• Vaccine Name: pABFHc2
• Target Pathogen: Clostridium botulinum
• Target Disease: Botulism
• Vaccine Ontology ID: VO_0004099
• Type: DNA vaccine
• Adjuvant:
  • Adjuvant name:
  • VO adjuvant ID: VO_0001241
  • Description: Previous research achieved protection in a murine model using purified FHc which had been obtained from cultures of recombinant Escherichia coli and recombinant Pichia pastoris. FHc has also been expressed in a Salmonella vector and achieved protection against intoxication in a murine model. Therefore, BoNT F could constitute a good candidate for DNA vaccination, and the given study constructed a DNA vaccine based on the Hc domain of BoNT subtype F in order to investigate the utility of DNA vaccination for protection against intoxication with this subtype (Bennett et al., 2003).
• DNA vaccine plasmid:
  • DNA vaccine plasmid name:
  • DNA vaccine plasmid VO ID: VO_0001005
• Preparation: DNA encoding the binding domain of BoNT subtype F (FHc) was obtained as the plasmid clone pHILD4.New.FHc. Recombinant plasmid DNA was purified using Endofree Mega-Q kits (Qiagen Ltd.). Cells were analysed for expression of FHc 24 h after transfection as follows: cells were fixed in 4% paraformaldehyde at 4 °C overnight, then washed in PBS and incubated in PBS containing 2% saponin and 10% foetal calf serum (PBS-SFCS) for 2 h at 37 °C. Primary antibody, from mice immunised with pABFHc2 and boosted with recombinant FHc protein, was diluted 1:500 in PBS-SFCS and incubated with fixed cells for 1 h at 37 °C. Following washing, anti-mouse IgG conjugated to fluorescein isothiocyanate was added and the incubation was continued for a further hour at 37 °C. The cells were washed in PBS and were visualised by fluorescent confocal microscopy (Bennett et al., 2003).
• Description: Previous research achieved protection in a murine model using purified FHc which had been obtained from cultures of recombinant Escherichia coli and recombinant Pichia pastoris. FHc has also been expressed in a Salmonella vector and achieved protection against intoxication in a murine model. Therefore, BoNT F could constitute a good candidate for DNA vaccination, and the given study constructed a DNA vaccine based on the Hc domain of BoNT subtype F in order to investigate the utility of DNA vaccination for protection against intoxication with this subtype (Bennett et al., 2003).

Mouse Response

• Host Strain: Balb/c mice (female, 6–8-week-old).
• Vaccination Protocol: Mice were injected with 50 μl and received up to five vaccinations. For protein boosting of DNA-vaccinated mice, E. coli-derived MBP-FHc was formulated in alhydrogel (20% (v/v)). A single dose of 5 μg in a volume of 100 μl was administered by i.p. injection. Blood was taken from a tail vein 12 days after each injection for serum antibody analysis by enzyme-linked immunosorbent assay (ELISA). All mice were microchipped in order to monitor antibody response and survival of individual animals. Mice were challenged with a purified preparation containing 10^4 MLD of botulinum toxin serotype F by i.p. injection (Bennett et al., 2003).
• Side Effects: None noted.
• Efficacy: A minimum of three vaccinations with pABFHc2, given over a 4-week period, were sufficient to protect 100% of mice against the high challenge dose (10^4 MLD of BoNT type F). Two doses of pABFHc2 protected up to 90% of vaccinated animals. A single dose of pABFHc2 protected 60% of mice when challenged with toxin at least 28 days after vaccination (Bennett et al., 2003).
• Description: Vaccination with DNA encoding the Hc domain of botulinum neurotoxin subtype A has been attempted but had limited success; thus a clinically viable DNA vaccine for subtype A was not achieved. BoNT F is serologically distinct from A and the amino acid sequences of type F toxins from different strains of Clostridia fall into a distinct phylogenetic group. Type F toxin cleaves VAMP (vesicle associated membrane protein), whereas BoNT A cleaves SNAP-25. Protection in a murine model has been previously achieved using purified FHc which had been obtained from cultures of recombinant Escherichia coli and recombinant Pichia pastoris. FHc was also expressed in a Salmonella vector and achieved protection against intoxication in a murine model. Therefore, BoNT F could constitute a good candidate for DNA vaccination. A DNA vaccine was constructed based on the Hc domain of BoNT subtype F in order to investigate the utility of DNA vaccination for protection against intoxication with this subtype (Bennett et al., 2003).