Abstract:

Objective To explore the feasibility of establishing a New Zealand rabbit Brucellosis spondylitis animal model based on the method used in constructing a rabbit spinal tuberculosis model.Methods Forty-eight New Zealand rabbits were randomly divided into an experimental group (16), a control group (16) and a blank group (16). In the experimental group, a gelatin sponge containing 0.1 ml of a M5 suspension of an attenuated sheep Brucella vaccine (3×10 ⁸ CFU/ml) was inserted in a hole drilled under the endplate of L6. In the control group, the gelatin sponge was immersed in 0.1 ml of a 0.9% NaCl solution. The blank group did not receive any treatment. Results Eight weeks after surgery, the survival rate of the rabbits in the experimental group was 75.0% (12/16), that in the control group was 87.5% (14/16), and that in the blank group was 100.0% (16/16). Four weeks after surgery, X-ray and CT 3D reconstruction results showed the intervertebral space in 5 rabbits from the experimental group became narrowed, and MRI examination showed that 7 rabbits had paravertebral soft tissue abscess formation. There was no paravertebral soft tissue abscess formation in the control group and the intervertebral disc showed no change. Eight weeks after surgery, X-ray and CT 3D reconstruction showed narrowing of the intervertebral space in 8 rabbits, and MRI examination showed paravertebral soft tissue abscess formation and disc signal change in 10 rabbits. Paravertebral soft tissue abscess formation and disc signal change was not observed in the control group. Histopathology analysis at 8 weeks after surgery showed pathological changes in the paravertebral soft tissue in the experimental group and the infiltration of inflammatory cells (predominantly lymphocytes). No changes in cell proliferation and inflammatory cell infiltration were found in the control group nor the blank group.Conclusion A new animal model of Brucellosis spondylitis can be established by drilling a hole in the upper endplate of the lumbar vertebrae, applying a gelatin sponge injected with an M5 suspension of the attenuated sheep Brucella vaccine and sealing the whole with paraffin wax.

Key words: Brucellosis, Spondylitis, Disease models, animal, Rabbits, Methods