Although immune cells fight infections, given their potential to cause damage, the brain must carefully regulate their entry. Cupovic et al. sought to better understand this process in mice infected with a neurotrophic coronavirus. They found that in response to infection, pockets of stromal cells in the brain rapidly expressed high amounts of the chemokines CCL19 and CCL21, secreted proteins that can attract virus-fighting T cells. Disrupting this important molecular circuitry increased the susceptibility of mice to the virus, and for the few T cells that could enter the brain, reduced their antiviral capabilities. Viral clearance led to reduced chemokine expression by stromal cells, indicating that the brain quickly rebuilds its barriers once an infection runs its course.
Immunity 10.1016/j.immuni.2015.12.022 (2016).