FIG. 1.

A single immunization of mice with CyaA carrying one copy of the LCMV epitope, in the absence of adjuvant, induces a specific T-cell proliferative response. (A) BALB/c mice were immunized i.p. with 10 μg of control CyaA-wt (□, ○) or with 10 μg of CyaA224LCMV1 (■, ●) in PBS (□, ■) or with 1 mg of alum (○, ●). Seven days later, spleen cells were stimulated in vitro with serial doses of the LCMV peptide and then monitored for the proliferative response. Results are expressed as mean [³H]thymidine incorporation in triplicate wells and are representative of three experiments. Standard deviations were always <2,000 cpm. (B) Assay for inhibition of proliferative response performed in the same conditions except that 10 μg of anti-CD4, anti-CD8, or control anti-HLA-Bw8 MAb per ml was added to the culture medium. Results are expressed as the mean percent inhibition calculated from triplicate wells, with standard deviations always <5%.