Alternative vaccination against equine botulism (BoNT/C).
BACKGROUND
In Europe the incidence of botulism in horses has increased in the last decade due to the growing popularity of haylage feeding. Recombinant vaccines are safer and less expensive to produce and are generally better tolerated than toxoids.


OBJECTIVE
To investigate whether the recombinant C-terminal half of the heavy chain of the botulinum neurotoxin C (Hc BoNT/C) in combination with an immunstimulatory adjuvant is an appropriate vaccine candidate for horses by testing its efficacy to induce neutralising antibodies and by comparing its immunogenic properties and adverse reactions to a commercial toxoid vaccine. Formation of oedema and local pain reactions were assessed. ELISA and Western blot assay against Hc BoNT/C and testing of neutralising antibody induction in a mouse protection assay were used to evaluate the immune response.


RESULTS
With the recombinant vaccine, only minor local swelling with full recovery after 5 days was noted after brisket injections. The toxoid vaccine produced local, painful reactions with longer recovery periods of up to 2 weeks. Horses vaccinated with either vaccine induced neutralising antibodies after the second booster vaccination, while seroconversion on ELISA and Western blot to Hc BoNT/C was apparent after the first recombinant vaccination, and at various time points in the vaccination schedule in horses that received commercial toxoid vaccine.


CONCLUSIONS
The recombinant vaccine showed fewer adverse reactions compared to the only commercially available vaccine but induced similar concentrations of neutralising antibodies. There was no correlation between the serological response to Hc BoNT/C and the neutralising capacity of serum.


CONCLUSIONS
Recombinant Hc BoNT/C is an appropriate vaccine candidate to stimulate production of neutralising antibodies against botulinum neurotoxin C in horses and creates only minor local reactions at the injection site.
Equine Clinic and Institute of Veterinary Bacteriology, Vetsuisse Faculty, University of Berne, Langgassstrasse 122-124, CH-3012 Berne, Switzerland.
J
J
Frey
S
S
Eberle
C
C
Stahl
C
C
Mazuet
M
M
Popoff
E
E
Schatzmann
V
V
Gerber
B
B
Dungu
R
R
Straub
D000276:Adjuvants, Immunologic; D000818:Animals; D000907:Antibodies, Bacterial / Q000096:biosynthesis / Q000097:blood*; D001428:Bacterial Vaccines / Q000009:adverse effects / Q000276:immunology*; D001681:Biological Assay / Q000662:veterinary; D015153:Blotting, Western / Q000662:veterinary; D001905:Botulinum Toxins / Q000276:immunology*; D001906:Botulism / Q000517:prevention & control / Q000662:veterinary*; D004797:Enzyme-Linked Immunosorbent Assay / Q000662:veterinary; D005260:Female; D006734:Horse Diseases / Q000517:prevention & control*; D006736:Horses; D007115:Immunization Schedule; D007117:Immunization, Secondary / Q000662:veterinary; D007074:Immunoglobulin G / Q000096:biosynthesis / Q000097:blood; D008297:Male; D051379:Mice; D009500:Neutralization Tests / Q000662:veterinary; D014614:Vaccines, Synthetic / Q000009:adverse effects / Q000276:immunology
D000276:Adjuvants, Immunologic; D000907:Antibodies, Bacterial; D001428:Bacterial Vaccines; D007074:Immunoglobulin G; D014614:Vaccines, Synthetic; D001905:Botulinum Toxins; C096324:botulinum toxin type C