Figure 3.

Antigen dependence of protective CTL memory varies with the readout: i.v. challenge infection with different virus doses. Mice were immunized with irradiated (25 Gy) GP2.9 cells (3 × 10⁶ or 10⁵ cells) and frequencies of LCMV-GP-specific CTLp were determined 10 (solid triangles) or 60 days (open triangles) later. Alternatively, mice were challenged i.v. with 200 pfu of LCMV WE, and virus titers were assessed 5 days later, or they were challenged with 10⁴ pfu of LCMV WE and virus titers were assessed 3 days later. Additional groups of mice were challenged with 10⁶ pfu of LCMV Cl-13, and virus titers were assessed in the blood 10 days later. The horizontal line indicates the detection limit. One representative experiment of two is shown.