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SARS-CoV-2 spreads particularly quickly in the wet
The nasal cavity appears to play a much more important role in the course of COVID-19 than previously thought. An American research team examined how the SARS-CoV-2 coronavirus spreads through the body and found that it replicates fastest in the nasal cavity. There it is also decided whether it affects the lungs and worsens the disease so massively.
In a recent study, researchers from the University of North Carolina mapped the pathways of SARS-CoV-2 within the airways. The team was amazed to see that the virus affects the nasal cavity to a high degree and spreads particularly quickly there. The new type of coronavirus appears to multiply less well in the lower airways. This groundbreaking finding could have a major impact on early intervention options to prevent the virus from reaching the lungs. The study was recently presented in the renowned "Cell" journal.
The nose was initially assigned a subordinate role
When the SARS-CoV-2 coronavirus first appeared at the end of 2019, science assumed that the virus primarily affected the throat and lungs. The nose was initially considered to have no significant role. However, the current study reveals that the nasal cavity plays a major role in the spread of viruses within the body. Here SARS-CoV-2 can multiply particularly quickly and here it is also decided whether it affects the lower respiratory tract and massively worsens the disease. This could be one of the reasons why the course of the disease can be so different from person to person.
Can nasal irrigation and sprays prevent serious infections?
"This is a groundbreaking study that reveals new and unexpected insights into the mechanisms that regulate the progression and severity of the disease after SARS-CoV-2 infection," said Professor Ralph Baric, one of the study authors. “If the nose is the dominant starting point from which lung infections are sown, then the widespread use of masks to protect the nasal passages and all therapeutic strategies that reduce the virus in the nose, such as nasal irrigation or antiviral nasal sprays, could be beneficial "Adds medical professor Richard Boucher, another author of the study.
SARS-CoV-2 can multiply faster in certain cells
In the study, the research team tried to better understand a number of things about the virus, including which cells in the airways infect it and how it causes pneumonia in those affected, and how the virus gets into the lungs. The team used different isolates of SARS-CoV-2 to find out how efficiently the virus can infect cultured cells from different parts of the human respiratory system.
The researchers found striking patterns of high infectivity of SARS-CoV-2 in the cells that line the nasal passages. In contrast, the virus was able to replicate relatively more slowly in the cells of the pharynx, bronchi and lungs. The results suggest that the virus tends to nest firmly in the nasal cavity first. But in some cases, the virus is aspirated into the lungs, where it can cause more serious illnesses, including potentially fatal pneumonia.
Why can SARS-CoV-2 spread quickly in the nose?
The virus needs a specific receptor to enter the cells. This so-called ACE2-Rezepror, a protein that is on the surface of certain cells, is particularly often present in the cells that line the nasal cavity. ACE2 receptors also occur in the lower airways, but rarely, as the research work documents.
SARS-CoV-2 affects only two types of cells in the airways
The researchers also found that SARS-CoV-2 only affects cells that line the respiratory tract, so-called epithelial cells. In addition, the coronavirus can penetrate pneumocytes. These are specialized cells that line the alveoli in the lungs and thus help in the transfer of inhaled oxygen into the bloodstream. Apart from these cell types, SARS-CoV-2 does not appear to affect any other cells in the airways.
Glowing corona viruses
During the study, the researchers also developed a way to develop a fluorescent version of SARS-CoV-2, which makes it easier to track in the body. This could also be useful for future studies. "These results, using a novel and innovative methodology, open up new directions for future studies on SARS-CoV-2 that could guide therapeutic development and practices to reduce the transmission and severity of COVID-19," summarized James Kiley from the study team. (vb)
Author and source information
This text corresponds to the requirements of the medical literature, medical guidelines and current studies and has been checked by medical doctors.
Graduate editor (FH) Volker Blasek
- UNC School of Medicine: Researchers Map SARS-CoV-2 Infection in Cells of Nasal Cavity, Bronchia, Lungs (published: June 1, 2020), news.unchealthcare.org
- Yixuan J. Hou, Kenichi Okuda, Caitlin E. Edwards, et al .: SARS-CoV-2 Reverse Genetics Reveals a Variable Infection Gradient in the Respiratory Tract; in: Cell, 2020, cell.com