Individual and bivalent vaccines against botulinum neurotoxin serotypes A and B using DNA-based Semliki Forest virus vectors

We evaluated individual and bivalent replicon vaccines against Clostridiumbotulinum neurotoxin serotypes A (BoNT/A) or B (BoNT/B). The DNA replicon vaccine (pSCARSBHc) encoding the Hc domain of BoNT/B (BHc) induced better responses and protection against BoNT/B mouse challenge than conventional DNA vaccine. The dual-expressing DNA vaccine (pSCARSA/BHc) protected similarly to a DNA replicon vaccine mixture (pSCARSAHc + pSCARSBHc). Additionally, recombinant SFV particles, VRP-AHc or VRP-BHc, protected mice from high-dose BoNT/A or BoNT/B challenge, respectively. Mice given either dual-expressing VRP-A/BHc or mixture of VRP-AHc and VRP-BHc were protected from challenge with serotype A/B mixtures. These data justify further testing in other animals or humans.