CCR9 and viral infectious disease: Using the “My GeneSet” tool from ImmGen, we selected four proteins with high gene expression values in early effector T cells: TNFSF8, a cytokine that induces proliferation of T cells and that has been shown to be upregulated in CD8+ T cells primed during chronic infection (31); TLR7, a receptor selectively upregulated by exhausted CXCR5+ CD8+ T cells (29); CCR9, a chemokine receptor that regulates early phases of inflammation (32); and CD83, which is upregulated upon T cell stimulation during virus infection (33) (Figure 7A).