MHC class II positive macrophages are targets of VV infection in the CNS. Wild type mice were infected intrathecally with 1.000 PFUs of VV (eGFP), a replication competent recombinant VV expressing enhanced green fluorescent protein (eGFP) in infected cells. On day 4 after infection, mice were sacrificed, and spleen and CNS mononuclear cells were isolated and analyzed by flow cytometry. In the live cell gate, the following populations were defined based on their expression of CD11b and CD45: (A) spleen (SPL), left panel: (1) CD11blowCD45high lymphocytes, (2) CD11bintCD45high dendritic cells, (3) CD11bhighCD45high macrophages. (A) CNS, right panel: (1) CD11blowCD45high lymphocytes, (2) CD11bintCD45int microglia, (3) CD11bhighCD45high macrophages. (B) These populations were analyzed as to their expression of eGFP and MHC class II by flow cytometry. Numbers indicate percentages of positive cells in each quadrant or gate (representative out of 3 independent experiments).