Single dose of DPX-rPA, an enhanced-delivery anthrax vaccine formulation, protects against a lethal Bacillusanthracis spore inhalation challenge

Single-dose delivery of DPX-rPA (recombinant protective antigen) in mice induces rapid and sustained anti-rPA immunoglobulin G (IgG) response. Groups of nine CD-1 mice were vaccinated (intramuscularly (i.m.)) once with DPX-rPA dosed at either 10？μg (purple circles), 4？μg (gray squares), 2？μg (green diamonds), 0.5？μg (dark purple downwards triangles), or 0.05？μg (orange upwards triangles) or once with 10？μg alum-rPA control vaccine (black x). Immunizations are indicated with arrows. Endpoint anti-rPA IgG titers, presented as Log10 values, at Weeks 3, 4, 8, 12, 16, and 20 post immunization determined by enzyme-linked immunosorbent assay (ELISA) using plates coated with rPA antigen. Results are shown as mean？±？SEM. Significance shown was determined by two-way analysis of variance (ANOVA) with Tukey’s multiple comparisons test of at least p？<？0.05, on Weeks 3, 4, 8 and 20: *, DPX-rPA (0.05？μg) compared to DPX-rPA (2, 4, 10？μg), DPX-rPA (0.5？μg) vs. DPX-rPA (4, 10？μg); +, DPX-rPA (0.05？μg) vs. DPX-rPA (2, 4, 10？μg), DPX-rPA (0.5？μg) vs. DPX-rPA (2, 4, 10？μg); ？, DPX-rPA (0.05？μg) vs. DPX-rPA (2, 4, 10？μg), and alum, DPX-rPA (0.5？μg) vs. DPX-rPA (2, 4, 10？μg) and alum, DPX-rPA (2？μg) vs. DPX-rPA (10？μg), DPX-rPA (4？μg) vs. DPX-rPA (10？μg), DPX-rPA (10？μg) vs. alum; φ, DPX-rPA (0.05？μg) vs. all other groups, DPX-rPA (0.5？μg) vs. DPX-rPA (μg), DPX-rPA (2？μg) vs. DPX-rPA (10？μg), DPX-rPA (4？μg) vs. DPX-rPA (10？μg), DPX-rPA (10？μg) vs. alu