While WT mice are able to survive infection with either strain, Armstrong (Arm) virus is ably cleared within 8 days and induces robust memory CD8+ T cell responses, whereas infection with Clone 13 (Cl-13) produces a chronic viremic state and leads to CD8+ T cell exhaustion beginning 1–2 weeks p.i. (17, 21, 22). This evidence concerns the gene CD8A and infection.