Abstract:
BACKGROUND : Bacillus (B.) anthracis, the causal agent of anthrax, is effectively controlled by the Sterne live spore
vaccine (34F2) in animals. However, live spore vaccines are not suitable for simultaneous vaccination and antibiotic
treatment of animals being at risk of infection in an outbreak situation. Non-living vaccines could close this gap.
RESULTS : In this study a combination of recombinant protective antigen and recombinant Bacillus collagen-like
antigen (rBclA) with or without formalin inactivated spores (FIS), targeted at raising an immune response against
both the toxins and the spore of B. anthracis, was tested for immunogenicity and protectiveness in goats. Two
groups of goats received from local farmers of the Kars region of Turkey were immunized thrice in three weeks
intervals and challenged together with non-vaccinated controls with virulent B. anthracis, four weeks after last
immunization. In spite of low or none measurable toxin neutralizing antibodies and a surprisingly low immune
response to the rBclA, 80% of the goats receiving the complete vaccine were protected against a lethal challenge.
Moreover, the course of antibody responses indicates that a two-step vaccination schedule could be sufficient for
protection.
CONCLUSION : The combination of recombinant protein antigens and FIS induces a protective immune response in
goats. The non-living nature of this vaccine would allow for a concomitant antibiotic treatment and vaccination
procedure. Further studies should clarify how this vaccine candidate performs in a post infection scenario
controlled by antibiotics.
