Figure 2.

Humoral and cellular immune responses induced by TAT-NP vaccine. Anti-NP IgG was determined by ELISA on day 42. Mice were immunized three doses intranasally with NP or TAT-NP, whereas control animals received PBS, at an interval of 2 weeks. (A) The antibody responses of IgG1 and IgG2a detected in sera after the last immunization. End-point ELISA titers were expressed as the reciprocal of the highest sample dilution that yielded an OD ≥ mean+2 × SD of control mouse group. Results are expressed as mean ± SD of three tested mice in each group. (B) The ratio of IgG2a/IgG1 2 weeks after the last immunization. Two weeks after the last immunization, splenocytes were harvested and stimulated with peptides recognized by MHC class I and class II restricted epitopes of NP. Results are expressed as number of spots of cells producing cytokines per 10⁶ spleen cells. Detection of IFN-γ secreting CD4⁺ (C) and CD8⁺ (D) T cells. Data shown as mean numbers of spot-forming cells (SFCs) ± SD. n = 3 per group. Each sample was tested in triplicates. * indicates significant differences (P < 0.05, two-tailed Student’s t-test).