Submitted to: Journal of Wildlife Diseases
Publication Type: Peer reviewed journal
Publication Acceptance Date: 5/1/2003
Publication Date: 10/1/2003
Citation: Olsen, S.C., Holland, S. 2003. Safety of revaccination of pregnant bison with brucella abortus strain rb51 during pregnancy. Journal of Wildlife Diseases. 39:824-829. Interpretive Summary: Brucella abortus is a disease that causes abortion and associated economic losses in infected cattle herds. The infection of bison with Brucella abortus in Yellowstone National Park poses 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 these studies bison cows from a herd infected with Brucella abortus were revaccinated with B. abortus strain RB51 during pregnancy. Although bison developed antibody responses to RB51, no adverse effects were noted by RB51 vaccination during pregnancy. Persistence of field strain in some bison suggests that use of RB51 vaccination alone will not be sufficient to eliminate brucellosis in an infected bison herd. These data will be of benefit to the National Park Service and the states of Montana, Wyoming, and Idaho in their efforts to resolve the brucellosis problem in the Yellowstone National Park bison, and also be of benefit to state regulatory officials in states containing private bison herds. Demonstration that RB51 vaccine is safe in pregnant bison provides a tool for enhancing immunity and reducing transmission of brucellosis in bison, which will help prevent transmission of brucellosis to cattle herds and assist in the completion of the Brucellosis Eradication Program.
Technical Abstract: From December of 1998 through February of 1999, a study was conducted in a Brucella-infected bison herd to evaluate the safety of booster vaccination of adult bison with 6 x 10**9 CFU of Brucella abortus strain RB51 (SRB51), in bison which had previously been vaccinated as yearlings with 1 x 10**10 CFU of SRB51. Abortions or other adverse effects were not observed after SRB51 vaccination. At 10 weeks after adult vaccination, pregnant and nonpregnant bison (n = 65) were randomly selected for bacteriologic sampling of targeted maternal tissues during abattoir processing. Fetal tissues were also sampled in pregnant bison. The SRB51 vaccine was recovered from tissue samples of 8 of 48 pregnant bison and none of the 17 nonpregnant bison. In 3 of the 8 culture-positive bison, SRB51 was recovered from fetal tissues. In 3 additional bison, 1 pregnant and 2 nonpregnant, B. abortus biovar 1 field strains were recovered from internal iliac or supramammary lymphatic tissues. The results of this study suggest the possibility that the SRB51 vaccine can be safely used to booster vaccinate pregnant bison in a Brucella-infected bison herd. Our data also reaffirms the potential for B. abortus field strains to persist in bison until attainment of reproductive age, despite extensive use of vaccination and serologic testing.