Protection of BALB/c mice against homologous and heterologous species of Brucella by rough strain vaccines derived from Brucella melitensis and Brucella suis biovar 4.

OBJECTIVE: To evaluate stable rough mutants derived from Brucella melitensis 16M and B suis 2579 (biovar 4) as vaccines against homologous and heterologous Brucella spp in the BALB/c mouse model. DESIGN, ANIMALS, AND PROCEDURE: Rough mutants VTRM1 and VTRS1 were obtained from B melitensis 16M and B suis 2579, respectively, by allelic exchange of rfbU gene encoding mannosyltransferase with a Tn5-disrupted rfbU gene. Mice were vaccinated with VTRM1 or VTRS1 and challenge exposed 8 weeks later. RESULTS: VTRM1 and VTRS1 replicated extensively in the spleen during the first 3 weeks of infection, then decreased rapidly. Antibodies specific for the O polysaccharide were not detected in sera of mice inoculated with either rough strain. Vaccination with VTRM1 or VTRS1 induced protection against virulent strains of B abortus (2308), B melitensis (16M), B suis biovar 1 (750), and B suis biovar 4 (2579). VTRM1 also protected against B ovis (PA) and against 4 field isolates of B abortus from bison or elk. VTRS1 conferred protection against 4 field isolates of B suis biovar 4 from reindeer. Vaccines prepared from live VTRM1 or VTRS1 provided significantly greater protection than that afforded by vaccines of killed cells in QS-21 adjuvant. Vaccination with VTRM1 containing VTRS1 gave minimal protection against the antigenically unrelated Listeria monocytogenes, thus demonstrating the immunologic specificity of protection against Brucella spp. CONCLUSIONS AND CLINICAL RELEVANCE: Results encourage evaluation, in primary host species, of VTRM1 and VTRS1, along with RB51, as alternative vaccines to strain 19, Rev 1, or other smooth phase vaccines.

Antibiotic treatment and post-handling survival of reindeer calves in Alaska.

Free ranging reindeer (Rangifer tarandus tarandus) are driven into corral systems and handled each summer on the Seward Peninsula (Alaska, USA). During June and July of 1995-96 reindeer calves were inspected for injury, handled, weighed, and randomly treated with long-acting oxytetracycline. Calves that returned to subsequent handlings within the same year, received treatment only if they had been treated during their first handling. The effects of prophylactic antibiotic treatment and other factors, including weight, handling related injury, and sex on post-handling survival in reindeer calves were evaluated. Return rates of yearlings in 1996 and 1997 were analyzed using logistic regression. Weight change of calves between handlings was examined using a general linear model. Calf weight and handling injury were the only factors that significantly affected calf survival. No factor had a significant effect on calf weight change between handlings. Apparently, long-acting oxytetracycline was not an effective prophylactic treatment for this capture operation. The benefits of prophylactic antibiotic treatment have not been quantified and further studies of the effects and efficacy of prophylactic treatments are recommended. Ineffective treatments should be avoided because they may add additional stress to the captured animal. Managers should evaluate the potential effectiveness of a prophylactic treatment before indiscriminately applying one. Preventing calf injuries was the most effective method of reducing post-handling mortality in this study and should be given a high priority in the design of capture operations.

The pathogenicity of Brucella suis biovar 4 for bison.

The pathogenicity of Brucella suis biovar 4 for bison (Bison bison) was evaluated by inoculation of 2.1 x 10(7) colony forming units (CFU) in 0.1 ml saline into the conjunctival sac of six pregnant cows. Six pregnant bison were inoculated with 1.27 x 10(7) CFU of Brucella abortus strain 2308 as a positive control. Bison were inoculated on 23 January 1992, and observed until calving or abortion after which they were euthanized, and necropsied. Bacteriological and histological examinations were conducted on lymph nodes, reproductive tract, mammary gland, and internal organs. Terminal serum samples from calves and cows were evaluated by card, rivanol precipitation, standard tube agglutination, cold complement fixation tube, indirect bison conjugated enzyme linked immunosorbent assay (ELISA), competitive ELISA, and particle-concentration fluorescence immunoassay. No clinical signs of brucellosis were seen in bison inoculated with B. suis biovar 4, and infection was found only in lymph nodes of two animals. There was no evidence of metastasis of this organism to the mammary gland or the reproductive tract. There were no detectable levels of antibodies to Brucella spp. in terminal blood samples taken from B. suis biovar 4-challenged bison. Brucella abortus was isolated from several tissues in all control bison. All B. abortus-challenged animals developed uterine infection and five developed mammary gland infection. Reproductive disease resulted in abortions in five B. abortus-challenged bison and neonatal death in the remaining calf. Brucella suis biovar 4 does not appear to be pathogenic for bison.