Immunization with modified VV Ankara (MVA) confers protective immunity against viral encephalitis. Wild type mice were immunized subcutaneously with a replication deficient strain of VV (Modified Vaccinia Virus Ankara, MVA) or PBS emulsified in complete Freund’s Adjuvant (CFA). On day 10 after immunization, mice were challenged intrathecally with VV, and weight courses were monitored daily as percentage of initial body weight (A, n = 5 mice per group). On day 4 after infection, CNS infiltrating mononuclear cells were isolated. (B) Absolute numbers of CNS infiltrating CD4+ and CD8+ T cells. Horizontal bars indicate means (Student’s t test; n ≥ 5 per group). (C) CNS derived T cells were analyzed as to their specificity to the VV MHC class I restricted epitope B8R by multimer staining and to their IL-17 and IFN-γ cytokine status by intracellular cytokine staining in the CD3+CD8+ CTL and CD3+CD4+ T helper cell compartment, respectively. Numbers indicate percentages of cells in the depicted gates or quadrants; representative out of more than 5 independent experiments).