Leukocyte accumulation in the CNS after WNV-E218A infection by an intracranial route.

<p>Wild type and <i>Ifit1^−/−</i> mice were inoculated with 10⁵ PFU of WNV-E218A by intracranial injection. (<b>A–C</b>) Brains were harvested on day 6 after infection, and leukocytes were isolated by percoll gradient centrifugation. The total number of (<b>A</b>) microglia (CD11b^high/CD45^low) and macrophages (CD11b^high/CD45^high), or (<b>B</b>) CD3⁺CD4⁺ or CD3⁺CD8⁺ T cells was determined by multiplying the percentage of each cell population by the total cell count. (<b>C</b>) Brain leukocytes were stained with a D^b-NS4b tetramer or stimulated <i>ex vivo</i> with a D^b-restricted NS4B WNV peptide and then stained for CD3, CD8, granzyme B, IFN-γ or TNF-α, and analyzed by flow cytometry. Data represent the average of at least two independent experiments with 4 to 7 mice per experiment (<i>n</i> = 8 to 14). Asterisks indicate values that are statistically significant between wild type and <i>Ifit1^−/−</i> mice (**, <i>P</i><0.005; ***, <i>P</i><0.0005).