Researchers at Yale School of Medicine have found that coronavirus can directly infect the central nervous system.
For the study, the researchers used both mouse and human brain tissue. They intended to understand some of the virus’s effects on brain cells.
The study, published today in the Journal of Experimental Medicine, may help researchers develop treatments for the various neurological symptoms associated with Covid-19.
Though Covid-19 is considered to primarily be a respiratory disease, SARS-CoV-2 can infect many other organs in the body. This includes the central nervous system, where the infection is associated with a variety of symptoms ranging from headaches and loss of taste and smell to impaired consciousness, delirium, strokes, and cerebral haemorrhage.
Lead author Akiko Iwasaki, a professor at Yale School of Medicine said: “Understanding the full extent of viral invasion is crucial to treating patients, as we begin to try to figure out the long-term consequences of Covid-19, many of which are predicted to involve the central nervous system.”
Iwasaki and the team analysed the ability of SARS-CoV-2 to invade human brain organoids, miniature 3D organs grown in the lab from human stem cells.
The researchers revealed that the virus was able to infect neurons in these organoids and use the neuronal cell machinery to replicate.
The Yale team determined that the ACE2 protein is, in fact, produced by neurons and that blocking this protein prevents the virus from human brain organoids.
The researchers also analysed the brains of three patients who succumbed to Covid-19. They said in their study that the virus was detected in the cortical neurons of one of these patients. The infected brain regions were associated with ischaemic infarcts in which decreased blood supply causes localised tissue damage and cell death. Microinfarcts were detected in the brain autopsy of all three patients.
SARS-CoV-2 can also cause dramatic alterations in the brain’s blood vessels that could potentially disrupt the organ’s oxygen supply, the authors wrote.
Central nervous system infection was much more lethal in mice than infections limited to the lungs, the researchers found.
Co-senior author Kaya Bilguvar, an associate professor at Yale School of Medicine, said: “Our study clearly demonstrates that neurons can become a target of SARS-CoV-2 infection, with devastating consequences of localised ischaemia in the brain and cell death.”
He added: “Our results suggest that neurologic symptoms associated with Covid-19 may be related to these consequences, and may help guide rational approaches to the treatment of Covid-19 patients with neuronal disorders.”