How does SARS-CoV-2 get into the brain and what are the possible consequences?
Infection with the Coronavius SARS-CoV-19 not only affects the airways, but can also affect a large number of organs. Given the neurological symptoms found in many of those affected, early suspicion arose that the pathogens could also affect the brain. A current study has now shown for the first time how SARS-CoV-2 enters the brain.
How the SARS-CoV-2 coronavirus can penetrate the brain and how the immune system responds to the virus has been analyzed by a research team from Charité – Universitätsmedizin Berlin using tissue samples from COVID- patients. 19 deceased. The olfactory mucous membrane nerve cells probably form the gateway for the pathogen. The results of the current research were published in the journal “Nature Neuroscience”
COVID-19 can affect different organs
At the outset of the SARS-CoV-2 pandemic, the main focus was on respiratory complaints of the sick, but it soon became clear that COVID-19 is not just a respiratory disease. Researchers from the University Hospital of Erlangen and the Charité – Universitätsmedizin Berlin have recently shown, for example, that the intestines are particularly susceptible to the coronavirus.
Obvious neurological symptoms
It is now considered certain that the cardiovascular system, gastrointestinal tract and central nervous system can also affect the lungs, according to the Charité. More than a third of those affected by COVID-19 also show neurological symptoms such as loss of smell and taste, headache, tiredness, dizziness and nausea. Stroke and other serious illnesses have also been documented in isolated cases.
The neurological symptoms suggested that the coronavirus entered the brain and affected some cells there, but the question was how it got there. Using tissue samples from 33 people who had died as a result of COVID-19 infection, the research team led by Dr. Helena Radbruch and Professor Dr. Frank Heppner of Charité – Universitätsmedizin Berlin is now tracing the path of the virus to the brain.
“Using the most modern methods, the researchers analyzed samples of the olfactory mucosa as well as four different brain regions: They looked for SARS-CoV-2 genetic material and a protein in the virus envelope – the spike protein as the ‘ to be called, both in the tissue network and in individual cells, “reports said. Charité.
Virus can be detected in neuroanatomical structures
The researchers found the virus in a variety of neuroanatomical structures that link the eyes, mouth and nose to the brain stem. The highest viral load was found in the olfactory mucosa. Using special stains and electron microscope images, whole coronavirus particles could be made visible for the first time – inside the nerve cells, but also on the attachments of the cover cells located there.
Odor mucous membrane as access port
“Based on this data, we assume that SARS-CoV-2 can use the olfactory mucous membrane as a gateway to the brain,” explains Professor Heppner. This is also anatomically obvious, as mucous membrane cells, blood vessels, and nerve cells are very close together. “From the olfactory mucosa, it is likely that the virus uses neuroanatomical connections such as the olfactory nerve to reach the brain,” the neuropathologist continues.
Spread in the brain
However, it remains unclear how the virus moves from the nerve cells in the brain. Although the data obtained suggests that it migrates from nerve cell to nerve cell to reach the brain, it is likely that the virus is also being transmitted through the blood vessel system at the same time, as was also found in the walls of the vessel in the brain, according to Dr. A broken wheel. SARS-CoV-2 is not the only virus that can enter the brain through specific channels. This also applies, for example, to herpes simplex viruses and rabies virus, which cause rabies.
The researchers also found activated immune cells in the brain and in the olfactory mucosa and discovered their immune signatures in the cerebrovascular fluid. In addition, in some of the cases examined, tissue damage caused by stroke, induced by blockages of the blood vessels (thromboembolism) in the brain, was discovered.
Does brain involvement cause serious disease?
Overall, SARS-CoV-2 infection in the nerve cells in the olfactory mucosa provides “a good explanation for the typical neurological symptoms of COVID-19 sufferers, such as odor and taste disorders,” according to Professor Heppner. “We also found SARS-CoV-2 in brain regions that control vital functions such as breathing,” the expert emphasized.
Therefore, “it cannot be ruled out that in the case of severe COVID-19 courses, virus infestation in these parts of the brain makes breathing more difficult – in addition to impaired respiratory function due to lung virus pest,” explains Heppner. The same could also apply to the heart and circulation.
However, it should be mentioned in relation to the results of the study that the COVID-19 victims investigated had all died of the disease and therefore had a serious course by definition. “So the results of our study cannot necessarily be transferred to mild or moderate cases,” Professor Heppner stressed. (fp)
Author and source information
This text corresponds to the requirements of the current medical literature, medical guidelines and studies and has been verified by medical professionals.
Dipl. Geogr. Fabian Peters
- Jenny Meinhardt, Josefine Radke, Carsten Dittmayer, Jonas Franz, Carolina Thomas, Ronja Mothes, Michael Laue, Julia Schneider, Sebastian Brünink, Selina Greuel, Malte Lehmann, Olga Hassan, Tom Aschman, Elisa Schumann, Robert Lorenz Chua, Christian Conrad, Roland Eils, Werner Stenzel, Marc Windgassen, Larissa Rößler, Hans-Hilmar Goebel, Hans R. Gelderblom, Hubert Martin, Andreas Nitsche, Walter J. Schulz-Schaeffer, Samy Hakroush, Martin S. Winkler, Björn Tampe, Franziska Scheibe, Péter Körtvély . , Dirk Reinhold, Britta Siegmund, Anja A. Kühl, Sefer Elezkurtaj, David Horst, Lars Oesterhelweg, Michael Tsokos, Barbara Ingold-Heppner, Christine Stadelmann, Christian Drosten, Victor Max Corman, Helena Radbruch, Frank L. Heppner: Olfactory transmucosal SARS Invasion of -CoV-2 as a port of entry into the central nervous system in individuals with COVID-19; in: Nature Neuroscience (published November 30, 2020), nature.com
- Charité – Universitätsmedizin Berlin: How SARS-CoV-2 goes to the brain (published November 30, 2020), charite.de
This article is for general guidance only and should not be used for self-diagnosis or self-treatment. He cannot substitute a visit to the doctor.