Antigen-specific vaccine-elicited T cell proliferation.

<p>Different experimental groups were designed for the development of the pre-clinical trials of the vaccine candidate in mice. Two groups represent negative controls: one composed by animals which received only the adjuvant (A), and other composed by animals that received the adjuvanted empty-virosome (VA). The third group received non-formulated proteins with adjuvant in the dosage of 1 μg of each component [PA (1+1+1)]. The fourth received the same non-formulated proteins, but was primed with non-adjuvanted LJL143 three weeks before the first immunization (Pre-LJL PA). The three remaining groups received different formulations of adjuvanted formulated antigens (VPA). Two different VPA combinations were tested regarding antigen quantities: 1+1+1 or 1+5+5 indicate the administered dosages of formulated LJL143, KMP11 and LeishF3+ (individual virosome formulations). VPA (Mix) refers to the third virosome formulation tested, in which the three antigens (1μg each) were simultaneously formulated in the same virosome. Mice were immunized 3 times i.m. (separated by 4 weeks each), euthanized 4 weeks after the last immunization, and their spleens collected and processed. Frequencies of proliferating splenic T cells (CD4⁺ and CD8⁺) were determined by flow cytometry, after four days of culture with the pool of antigens (10 μg/ml each) (i), or each of the individual antigens (10 μg/ml) (ii). Each dot represents one animal. Average and SD of the values within each group are shown. Statistical differences are properly identified (One-Way ANOVA or Unpaired t-test (for comparison between primed and non-primed animals): * p≤0.05, ** p≤0.01, *** p≤0.001 and **** p≤0.0001).