A new study from the Keck School of Medicine at USC in Los Angeles (United States), published in Nature Cell Biologyrevealed details of how the Covid-19 virus enters the body, infects healthy cells and becomes lethal.
This way, it is possible to understand not only how SARS-CoV-2 acts in the body, but how to treat it efficiently depending on the time of infection.
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Study on Covid-19
The study may explain why some cases of Covid-19 are mild and others severe, and how the situation worsens depending on the person infected. To begin with, the team discovered that SARS-CoV-2 infects the body in two different ways.
The first is when the target is cells in the lung lining. In this case, two viral proteins infect these cells, one activating and the other blocking the immune system. This is contradictory, but it is precisely this contradiction that balances the action and reaction of the virus and makes the infection remain mild in the body.
The second route of infection is when the virus enters through the immune system. In this case, the reproduction capacity of the two viral proteins decreases and the protein that blocks the immune system prevails over the one that stimulates it. These are the cases associated with inflammation and severe symptoms of Covid-19.
Infection
According to MedicalXpress, building on the previous findings, the researchers pursued the study based on two questions: Why is there so little inflammation when SARS-CoV-2 is in lung cells? And why, for people who don’t recover from infections in the first seven to ten days, do their symptoms get so much worse?
See some of the discoveries:
- The researchers began by tracking all the proteins that make up the SARS-CoV-2 virus to understand which ones regulate the production of cytokines (proteins associated with the immune system’s response to infections);
- They found that when the virus enters the lung lining cell, the two viral proteins are produced normally. However, they balance each other, with one of them protecting the cell nucleus and preventing a more serious infection;
- In the immune system, SARS-CoV-2 uses its own spike protein to connect to another type of protein already present in the body;
- This connection prevents the production of the protein that would protect the individual from infection. In other words, of the two SARS-CoV-2 proteins, only the one that worsens inflammation is produced, making this condition more serious;
- The researchers also carried out a test on human immune system cells genetically modified to lack the TLR1 protein, which allows connection with the SARS-CoV-2 spike and takes the virus “into the body”. In this case, there was no infection.
How important is the study in the treatment of Covid-19
The research provided details on how the infection works in the body, but also provided important information on how to manage severe cases of the disease.
In experiments with laboratory mice, treating Covid-19 with a drug that blocks TLR1 (a protein that allows connection with the spike) allowed longer survival and less weight loss compared to the unmodified group.
This gives an important tip: in the initial phase, Covid is best treated by preventing the virus from replicating. At a later stage, the treatment works better by controlling inflammation.
