Comparable numbers of virus - specific CD8 [UNK] T cells derived from immunized CCR5 [UNK] / [UNK] or CCR5 [UNK] / [UNK] mice were present within the CNS of MHV - infected RAG1 [UNK] / [UNK] mice following adoptive transfer , indicating that CCR5 is not required for trafficking of these cells into the CNS .