Submitted to: Wildlife Disease Association Annual Meeting
Publication Type: Abstract Only
Publication Acceptance Date: April 27, 2000
Publication Date: N/A
Technical Abstract: Brucellosis is caused by an intracellular bacteria and the disease is characterized by abortion and fetal losses. Brucella abortus is known to be prevalent in bison populations within Yellowstone National Park and Grand Teton National Park in the United States, and Mackenzie Bison Sanctuary in Canada. In a series of studies, we have vaccinated bison heifer calves with B. abortus strain RB51 (SRB51) and characterized persistence of the vaccine strain, immune responses after vaccination, and vaccine-induced protection against experimental challenge with virulent B. abortus during pregnancy. SRB51 can be recovered from the lymph node draining the site of vaccination (superficial cervical) in some bison for up to 18 weeks after vaccination. Vaccinated bison do not appear to shed SRB51 from mucosal surfaces after vaccination. When compared to non- vaccinates, bison vaccinated with SRB51 have antibody responses that peak between 4 to 6 weeks after vaccination and dissipate by 18 weeks after vaccination. Proliferative responses of peripheral blood mononuclear cells to killed SRB51 bacteria are greater than non-vaccinates at 12 weeks after vaccination. Bison were pasture bred, pregnancy confirmed by rectal palpation, and pregnant bison intraconjunctivally challenged with 1 x 10**7 CFU of virulent Brucella abortus strain 2308 at 180 days gestation. Dams and calves were euthanized within 24 hours after parturition or abortion and samples obtained for histologic and bacteriologic examination.