SARS-CoV-2 evolves more rapidly in the brain than in the lungs, which may explain the neurological symptoms with COVID-19 and long COVID. The new study using mouse models found that the virus accumulated more mutations in the brain, particularly in the spike protein.

I’ve linked to the news release in the post above. In this comment, for those interested, here’s the link to the peer reviewed journal article:

https://www.nature.com/articles/s41564-024-01786-8

From the linked article:

A new study published in Nature Microbiology has revealed that SARS-CoV-2, the virus responsible for COVID-19, evolves more rapidly in the brain than in the lungs, possibly explaining some of the neurological symptoms associated with the disease. This finding may provide insight into the mysterious phenomenon of long COVID and might eventually lead to targeted treatments that specifically address the virus in the central nervous system.

The researchers found that SARS-CoV-2 evolved differently in the brain compared to the lungs. In the lungs, the virus looked similar to the original strain used to infect the mice. However, in the brain, the virus had accumulated more mutations, particularly in the spike protein. These mutations often disrupted the furin cleavage site.

One of the key findings was that viruses with these spike protein mutations were better at infecting the brain. When the researchers used these brain-adapted viruses to directly infect the brains of other mice, the mutations persisted. Interestingly, when the brain-adapted virus spread back to the lungs, it tended to revert to its original form. This suggests that different parts of the body create different selective pressures on the virus, influencing how it evolves.