According to a new study, the virus responsible for Covid-19 is capable of infecting neurons. This phenomenon could explain the loss of smell, the headaches and perhaps even the strokes of some patients.
Headaches, loss of smell, cerebrovascular accidents (CVA)… These neurological symptoms of Covid-19 are known to scientists, but they do not know precisely the reasons for their development. An international study, published on January 12 in the journal Journal of Experimental Medicine, offers a new explanation for these neurological damage caused by Covid-19. They would be linked to the fact that the virus responsible for Covid-19, SARS-CoV-2, infects the neurons of certain patients.
SARS-CoV-2 enters neurons and multiplies there
Researchers from the National Institute for Health and Medical Research (Inserm), the Sorbonne University in Paris, Yale University in the United States, the Pitié-Salpêtrière Hospital AP-HP as well as the National Center for Scientific Research (CNRS) at the Institut du Cerveau worked together to reach these conclusions. They used three different analyses: one on mice, a second on brain cells grown in the laboratory and the last on brain tissue from deceased Covid-19 patients.
In mice first, the regions of the brain infected by the virus underwent significant remodeling at the level of the cerebral vascular network. This is the first time that this phenomenon has been observed. Then, in brain cells grown in the lab, the researchers estimate that SARS-CoV-2 enters neurons and multiplies there. Infected cells are not destroyed but undergo a noticeable metabolic change. As for the other brain cells – located near those infected with SARS-CoV-2 – they are deprived of oxygen and die. Finally, the virus was also found in the neurons of patients who died of Covid-19.
The unknown remains the path taken by the virus to reach the brain
According to A press release published on the Inserm website: “dTaken together, these results confirm the brain tropism of SARS-CoV-2 and its ability to infect neurons. They also suggest that the neurological symptoms observed in Covid-19 could be a consequence of this direct attack on the central nervous system”.
According to the researchers, it would be possible to avoid neuronal infection by blocking the ACE2 protein – present on the surface of cells – with antibodies or cerebrospinal fluid from a patient with Covid-19. The ACE2 protein would be used by the virus to enter and settle in the body, in particular on the lungs. Nevertheless, for neurons, the role of this protein as an entry pathway remains to be proven.
It remains to be determined how the virus enters neurons. Studies should be carried out over the next few months to find out the path taken by SARS-CoV-2 to reach the brain.