Attitudes of oncologists, family doctors, medical students and lawyers to euthanasia

OBJECTIVE: To evaluate clearance of the vaccine strain, immunologic responses, and potential shedding of Brucella abortus strain RB51 organisms after vaccination of bison calves. ANIMALS: Fourteen 7-month-old female bison calves. PROCEDURE: 10 bison calves were vaccinated SC with 1.22 x 10(10) colony-forming units of B abortus strain RB51. Four bison calves were vaccinated SC with 0.15M NaCl solution. Rectal, vaginal, nasal, and ocular swab specimens were obtained to evaluate potential shedding by vaccinated bison. The superficial cervical lymph node was biopsied to evaluate clearance of the vaccine strain. Lymphocyte proliferative responses to strain RB51 bacteria were evaluated in lymph node cells obtained from biopsy specimens and also in peripheral blood mononuclear cells. RESULTS: Strain RB51 was recovered from superficial cervical lymph nodes of vaccinates examined 6, 12, and 18 weeks after vaccination (4/4, 3/4, and 1/4, respectively) but not in vaccinates examined at 24 weeks (0/3) after vaccination or nonvaccinates examined at all sample collection times (n = 1 bison/sample period). Serologic, immunologic, and bacterial culture techniques failed to reveal shedding of strain RB51 by vaccinates or infection of nonvaccinated bison. Lymphocyte proliferative responses were evident in lymph node cells and blood mononuclear cells from strain RB51-vaccinated bison beginning 12 weeks after vaccination. CONCLUSION: Strain RB51 was cleared from bison by 18 to 24 weeks after vaccination. Bison vaccinated with strain RB51 did not shed the vaccine strain to nonvaccinated bison housed in close proximity. Strain RB51 did not induce antibody responses in bison that would interfere with brucellosis surveillance tests, but did stimulate cell-mediated immunity.