To understand if BBB breakdown mediated by release of granzyme B by OT-I cells following Ag-recognition on the BBB is required for their CNS entry, we induced the CD8+ T cell driven autoimmune neuroinflammation in VE-cadherin-GFP ODC-OVA mice by transferring either naïve OT-I or naïve OT-I GrB−/− cells one day prior to infection with LCMV-OVA. Here, CD8A is linked to infection.