Fig. 2.

a–c Humoral and cell-mediated immune responses induced by VP1-OVA_252-270 PLPs or VP1-TRP2_180-192PPs. a VP1-OVA_252-270-specific antibody endpoint titres after single or double immunisation in weekly intervals. Three C57BL/6 have been s.c. immunised with 100 μg capsoids for the single dose schedule and with 50 μg VP1-OVA_252-270 specific capsoids for each dose during the two vaccinations schedule. Sera were pooled and appropriately diluted for ELISA performance. b H2-K^b-OVA_257-264-tetramer/anti-CD8 labelling of splenocytes after two s.c. immunisations of mice each with 50 μg VP1-OVA_252-270 VLPs. The OVA_257-264 -specific CD8 T cells within splenocyte population isolated 3 days after the second application could be significantly measured after in vitro restimulation with 4 μgml⁻¹ VP1-OVA_252-270 for 3 days (*P<0.05, unpaired t test). Antigen specific analysis was performed by staining the splenocytes with PE-labelled H-2K^b -tetramers loaded with the OVA_257-264 peptide. Cells were counterstained with anti-CD8α/FITC monoclonal antibodies and analysed by using a FACSCalibur. Each experiment was repeated twice with similar results. c TRP2_180-188-specific CD8 T cell responses were measured by IFNγ-ELISPOT as described in Materials and Methods. Five days before the restimulation of splenocytes in vitro (each sample with 1 μg TRP2_180-188 peptides) three C57BL/6 mice were s.c. immunised twice with 50 μg VP1- or VP1-TRP2_180-192 PPs in a weekly interval. In the therapeutic setting immunisation started at day 4 after s.c. implantation of 10⁵ MO5 melanoma cells. The following H2-K^b -restricted CD8 T cell frequencies specific for the TRP2_180-188 epitope were significantly different from controls (*P<0.05, unpaired t test, mean values of n=3± standard deviation SD). Each experiment was repeated twice with similar results