Figure 4

ELISPOT assays of immunized mice. Mice, 5 per group, were immunized three times by the intraperitoneal route with 100 μg of recombinant PapMV NP-12, PapMV NP-C and PapMV nanoparticles that were either untreated or cross-linked with glutaraldehyde. Two weeks after the second boost, spleens were extracted and ELISPOT assays performed. The precursor frequency of specific T cells was determined by subtracting the background spots in medium alone from the number of spots seen in wells reactivated with NP_147-155 peptide. ** p ≤ 0.01 and * p ≤ 0.05.