FIG. 2.

DNA immunization induces PrP T-cell responses. PrPKO mice were immunized three times (A) or once (B) either with pCMV or with pCMV-PrPLII. Six weeks after the final immunization, splenocytes were harvested, incubated together with the indicated semipurified protein stimulus at 1 μg/ml for 36 h, and subjected to ICCS. Circles and percentages shown (values given after subtraction of the control value) indicate the PrP-specific CD4⁺ T-cells (A and upper panel in B) or the PrP-specific CD8⁺ T-cells (B, lower panel). PrPrec, recombinant PrP.