Failure of extrathymic T cells to control LCMV-ARM following adoptive transfer in RAG1^-/- mice. RAG1^-/- mice were infected with 200 pfu LCMV-ARM intravenously, and viral titers in the spleen, mLNs, and lung were determined on day 30. Recipients were either untreated (▦) or received 30 × 10⁶ splenocytes from naive OM → RAG1-/- chimeras (extrathymic T cells; □) or C57Bl/6J mice (thymic T cells; ▪) 2 days before LCMV infection. Data represent means for 3 mice per group.