Rapid recruitment and activation of CD8+ T cells after herpes simplex virus type 1 skin infection.

After localized infection, naive antigen-specific T cells must localize to those lymph nodes (LNs) draining the site of infection before engaging antigen-bearing dendritic cells. Given that naive precursors are initially distributed randomly throughout the secondary lymphoid compartment, it is unclear how long it takes most antigen-specific precursors to mobilize to draining LNs and become recruited into the primary T cell response. Here, we have examined the kinetics of these events, measuring the period over which naive precursors are recruited into the primary T cell response after cutaneous infection with herpes simplex virus type 1 (HSV-1). We show that despite prolonged MHC class-I-restricted antigen presentation, most naive HSV-specific precursors were recruited from the circulation in the first 4 days after inoculation. Furthermore, this prolonged presentation was also not essential for memory development, as truncating the period of antigen presentation to around 4 days did not affect the level of contraction, or long-term stability of the HSV-specific CD8(+) memory T cell pool. Thus, despite initially being dispersed throughout the entire circulation, the recruitment of naive precursors is achieved quite quickly, even when priming is restricted to a small number of draining LNs.