A recombinant Holo-toxoid Vaccine against Botulism

Food Research Institute, University of Wisconsin, Madison, Wisconsin and Department of Microbiology and Molecular Genetics, Medical College of Wisconsin, Milwaukee, Wisconsin

^* To whom correspondence should be addressed. Email: mbaldwin{at}mcw.edu.

	Abstract

The botulinum neurotoxins (BoNT) are the most toxic proteins for humans and designated Category A Select Agents. The current vaccine against botulism is in limited supply and there is a need to develop new vaccine strategies. A recombinant BoNT/A toxoid was produced in Clostridium botulinum that contained a double amino acid substitution, R363A, Y365F (termed BoNT/A^RYM). BoNT/A^RYM was non-catalytic for SNAP25 and non-toxic for mice. Immunization with BoNT/A^RYM protected mice from challenge at levels that were similar to chemically inactivated BoNT/A toxoid. BoNT/A^RYM elicited an immune response against the light chain and heavy chain components of the toxin. Neutralizing anti-BoNT/A^RYM sera blocked BoNT toxicity in primary cortical neurons and blocked ganglioside binding by the heavy chain. BoNT/A^RYM represents a viable vaccine candidate for a holo-toxoid against botulism.