CD5 and infection: Results showed that the size and weight of the thymus (Fig. 2a, b) and the number of thymocytes (Fig. 2c) were remarkably reduced in mice starting at week 5–6 after infection, accompanied by an aberrant development of T cells (Fig. 2d), reduced expression of CD5 (Fig. S2a–c), and decreased proliferation of naive T cells (Fig. 2e, f).