Scientists in the UK and Switzerland have uncovered how the coronavirus affects the brain of a person with COVID-19. The infection does not cause neuronal death, but it does provoke inflammatory responses that may explain neurological symptoms. The article of the specialists has been published in the bioRxiv preprint repository.
Researchers studied the spread and effect of the SARS-CoV-2 coronavirus in the central nervous system (CNS) of K18-hACE2 transgenic mice that expressed the human ACE2 enzyme, a protein that serves as the entry point of the virus into the cell. One group of rodents was infected with low doses of coronavirus, and another was first infected with the influenza A virus, and then three days later with the coronavirus. The third group of animals was used for control. Mice were euthanized on the third to seventh day after dosing with SARS-CoV-2.
It turned out that the coronavirus entered the central nervous system and spread through neurons on the seventh day of infection. First, it affected the olfactory bulb, and then penetrated into the lower regions of the brain and spinal cord. The infection did not cause death of nerve cells, damage to axons or demyelination, but there was an increased activity of immune cells of the nervous system – macrophages and T cells, which caused moderate inflammation. All this was accompanied by the death of microglial and endothelial cells during apoptosis.
Microgliosis and apoptosis of immune cells indicate that it is microglial cells that may play an important role in the mechanism of development of neurological disorders during prolonged COVID-19.
It is known that the SARS-CoV-2 coronavirus not only affects the respiratory system, but also affects the brain, causing neurological symptoms such as loss of smell and taste, headache, fatigue or more serious complications such as cerebrovascular disease.
