Splenocytes were isolated from both sets of mice;
CNS mononuclear cells were isolated from only those mice inoculated by the i.c. route. An intracellular IFN-γ assay was used to quantify the percentage of CD8+ T cells specific for the MHV spike protein CD8+ T-cell epitope S598 and for gp33 (19, 25). As shown in Fig. Fig.2,2, S598 and gp33 epitope-specific CD8+ T cells are detected in both the spleen and the CNS. Response in the spleen is similar whether inoculation is carried out either i.c. or i.p.; following i.c. infection, the levels of CD8+ T cells specific for both epitopes are higher in the CNS, the site of viral replication, than in the spleen, as observed previously