CD4 and nervous system disorder: Experiments in wild-type mice and monocyte recruitment deficient CCR2 knockout mice, variously depleted of CD4+ and CD8+ T lymphocytes and infected with NSs gene deleted RVFV, demonstrated that both CD4+ and CD8+ T cell populations and monocytes were critical for prevention of RVFV-neurologic disease and that this immune control occurs in the periphery not the central nervous system [135].