Figure 1.

Induction of LCMV-specific CTLs after immunization with CyaA224LCMV or CyaA224LCMV-E5. On days 0 and 21, BALB/c mice were injected with 50 μg of wild-type CyaA (A and B), CyaA224LCMV (C and D), or CyaA224LCMV-E5 (E and F) mixed with 1 mg of alum. Seven days later, spleens were harvested and cell suspensions were restimulated in vitro with peptide p118-132 (1 μg/ml) in the presence of irradiated syngenic spleen cells. After 5 days in culture, harvested cells were assayed for the presence of peptide or virus-specific cytolytic T cells in a standard 4-h ⁵¹Cr-release assay using the following cells. (A, C, and E) P815 target cells incubated with medium alone (○) or with peptide p118-132 (•). (B, D, and F) J774 target cells incubated with medium alone (□) or infected with LCMV (▪). Control LCMV-immune mice showed high levels of cytotoxic activity [50–60% of lysis at a 50:1 effector/target (E:T) ratio].