CXCL9 and infection: Proof-of-concept studies have used models of systemic viral (vaccinia, VSV, and lymphocytic choriomeningitis virus) and bacterial (Lm) infections in which microbial pathogens are rapidly captured in subcapsular draining lymph nodes (dLNs) or splenic marginal zone CD169+ macrophages and drive subsequent homing of CD8+ TM cells in response to chemotactic cues (e.g., CXCL9 and CXCL10) produced by innate immune and structural cells (24–27).