Cells were harvested from the CNS of mice 7 days p.i. and stimulated ex vivo with S598 or S598 Q600Y peptides. Cell aliquots were subsequently stained for CD8 (PE-Cy7-anti-CD8a) and Vb (FITC-anti-Vb2, 3, 4, 5.1/5.2, 6, 7, 8, 9, 10 b , 11, 12, 13 or 14, BD-Pharmingen) followed by intracellular staining for IFN-c (PEanti-IFN-c). Data were collected using a Becton Dickinson LSR II instrument at the University of Iowa Flow Cytometry Facility. Data are expressed as the proportion of antigen-specific CD8 T cells that express each Vb chain.