Antiviral T cell dynamics after acute versus persistent infection. (A) TPM was used to examine the dynamics of CD8⁺ P14 (red) and CD4⁺ SMARTA (green) T cells in the spleen after an acute (Arm) or a persistent (CL13) infection (n = 5 mice). Representative 3D reconstructions of two-photon z stacks are shown for infected mice at day 7 after infection (left). The dashed white lines demarcate the border between the splenic red (RP) and white pulp (WP). The white boxes represent regions of interest from the white or red pulp magnified in the panels on the right. The magnified views show antiviral T cell movement over a 5-min time interval. Blue tracks follow the movement of P14 cells, whereas magenta tracks follow SMARTA cells. Note that nearly all highlighted T cells move over the denoted time interval except for P14 and SMARTA cells residing in the red pulp of CL13-infected mice (yellow arrowheads). Bars: (left) 100 µm; (right) 40 µm. See Videos 1–3. (B and C) Mean track velocities (µm/min) of CD8⁺ P14 (red) and CD4⁺ SMARTA (green) cells were quantified in the splenic red and white pulp at days 4 (B) and 7 (C) after Arm or CL13 infection (n = 5 mice). Asterisks denote statistically significant differences (P < 0.05). Each dot represents the track of an individual T cell. Horizontal black bars denote the mean of each group. Data are representative of five independent experiments.