Figure 1. Antibody responses of mice injected with pVax-FcBoNT/A with subsequent electroporation, or recombinant protein A, at day 0 and boosted with plasmid pVax-FcBoNT/A with electroporation or a recombinant protein injection at day 30 and day 60.The immunization regimen are indicated below the figure in the immunization section and the days of treatment appear in bold characters. DNA means a pVax-FcBoNT/A electroporation treatment and protein means a recombinant protein immunization. Swiss mice (n = 4) were treated with 40µg of plasmid DNA or 1µg of recombinant FcBoNT/A homogenized in 1mg aluminum hydroxide. Total antibody titer was determined by ELISA of serum samples at different time points of the treatment at days 30, 45, 60, and 75 and represented as histograms. Results show mean ± SEM values. ***(p < 0.001) indicates a significant difference between total antibody titers obtained with protein injections and those obtained with plasmid electroporation. The neutralizing titers at day 75 are indicated in bold characters above the bars for each immunization regimen. Swiss mice (n = 5) were challenged with 10 MLD of BoNT/A mixed with serial dilutions of antiserum collected at day 75. The final neutralizing titer was determined by a mathematical formula (barycenter calculation) using the two highest dilutions, knowing that 1 IU corresponds to neutralization of 5000 MLD.