Protection against infection and abortion induced by virulent challenge exposure after oral vaccination of cattle with Brucella abortus strain RB51
Objectives - To determine efficacy of orally administered Brucella abortus vaccine strain RB51 against virulent B abortus challenge exposure in cattle as a model for vaccination of wild ungulates. Animals - 20 mixed- breed beef cattle obtained from a brucellosis-free herd. Procedure - Sexually mature, Brucella-negative beef heifers were vaccinated by mixing > 1010 viable RB51 organisms or diluent with their feed. Heifers were fed individually and consumed their entire ration. Each heifer received approximately 3 X 1010 colony-forming units (CFU). Six weeks after oral vaccination, heifers were pasture-bred to brucellosis-free bulls. At approximately 186 days' gestation, heifers were challenge exposed conjunctively with 107 CFU of virulent B abortus strain 2308. Results - Vaccination with the rough variant of B abortus RB51 did not stimulate antibodies against the O-polysaccharide (OPS) of B abortus. After challenge exposure and parturition, strain 2308 was recovered from 80% of controls and only 20% of vaccinates. Only 30% of the vaccinates delivered dead, premature, or weak calves, whereas 70% of the controls had dead or weak calves. Conclusions - Cattle vaccinated orally with the rough variant of B abortus strain RB51 develop significant (P < 0.05) protection against abortion and colonization and do not produce OPS-specific antibodies. Clinical Relevance - Results encourage further investigation into use of strain RB51 to vaccinate wild ungulates (elk and bison) orally.
Publication Source (Journal or Book title)
American Journal of Veterinary Research
Elzer, P., Enright, F., Colby, L., Hagius, S., Walker, J., Fatemi, M., Kopec, J., Beal, V., & Schurig, G. (1998). Protection against infection and abortion induced by virulent challenge exposure after oral vaccination of cattle with Brucella abortus strain RB51. American Journal of Veterinary Research, 59 (12), 1575-1578. Retrieved from https://digitalcommons.lsu.edu/animalsciences_pubs/525