While sham-immunized mice died at day 6 after infection and largely failed to recruit either CD4+ T helper cells or VV-specific CTLs into the CNS compartment (Figure 3A,B), MVA immunized animals harbored both antigen specific CTLs and CD4+ T cells in the CNS and recovered from VV encephalitis (Figure 3A-C). This evidence concerns the gene CD4 and infection.