The S1 protein is likely to cause the brain to release inflammatory products causing a brain storm, the researchers said. Credit: Alice Gray
A study published in The neuroscience of nature shows how the spike protein crosses the blood-brain barrier.
There is more and more evidence that people with COVID-19 you suffer from cognitive effects such as brain fog and fatigue.
And researchers are finding out why. SARS-CoV-2 the virus, like many viruses before, is bad news for the brain. In a study published on December 16, 2020 in The neuroscience of nature, the researchers found that the spike protein, often described as the red arms of the virus, can cross the blood-brain barrier in mice.
This strongly suggests that SARS-CoV-2, the cause of COVID-19, may enter the brain.
The spike protein, often called the S1 protein, dictates which cells the virus can enter. Usually, the virus does the same thing with its binding protein, said lead author William A. Banks, a professor of medicine at University of Washington School of Medicine and a physician and researcher at the Veterans Health System in Puget Sound. Banks said that binding proteins, such as S1, usually cause damage on their own because they detach from the virus and cause inflammation.
The S1 protein probably causes the brain to release cytokines and inflammatory products, he said.
In scientific circles, the intense inflammation caused by COVID-19 infection is called a cytokine storm. The immune system, after seeing the virus and its proteins, reacts excessively in its attempt to kill the invading virus. The infected person is left with brain fog, fatigue and other cognitive problems.
Banks and his team saw this reaction to the HIV virus and wanted to see if the same thing would happen with SARS CoV-2.
Banks said that SARS-CoV2 protein S1 and HIV-1 GP 120 protein work similarly. They are glycoproteins – proteins that have a lot of sugars on them, the hallmarks of proteins that bind to other receptors. Both proteins function as arms and hands for their viruses by grabbing other receptors. Both cross the blood-brain barrier and S1, like gp120, is probably toxic to brain tissue.
“It was like deja vu,” said Banks, who has worked extensively on HIV-1, gp120 and the blood-brain barrier.
The banks’ laboratory is studying the blood-brain barrier alzheimer, obesity, diabetes and HIV. But they put their work on hold and all 15 people in the lab began their experiments on the S1 protein in April. They hired Jacob Raber, a longtime collaborator in the departments of Behavioral Neuroscience, Neurology and Radiology, as well as his teams at the University of Oregon Health and Science.
The study could explain many of the complications of COVID-19.
“We know that when you have COVID infection you have trouble breathing and that’s because there is an infection in the lungs, but an additional explanation is that the virus enters the respiratory centers of the brain and causes problems there as well,” Banks said.
Raber said in their experiments S1 transport was faster in the olfactory bulb and kidneys in males than in females. This observation could refer to the increased susceptibility of men to more severe COVID-19 outcomes.
As for people who get the virus easily, Banks has a message:
“You don’t want to mess with this virus,” he said. “Many of the effects of COVID could be exacerbated or perpetuated or even caused by the virus entering the brain, and these effects could last a long time.”
Reference: “SARS-CoV-2 S1 protein crosses the blood-brain barrier in mice” by Elizabeth M. Rhea, Aric F. Logsdon, Kim M. Hansen, Lindsey M. Williams, May J. Reed, Kristen K. Baumann, Sarah J Holden, Jacob Raber, William A. Banks and Michelle A. Erickson, 16 December 2020, The neuroscience of nature.
DOI: 10.1038 / s41593-020-00771-8
This study was partially supported by a COVID-19 supplement funded by the National Institute on Aging on a joint RF1 grant from banks and Raber.