Evaluation of a commercially available vaccine against Corynebacterium pseudotuberculosis for use in sheep

Objective-To evaluate the efficacy of a commercially available bacterin-toxoid vaccine for preventing Corynebacterium pseudotuberculosis-induced abscesses in sheep. Design-Prospective randomized controlled trial. Animals-31 mixed-breed sheep seronegative for C pseudotuberculosis. Procedure-Sheep were randomly assigned to vaccinate (n = 20) or nonvaccinate (11; control) groups. Sheep in the vaccinate group received 2 doses of serial A or serial B bacterin-toxoid vaccine at 4-week intervals. Serologic testing was conducted after vaccination to document an antibody response to vaccination. All sheep were challenge inoculated with virulent C pseudotuberculosis organisms 32 weeks after the second vaccination. Twenty weeks after challenge inoculation, all sheep were examined for external and internal abscesses secondary to C pseudotuberculosis infection. Results-Vaccinated sheep developed an antibody response to both components of the vaccine, as measured by use of ELISA tests. After challenge inoculation, vaccinated sheep had significantly less external, internal, and total abscesses than control sheep. Clinical Implications-Vaccination of sheep with a commercially available bacterin-toxoid against C pseudotuberculosis could substantially decrease the prevalence and number of abscesses that form secondary to C pseudotuberculosis infection.