Mononuclear cells were harvested from the brains of acutely ill mice 7 days p.i. and analyzed for expression of IFN-c by an intracellular cytokine staining protocol as previously described [28] . Unless otherwise noted, peptides corresponding to epitopes were used at a final concentration of 1 mM and cells were stimulated in the presence of 500 mM TCEP (Sigma, St. Louis, MO). Cells were analyzed using a FACScan flow cytometer (BD Biosciences, Mountain View, CA). Data sets were analyzed using FlowJo software (Tree Star, Inc, Ashland, OR). All antibodies and reagents were purchased from BD Pharmingen (San Diego, CA).