Submitted to: United States Animal Health Association Proceedings
Publication Type: Proceedings
Publication Acceptance Date: October 12, 1996
Publication Date: N/A
Technical Abstract: A conditional license was granted in February of this year for a new brucellosis vaccine for cattle, Brucella abortus strain RB51 (SRB51). As the first new brucellosis vaccine in 50 years, SRB51 has already been utilized widely with at least 46 states allowing its use at the present time. However, data on its potential use in bison or pregnant cattle is lacking. We have found that bison vaccinated with SRB51 at 3 months of age remain seronegative on brucellosis surveillance tests and demonstrate significant protection following challenge during midgestation as adults. Of 4 SRB51-vaccinated and 3 B. abortus strain 19-vaccinated bison that were challenged, 1 SRB51-vaccinated bison aborted at 6 weeks following challenge while the remaining bison delivered full-term, clinically normal calves. Brucella were not isolated from fetal tissues obtained at necropsy from full-term calves of SRB51-vaccinated or strain 19-vaccinated dams. As SRB51 may be used as an adult vaccine in infected or potentially exposed herds, a dosage and route of administration that is safe and efficacious in pregnant cattle must be determined. We have found that subcutaneous inoculation of pregnant cattle during the sixth month of gestation with 1 x 10(9)CFU of SRB51 or 3 x 10(8) CFU of S19 does not induce abortion or placentitis. Data from these studies and others suggests that SRB51 is efficacious as a calfhood vaccine in bison and safe as an adult vaccine in pregnant cattle although additional studies are warranted.