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Compiled by Zakiyah Ebrahim
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Health24
30 minutes ago
- Data shows that a large number of people infected with SARS-CoV-2 do not experience any symptoms.
- However, these people are still capable of transmitting the virus, so it is important to understand how this happens.
- According to a new study, the answer may lie in the virus’s ability to prevent its genome from being recognized.
People who become infected with Covid-19, the disease caused by the SARS-CoV-2 virus, experience mild to severe illness or even death, and then there are those who do not exhibit any symptoms.
A recent study, published in PLOS Medicine, estimated that 20% of SARS-CoV-2 infections are asymptomatic (show no symptoms) but remain contagious, so the question arises, how does this happen?
According to new research from Aarhus University and Aarhus University Hospital in Denmark, the virus has the ability to prevent its genome (its genetic material) from being recognized.
The findings were published in EMBO reports.
Immune cells and SARS-CoV-2
To understand the phenomenon in depth, the researchers looked at specialized immune cells, called alveolar macrophages (AM), found in our lungs. They form an important defense against pathogens in the lungs.
According to a research article published in American Journal of Respiratory and Intensive Care Medicine, AMs clear the air spaces of infectious particles that have bypassed the mechanical defenses of the respiratory tract, such as the nasal passages.
Since the lungs contain a significant number of these immune cells, they are likely the first cell type to encounter an invading virus, the researchers explained.
Digging deeper, the team looked at interferons, a group of cytokines that are essential for fighting viruses. When our body recognizes a viral infection, our immune system starts the production of these interferons.
Previous research has shown that AMs produce large amounts of interferons when infected with respiratory viruses, such as influenza.
According to a press release from Aarhus University, new research also shows that interferon production in infected epithelial cells can be inhibited by the new coronavirus, which normally infects the epithelial layer, the outermost cell layer of the lungs.
However, although the epithelial layer is the target of the virus, the researchers suggest that it should be assumed that the first cell type encountered by the virus is AM. These cells, therefore, play an important role in how quickly an immune response to a SARS-CoV-2 infection can be initiated, they explain.
The process
Taking all of the above into account, the team set out to investigate how these cells react to SARS-CoV-2.
To do this, AMs obtained from bronchoalveolar lavages (BAL), also known as lung lavage or lung lavage, from donors diagnosed with non-infectious lung disorders were challenged with SARS-CoV-2.
After this, they examined the activation of the immune system in these cells by finding the coronavirus.
The new coronavirus can hide its genome so that it is not recognized
Alveolar macrophages have the potential to produce large amounts of interferons during a viral infection, such as influenza, but the researchers did not see interferon production in cells when alveolar macrophages were exposed to the SARS-CoV-2 virus.
This, therefore, suggests that in some people, SARS-CoV-2 may prevent its genomic material from being recognized by alveolar macrophages. As a result, it does not induce interferon production, say the authors.
This explains why there is no activation of the immune system in the early stages of a SARS-CoV-2 infection, eventually allowing the virus to spread more widely in the community before symptoms show up in individuals, they explained. the researchers.
However, they added that more research is needed to understand how the virus can avoid being recognized by the immune system.
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READ | Severe Covid-19 in Younger People Could Be Due to Faulty Genes and an Autoimmune Condition
Image: Getty / Dowell
