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Abstract

Objective

To determine the ability of Brucella abortus strain RB51 to induce placentitis and abortion in bison after SC vaccination.

Animals

10 pregnant bison cows, 3 to 10 years old and at 3 to 8 months' gestation.

Procedure

Pregnant bison cows on a Montana ranch were vaccinated SC with 109 colony-forming units of B abortus strain RB51. Two cows, identified prior to the study, were euthanatized and examined 5 weeks after vaccination to obtain optimal histologic samples of placenta. Other cows were euthanatized and examined after abortion. After euthanasia, tissue specimens were collected for histologic and immunohistochemical evaluation. Tissue and fluid specimens for bacteriologic culture were also collected during necropsy.

Results

Of 8 cows, 2 aborted at 68 and 107 days after vaccination. Aborting cows had endometritis. Strain RB51 was isolated from reproductive tissues and supramammary lymph nodes. Fetal lesions were not seen; however, fetal bronchial lymph nodes and amniotic fluid contained strain RB51. Cows examined 5 weeks after vaccination had placentitis and endometritis, with numerous bacteria within trophoblastic epithelial cells that were immunoreactive for strain RB51 antigen. Strain RB51 was isolated from placentomes and numerous lymph nodes. Fetal lesions were not seen 5 weeks after vaccination; however, strain RB51 was isolated from numerous lymph nodes and lung, allantoic fluid, and rectal swab specimens.

Conclusions

The vaccine candidate B abortus RB51 has tropism for the bison placenta, and can cause placentitis, which induces abortion in pregnant bison. The vaccine dose used was similar to that being tested in cattle, but may not be appropriate for pregnant bison. (Am J Vet Res 1996;57:1604–1607)

Free access
in American Journal of Veterinary Research

Abstract

Objective

To establish that female calves vaccinated with Brucella abortus strain RB51 at 3, 5, and 7 months of age are protected against infection and abortion when challenged exposed during their first pregnancy.

Animals

Polled Hereford heifer calves obtained from a brucellosis-free herd.

Procedure

Calves were inoculated SC at 3, 5, or 7 months of age with strain RB51 (n = 26), strain 19 (n = 16), or sterile saline solution (n = 15). Calves were bred at 16 to 17 months of age and challenged exposed during the first pregnancy with virulent B abortus strain 2308.

Results

After vaccination, none of the heifers given strain RB51 developed serum antibodies that reacted in the standard tube agglutination test, but reacted in a dotblot assay, using RB51 antigen. B abortus was cultured from biopsy specimens of superficial cervical lymph nodes in the RB51 and S19 vaccinates at 10 weeks, but not at 12 weeks after vaccination. All 4 heifers that had been vaccinated with RB51 at 3 months of age were protected against infection and abortion when challenged exposed. Vaccination at 5 and 7 months of age gave equivalent protection. Heifers given strain 19 were 95% protected and controls (given saline solution) had a high incidence of infection and abortion.

Conclusions

Strain RB51 is protective at doses comparable to those of strain 19 in calves 3 to 10 months of age.

Clinical Relevance

Immunogenicity and failure to induce antibodies that interfere with the serologic diagnosis of field infections of B abortus make strain RB51 an effective vaccine. (Am J Vet Res 1996;57:1153—1156)

Free access
in American Journal of Veterinary Research

Abstract

OBJECTIVE To develop a noninvasive biomarker-based detection system specific for Mycobacterium bovis for monitoring infection in wild animals.

SAMPLE Serum samples from 8 experimentally infected yearling white-tailed deer (Odocoileus virginianus) and 3 age-matched control deer and from 393 Minnesota Department of Natural Resources hunter-harvested white-tailed deer in northwest Minnesota.

