Female NZW rabbits were immunized on days 0, 14 and 28 with the indicated vaccine formulation. Intramuscular immunization with 10 µg of BoNT/A toxoid combined with alum (n = 4) served as a control. BoNT/A Hcβtre (10 µg) was nasally delivered in the absence of adjuvant (n = 5) or combined with CT (2 µg; n = 6) or C48/80 (120 µg; n = 6). BoNT/A Hcβtre-Ad2F (20 µg) was delivered nasally in the absence of adjuvant (n = 5) or combined with CT (2 µg; n = 6) or C48/80 (120 µg; n = 6). BoNT/A Hc (20 µg) was delivered nasally combined with CT (2 µg; n = 3) or C48/80 (120 µg; n = 3). Serum samples collected on day 27 and day 40 were tested for the presence of anti-BoNT/A β-trefoil IgG by ELISA. Serum antibody titers were compared between groups by ANOVA followed by Tukey's multiple comparison test (GraphPad, Prism). a: serum anti-BoNT/A β-trefoil IgG titers significantly greater than those induced by intramuscular immunization with toxoid, nasal immunization with Hcβtre, nasal immunization with Hcβtre + CT, nasal immunization with Hcβtre + C48/80, nasal immunization with Hcβtre-Ad2F, nasal immunization with Hc + CT and nasal immunization with Hc + C48/80. b: serum anti-BoNT/A β-trefoil IgG titers significantly greater than those induced by nasal immunization with Hcβtre + CT and nasal immunization with Hcβtre + C48/80. c: serum anti-BoNT/A β-trefoil IgG titers significantly greater than those induced by intramuscular immunization with toxoid, nasal immunization with Hcβtre, nasal immunization with Hcβtre-Ad2F, nasal immunization with Hcβtre + CT, nasal immunization with Hcβtre + C48/80, nasal immunization with Hc + CT and nasal immunization with Hc + C48/80. d: serum anti-BoNT/A β-trefoil IgG titers significantly greater than those induced by intramuscular immunization with toxoid, nasal immunization with Hcβtre, nasal immunization with Hcβtre + CT, immunization with Hcβtre + C48/80, nasal immunization with Hcβtre-Ad2F and nasal immunization with Hc + C48/80.