The SARS-CoV-2 spike protein was found in neuronal cells, suggesting that neurons associated with smell may be infected.
An illustration of the new SARS-CoV2 virus. Image: Nexu Science Communication / Trinity College
The novel coronavirus
can enter people’s brains through the nose, according to a study published Monday (November 30) that may help explain some neurological symptoms seen in COVID-19 patients and inform the diagnosis and measures to prevent infection.
The research, published in the journal Neuroscience of nature, noted that SARS-CoV-2 not only affects the respiratory tract but also affects the central nervous system (CNS), causing neurological symptoms such as loss of smell, taste, headache, fatigue and nausea.
Although recent research has described the presence of viral RNA in the brain and cerebrospinal fluid, it is not clear where the virus enters and how it is distributed within the brain.
Researchers at Charite Universitatsmediz in Berlin, Germany examined the nasopharynx, the upper part of the throat that connects to the nasal cavity, a likely first site of viral infection and replication, and the brains of 33 patients, 22 men and 11 women, who died. with COVID-19 .
The median age at the time of death was 71.6 years, and the time elapsed from the start of COVID-19 death symptoms were a median of 31 days, they said.
The researchers said they found the presence of SARS-CoV-2 RNA, the genetic material of the virus, and proteins in the brain and nasopharynx, adding that intact viral particles were also detected in the nasopharynx.
The highest levels of viral RNA were found in the olfactory mucous membrane, they said.
According to the researchers, the duration of the disease was inversely correlated with the amount of detectable virus, indicating that higher levels of SARS-CoV-2 RNA were found in cases with a shorter duration of the disease.
The team also found SARS-CoV-2 spike protein in certain cell types within the olfactory mucosa layer, where it can take advantage of the proximity of endothelial and nerve tissue to enter the brain.
In some patients, SARS-CoV-2 spike protein was found in cells that express neuron markers, suggesting that olfactory sensory neurons may be infected, as well as in areas of the brain that receive smell and taste signals, the researchers said.
SARS-CoV-2 was also found in other areas of the nervous system, including the brainstem, the brain’s main center of respiratory and cardiovascular control, they said.
The researchers noted that more COVID-19 Autopsy studies that include a wide range of specimens are needed to identify the precise mechanisms that mediate virus entry into the brain and to examine other possible ports of entry.
