FIG. 5.

Proliferation of mononuclear cells stimulated by DNA vaccination. Mononuclear cells were harvested from mice 14 weeks after vaccination with 50 μg of pcDNA3/P42. After stimulation for 72 h with purified P42 protein, [³H]thymidine was added and incubated for 16 h, and then the incorporated radioactivity was measured with a liquid scintillation counter. The stimulation index (S.I.) was defined as the ratio of counts per minute in spleen cells stimulated with pcDNA3/P42 versus counts per minute in spleen cells stimulated with pcDNA3.