Abstract:
Anthrax is primarily recognized as an affliction of herbivores with incubation period ranging from three
to five days post-infection. Currently, the Sterne live-spore vaccine is the only vaccine approved for
control of the disease in susceptible animals. While largely effective, the Sterne vaccine has several
problems including adverse reactions in sensitive species, ineffectiveness in active outbreaks and
incompatibility with antibiotics. These can be surmounted with the advent of recombinant peptides
(non-living) next generation vaccines. The candidate vaccine antigens comprised of recombinant
protective antigen (PA), spore-specific antigen (bacillus collagen-like protein of anthracis, BclA)
and formaldehyde inactivated spores (FIS). Presently, little information exists on the protectivity
of these novel vaccine candidates in susceptible ruminants. Thus, this study sought to assess the
immunogenicity of these vaccine candidates in goats and evaluate their protectivity using an in vivo
mouse model. Goats receiving a combination of PA, BclA and FIS yielded the highest antibody and
toxin neutralizing titres compared to recombinant peptides alone. This was also reflected in the passive
immunization experiment whereby mice receiving immune sera from goats vaccinated with the antigen
combination had higher survival post-challenge. In conclusion, the current data indicate promising
potential for further development of non-living anthrax vaccines in ruminants.
