Figure 3.

Adjuvant effect of vectorized delivery of alpha-GalactosylCeramide (α-GalCer) on bacteriophages in antigen-specific adaptive immune response. IL-2 release of mouse Vα14 invariant natural killer T hybridoma cell line FF13 (A) or OTI hybridoma cell line (B) in response to α-GalCer or OVA SIINFEKL peptide delivered by phage particles. LPS-free fdOVA filamentous bacteriophages were conjugated to α-GalCer, and fdOVA or fdOVA/α-GalCer were presented by mouse bone marrow-derived dendritic cells to stimulate FF13 or OTI hybridoma cells. Soluble form of α-GalCer was used as positive control in (A). Synthetic OVA_257–264 peptide was used as positive control in (B). Supernatants were diluted 1:10 (A) or left undiluted (B) and assayed in duplicate. Mean ± SD is reported, one representative experiment of two is shown. (C,D) Group of mice (n = 4/group) were primed (day 0) and boosted (day 14) with fdOVA (SIINFEKL peptide) bacteriophages delivering or not the α-GalCer as indicated on the x-axis. As control, mice were inoculated twice with vehicle alone (phosphate buffered saline, PBS). At day 21, splenocytes were isolated and percentage of OVA_257–264-specific CD8⁺ T cells producing IFN-γ (C) and percentage of H2Kb-SIINFEKL dextramer positive CD8⁺ T cells (D) were evaluated. Average + SEM is reported. Difference were statistical significant by one-way analysis of variance followed by a Dunnett’s multiple comparison test. *p < 0.05. Abbreviation: ns, not significant.