EVALUATION OF SEROLOGIC RESPONSES, LYMPHOCYTE PROLIFERATIVE RESPONSES, AND CLEARANCE FROM LYMPHATIC ORGANS AFTER VACCINATION OF BISON WITH BRUCELLA-ABORTUS STRAIN RB51

Objective-To evaluate clearance of the vaccine strain, immunologic res ponses, and potential shedding of Brucella abortus strain RB51 organis ms after vaccination of bison carves. Animals-Fourteen 7-month-old fem ale 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, n asal, and ocular swab specimens were obtained to evaluate potential sh edding by vaccinated bison. The superficial cervical lymph node was bi opsied to evaluate clearance of the vaccine strain. Lymphocyte prolife rative responses to strain RB51 bacteria were evaluated in lymph node cells obtained from biopsy specimens and also in peripheral blood mono nuclear cells. Results-Strain RB51 was recovered from superficial cerv ical lymph nodes of vaccinates examined 6, 12, and 18 weeks after vacc ination (4/4, 3/4, and 1/4, respectively) but not in vaccinates examin ed at 24 weeks (0/3) after vaccination or nonvaccinates examined at al l sample collection times (n = 1 bison/sample period). Serologic, immu nologic, and bacterial culture techniques failed to reveal shedding of strain RB51 by vaccinates or infection of nonvaccinated bison. Lympho cyte proliferative responses were evident in lymph node cells and bloo d mononuclear cells from strain RB51-vaccinated bison beginning 12 wee ks after vaccination. Conclusion-Strain RB51 was cleared from bison by 18 to 24 weeks after vaccination. Bison vaccinated with strain RB51 d id 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 stimulat e cell-mediated immunity.