J. Bevins, DVM, Ph.D.
Institute of Arctic Biology and Agricultural and Forestry Experiment Station

Supporting Agency: U.S.Department of Agriculture

Brucellosis is enzootic in Alaskan reindeer herds, with a prevalence of serologically positive animals ranging from <1% to >20%. The disease causes reproductive losses in reindeer, primarily through abortion. Although there is an effective vaccine available for the prevention of brucellosis in reindeer, a killed B. suis 4 in adjuvant, vaccinated reindeer cannot be distinguished from those that are infected with B. suis 4. This has caused difficulties in: (1) evaluating the prevalence of brucellosis in vaccinated herds, (2) evaluating the efficacy of the vaccine as used under field conditions, and (3) designating vaccinated reindeer as being free of actual infection. The objective of this research is to produce a vaccination and serologic testing protocol that both effectively immunizes reindeer against B. suis 4 infection, and allows discrimination of immunized reindeer from those which are infected. Persistence of immunity in reindeer vaccinated as fawns through the time of sexual maturity will also be investigated. Forty-five reindeer will be vaccinated as seven-month-old fawns and one of three vaccines: killed B. suis 4, RB51, and B. neotomae vaccines. It is expected that reindeer vaccinated with killed B. suis 4 will be differentiated from infected reindeer by means of a competitive ELISA. Similarly, it is expected that reindeer vaccinated with live avirulent rough strains will be will be differentiated from infected animals because of a lack of detectable antibody production. Vaccines will be evaluated on the discrimination and also on production of cell-mediated immunity. Reindeer vaccinated with the most promising of these vaccines will be challenged with virulent B. suis 4, along with 15 unvaccinated control reindeer at the time of sexual maturity. Vaccine efficacy will be judged according to numbers of reindeer protected from infection and abortion in vaccinated and control groups.