Click to read the original text to view the English original text Promotion | Tsinghua University Shenzhen International Graduate School 2022 Global Recruitment! Click the applet below to view the copyright statement: This article is translated by Springer Nature Shanghai Office
.
The Chinese content is for reference only, and the original English version shall prevail
.
.
Preliminary indications from South Africa and the United Kingdom suggest that the new coronavirus (SARS-CoV-2) variant Omicron is less dangerous than the previous Delta variant
.
Now, multiple laboratory studies have come up with an interesting explanation for the difference: Omicron is more likely to infect cells in the upper respiratory tract and less likely to infect cells deep in the lungs
.
"This observation is intriguing and may explain some of the symptoms we see in patients," said Melanie Ott, a virologist at the Gladstone Institute of Virology in San Francisco who was not involved in the study
.
But she also noted that while Omicron causes disease Severity has decreased, but its high contagion still quickly fills hospitals
.
A doctor in Uzhhorod, Ukraine, examines the lungs of a COVID-19 patient
.
The Omicron variant may have less damage to the lungs than previous popular strains
.
Source: Serhii Hudak/Ukrinform/Barcroft Media via Getty South Africa's official body announced on December 30 that South Africa has passed its peak Omicron without a significant increase in mortality
.
A U.
K.
government report released on December 31 found that among those infected in Omicron in England, about half of those infected in Delta required hospitalization or emergency care
.
However, as the number of vaccinations and/or infections increases, the immune protection of the population itself increases
.
Therefore, it is difficult to tell whether the disease caused by Omicron is really milder than that of the previous variant
.
To find out, the researchers turned to animals and cells grown in the lab
.
University of Washington virologist Michael Diamond and colleagues infected hamsters and mice with variants such as Omicron to track the spread of the disease
.
They found a surprising difference: After a few days, the virus levels in the lungs of animals infected with Omicron were at least 10 times lower than those infected with the other variants [1]
.
Other teams have also noted that Omicron levels are lower in lung tissue than in previous variants [2,3]
.
Diamond said he was particularly surprised to see animals infected with Omicron lose almost no weight, while animals infected with other mutant strains lost weight rapidly, because rapid weight loss means that the infection caused very serious disease
.
"All variants of SARS-CoV-2 infected hamsters easily and at high levels," he said, "but obviously the hamsters infected with Omicron were slightly different
.
" The lung is where the virus causes the most damage, and a lung infection can Triggers an inflammatory immune response that destroys infected and uninfected cells, leading to tissue scarring and hypoxia
.
Fewer infected cells in the lungs may mean less disease
.
Another team found that Omicron was significantly inferior in infecting lung cells and lung organoids (mini-lung models) [4]
.
The experiments also uncovered a possible factor in the difference—the TMPRSS2 protein, which grows prominently on the surface of cells in organs such as the lungs, but is barely present on most cells in the nose and throat
.
Previous variants used this protein to infect cells (see: How does the new coronavirus infect cells? Why is Delta so toxic? | Long article in Nature), but the researchers found that Omicron was unable to bind tightly to TMPRSS2, and was more likely to be Into cells during cellular uptake [5,6]
.
In love with the respiratory tract Ravindra Gupta, a virologist at the University of Cambridge in the United Kingdom and co-author of one of the TMPRSS2 studies [4], said the difficulty in accessing lung cells may help explain why Omicron is more "well-rounded" in the upper respiratory tract rather than in the lungs
.
The theory might also explain why, in some ways, Omicron is nearly as infectious as measles, which has long been seen as a benchmark for high infectivity, Diamond said
.
If Omicron remains stuck in the upper respiratory tract, Gupta says, viral particles can "hide on a ride": They can attach to material exhaled from the nose and mouth and find new hosts
.
Other data provide direct evidence that Omicron replicates much more readily in the upper airways than in the lungs [2,5]
.
The latest results, Ott said, may mean that "Omicrons are less likely to establish local infections in the upper respiratory tract, making them less likely to get into the lungs and wreak havoc
.
" That may be good news, but the host's immune response plays a role in determining the severity of the disease also plays a key role, and scientists need more clinical data to explain how the basic biology of Omicron affects the disease progression it causes in humans
.
Audrey John, a pediatric infectious disease specialist at the Children's Hospital of Philadelphia, said that Omicron's infection method may also have lessons for children (see: What's the secret to children being less susceptible to the new crown? | Long article in Nature)
.
The nasal passages of young children are relatively small, and infants can only breathe through the nose
.
These factors can cause children to have more severe upper respiratory symptoms than adults, John said
.
But she added that she has yet to see a surge in the number of children hospitalized for conditions such as croup, which can indicate a serious upper airway infection
.
While we don't know enough about Omicron yet, Gupta says the alarm raised in late November by the discovery of a large number of mutations in the Omicron genome has not yet been lifted (see: Omicron variants that alarm scientists)
.
The earliest warnings, he said, seemed to warn us that it was difficult to infer from the genetic sequence of a virus how it would infect life
.
References: 1.
Diamond, M.
et al.
Preprint at Research Square https://doi.
org/10.
21203/rs.
3.
rs-1211792/v1 (2021).
2.
McMahan, K.
et al.
Preprint at bioRxiv https://doi.
org/10.
1101/2022.
01.
02.
474743 (2022).
3.
Bentley, EG et al.
Preprint at bioRxiv https://doi.
org/10.
1101/2021.
12.
26.
474085 (2021).
4.
Meng, B.
et al.
Preprint at bioRxiv https://doi.
org/10.
1101/2021.
12.
17.
473248 (2021).
5.
Peacock, TP et al.
Preprint at bioRxiv https://doi.
org/10.
1101/2021.
12.
31.
474653 ( 2022.
On the news section of Nature on January 5 © naturedoi: 10.
1038/d41586-022-00007-8Click to read the original text to view the English original text Promotion | Tsinghua University Shenzhen International Graduate School 2022 Global Recruitment! Click the applet below to view the copyright statement: This article is translated by Springer Nature Shanghai Office
.
The Chinese content is for reference only, and the original English version shall prevail
.
