Type I interferon's role in how a flavivirus infects the brain
Flaviviruses have existed for thousands of years and still hit the headlines, most recently with Zika virus. They can fatally infect the human brain. Your body defends against them by making the protein interferon type I (IFN-I). How IFN-I affects the ability of flaviviruses to infect different cells (tropism), which determines the infection's spread, isn't clear. Researchers investigate by infecting the brains of normal mice and mice genetically altered so they're unresponsive to IFN-I, with the flavivirus, Langat virus. Combining optical projection tomography (OPT) with MRI revealed virus distribution in the brain (pictured). In normal mice (two views left), the virus only infected grey matter in sensory brain areas. In mutants (right), it spread further, infecting white matter. The team revealed the spread into white matter-targeted cells called microglia. Normal mice brains had more IFN-I activity, which protected microglia, uncovering IFN-I's role in viral tropism.
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