Figure 2. Migration of CD8 T-cell subsets during chronic viral infection. Both stem cell-like and terminally differentiated CD8 T cells are circulating after the onset of viral infection. After the establishment of T-cell exhaustion, stem cell-like cells become resident and mainly reside in the lymphoid organs, especially in the white pulp of the spleen. A fraction of the transitory CD101⁻Tim-3⁺ CD8 T cells circulate via the blood and migrate other inflamed tissues corresponding to the expression of a fractalkine receptor CX3CR1. In the red pulp of the spleen and non-lymphoid tissues, CD101⁻Tim-3⁺ CD8 T-cell subset differentiates into terminally differentiated CD101⁺Tim-3⁺ CD8 T cells and become resident.