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Objective—To develop an aerosol exposure method for induction of brucellosis in rhesus macaques ( Macaca mulatta ).

Animals—10 adult rhesus macaques.

Procedure—8 rhesus macaques were challenge exposed with 102 to 105 colony-forming units of Brucella melitensis 16M by use of an aerosol-exposure technique, and 2 served as control animals. All macaques were euthanatized 63 days after challenge exposure. Gross and microscopic lesions, bacterial burden in target organs, and histologic changes in tissues were evaluated.

Results—Grossly, spleen weights were increased in exposed macaques, compared with spleen weights in control macaques. Histologically, there was inflammation in the liver, kidneys, spleen, testes, and epididymides in exposed macaques. The spleen and lymph nodes had increased numbers of lymphohistiocytic cells. Morphometrically, the spleen also had an increased ratio of white pulp to red pulp. Areas of hepatitis and amount of splenic white pulp increased with increasing exposure dose.

Conclusions and Clinical Relevance—Pathologic findings in rhesus macaques after aerosol exposure to B melitensis are similar to those observed in humans with brucellosis.

Impact for Human Medicine—These results may aid in the development of a vaccine against brucellosis that can be used in humans. ( Am J Vet Res 2004;65: 644–652)

Full access
in American Journal of Veterinary Research


Objective—To characterize effects of intranasal inoculation of virulent Brucella melitensis strain 16M in mice.

Animals—Female Balb/c mice, 6 to 8 weeks old.

Procedure—Studies were designed to elucidate gross morphologic lesions, bacterial burden in target organs, and histologic changes in tissues following experimental intranasal inoculation of mice with B melitensis 16M, which could be used to characterize a model for testing vaccine efficacy.

Results—Measurable splenomegaly was evident at 3 and 7 weeks after inoculation. A demonstrable increase in splenic colony-forming units (CFU) from infected mice increased over time with increasing dose when comparing inocula of 103, 104, and 105 CFU. Recovery of brucellae from the lungs was possible early in infection with 101, 103, and 105 CFU, but only the group inoculated with 105 CFU consistently yielded quantifiable bacteria. At a dose of 101 CFU, few organisms were located in the spleen. Bacteria were recovered up to 140 days after inoculation in mice given 103 CFU. At an inoculum of 105 CFU, bacterial counts were highest early in infection. Histologic examination of tissues revealed an increase in white pulp and marginal zone in the spleen and lymphohistiocytic hepatitis.

Conclusion and Clinical Relevance—Changes in the spleen and liver increased with increases in dose and with increased time following intranasal inoculation with B melitensis 16M. Surprisingly, histologic changes were not observed in the lungs of inoculated mice. (Am J Vet Res 2001;62:398–405)

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in American Journal of Veterinary Research


Immunodeficiency was diagnosed as the cause of severe debilitating disease characterized by weight loss, failure to grow, and persistent infections that failed to respond to treatment in 12 young llamas. The llamas were affected after maternal-acquired immunity had decreased; failure of passive transfer of immunoglobulins thus was not suspected. Areas of lymph nodes containing T lymphocytes were hypocellular, suggesting T-cell involvement. High serum immunoglobulin concentrations were not found, despite the existence of infectious disease, suggesting at least secondary B-cell involvement. Results of lymphocyte blastogenesis assays were suggestive of B- and T-cell involvement. It was not possible to determine whether the condition was inherited or acquired.

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in Journal of the American Veterinary Medical Association