PROCEDURES 8 yearling deer were inoculated with 2 × 108 CFUs of virulent M bovis strain 1315 (day 0), and sera were obtained on days 0, 19, 48, and 60; sera were obtained from 3 uninoculated control deer on those same days. Sera from these deer and 9 M bovis-positive hunter-harvested deer were tested for 3 Mycobacterium-specific biomarkers (MB1895c, MB2515c, and polyketide synthase 5) by use of an indirect ELISA. That same ELISA was used to test sera obtained from 384 exposed noninfected deer in northwest Minnesota from 2007 through 2010, concurrent with an outbreak of tuberculosis involving cattle and deer in that region.

RESULTS ELISA results revealed that tuberculosis infection could be detected as early as 48 days after inoculation in experimentally infected deer. Results for 384 deer sera revealed that prevalence of tuberculosis decreased over the 4-year period.

CONCLUSIONS AND CLINICAL RELEVANCE Results suggested that the prevalence of tuberculosis in Minnesota deer decreased after 2009 but tuberculosis may have persisted (as subclinical disease) at extremely low levels, as indicated by the presence of low concentrations of circulating biomarkers. Biomarker-based diagnostic tests may offer a specific approach for early identification of M bovis infection.

Full access
in American Journal of Veterinary Research

Abstract

Objective—To determine prevalence of tuberculosis caused by infection with Mycobacterium bovis in cervids on privately owned ranches in northeastern lower Michigan.

Design—Epidemiologic survey.

Animals—Cervids on 96 privately owned ranches.

Procedures—A combination of slaughter and skin tuberculin testing was used to collect data. Infection with M bovis was confirmed by use of standard necropsy and bacteriologic culture techniques.

Results—Cervids with tuberculosis were detected on 1 of the 96 ranches. The apparent prevalence of tuberculosis in cervids from the 96 ranches was 1.1 cases/100 cervids (21 cases/1,867 cervids tested). For the ranch with infected cervids, prevalence of infection with M bovis was 12.1 cases/100 cervids (21 cases/174 cervids tested). No obvious gross lesions were seen in 8 of 21 white-tailed deer and 1 coyote with culture-confirmed M bovis infection.

Conclusions and Clinical Relevance—The lack of visible lesions in a substantial proportion of infected animals should be taken into consideration in studies involving detection and prevalence of tuberculosis. (J Am Vet Med Assoc 2002;220:656–659)

Full access
in Journal of the American Veterinary Medical Association

Abstract

Objective—To determine the distribution of lesions and extent of tissues infected with Mycobacterium bovis in a captive population of white-tailed deer.

Design—Cross-sectional study.

Animals—116 captive white-tailed deer.

Procedure—Deer were euthanatized, and postmortem examinations were performed. Tissues with gross lesions suggestive of tuberculosis were collected for microscopic analysis and bacteriologic culture. Tissues from the head, thorax, and abdomen of deer with no gross lesions were pooled for bacteriologic culture. Tonsillar, nasal, oral, and rectal swab specimens, fecal samples, and samples of hay and pelleted feed, soil around feeding sites, and water from 2 natural ponds were collected for bacteriologic culture.

ResultsMycobacterium bovis was isolated from 14 of 116 (12%) deer; however, only 9 of 14 had lesions consistent with tuberculosis. Most commonly affected tissues included the medial retropharyngeal lymph node and lung. Five of 14 tuberculous deer had no gross lesions; however, M bovis was isolated from pooled tissue specimens from the heads of each of these deer. Bacteriologic culture of tonsillar swab specimens from 2 of the infected deer yielded M bovis. Mean (± SEM) age of tuberculous deer was 2.5 ± 0.3 years (range, 0.5 to 6 years). Mycobacterium bovis was not isolated from feed, soil, water, or fecal samples.

Conclusions and Clinical Relevance—Examination of hunter-killed white-tailed deer for tuberculosis commonly includes only the lymph nodes of the head. Results of such examinations may underestimate disease prevalence by as much as 57%. Such discrepancy should be considered when estimating disease prevalence. (J Am Vet Med Assoc 2000;216:1921–1924)

Full access
in Journal of the American Veterinary Medical Association