Berlin. It was originally called a lung virus, but it is now clear: Sars-CoV-2 is more than that, it is a multi-organ virus. In addition to the lungs, researchers were also able to detect the pathogen in the brain, among other things. But how does the coronavirus get there?
Experts in neuropathology, pathology, forensic medicine, virology and clinical care at the Berlin Charité have investigated this question. They analyzed tissue samples from 33 people who had died in connection with Sars-CoV-2. They published their results in the journal Nature Neuroscience, which show that the nerve cells in the olfactory mucosa transmit the coronavirus to the brain.
For the first time intact corona particles made visible
In their investigations, the scientists also researched individual cells in which they looked for the genetic material of the coronavirus and its spike protein. The highest viral load was ultimately found in the olfactory mucosa. With the help of special stains and electron microscope images, the researchers were able to make intact coronavirus particles visible for the first time. These particles were detectable both inside nerve cells and on the extensions of the cover cells in the olfactory mucosa.
“On the basis of this data, we assume that Sars-CoV-2 can use the olfactory mucosa as a gateway into the brain,” said Prof. Frank Heppner, director of the Institute for Neuropathology at the Charité, in a communication from the university. “From the olfactory mucosa, the virus apparently uses neuroanatomical connections such as the olfactory nerve to reach the brain.”
Coronavirus may migrate from nerve cell to nerve cell
The neuropathologist points out, however, that the study only examined corona patients who had a severe course of the disease during their lifetime and then died as a result of the disease. “The results of our study can therefore not necessarily be transferred to mild or moderate cases.”
It is also largely unclear how exactly Sars-CoV-2 moves from the nerve cells. “Our data suggest that the virus migrates from nerve cell to nerve cell in order to reach the brain,” says neuropathologist Helena Radbruch from Charité, who also participated in the study. “However, the virus is probably also transported via the blood vessel system at the same time, since the virus could also be detected in the vascular walls in the brain.”