How brain protects neurons against lethal viruses
doi:10.1038/nindia.2020.111 Published online 20 July 2020
An international research team has discovered how the brain prevents the entry of specific viruses through neurons that transmit sensory input from the nose to the brain1.
They have shown that the brain uses microglia — specific immune cells — to neutralise vesicular stomatitis virus (VSV), a potentially lethal virus that infects livestock animals and even humans. The microglia help control the viral infection without damaging the brain neurons.
These results, the researchers say, may have implications for understanding other respiratory viruses, including SARS-CoV-2, which affects the sense of taste and smell in COVID-19 patients.
The nose has a specific cell barrier. This barrier’s surface is especially vulnerable to infection, yet respiratory infections rarely cause fatal brain infections.
To shed light on this, the scientists, including a researcher from the Indian Institute of Technology in Indore, India, infected mice with VSV. They found that the mice brain halted the growth of VSV.
Sophisticated imaging of the mice brain revealed that the brain suppressed the viral infection by recruiting microglia. But, the microglia didn’t show any traces of the virus inside them. These immune cells, the researchers found, capture virus particles from nearby neurons and present them to other immune cells, triggering a release of antiviral proteins. These proteins then help control the viral infection.
According to these findings, treatments that support immune cell and microglia function may protect the brain against nasal viruses, the researchers say.
1. Moseman, E. A. et al. T cell engagement of cross-presenting microglia protects the brain from a nasal virus infection. Sci. Immunol.5, eabb1817 (2020)