Summary: Mice exposed to COVID-19 through the nasal passage, researchers noted a rapid and escalated attack on the brain by the virus that triggered a more severe outcome of the infection, even after the lungs were cleared of the disease. Researchers also found virus levels were over 1,000 times higher in the brain than other parts of the body.

Source: Georgia State University

Georgia State University biology researchers have found that infecting the nasal passages of mice with the virus that causes COVID-19 led to a rapid, escalating attack on the brain that triggered severe illness, even after the lungs were successfully clearing themselves of the virus.

Assistant professor Mukesh Kumar, the study’s lead researcher, said the findings have implications for understanding the wide range in symptoms and severity of illness among humans who are infected by SARS-CoV-2, the virus that causes COVID-19.

“Our thinking that it’s more of a respiratory disease is not necessarily true,” Kumar said. “Once it infects the brain it can affect anything because the brain is controlling your lungs, the heart, everything. The brain is a very sensitive organ. It’s the central processor for everything.”

The study, published by the journal “Viruses,” assessed virus levels in multiple organs of the infected mice. A control group of mice received a dose of sterile saline solution in their nasal passages.

Kumar said that early in the pandemic, studies involving mice focused on the animals’ lungs and did not assess whether the virus had invaded the brain. Kumars’ team found that virus levels in the lungs of infected mice peaked three days after infection, then began to decline. However, very high levels of infectious virus were found in the brains of all the affected mice on the fifth and sixth days, which is when symptoms of severe disease became obvious, including labored breathing, disorientation and weakness.

Image Credit:  EPAGeorgia State University

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