Biosafety and antibody responses of adult bison bulls after vaccination with Brucella abortus strain RB51.

OBJECTIVE

To evaluate clearance, antibody responses, potential shedding, and histologic lesions in reproductive tissues of adult bison bulls after vaccination with Brucella abortus strain RB51.

ANIMALS

61 two- and 3-year-old bison bulls.

PROCEDURE

12 bison bulls were vaccinated s.c. with B abortus strain RB51, 3 were inoculated s.c. with 0.15 M NaCl, and antibody responses were evaluated. Various specimens were obtained to evaluate bacterial shedding. Four vaccinates and 1 control were necropsied 10, 20, and 30 weeks after vaccination. In a separate experiment, bison bulls were vaccinated s.c. with 0.15 M NaCl, or by hand or ballistically with strain RB51. Antibody responses were monitored 6 weeks after vaccination and during necropsy 13 weeks after vaccination. Tissue specimens obtained during necropsy from both studies were evaluated bacteriologically and histologically.

RESULTS

Strain RB51 was recovered at various times from semen of 3 of 12 vaccinated bison bulls in experiment 1. During necropsy, strain RB51 was recovered 10 and 20, but not 30, weeks after vaccination. In experiment 2, strain RB51 was recovered from lymphoid tissues of hand- and ballistic-vaccinated bison bulls during necropsy. In both experiments, microscopic lesions in testes, epididymis, and seminal vesicles were minimal and did not differ between strain RB51-vaccinated and saline-inoculated bison bulls.

CONCLUSIONS AND CLINICAL RELEVANCE

Strain RB51 does not induce relevant inflammatory lesions in reproductive tissues of adult bison bulls. Shedding of strain RB51 in semen may be transient in some bison bulls; however, the importance of this observation is unknown.