Submitted to: United States Animal Health Association Proceedings
Publication Type: Proceedings
Publication Acceptance Date: 10/21/2004
Publication Date: 10/21/2004
Citation: Bricker, B.J., Olsen, S.C. 2004. NADC studies on bison brucellosis vaccines and molecular techniques for brucella epidemiologic tracebacks. United States Animal Health Association Proceedings. p. 201-204. Interpretive Summary: Brucella abortus is a disease that causes abortion and associated economic losses in infected cattle herds. The ability to trace the source of infection would benefit the national eradication program. Scientists at NADC have developed an assay, the HOOF-Prints assay, that uses molecular techniques for epidemiologic comparisons. The persistence of Brucella abortus in wildlife reservoirs pose a risk to the completion of the Brucellosis Eradication Program for cattle. Development of a protective vaccine for bison would be beneficial in resolving the controversy caused by brucellosis in bison. In a series of studies, we demonstrated that bison vaccinated with the B. abortus strain RB51 vaccine were protected against abortion or infection as pregnant adults. Our data suggests that the calfhood vaccination with RB51 protects bison against abortion and fetal infection, and also prevents shedding of Brucella in milk. As brucellosis is transmitted laterally through fluids associated with the birth or abortion of an infected fetus, or vertically to the calf through the ingestion of milk containing B. abortus, our data suggest that calfhood vaccination with RB51 will prevent transmission of brucellosis in bison. This data will be of benefit to the National Park Service, the Animal and Plant Health Inspection Service, and the states of Montana, Wyoming, and Idaho in their efforts to resolve the brucellosis problem caused by wildlife reservoirs of brucellosis. Demonstration that RB51 vaccine protects bison will also help prevent transmission of brucellosis to cattle herds and assist in the completion of the Brucellosis Eradication Program.
Technical Abstract: As the Brucellosis Eradication Program for cattle nears completion in the United States after 70 years of regulatory efforts, the persistence of Brucella abortus in wildlife reservoirs remains a concern for reintroduction of brucellosis to cattle. Within the last year, Brucella-infected cattle herds in Wyoming were identified which lead to the loss of that state's Brucellosis-Free status. Molecular tools for epidemiologic tracebacks on infected herds have previously not been available for brucellosis. Based on analysis of the Brucella abortus genomic sequence, scientists at NADC identified intergenic, noncoding regions containing repeated strings of nucleotides that are more apt to mutate than coding regions. An assay was developed, the 'HOOF-Prints' assay, to evaluates multiple loci containing these tandem repeats. This assay looks promising for use in Brucella epidemiologic tracebacks. In a series of efficacy studies at NADC, scientists demonstrated that hand or ballistic vaccination with RB51 reduced abortions, uterine/mammary infections, and maternal infections. The reduction in abortions or uterine/mammary infections was a trend that was consistent across all studies. Our data suggests that irregardless of parental or ballistic delivery, RB51 protects bison against Brucella infections or abortions. As brucellosis is transmitted laterally through fluids associated with the birth or abortion of an infected fetus, or vertically to the calf through the ingestion of milk containing B. abortus, our data suggest that calfhood vaccination with RB51 will prevent transmission of brucellosis in bison.