Submitted to: Journal of Wildlife Management
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/5/1999
Publication Date: N/A
Interpretive Summary: Brucella abortus is a disease of cattle that causes abortion and associated economic losses in infected herds. The infection of bison and elk with Brucella abortus in the areas surrounding Yellowstone National Park (NP) pose a risk to the completion of the Brucellosis Eradication Program (BEP) for cattle. Development of an efficacious and safe vaccine for use in bison nand elk would be beneficial in resolution of the problem associated with Brucella infections in these wildlife populations. In these studies, we evaluated the biosafety of the B. abortus strain RB51 vaccine in bison calves by monitoring persistence, tissue localization, histological lesions, and potential for shedding. Our data suggests the vaccine is safe as a calfhood vaccine in bison as we found that the RB51 bacteria localized in lymphatic tissues and did not cause significant lesions in any tissues. Although bison calves appear to take longer to clear a similar dosage of strain RB51 than cattle, no adverse effects appear to be associated with persistence. Vaccinated bison do not appear to shed the RB51 vaccine to other bison in close association with them. The results of this study imply that the B. abortus strain RB51 vaccine is safe for use as a calfhood vaccine in bison. This data will assist the NP Service, U.S. Fish and Wildlife Service, regulatory personnel in APHIS, and the states of Mont., Wyo., and Idaho in resolution of the brucellosis problem in the Yellowstone NP bison. This data will also be of assistance to APHIS and regulatory personnel in states containing privately-owned bison for development of brucellosis control programs and vaccine recommendations. Development of efficacious brucellosis control programs for bison will prevent transmission to cattle herds and assist in the completion of the BEP.
Technical Abstract: Vaccines are considered one of the primary management actions by which the prevalence of brucellosis in Greater Yellowstone Area (GYA) ungulates will be decreased. Before their use, however, vaccine safety and efficacy must be demonstrated. Thirty-seven 5-month-old heifer calves were vaccinated with Brucella abortus strain RB51 per manufacturer's recommendation. The persistence, pathology, shedding, and transmission of RB51 were assessed b serial necropsy and serology of calves and RB51 serology of non-vaccinated commingling adult females. With the exception of 1 calf, dot-blot titers at necropsy were less than 1:80. RB51 was cultured from lymphatic tissue of 4/4, 4/4, 1/4, 3/4, and 0/4 calves at 14, 18, 22, 26, and 30 weeks post- nation, respectively. No gross lesions were observed. Mild histologic changes were detected only in the draining lymph node at early sampling times. Adverse clinical effects were not observed in vaccinates. Swabs from nasopharynx, conjunctiva, rectum, and vagina were uniformly culture-negative for RB51. Dot-blot titers of 10 bison cows were negative at a 1:20 dilution at 26 weeks after vaccination. Our results suggest that RB51 persists longer in bison calves than in domestic cattle and is systemically distributed within lymphatic tissues. However, bison apparently clear the RB51 vaccine strain without shedding and transmission, and have no significant adverse reactions.